WO2015036727A1

WO2015036727A1 - Survey device and method of surveying

Info

Publication number: WO2015036727A1
Application number: PCT/GB2014/000363
Authority: WO
Inventors: David Simmonds
Original assignee: ADVANTICA INTELLECTUAL PROPERTY Ltd
Current assignee: ADVANTICA INTELLECTUAL PROPERTY Ltd
Priority date: 2013-09-12
Filing date: 2014-09-12
Publication date: 2015-03-19
Anticipated expiration: 2016-03-12
Also published as: GB2518191B; GB2518191A; GB201316280D0

Abstract

A survey device, for surveying an installation to which a cathodic protection voltage is applied, the cathodic protection voltage exhibiting at least a first transition event (e.g. switch on/off), comprising at least one input adapted to receive an input signal corresponding to electrical activity (e.g. voltage or current detected) arising at the installation from the cathodic protection voltage. A processor is coupled to the inputs and is operable to (i) receive one or more detection signals (e.g. sampled/digitised), at least one detection signal corresponding to or being based upon the input signal; (ii) determine, from the at least one detection signal, the occurrence of the first transition event; and (iii) take a measurement of the electrical activity a predetermined time delay (e.g. configurable by a User on a PDA coupled to the survey device) after the first transition event. The survey device may operate in automatic mode, in which transition events at or near an expected time are monitored, and in the event of discrepancies from the expected, timings such as currently estimated modulation period are adjusted. Also disclosed is a method for surveying an installation to which a cathodic protection voltage is applied.

Description

Survey device and method of surveying

The present invention relates to electronic surveying of equipment installations, and more particularly relates to a survey device and method of surveying cathode-protected installations.

It is well known to apply a cathodic (negative) voltage to an underground cable or pipe (hereinafter "pipe") to reduce corrosion of that pipe. If the pipe is at a positive voltage relative to ground, electrolytic effects can occur which damage the pipe. It should be noted that such cathodic protection voltage may be applied even when the pipe is coated to insulate it from the ground, because it is common for that insulation to develop holes or other faults which could result in localised damage.

Steel pipelines are normally protected from corrosion using Cathodic Protection (CP). It is very common for an electrical current to be fed (impressed) into the pipeline steel work to ensure that the protection levels are sufficient to prevent corrosion. On a regular basis, tests need to be performed to ensure that the CP system is providing adequate protection. Similar systems are sometimes protected using a sacrificial anode.

When performing either a Test Post Survey or Close Interval Protection Survey (CIPS) on a pipeline that is protected using an impressed cathodic protection system, it is normal practice for the impressed current to be switched ON and OFF at regular intervals. During a Test Post survey, the ON and the OFF potentials are recorded. During a CIPS survey, the ON and the OFF potentials are recorded as the surveyor walks along the pipeline using a pair of copper/copper sulphate (reference) cells fitted to the bottom of walking poles. Typically, the switching duty cycles are between 1 and 3 seconds.

Due to the capacitive and inductance features of the pipeline, the switching edges are often not sharp and can also contain spikes. Therefore it is an industry standard that the ON and OFF potentials should be recorded at a specified delay after the switching has occurred. This requires accurate determination the switching times. The equipment that is on the market at the moment uses GPS timing; the switching occurs based on the time pulse generated by a GPS receiver.

US2001047247A1 discloses Cathodic protection voltages used to resist the damage to pipes or cables from electrolytic effects, in which the cathodic voltage on the pipes is modulated. This modulation is applied using an interrupter, and the timing of the modulation pattern is synchronised using an external time signal such as GPS.

A problem arises when seeking to survey a pipe installation using a given interrupter, where the lag between the GPS signal and the switching of the interrupter is unknown. In one scenario, due to this incompatibility, erroneous readings are taken. In another scenario, surveyors are forced to use interrupters and measuring equipment supplied by the same company. Thus, when a survey or test is being performed whilst the cathodic protection current is being interrupted, a problem to be solved is to detect the ON and/or OFF edges and then to record the ON and/or OFF potentials at the specified delay after the edge(s).

There is a need for a survey device that overcomes the aforementioned problems and provides improved usability.

The present invention provides a survey device, for surveying an installation to which a cathodic protection voltage is applied, the cathodic protection voltage exhibiting at least a first transition event, comprising: at least one input adapted to receive an input signal corresponding to electrical activity arising at the installation from the cathodic protection voltage; a processor, coupled to the inputs; wherein the processor is operable to receive one or more detection signals, at least one detection signal corresponding to or being based upon the input signal; determine, from the at least one detection signal, the occurrence of the first transition event; and take a measurement of the electrical activity a predetermined time delay after the first transition event.

Preferably, the cathodic protection voltage has a modulated waveform and the cathodic protection voltage has a second transition event. Preferably, the modulated waveform has a periodicity T.

Preferably, the first transition event is voltage switch-ON and the second transition event is voltage switch-OFF, or vice versa.

In one embodiment, the device is operable in automatic mode; wherein the processor is operable to determine whether the first transition event and the second transition event have been detected for a first predetermined number of cycles; and if not, continuously detect instances of the first transition event and the second transition event until this is satisfied. Preferably, if the first transition event and the second transition event have been detected for a first predetermined number of cycles, the processor is operable to generate a current estimate of T; and enter synchronised mode of operation. Preferably, in said synchronised mode the processor is operable to detect further instances of the first transition event and/or the second transition event; and determine whether the first transition event and/or the second transition event is at the expected time based on the current estimate of T or at that time within a predetermined tolerance.

Preferably, if is determined that the first transition event and/or the second transition event is at the expected time, the processor is operable to generate a new current estimate of T based on the detected further instances of the first transition event and/or the second transition event, in the event of difference from the current estimate of T. Preferably, the processor is operable to take a measurement of the electrical activity after the generation of the new current estimate of T. Preferably, if the determination is negative, the processor is operable, to determine whether this condition persists for a timeout period, and if so, to continuously detect instances of the first transition event and the second transition event until the first transition event and the second transition event have been detected for a first predetermined number of cycles.

In one embodiment, if the determination is negative, the processor is operable to determine whether this condition persists for a timeout period, and if not, to take a measurement of the electrical activity.

Preferably, the first predetermined number of cycles is 2.

Preferably, the predetermined tolerance is up to 5% of T, more preferably up to 2% of T, and more preferably up to 1 % of T.

In a further embodiment, the device is operable in manual mode; wherein the processor is operable to receive a specified value for period T. Preferably, the specified value for period T is received from a user via a user input device. Preferably, the processor is operable to determine whether the first transition event and the second transition event have been detected at a rate corresponding to the specified value for period T for a second predetermined number of cycles; and if not, to issue an error notification. Preferably, if the first transition event and the second transition event have been detected for a first predetermined number of cycles, the processor is operable to enter synchronised mode of operation; and take a measurement of the electrical activity at an instant dependent upon said specified value for period T.

Preferably, the second predetermined number of cycles is 2 to 5, and more preferably 3.

The electrical activity may comprise potential difference, current flow or a combination thereof.

Preferably, the inputs are adapted to be connected to probes to be used in a survey; and the input signal corresponds to electrical activity detected using the probes. In some embodiments the probes comprise reference cells. In others, they may comprise metal or metallic conductors.

The installation comprises a pipeline, or any installation subject to cathodic protection. Preferably, the pipeline comprises a subsurface pipeline.

Preferably, the first transition event and/or the second transition event are detected when a change in detected electrical activity greater than a predetermined threshold is determined by the processor.

The device preferably further includes an analog-to-digital converter (ADC). Preferably, the input signal is an analog signal and the detection signal is a sampled digital signal based on the analog signal. Preferably, the first transition event and/or the second transition event are detected when the difference greater than a predetermined threshold between successive, or two- or more apart, sampled digital values is determined by the processor.

Preferably, the predetermined time delay is 200-600ms, and more preferably about 400ms.

The present invention further provides a method of or surveying an installation to which a cathodic protection voltage is applied, the cathodic protection voltage exhibiting at least a first transition event, comprising: providing at least one input adapted to receive an input signal corresponding to electrical activity arising at the installation from the cathodic protection voltage; providing a processor, coupled to the inputs; operating the processor to receive one or more detection signals, at least one detection signal corresponding to or being based upon the input signal; determine, from the at least one detection signal, the occurrence of the first transition event; and take a measurement of the electrical activity a predetermined time delay after the first transition event.

The first transition event may be voltage switch-ON and the second transition event is voltage switch- OFF, or vice versa.

Preferably, the method is operable in automatic mode; the method comprising determining whether the first transition event and the second transition event have been detected for a first predetermined number of cycles; and if not, continuously detecting instances of the first transition event and the second transition event until this is satisfied. Preferably, if the first transition event and the second transition event have been detected for a first predetermined number of cycles, the method comprises generating a current estimate of T; and entering synchronised mode of operation. Preferably, in said synchronised mode, the method comprises detecting further instances of the first transition event and/or the second transition event; and determining whether the first transition event and/or the second transition event is at the expected time based on the current estimate of T or at that time within a predetermined tolerance. Preferably, if the determination is positive, the method comprises generating a new current estimate of T based on the detected further instances of the first transition event and/or the second transition event, in the event of difference from the current estimate of T. Preferably, the method comprises taking a measurement of the electrical activity after the generation of the new current estimate of T.

Preferably, if the determination is negative, the method comprises determining whether this condition persists for a timeout period, and if so, to continuously detect instances of the first transition event and the second transition event until the first transition event and the second transition event have been detected for a first predetermined number of cycles. Preferably, if the determination is negative, the method comprises determining whether this condition persists for a timeout period, and if not, to take a measurement of the electrical activity.

Preferably, the first predetermined number of cycles is 2.

Alternatively, the method is operable in manual mode and comprises receiving a specified value for period T. Preferably, the specified value for period T is received from a user via a user input device. Preferably, the method comprises determining whether the first transition event and the second transition event have been detected at a rate corresponding to the specified value for period T for a second predetermined number of cycles; and if not, issuing an error notification. Preferably, if the first transition event and the second transition event have been detected for a first predetermined number of cycles, the method comprises entering synchronised mode of operation; and taking a measurement of the electrical activity at an instant dependent upon said specified value for period T. Preferably, the second predetermined number of cycles is 2 to 5, and more preferably 3.

Preferably, the electrical activity comprises potential difference, current flow or a combination thereof.

Preferably, the inputs are adapted to be connected to probes to be used in a survey; and the input signal corresponds to electrical activity detected using the probes.

Preferably, the installation comprises a pipeline. Preferably, the pipeline comprises a subsurface pipeline.

The method preferably further includes providing an analog-to-digital converter (ADC); wherein the input signal is an analog signal and the detection signal is a sampled digital signal based on the analog signal. Preferably, the first transition event and/or the second transition event are detected when the difference greater than a predetermined threshold between successive, or two- or more apart sampled digital values is determined by the processor.

According to another aspect of the invention there is provided a survey device, for surveying an installation to which a cathodic protection voltage is applied, comprising: a plurality of inputs, each input corresponding to a socket on the survey device adapted to receive a connection to a probe; wherein each input is adapted to receive an input signal corresponding to electrical activity arising at the installation from the cathodic protection voltage when a probe is connected in the corresponding socket; the device further comprising a processor, coupled to the inputs; wherein the processor is operable to receive one or more detection signals, at least one detection signal corresponding to or being based upon an input signal; determine a test mode to use; and take a measurement of the electrical activity based upon the test mode determined.

Preferably, the processor is operable to determine a test mode to use dependent upon a selection received from a user. Preferably, the selection is received via communication link from a PDA operable by a user. Preferably, the communication link comprises a wireless communication link.

In another embodiment, the processor is alternatively or additionally operable to determine a test mode to use dependent upon at which inputs input signal(s) is(are) received. The survey device preferably further includes circuitry for generating, for each input, a signal indicating whether an input signal is received at that input. Preferably, the circuitry comprises one or more of (i) an amplification and thresholding circuit, (ii) a thresholding circuit, (iii) a buffer, and (iv) a current-to-voltage conversion and thresholding circuit.

In another embodiment, the processor is alternatively or additionally operable to determine a test mode to use dependent upon which sockets are detected to have probes connected. The survey device preferably further includes circuitry for generating, for each input, a signal indicating whether a connector is present in the socket corresponding to that input. Preferably, the circuitry comprises an optical transmitter and optical receiver, the transmitter and receiver being diametrically opposed on the sides of a socket.

Preferably, one of the inputs comprises a common input used in a plurality of test modes. Preferably, one of the inputs comprises a first channel input for voltage measurement in a plurality of test modes. Preferably, one of the inputs comprises a second channel input for voltage measurement in a plurality of test modes. Preferably, one of the inputs comprises a third channel input for current measurement in a plurality of test modes. Preferably, one of the in outs comprises a fourth channel input for analog signal measurement from an aerial in a Pearson test mode.

The survey device may be operable in a test post test mode; wherein the device is adapted to have the common input connected by a short cable to a test post and the first channel input connected by a short cable to a reference cell in the vicinity of the test post.

The survey device may be operable in a single wire CIPS test mode; wherein the device is adapted to have the common input connected by a long cable to a test post and the first channel input connected by a short cable to a reference cell in the vicinity of the survey device. The survey device may be operable in a dual wire CIPS test mode; wherein the device is adapted to have the common input connected by a long cable to a test post, the first channel input connected by a short cable to a reference cell in the vicinity of the survey device, and the second channel input connected by a long cable to a reference cell in the vicinity of the test post.

The survey device may be operable in a test post current measurement test mode; wherein the device is adapted to have the common input connected by a short cable to a test post and the third channel input connected by a short cable to a ground spike in the vicinity of the test post.

The survey device may be operable in a Pearson test mode; wherein the device is adapted to have the common input connected by an aerial cable to a grounded first user remote from the survey device and the Pearson channel input connected by a short cable to a grounded second user in the vicinity of the survey device.

According to another aspect of the invention there is provided a method for surveying an installation to which a cathodic protection voltage is applied using a survey device, the survey device comprising: a plurality of inputs, each input corresponding to a socket on the survey device adapted to receive a connection to a probe; wherein each input is adapted to receive an input signal corresponding to electrical activity arising at the installation from the cathodic protection voltage when a probe is connected in the corresponding socket; the device further comprising a processor, coupled to the inputs; wherein the method comprises operating the processor to receive one or more detection signals, at least one detection signal corresponding to or being based upon an input signal; determine a test mode to use; and take a measurement of the electrical activity based upon the test mode determined.

Preferably, operating the processor to determine a test mode to use comprises operating the processor to determine the test mode dependent upon a selection received from a user. Preferably, the selection is received via communication link from a PDA operable by a user. Preferably, the communication link comprises a wireless communication link.

In another embodiment, operating the processor to determine a test mode to use alternatively or additionally comprises operating the processor to determine the test mode dependent upon at which inputs input signal(s) is(are) received. Preferably, operating the processor to determine a test mode to use comprises using circuitry for generating, for each input, a signal indicating whether an input signal is received at that input. Preferably, the circuitry comprises one or more of (i) an amplification and thresholding circuit, (ii) a thresholding circuit, (iii) a buffer, and (iv) a current-to-voltage conversion and thresholding circuit.

In another embodiment, operating the processor to determine a test mode to use alternatively or additionally comprises operating the processor to determine a test mode to use dependent upon which sockets are detected to have probes connected. Preferably, operating the processor to determine a test mode to use comprises using circuitry for generating, for each input, a signal indicating whether a connector is present in the socket corresponding to that input. Preferably, the circuitry comprises an optical transmitter and optical receiver, the transmitter and receiver being diametrically opposed on the sides of a socket.

Preferably, one of the inputs comprises a common input used in a plurality of test modes. Preferably, one of the inputs comprises a first channel input for voltage measurement in a plurality of test modes. Preferably, one of the inputs comprises a second channel input for voltage measurement in a plurality of test modes. Preferably, one of the inputs comprises a third channel input for current measurement in a plurality of test modes. Preferably, one of the inputs comprises a fourth channel input for analog signal measurement from an aerial in a Pearson test mode.

The method may be operable in a test post test mode; when the device is adapted to have the common input connected by a short cable to a test post and the first channel input connected by a short cable to a reference cell in the vicinity of the test post.

The method may be operable in a single wire CIPS test mode; when the device is adapted to have the common input connected by a long cable to a test post and the first channel input connected by a short cable to a reference cell in the vicinity of the survey device.

The method may be operable in a dual wire CIPS test mode; when the device is adapted to have the common input connected by a long cable to a test post, the first channel input connected by a short cable to a reference cell in the vicinity of the survey device, and the second channel input connected by a long cable to a reference cell in the vicinity of the test post.

The method may be operable in a test post current measurement test mode; when the device is adapted to have the common input connected by a short cable to a test post and the third channel input connected by a short cable to a ground spike in the vicinity of the test post.

The method may be operable in a Pearson test mode; when the device is adapted to have the common input connected by an aerial cable to a grounded first user remote from the survey device and the Pearson channel input connected by a short cable to a grounded second user in the vicinity of the survey device.

According to another aspect of the invention there is provided a survey device, for surveying an installation to which a cathodic protection voltage is applied, comprising: at least one input adapted to receive an input signal corresponding to electrical activity arising at the installation from the cathodic protection voltage; a processor, coupled to the inputs; wherein the processor is operable to receive one or more detection signals, at least one detection signal corresponding to or being based upon the input signal; and take a measurement of the electrical activity.

The processor may be operable to (i) receive via wired or wireless communication link with a PDA a user input at the PDA designating a sampling rate for take a measurement of the electrical activity, and/or (ii) transmit one or more measurements of the electrical activity via wired or wireless communication link to a PDA.

According to another aspect of the invention there is provided a method of or surveying an installation to which a cathodic protection voltage is applied, comprising: providing at least one input adapted to receive an input signal corresponding to electrical activity arising at the installation from the cathodic protection voltage; providing a processor, coupled to the inputs; operating the processor to receive one or more detection signals, at least one detection signal corresponding to or being based upon the input signal; and take a measurement of the electrical activity a predetermined time delay after the first transition event.

The method may comprise operating the processor to (i) receive via wired or wireless communication link with a PDA a user input at the PDA designating a sampling rate for take a measurement of the electrical activity, and/or (ii) transmit one or more measurements of the electrical activity via wired or wireless communication link to a PDA.

For each of the above aspects, particular embodimeits may include the following. The electrical activity may comprise sensed electrical activity.

The electrical activity may comprise electrical activity sensed by a probe relative to ground or to a reference electrode.

The processor may be operable to take a measurement of the electrical activity a predetermined time delay after the determined occurrence of the first transition event.

The one or more detection signals may include a first detection signal, and wherein the processor is operable to determine, from the first detection signal, the occurrence of the first transition event.

The cathodic protection voltage is applied by a protection system, the protection system including an interrupter for causing the first transition event and/or second first transition event; wherein the survey device is not coupled, in use, to the interrupter and/or protection system.

The survey device may comprise a portable survey device. The may be interoperable, in use, with a PDA.

The survey device may further comprise a communications interface providing, in use, a wired or wireless communication link.

The survey device may be operable to communicate, in use, with a PDA via the communication link.

The may be operable to receive a user selection from the PDA via the communication link, the user selection designating one of a plurality of test modes and being received from the user at the PDA, each test mode corresponding to one of the plurality of inputs.

The processor may be operable to determine a test mode to use based on the received user selection.

The may be operable to take a measurement of the electrical activity based only upon the test mode determined.

Each test mode may correspond to a single type of measurement.

The plurality of inputs, communications interface and processor may be integrated into a single portable housing.

The survey device may further comprise at least one communications interface adapted for providing a wired or shortrange wireless communication link with a PDA in situ.

The processor may be operable to take a measurement of the electrical activity based on the detection signals and the received sampling rate.

According to another aspect of the invention there is provided a recordable, rewritable or storable medium having recorded or stored thereon data defining or transformable into instructions for execution by processing circuitry and corresponding to at least the steps of any of claims 33 to 64, 93 to 120 or 133 to 144.

According to another aspect of the invention there is provided a server computer incorporating a communications device and a memory device and being adapted for transmission on demand or otherwise of data defining or transformable into instructions for execution by processing circuitry and corresponding to at least the steps of any of claims 33 to 64, 93 to 120 or 133 to 144.

Current approaches to CP use GPS timing. The interrupter will switch its output at a time relative to a time pulse generated by a GPS receiver. The measuring/survey device will also take its measurement relative to this GPS pulse. Typically, however, the delay between the GPS pulse and the switch / reading taking place (set by equipment (interrupter) manufacturer) may be unavailable. Thus, surveyors may not have available measurement devices completely interoperable, in terms of timing and measurement, with the interrupter; and if timing approximations or estimations are used, this may give erroneous results, if at all.

The present invention makes it possible for one survey device to record accurate ON and OFF voltages from any interrupter supplier.

A further advantage of the invention is that GPS signal detection may be omitted from the survey device, reducing its complexity and cost.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 (PRIOR ART) is a schematic view of a pipeline installation in which cathodic protection is used in a known manner;

Figure 2 shows the detected voltage waveform arising at the pipeline installation of Fig. 1 , in the case of a periodic CP voltage applied;

Figure 3 shows (a) a view of the front of the housing of the survey device in accordance with a preferred embodiment, (b) schematically the internal electronics of the survey device, (c) and (d) the means of detecting connectors in the sockets of the survey device, and (e) circuitry for detecting signals at the inputs of the survey device;

Figure 4 illustrates the operation of the survey device of Fig. 3, in an automatic mode;

Figure 5 shows the detection of transition events within a tolerance of expected times, in the process of Fig.4;

Figure 6 illustrates the operation of the survey device of Fig. 3, in a manual mode;

Figure 7 shows the deployment of the survey device of Fig. 3 in use, namely (a) for voltage measurement at the Test Post, (b) for a single wire CI PS survey, (c) for dual wire CI PS survey, (d) for a current measurement at the Test Post, and (e) for a Pearson survey; and

Figure 8 illustrates the waveform for the CP voltage applied, in three scenarios in which SSD 30 may be used.

In the description and drawings, like numerals are used to designate like elements. Unless indicated otherwise, any individual design features, components or steps may be used in combination with any other design features, components or disclosed herein.

As used herein, "electrical activity" is taken to mean any detectable voltage, current or voltage- or current-generated field of uniform, varying, modulated, periodic, regular or irregular waveform or magnitude. Typically as used herein, "electrical activity" will refer to voltage (potential difference) or current.

As used herein, "switch-ON" means a voltage transition from a low voltage (LOW) to a high voltage (HIGH), or a corresponding current quantity transition, and "switch-OFF" means a voltage transition from a high voltage (HIGH) to a low voltage (LOW), or a corresponding current quantity transition. Unless indicated otherwise "OFF voltage" means a low voltage (LOW) and "ON voltage" means a high voltage (HIGH), although the converse may be implemented in practice.

As used herein, "long" or "long cable" refers for example a cable that is one or two orders of magnitude longer that another cable used in testing, and may involve a cable with a length in the tens or hundreds of meters, or possibly up to a few kilometres. Also "short" or "short cable" refers for example a cable that is one or two orders of magnitude shorter that another cable used in testing, and may involve a cable with a length in the 1-10 meters, and more particularly 1-5 meters, and more particularly 1-3 meters.

While reference is made herein to measurement of subsurface metal (steel) pipeline protection effects, it will be appreciated that the techniques are applicable to any scenario in which an installation is subject to cathodic voltage protection.

Figure 1 (PRIOR ART) is a schematic view of a pipeline installation in which cathodic protection is used in a known manner. Here, a gas pipe 10 is to be protected against corrosion by having a cathodic (negative) protection voltage applied thereto. That voltage is derived from a power supply 11 , and rectified by a rectifier 12 so as to generate a cathodic voltage on a line 13 relative to ground. During testing of the CP on the gas pipe 10, the line 13 is connected via an interrupter 14 to the pipe 10. The interrupter 14 comprises a switch 15 connected between the line 13 and the pipe 10, the switching of which is controlled by a control unit 16. The control unit 16 is powered from a power supply 17 within the interrupter 14, connected between the control unit 16 and ground.

Figure 2 shows the detected voltage waveform arising at the pipeline installation of Fig. 1 , in the case of a periodic cathodic protection voltage applied. The waveform in this case is periodic, with period T, but may have a pulse or any other suitable waveform. A first transition event is voltage switch-ON E₁ (occurring at instant h) and a second transition event is voltage switch-OFF E₂ (occurring at instant j).

In this case, the voltage switch-ON is carried out by interrupter 14 (Fig. 1) in response to a GPS pulse (which occur at a rate of one per second, but only one of which is shown) at g. A problem arises as t, is not known; as a consequence, even if GPS pulse at g is received, and given that voltage measurement must be taken at i (a predetermined time delay t₂ after switch on at h), the result is that t3 is also unknown. As it is desired for t₂ to be a conventional 400ms after En in order to take measurement in a standardised way for comparison, an approximation or estimation for t₂ (or ¾) can lead to errors or inaccuracies. This is particularly the case when it is impossible or undesirable to deploy specially designed and interoperating interrupter and survey device pairs.

Figure 3 shows a survey device 30 (also referred to as Smart Survey Device or SSD herein) in accordance with a preferred embodiment, i.e. (a) a view of the front of the housing and (b) schematically showing the internal electronics. The SSD 30 is adapted for use in the scenario of Figs 1 and 2, except where indicated in the following.

As seen in Fig. 3(a), SSD 30 has a front panel 32 including a plurality (here 4) of status LEDs 34. The latter indicate, in this embodiment, power status, GPS signal reception status, status of connection to a further device (as will be described further hereinafter) and measuring status.

The SSD 30 includes 4 inputs in this embodiment - a common input 36 (e.g. colour coded red), a first channel input 38 (e.g. colour coded black) for voltage measurement, rated at ±50V, a second channel input 40 (e.g. colour coded yellow) for voltage measurement, rated at ±50V, and a third channel input 42 (e.g. colour coded blue) for current measurement, rated at 10A. The SSD 30 preferably also includes a fourth input 44 (see Fig. 3(b); not shown in Fig. 3(a)) for Pearson survey measurements.

Turning to Fig. 3(b), for Pearson survey deployment, signals are received at fourth input 44 and passed via Pearson signal conditioning circuit 46 to processor 48. Pearson signal conditioning circuit 46 is of a type known in the art of variable gain analog signal detection. Similarly, processor 48 is of the type well known in the art for small mobile portable devices. Such a processor 48 is suitably a high performance Cortex-M3 based MCU operating at 12 MHz available from ARM; however, it will be appreciated by persons skilled in the art that any suitable processor may be used.

Signals received at common input 36, first channel input 38, second channel input 40, and third channel input 42 are digitised at ADC 49 whereby digital signals corresponding to the original analog measurements are received at processor 48 for funher processing. Optionally, ADC 49 may Include an integral filter, for filtering out unwanted signals such as 50/60Hz interference signals from mains supplies.

Processor 48 controls the activation and deactivation of status LEDs 34. In addition, processor 48 is operable to store captured data and measurements, for a single test/survey or for data logging, to a removable storage device such as an SD card (not shown) via SD card reader(/writer) 50. Processor 48 is also coupled for communication with GPS receiver module 52, which receives GPS signals, including timing pulses for use (optionally) by the system and location data, which optionally can be appended to any measurements and logs taken by the SSD 30.

For receiving user commands and delivering messages, options and data to the user, two communication channels are available - USB connection 54 and Bluetooth (wireless connection) 56; however, it will be appreciated that any suitable wired or wireless techniques or protocols may be used for communication in the field and elsewhere.

Referring briefly to Fig. 7(a), this shows the deployment of the SSD 30 in use, namely for voltage measurement at the Test Post 70. Using PDA 70, the user can communicate with SSD 30 via Bluetooth or USB connection 71. The PDA 70 may have a keyboard or touch screen via which the user can enter commands, with options being displayed to the user (e.g. via Windows, Icons, Menus and Pointers) in conventional user interface (Ul) fashion. PDA 70 suitably runs Ul software for this purpose. PDA 70, although referred to as a personal digital assistant, may comprise a smartphone, tablet or laptop computer, or the like.

Returning to Fig. 3(b), as is well known in the art of portable processor-based devices, SSD 30 suitably includes solid state memory devices (volatile and non-volatile) (not shown) for permanent and where appropriate temporary storage of programs and data. Programs to be run on processor 48 for operating the SSD 30, detecting transition events, modulation periods, taking readings and handling communications with GPS devices, or with PDA 70 (Fig. 7) are stored in non-volatile memory (not shown) of SSD 30.

The use of such programs will be elaborated in more detail hereinafter, with reference to Fig. 4. In accordance with embodiments of the invention, SSD 30 is operable in either automatic or manual mode, for the convenience of the user.

In use, SSD 30 can measure the pipeline potential (with respect to ground) and automatically detect the switching rate of the interrupter 14 (automatic mode) or it can be sent the switching rate (by the user, via PDA 70) and operate in manual mode.

In both modes, a broken wire or bad connection can be detected by the voltage exceeding a threshold voltage (normally voltages are negative) and SSD 30 will report this as an error, either by sending a message to the controlling PDA 70 and/or logging this in the internal memory (not shown) and for example by illuminating a red LED.

As discussed above in Relation to Fig. 2, the on and off values (e.g. voltages) are recorded after the predetermined/configurable delay after the edges or transition events (E^ E₂; Fig. 2) have been detected.

Returning to Fig. 3, SSD 30 is configured to perform multiple types of test (herein "Test modes"), as described in more detail hereinafter with reference to Figs 7(a) to 7(e). In certain embodiments, SSD 30 includes stored control programs, whereby processor 48 is operable to determine a test mode to use. In a preferred embodiment, processor 48 determines the test mode to use dependent upon a selection received from a user. This is suitably received from user as a command via the Ul on PDA 70, e.g. by selecting from a dropdown menu, from tabs in a window, or using radio buttons.

In another embodiment, processor 48 determines the test mode to use dependent upon which inputs 38-44 (i.e. the physical sockets corresponding to the inputs, for receiving connectors attached to probes; not shown) are detected to have probes physically connected. As seen in Fig. 3(c), this may for example involve using an optical transmitter-receiver pair, comprising optical transmitter 102 driven by driver circuit 104 and optical detector 106 feeding detector circuit 108 (the latter for example comprising or incorporating a thresholding circuit). Transmitter 102 and detector 106 are positioned diametrically opposed at windows 110 in the socket 112, as best seen in Fig. 3(d). The presence of the connector 114 (attached to cables, and thus to probes, spikes etc.; see Fig. 7) may block the optical path between transmitter 102 and detector 106 when in socket 112. Thus, a HIGH signal output by detector 108 may indicate the absence of a connector 114 in the socket 112, and a LOW signal indicates that a connector is present. As indicated, one or more further optical transmitter- receiver pairs 102', 106' and 102", 106" may be provided, for detecting the connector 114 at different points along the socket 112.

Thus, for example, if the common input 36 and either the first channel input 38 or the second channel input 40 is detected to have the connector of a probe inserted, the test mode is determined to be a voltage measurement mode, such as Test Post (Fig. 7(a)), CIPS Single Wire (Fig. 7(b)). If the common input 36 and both the first channel input 38 and the second channel input 40 is detected to have the connector of a probe inserted, the test mode is determined to be a voltage measurement mode, such as CIPS Dual Wire (Fig. 7(c)). Further, if the common input 36 and the third channel input 42 are detected to have the connector of a probe inserted, the test mode is determined to be a current measurement mode, such as Current Measurement at Test Post (Fig. 7(d)). Finally, if the common input 36 and the fourth channel input 44 are detected to have the connector of a probe inserted, the test mode Is determined to be an induced current measurement mode, such as Pearson (Fig. 7(e)).

In another embodiment, processor 48 alternatively or additionally determines the test mode to use dependent upon which inputs 38-44 at which inputs the inputs signal(s) is (are) received, and the test mode determined as in the foregoing paragraph. For example, as seen in Fig. 3(e), SSD 30 may include circuitry (e.g. amplifier and thresholding circuit 120) coupled to the fourth channel input 44 (Pearson). SSD 30 may include circuitry (e.g. thresholding circuits 122, 124) coupled to the first channel input 38 (black) and the second channel input 40 (yellow). SSD 30 may include circuitry (e.g. current conversion and thresholding circuit 126) coupled to the third channel input 44 (blue). SSD 30 may include circuitry (e.g. buffer 128) coupled to the common input 36 (red). A as will be appreciated by persons skilled in the art, circuitry 120-128 may be separate, as indicated, or may be integrated into ADC 49 or processor 48 (Fig. 3(b)). In certain embodiments, processor 48 (Fig. 3(b)) may determine the test mode to use based on a procedure according to the following pseudocode. However, person skilled in the art will appreciate that may variants or alternatives to this may be used. do

do

Check for user input

If test mode entered then set user-entered test mode as current test mode

Else

Check signal level at each input channel

If signals non-zero then

set current test mode dependent upon input channels at which signals appear

If signals are zero then

Check for presence of connector in each input channel socket If connector detected than set current test mode dependent upon input channels at which signals appear

Else set default test mode as current test mode or display error msg while no test mode set

while system is on

Once the test mode is determined, a measurement of the electrical activity is taken based upon the test mode.

Referring briefly to Figure 8, illustrates the waveform for the CP voltage applied, in three scenarios in which SSD 30 may be used. (Note that, while voltage levels in Fig. 8 are indicated as reaching OV, this Is for the purposes of illustration. The OFF voltage never goes to exactly zero as it goes to the potential of steel vs ground; this often between -0.2V and -0.8V.)

In the first scenario the CP voltage is a periodic waveform (Fig. 8(a)) of periodicity T. Here, measurements (samples) are taken by SSD 30 at S, (CP ON) and S₂ (CP OFF).

In another scenario (Fig. 8(b)), the waveform is aperiodic, and again samples are taken both when the CP is OFF (S₃) and when it is ON (S₄).

Finally, SSD may also operate in a simple scenario - testing when the CP is ON for a period (Fig. 8(c)) - and here SSD 30 effectively functions like a multimeter, sampling at S₅, S₆ and S₇. When (e.g. Fig. 8(c)) no interrupter is present, the sampling rate is configured via PDA 70 (Fig. 7). Although SSD 30 is able to operate in multiple scenarios (including those of Figs 8(a)-(c)), the following description is provided, by way of example, largely in relation to the scenario of Fig. 8(a); however, it will be appreciated by skilled persons that the techniques described are applicable to the scenarios of Figs 8(b) and (c), as well as others.

Figure 4 illustrates the operation of the survey device of Fig. 3, in an automatic mode. Automatic Mode: Detection Phase

The SSD 30 starts the process at step s2. As the user (e.g. via PDA 70; not shown) has selected automatic mode, the system enters auto detection phase at s4. The SSD 30 thus looks for the switching edges (E^ E₂; Fig. 2) for whether a voltage change greater than an on/off threshold value (also configurable via PDA 70; not shown) is detected. If the voltage change is less than this threshold (or if the polarity is incorrect), then an error message is raised and for example a red LED illuminated.

If the ON and OFF voltages can be detected, the ON/OFF cycle is monitored to determine (s6) if this is the case for (in this embodiment) two complete cycles and, if found to be stable, will use the time measurements to define the ON and OFF cycle timings (i.e. times of Ei to E₂, E₂ to E, and/or the current value for period T; Fig. 2). It will be appreciated that this determination could be based on stable detection for 3 or more cycles.

The timeout for detecting the on/off switching can be set configured from external commands from PDA 70 (not shown). Detection of stable timings results in Synchronised Phase (s8) being entered.

Automatic Mode: Synchronised Phase

Prior to this phase the ON and OFF edges have already been detected (s4, s6) but minor adjustments are continuously made. Using the determined timings the ON and OFF edges, i.e. the current value of T, SSD 30 tries to detect (s10) switching (E _t E₂; Fig. 2) based on these.

Figure 5 shows the detection of transition events within a tolerance of expected times, in the process of Fig, 4. Referring briefly to Fig. 5, this determination is based on detection of E^ E₂ (Fig. 2) in windows w1 , w2, w3, etc. around the instants when switching/transitions are expected. These windows w1 , w2, w3 correspond to a predetermined (and configurable via PDA 70) tolerance in the value of T, which may be of the order of up to 5%, more preferably up to 2%, and more preferably up to 1 .

Returning to Fig. 4, if E_{1 f} E₂ are detected at the expected instances with the tolerance, then (at step s12) the timings (i.e. times of E-t to E₂ , E₂ to E, and/or the current value for period T; Fig. 2) are adjusted to conform to the latest detection of E E₂. Next, at s14, readings (in this case voltage) are taken, i.e. at an instant t₂ after E, (see Fig. 2). A reading is also taken after E₂.

If, at step s10, Ei, E₂ are not detected at the expected instances with the tolerance, then the system waits (s16) for a timeout (which may be one or a multiple of periods T). If no timeout occurs, readings (in this case voltage) are taken (s18) at the expected time, i.e. at an instant t₂ after Ei (see Fig. 2), based on the current estimated value of T. If after the switching timeout no edges have been detected, an error message is sent to the controlling PDA 70 (not shown) and control will return to the detection phase s4.

Should the signal amplitude temporarily drop below the threshold, and reliable edge detection is not possible, the ON and OFF voltages will be recorded based on the previous timings.

During the CIPS surveys, this methodology allows for the test probes (see Fig. 7; discussed further below) to momentarily lose connection without causing SSD 30 to immediately start looking for the switching edges (E^ E₂). One or two bad potential readings may be recorded, but synchronisation will not be immediately lost.

Manual Mode: Detection Phase

Figure 6 illustrates the operation of the survey device of Fig. 3, in a manual mode. In manual detection mode, the switching cycle time T (Fig. 2) is sent to SSD 30, e.g. by the user entering (step s20) the value via the Ul on PDA 70 (see Fig. 7). Manual detection phase s22 is thus entered. The SDD 30 looks for the ON and OFF edges (E^ E₂; see Fig. 2) for 3 complete cycles and if these can be determined (s24) then (i) synchronised phase s26 is entered, whereby (ii) SSD 30 measures (step s28) the on and off potentials at the specified rates corresponding to T, i.e. readings (in this case voltage) are taken, i.e. at an instant t₂ after E, (see Fig. 2), in the case of the ON potential. This occurs regardless of whether edges (E_{1 t} E₂; see Fig. 2) can be determined.

If the switching edges (E^ E₂; see Fig. 2) cannot be identified then an error message is returned (step s30); alternatively, the system may be configured to keep trying until commanded by the user (via the Ul on PDA 70) to stop.

It should be noted that in alternative embodiments, the interrupter 14 is not GPS linked or synchronised by other means. The SSD 30 according to such embodiments could still operate in such scenarios, provided the period T was constant or substantially constant.

Figure 7 shows the deployment of the survey device of Fig. 3 in use. Referring to Fig. 7(a), this shows voltage measurement at the test post 72. The latter is a post permanently installed at a suitable site and electrically connected by connector 74 to subsurface steel gas pipe 10. (The test post 72 may also contain connections to other assets, for example anodes.) In this survey mode, the test post 72 is connected to the common input 36 of SSD 30 via cable 76, and first channel input 38 is connected to a measuring probe (here, first reference cell 78) via cable 80. First reference cell 78 is sunk a short distance in to the ground 82 at point 84, the latter being close (within a few metres) of test post 72. SSD 30 can thus take potential readings relative to ground in the vicinity of test post 72.

Referring to Fig. 7(b), this shows the configuration for a single wire CIPS survey. This is the same as the mode shown in Fig. 7(a), except as described as follows. In this mode, an elongated trailing wire or cable 76' is used, and first reference cell 78 is sunk a short distance into the ground 82 at point 86, the latter being a significant distance di (which could be, e.g., 20-30 metres; however, in some embodiments this could be up 1-2 miles) of test post 72. SSD 30 can thus take potential readings relative to ground (using first reference cell 78 and via cable 80) at points along a substantial length of pipe 10 extending from test post 72.

Referring to Fig. 7(c), this shows the configuration for a dual wire CIPS survey. This is the same as the mode shown in Fig. 7(b), except as described as follows. A further cable 88 connects a second reference cell 90, in the ground at point 84 close to test post 72, to second channel input 40 of the SSD 30. SSD 30 can thus obtain a reference potential for point 84 via reference cell 90 and further cable 88, so that changes to the voltage at the test post 72 are logged. This enables the user to determine whether a change in voltage at the moving point 86 (taken using first reference cell 78 via cable 80) is due to a coating defect on the pipe 10 or to a voltage change on the CP system. (Alternatively, a second SSD 30 (not shown) can be left at test post 72 to log the test post voltage over time, with the readings logged by the two SSDs 30 being compared later.)

For each of the scenarios in Figs 7(c) and (d), rather than a single reference cell, two reference cells, connected together at the end of a pair of walking poles, may be used.

Referring to Fig. 7(d), this shows the configuration for a current measurement at the Test Post 72. This is the same as the mode shown in Fig. 7(a), except as described as follows. In this survey mode, a ground spike 92 is driven into the ground 82 at point 94, the latter being close (within a few metres) of test post 72. Such a ground spike 92 will typically have an exposed metal area of exactly 1 cm², with the rest being covered with electrically insulating material. The ground spike 92 is connected to third channel input 42 of SSD 30 via cable 96. SSD 30 can thus take readings of current flowing in the ground 82 in the vicinity of test post 72.

Referring to Fig. 7(e), this shows the configuration for a current measurement in a Pearson survey. This is the same as the mode shown in Fig. 7(d), except as described as follows. An AC power source 100 (e.g. a generator operating at 175 or 925 Hz) supplies AC power to test post 72, and thus to pipe 10, via power cable 102. Earth spikes (not shown) on the boots of first user 104 are connected by long cable 96' to the third channel input 42 of SSD 30, while earth spikes (not shown) on the boots of second user 106 are connected by cable 76 to the fourth (Pearson) input 46 of SSD 30. The long cable 96' may, for example, be of the order 20-30 m long, although any suitable length may be used. In this survey mode, the long cable 96' acts as an aerial for receiving an induced signal as induced as a result of the voltage applied to the pipeline by the generator for the duration of the test. In other words, the long cable 96' enables an amplitude modulated signal induced in it to be fed back to third channel input 42 of SSD 30. The amplitude modulated signal may be processed - see Pearson signal conditioning circuit 46 of Fig. 3(b) - in a manner known in the art, so as to detect the position of coating defects in the pipe 10, which will cause artefacts in the induced (amplitude modulated) signal.

While embodiments have been described by reference to embodiments of survey devices having various components in their respective implementations, it will be appreciated that other embodiments make use of other combinations and permutations of these and other components.

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment' or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments.

Similarly it should be appreciated that in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment of this invention.

Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

Furthermore, some of the embodiments are described herein as a method or combination of elements of a method that can be implemented by a processor of a computer system or by other means of carrying out the function. Thus, a processor with the necessary instructions for carrying out such a method or element of a method forms a means for carrying out the method or element of a method. Furthermore, an element described herein of an apparatus embodiment is an example of a means for carrying out the function performed by the element for the purpose of carrying out the invention.

In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

As used herein, unless otherwise specified the use of the ordinal adjectives "first", "second", "third", etc., to describe a common object, merely indicate that different instances of like objects are being referred to, and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner.

All publications, patents, and patent applications cited herein are hereby incorporated by reference.

Any discussion of prior art in this specification should in no way be considered an admission that such prior art is widely known, is publicly known, or forms part of the general knowledge in the field.

In the claims below and the description herein, any one of the terms comprising, comprised of or which comprises is an open term that means including at least the elements/Features that follow, but not excluding others. Thus, the term comprising, when used in the claims, should not be interpreted as being limitative to the means or elements or steps listed thereafter. For example, the scope of the expression a device comprising A and B should not be limited to devices consisting only of elements A and B. Any one of the terms including or which includes or that includes as used herein is also an open term that also means including at least the elements/features that follow the term, but not excluding others. Thus, including is synonymous with and means comprising.

Similarly, it is to be noticed that the term coupled, when used in the claims, should not be interpreted as being limitative to direct connections only. The terms "coupled" and "connected," along with their derivatives, may be used. It should be understood that these terms are not intended as synonyms for each other. Thus, the scope of the expression a device A coupled to a device B should not be limited to devices or systems wherein an output of device A is directly connected to an input of device B. It means that there exists a path between an output of A and an input of B which may be a path including other devices or means. "Coupled" may mean that two or more elements are either in direct physical or electrical contact, or that two or more elements are not in direct contact with each other but yet still co-operate or interact with each other. For example, in the context of airflow, where an outlet of A is coupled to an inlet of B it may be that one or more additional devices are provided between the outlet of A and the inlet of B. Thus, while there has been described what are oelieved to be the preferred embodiments of the invention, those skilled in the art will recognize that other and further modifications may be made thereto without departing from the spirit and scope of the invention, and it is intended to claim all such changes and modifications as fall within the scope of the invention. For example, any formulas given above are merely representative of procedures that may be used. Functionality may be added or deleted from the block diagrams and operations may be interchanged among functional blocks. Steps may be added or deleted to methods described within the scope of the present invention.

As mentioned above, in one variant, the SSD may operate as a PDA-controlled multimeter. There may thus be provided in accordance with embodiments of the invention:

A. A survey device, for surveying an installation to which a cathodic protection voltage is applied, comprising:

at least one input adapted to receive an input signal corresponding to electrical activity arising at the installation from the cathodic protection voltage;

a processor, coupled to the inputs;

wherein the processor is operable to

receive one or more detection signals, at least one detection signal corresponding to or being based upon the input signal; and

take a measurement of the electrical activity.

B. A method of or surveying an installation to which a cathodic protection voltage is applied, comprising:

providing at least one input adapted to receive an input signal corresponding to electrical activity arising at the installation from the cathodic protection voltage;

providing a processor, coupled to the inputs;

operating the processor to

take a measurement of the electrical activity a predetermined time delay after the first transition event.

In the case of paragraph A above, particular embodiments may, where appropriate, be as set out in any of claims 2-32, 66 to 92 or 122 to 132 of the appended claims. In the case of paragraph B above, particular embodiments may, where appropriate, be as set out in any of claims 34-64, 94 to 120 or 134 to 144 of the appended claims.

Claims

Claims:

1. A survey device, for surveying an installation to which a cathodic protection voltage is applied, the cathodic protection voltage exhibiting at least a first transition event, comprising:

a processor, coupled to the inputs;

wherein the processor is operable to

receive one or more detection signals, at least one detection signal corresponding to or being based upon the input signal;

determine, from the at least one detection signal, the occurrence of the first transition event; and

2. The device of claim 1 , wherein the cathodic protection voltage has a modulated waveform and the cathodic protection voltage has a second transition event.

3. The device of claim 2, wherein the modulated waveform has a periodicity T.

4. The device of claim 2 or 3, wherein the first transition event is voltage switch-ON and the second transition event is voltage switch-OFF, or vic9 versa.

5. The device of claim 3, or any claim dependent thereon, wherein the device is operable in automatic mode; wherein the processor is operable to

determine whether the first transition event and the second transition event have been detected for a first predetermined number of cycles; and if not, continuously detect instances of the first transition event and the second transition event until this is satisfied.

6. The device of claim 5, wherein if the first transition event and the second transition event have been detected for a first predetermined number of cycles, the processor is operable to

generate a current estimate of T; and

enter synchronised mode of operation.

7. The device of claim 6, wherein, in said synch 'onised mode, the processor is operable to detect further instances of the first transition event and/or the second transition event; and determine whether the first transition event and/or the second transition event is at the expected time based on the current estimate of T or at that time within a predetermined tolerance.

8. The device of claim 7, wherein, if the determination is positive, the processor is operable to generate a new current estimate of T based on the detected further instances of the first transition event and/or the second transition event, in the event of difference from the current estimate of T,.

9. The device of claim 8, or any claim dependent thereon, wherein the processor is operable to take a measurement of the electrical activity after the generation of the new current estimate of T.

10. The device of claim 7, or any claim dependent thereon, wherein, if the determination is negative, the processor Is operable to determine whether this condition persists for a timeout period, and if so, to continuously detect instances of the first transition event and the second transition event until the first transition event and the second transition event have been detected for a first predetermined number of cycles.

11. The device of claim 7, or any claim dependent thereon, wherein, if the determination is negative, the processor is operable to determine whether this condition persists for a timeout period, and if not, to take a measurement of the electrical activity.

12. The device of claim 5, or any claim dependent thereon, wherein the first predetermined number of cycles is 2.

13. The device of claim 6, or any claim dependent thereon, wherein the predetermined tolerance is up to 5% of T, more preferably up to 2% of T, and more preferably up to 1 % of T.

14. The device of claim 2, or any claim dependent thereon, wherein the device is operable in manual mode; and

wherein the processor is operable to receive a specified value for period T.

15. The device of claim 14, wherein the specified value for period T is received from a user via a user input device.

16. The device of claim 14 or 15, wherein the processor is operable to determine whether the first transition event and the second transition event have been detected at a rate corresponding to the specified value for period T for a second predetermined number of cycles; and if not, to issue an error notification.

17. The device of claim 16, wherein, if the first transition event and the second transition event have been detected for a first predetermined number of cycles, the processor is operable to

enter synchronised mode of operation; and

take a measurement of the electrical activity at an instant dependent upon said specified value for period T.

18. The device of claim 16 or 17, wherein the second predetermined number of cycles is 2 to 5, and more preferably 3.

19. The device of any of the preceding claims, wherein the electrical activity comprises potential difference, current flow or a combination thereof.

20. The device of any of the preceding claims, wherein the inputs are adapted to be connected to probes to be used in a survey; and

the input signal corresponds to electrical activity detected using the probes.

21. The device of any of the preceding claims, wherein the installation comprises a pipeline.

22. The device of claim 21 , wherein the pipeline comprises a subsurface pipeline.

23. The device of any of the preceding claims, wherein the first transition event and/or the second transition event are detected when a change in detected electrical activity greater than a predetermined threshold is determined by the processor.

24. The device of any of the preceding claims, further including an anaiog-to-digital converter (ADC); wherein the input signal is an analog signal and the detection signal is a sampled digital signal based on the analog signal.

25. The device of claim 24, wherein the first transition event and/or the second transition event are detected when the difference greater than a predetermined threshold between successive, or two- or more apart sampled digital values is determined by the processor.

26. The device of any of the preceding claims, wherein the predetermined time delay is 200- 600ms, and more preferably about 400ms.

27. The device of any of the preceding claims, wherein the electrical activity comprises sensed electrical activity.

28. The device of any of the preceding claims, wherein the electrical activity comprises electrical activity sensed by a probe relative to ground or to a reference electrode.

29. The device of any of the preceding claims, wherein the processor is operable to take a measurement of the electrical activity a predetermined time delay after the determined occurrence of the first transition event.

30. The device of any of the preceding claims, wherein the one or more detection signals include a first detection signal, and wherein the processor is operable to determine, from the first detection signal, the occurrence of the first transition event.

31. The device of any of the preceding claims, wherein the cathodic protection voltage is applied by a protection system, the protection system including an interrupter for causing the first transition event and/or second first transition event;

wherein the survey device is not coupled, in use, to the interrupter and/or protection system.

32. The device of any of the preceding claims, wherein the survey device comprises a portable survey device.

33. A method of or surveying an installation to which a cathodic protection voltage is applied, the cathodic protection voltage exhibiting at least a first transition event, comprising:

providing a processor, coupled to the inputs;

operating the processor to

34. The method of claim 33, wherein the cathodic protection voltage has a modulated waveform and the cathodic protection voltage has a second transition event.

35. The method of claim 34, wherein the modulated waveform has a periodicity T.

36. The method of claim 34 or 35 wherein the first transition event is voltage switch-ON and the second transition event is voltage switch-OFF, or vice versa.

37. The method of claim 35, or any claim dependent thereon, wherein the method is operable in automatic mode; the method comprising

determining whether the first transition event and the second transition event have been detected for a first predetermined number of cycles; and if not, continuously detecting instances of the first transition event and the second transition event until this is satisfied.

38. The method of claim 37, wherein if the first transition event and the second transition event have been detected for a first predetermined number of cycles, the method comprises

generating a current estimate of T; and

entering synchronised mode of operation.

39. The method of claim 38, wherein, in said synchronised mode, the method comprises

detecting further instances of the first transition event and/or the second transition event; and determining whether the first transition event and/or the second transition event is at the expected time based on the current estimate of T or at that time within a predetermined tolerance.

40. The method of claim 39, wherein, if the determination is positive, the method comprises generating a new current estimate of T based on the detected further instances of the first transition event and/or the second transition event, in the event of difference from the current estimate of T.

41. The method of claim 40, or any claim dependent thereon, wherein the method comprises taking a measurement of the electrical activity after the generation of the new current estimate of T.

42. The method of claim 39, or any claim dependent thereon, wherein, if the determination is negative, the method comprises determining whether this condition persists for a timeout period, and if so, to continuously detect instances of the first transition event and the second transition event until the first transition event and the second transition event have been detected for a first predetermined number of cycles.

43. The method of claim 39, or any claim dependent thereon, wherein, if the determination is negative, the method comprises determining whether this condition persists for a timeout period, and if not, to take a measurement of the electrical activity.

44. The method of claim 37, or any claim dependent thereon, wherein the first predetermined number of cycles is 2.

45. The method of claim 38, or any claim dependent thereon, wherein the predetermined tolerance is up to 5% of T, more preferably up to 2% of T, and more preferably up to 1% of T.

46. The method of claim 34, or any claim dependent thereon, wherein the method is operable in manual mode; wherein the method comprises

receiving a specified value for period T.

47. The method of claim 46, wherein the specified value for period T is received from a user via a user input device.

48. The method of claim 46 or 47, wherein the method comprises determining whether the first transition event and the second transition event have been detected at a rate corresponding to the specified value for period T for a second predetermined number of cycles; and if not, issuing an error notification.

49. The method of claim 48, wherein, if the first transition event and the second transition event have been detected for a first predetermined number of cycles, the method comprises

entering synchronised mode of operation; and

taking a measurement of the electrical activity at an instant dependent upon said specified value for period T.

50. The method of claim 48 or 49, wherein the second predetermined number of cycles is 2 to 5, and more preferably 3.

51. The method of any of claims 33 to 50, wherein the electrical activity comprises potential difference, current flow or a combination thereof.

52. The method of any of claims 33 to 51 , wherein the inputs are adapted to be connected to probes to be used in a survey; and

the input signal corresponds to electrical activity detected using the probes.

53. The method of any of claims 33 to 52, wherein the installation comprises a pipeline.

54. The method of claim 53 wherein the pipeline comprises a subsurface pipeline.

55. The method of any of claims 33 to 54, wherein the first transition event and/or the second transition event are detected when a change in detected electrical activity greater than a predetermined threshold is determined by the processor.

56. The method of any of claims 33 to 55, further including providing an analog-to-digital converter (ADC); wherein the input signal is an analog signal and the detection signal is a sampled digital signal based on the analog signal.

57. The method of claim 56, wherein the first transition event and/or the second transition event are detected when the difference greater than a predetermined threshold between successive, or two- or more apart sampled digital values is determined by the processor.

58. The method of any of claims 33 to 57, wherein the predetermined time delay is 200-600ms, and more preferably about 400ms.

59. The method of any of claims 33 to 58, wherein the electrical activity comprises sensed electrical activity.

60. The method of any of claims 33 to 59, wherein the electrical activity comprises electrical activity sensed by a probe relative to ground or to a reference electrode.

61. The method of any of claims 33 to 60, wherein the processor is operable to take a measurement of the electrical activity a predetermined time delay after the determined occurrence of the first transition event.

62. The method of any of claims 33 to 61 , wherein the one or more detection signals include a first detection signal, and wherein the processor is operable to determine, from the first detection signal, the occurrence of the first transition event.

63. The method of any of claims 33 to 62, wherein the cathodic protection voltage is applied by a protection system, the protection system including an interrupter for causing the first transition event and/or second first transition event;

64. The method of any of claims 33 to 63, wherein the survey device comprises a portable survey device.

65. A survey device, for surveying an installation to which a cathodic protection voltage is applied, comprising:

a plurality of inputs, each input corresponding to a socket on the survey device adapted to receive a connection to a probe;

wherein each input is adapted to receive an input signal corresponding to electrical activity arising at the installation from the cathodic protection voltage when a probe is connected in the corresponding socket; the device further comprising

a processor, coupled to the inputs;

wherein the processor is operable to

receive one or more detection signals, at least one detection signal corresponding to or being based upon an input signal;

determine a test mode to use; and

take a measurement of the electrical activity based upon the test mode determined.

66. The survey device of claim 65, wherein the processor is operable to determine a test mode to use dependent upon a selection received from a user.

67. The survey device of claim 66, wherein the selection is received via communication link from a PDA operable by a user.

68. The survey device of claim 67, wherein the communication link comprises a wireless communication link.

69. The survey device of any of claims 65 to 68, wherein the processor is alternatively or additionally operable to determine a test mode to use dependent upon at which inputs input signal(s) is(are) received.

70. The survey device of claim 69, further including circuitry for generating, for each input, a signal indicating whether an input signal is received at that input.

71. The survey device of claim 70, wherein the circuitry comprises one or more of (i) an amplification and thresholding circuit, (ii) a thresholding circuit, (iii) a buffer, and (iv) a current-to- voltage conversion and thresholding circuit.

72. The survey device of any of claims 65 to 71 , wherein the processor is alternatively or additionally operable to determine a test mode to use dependent upon which sockets are detected to have probes connected.

73. The survey device of claim 72, further including circuitry for generating, for each input, a signal indicating whether a connector is present in the socket corresponding to that input.

74. The survey device of claim 73, wherein the circuitry comprises an optical transmitter and optical receiver, the transmitter and receiver being diametrically opposed on the sides of a socket.

75. The survey device of any of claims 65 to 74, wherein one of the inputs comprises a common input used in a plurality of test modes.

76. The survey device of any of claims 65 to 75, wherein one of the inputs comprises a first channel input for voltage measurement in a plurality of test modes.

77. The survey device of any of claims 65 to 76, wherein one of the inputs comprises a second channel input for voltage measurement in a plurality of test modes.

78. The survey device of any of claims 65 to 77, wherein one of the inputs comprises a third channel input for current measurement in a plurality of test modes.

79. The survey device of any of claims 65 to 78, wherein one of the inputs comprises a fourth channel input for voltage measurement in a Pearson test mode.

80. The survey device of claims 76, when dependent upon claim 75, wherein the device is operable in a test post test mode; when the device is adapted to have the common input connected by a short cable to a test post and the first channel input connected by a short cable to a reference cell in the vicinity of the test post.

81. The survey device of claims 76, when dependent upon claim 75, wherein the device is operable in a single wire CIPS test mode; when the device is adapted to have the common input connected by a long cable to a test post and the first channel input connected by a short cable to a reference cell in the vicinity of the survey device.

82. The survey device of claims 77, when dependent upon claims 75 or 76, wherein the device is operable in a dual wire CIPS test mode; when the device is adapted to have the common input connected by a long cable to a test post, the first channel input connected by a short cable to a reference cell in the vicinity of the survey device, and the second channel input connected by a long cable to a reference cell in the vicinity of the test post.

83. The survey device of claims 78, when dependent upon claim 75, wherein the device is operable in a test post current measurement test mode; when the device is adapted to have the common input connected by a short cable to a test post and the third channel input connected by a short cable to a ground spike in the vicinity of the test post.

84. The survey device of claims 79, when dependent upon claim 78, wherein the device is operable in a Pearson test mode; when the device is adapted to have the third channel input connected by an aerial cable to a grounded first user remote from the survey device and the Pearson channel input connected by a short cable to a grounded second user in the vicinity of the survey device.

85. The survey device according to any of claims 65 to 84, wherein the survey device is interoperable, in use, with a PDA.

86. The survey device according to any of claims 65 to 85, further comprising a communications interface providing, in use, a wired or wireless communication link.

87. The survey device according to any of claims 65 to 86, the survey device being operable to communicate, in use, with a PDA via the communication link.

88. The survey device according to any of claims 65 to 87, wherein the processor is operable to receive a user selection from the PDA via the communication link, the user selection designating one of a plurality of test modes and being received from the user at the PDA, each test mode corresponding to one of the plurality of inputs.

89. The survey device according to any of claims 65 to 88, wherein the processor is operable to determine a test mode to use based on the received user selection.

90. The survey device according to any of claims 65 to 89, wherein the processor is operable to take a measurement of the electrical activity based only upon the test mode determined.

91. The survey device according to any of claims 65 to 90, wherein each test mode corresponds to a single type of measurement.

92. The survey device according to any of claims 65 to 91 , wherein the plurality of inputs, communications interface and processor are integrated into a single portable housing.

93. A method for surveying an installation to which a cathodic protection voltage is applied using a survey device, the survey device comprising:

a processor, coupled to the inputs;

wherein the method comprises operating the processor to

determine a test mode to use; and

94. The method of claim 93, wherein operating the processor to determine a test mode to use comprises operating the processor to determine the test mode dependent upon a selection received from a user.

95. The method of claim 94, wherein the selection is received via communication link from a PDA operable by a user.

96. The method of claim 95, wherein the communication link comprises a wireless communication link.

97. The method of any of claims 93 to 96, wherein operating the processor to determine a test mode to use alternatively or additionally comprises operating the processor to determine the test mode dependent upon at which inputs input signal(s) is(are) received.

98. The method of claim 97, wherein operating the processor to determine a test mode to use comprises using circuitry for generating, for each input, a signal indicating whether an input signal is received at that input.

99. The method of claim 98, wherein the circuitry comprises one or more of (i) an amplification and thresholding circuit, (ii) a thresholding circuit, (iii) a buffer, and (iv) a current-to-voltage conversion and thresholding circuit.

100. The method of any of claims 93 to 99, wherein operating the processor to determine a test mode to use alternatively or additionally comprises operating the processor to determine a test mode to use dependent upon which sockets are detected to have probes connected.

101. The method of claim 100, wherein operating the processor to determine a test mode to use comprises using circuitry for generating, for each input, a signal indicating whether a connector is present in the socket corresponding to that input.

102. The method of claim 101 , wherein the circuitry comprises an optical transmitter and optical receiver, the transmitter and receiver being diametrically opposed on the sides of a socket.

103. The method of any of claims 93 to 102, wherein one of the inputs comprises a common input used in a plurality of test modes.

104. The method of any of claims 93 to 103, wherein one of the inputs comprises a first channel input for voltage measurement in a plurality of test modes.

105. The method of any of claims 93 to 104, wherein one of the inputs comprises a second channel input for voltage measurement in a plurality of test modes.

106. The method of any of claims 93 to 105, wherein one of the inputs comprises a third channel input for current measurement in a plurality of test modes.

107. The method of any of claims 93 to 106, wherein one of the inputs comprises a fourth channel input for voltage measurement in a Pearson test mode.

108. The method of claims 104, when dependent upon claim 103, wherein the device is operable in a test post test mode; when the device is adapted to have the common input connected by a short cable to a test post and the first channel input connected by a short cable to a reference cell in the vicinity of the test post.

109. The method of claims 104, when dependent upon claim 83, wherein the device is operable in a single wire CIPS test mode; when the device is adapted to have the common input connected by a long cable to a test post and the first channel input connected by a short cable to a reference cell in the vicinity of the survey device.

110. The method of claims 105, when dependent upon claims 103 and 104, wherein the device is operable in a dual wire CIPS test mode; when the device is adapted to have the common input connected by a long cable to a test post, the first channel input connected by a short cable to a reference cell in the vicinity of the survey device, and the second channel input connected by a long cable to a reference cell in the vicinity of the test post.

111. The method of claims 106, when dependent upon claim 103, wherein the device is operable in a test post current measurement test mode; when the device is adapted to have the common input connected by a short cable to a test post and the third channel input connected by a short cable to a ground spike in the vicinity of the test post.

112. The method of claims 107, when dependent upon claim 106, wherein the device is operable in a Pearson test mode; when the device is adapted to have the third channel input connected by an aerial cable to a grounded first user remote from the survey device and the Pearson channel input connected by a short cable to a grounded second user in the vicinity of the survey device.

113. The method according to any of claims 93 to 1 12, wherein the survey device is interoperable, in use, with a PDA.

114. The method according to any of claims 93 to 113, further comprising a communications interface providing, in use, a wired or wireless communication link.

115. The method according to any of claims 93 to 114, the survey device being operable to communicate, in use, with a PDA via the communication link.

1 16. The method according to any of claims 93 to 115, wherein the processor is operable to receive a user selection from the PDA via the communication link, the user selection designating one of a plurality of test modes and being received from the user at the PDA, each test mode corresponding to one of the plurality of inputs.

117. The method according to any of claims 93 to 116, wherein the processor is operable to determine a test mode to use based on the received user selection.

118. The method according to any of claims 93 to 117, wherein the processor is operable to take a measurement of the electrical activity based only upon the test mode determined.

119. The method according to any of claims 93 to 1 8, wherein each test mode corresponds to a single type of measurement.

120. The method according to any of claims 93 to 119, wherein the plurality of inputs, communications interface and processor are integrated into a single portable housing.

121. A survey device, for surveying an installation to which a cathodic protection voltage is applied, comprising:

a processor, coupled to the inputs;

wherein the processor is operable to

take a measurement of the electrical activity.

122. The survey device of claim 121 , wherein the processor is operable to (i) receive via wired or wireless communication link with a PDA a user input at the PDA designating a sampling rate for take a measurement of the electrical activity, and/or (ii) transmit one or more measurements of the electrical activity via wired or wireless communication link to a PDA.

123. The device of any of claims 121 to 122, wherein the cathodic protection voltage has a modulated waveform and the cathodic protection voltage has a second transition event.

124. The device of claim 123, wherein the modulated waveform has a periodicity T.

125. The survey device according to any of claims 121 to 124, further comprising at least one communications interface adapted for providing a wired or shortrange wireless communication link with a PDA in situ.

126. The survey device according to any of claims 121 to 125, wherein the processor is operable to take a measurement of the electrical activity based on the detection signals and the received sampling rate.

127. The device of any of claims 121 to 126, wherein the electrical activity comprises sensed electrical activity.

128. The device of any of claims 121 to 127, wherein the electrical activity comprises electrical activity sensed by a probe relative to ground or to a reference electrode.

129. The device of any of claims 121 to 128, wherein the processor is operable to take a measurement of the electrical activity a predetermined time delay after the determined occurrence of the first transition event.

130. The device of any of claims 121 to 129, wherein the one or more detection signals include a first detection signal, and wherein the processor is operable to determine, from the first detection signal, the occurrence of the first transition event.

131. The device of any of claims 121 to 130, wherein the cathodic protection voltage is applied by a protection system, the protection system including an interrupter for causing the first transition event and/or second first transition event;

132. The device of any of claims 121 to 131 , wherein the survey device comprises a portable survey device.

133. A method of or surveying an installation to which a cathodic protection voltage is applied, comprising:

providing a processor, coupled to the inputs;

operating the processor to

134. The method of claim 133, comprising operating the processor to (i) receive via wired or wireless communication link with a PDA a user input at the PDA designating a sampling rate for take a measurement of the electrical activity, and/or (ii) transmit one or more measurements of the electrical activity via wired or wireless communication link to a PDA.

135. The method of any of claims 133 to 134, wherein the cathodic protection voltage has a modulated waveform and the cathodic protection voltage has a second transition event.

136. The method of claim 135, wherein the modulated waveform has a periodicity T.

137. The method according to any of claims 133 to 136, further comprising at least one communications interface adapted for providing a wired or shortrange wireless communication link with a PDA in situ.

138. The method according to any of claims 133 to 137, wherein the processor is operable to take a measurement of the electrical activity based on the detection signals and the received sampling rate.

139. The method of any of claims 133 to 138, wherein the electrical activity comprises sensed electrical activity.

140. The method of any of claims 133 to 139, wherein the electrical activity comprises electrical activity sensed by a probe relative to ground or to a reference electrode.

141. The method of any of claims 133 to 14C, wherein the processor is operable to take a measurement of the electrical activity a predetermined time delay after the determined occurrence of the first transition event.

142. The method of any of claims 133 to 141 , wherein the one or more detection signals include a first detection signal, and wherein the processor is operable to determine, from the first detection signal, the occurrence of the first transition event.

143. The method of any of claims 133 to 142, wherein the cathodic protection voltage is applied by a protection system, the protection system including an interrupter for causing the first transition event and/or second first transition event;

144. The method of any of claims 133 to 143, wherein the survey device comprises a portable survey device.

145. A recordable, rewritable or storable medium having recorded or stored thereon data defining or transformable into instructions for execution by processing circuitry and corresponding to at least the steps of any of claims 33 to 64, 93 to 120 or 133 to 144.

146. A server computer incorporating a communications device and a memory device and being adapted for transmission on demand or otherwise of data defining or transformable into instructions for execution by processing circuitry and corresponding to at least the steps of any of claims 33 to 64, 93 to 120 or 133 to 144.

147. A survey device substantially as hereinbefore described with reference to the accompanying drawings.

148. A method substantially as hereinbefore described with reference to the accompanying drawings.