MXPA97001041A - Electronic signal measurement device for the acquisition and deployment of short analogue signal events - Google Patents

Abstract

The present invention relates to an electronic signal measuring device for the acquisition and display of short-duration analog signal events, in the form of a portable instrument that includes detection circuits for maximum and minimum signal values to capture the ends of an analog signal of rapid change. The captured values are then digitized by an analogue to digital converter to generate data that can be stored and subsequently displayed in the form of a histogram, evidencing the occurrence or lack of occurrence of a particular type of event.

Description

ELECTRONIC SIGNAL MEASUREMENT DEVICE PORA LÍ ACQUISITION AND DEPLOYMENT OF SHORT-TERM ANALOG SIGNAL EVENTS BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates generally to electronic signal measuring devices, and very particularly to a system for acquiring and displaying analog events of short duration in which the maximum and nni magnitudes of a variable analog signal are detected. by detectors of peaks and valleys and then digital! They are stored by an analog-to-digital converter, stored and then read at a slower speed to be displayed in an electronic strip graph format for highlighting signal anomalies.

DESCRIPTION OF THE PREVIOUS TECHNIQUE In the field of automotive repair, as well as in other fields, it has long been important to have instruments available to observe electrical signals that occur at various points within the numerous electrical circuits and signal path residing in a car. Parameter measurements such as current, voltage, resistance, signal frequency, etc., allow a repair technician to locate and diagnose the numerous problems that occur in the vehicle. Such parameters are typically measured using available apparatus ranging from simple voltage, current and resistance meters to sophisticated computerized electronic diagnostic equipment. Among the most difficult conditions to measure are intermittent faults, that is, short signal transitions. Previous measurement systems have sampled the analogue signals slowly and thus have quickly ignored components of variable signals, or have sought to detect quickly variable components by sampling at a speed greater than the rate of signal change. Sampling systems that sample at frequencies greater than the input signal frequency are well known in the art. For example, an oscilloscope that operates under this general principle contains complex and expensive electronic components, lower sampling speeds, intermittent faults may not be captured by the oscilloscope; At higher sample rates, intermittent faults are less likely to be deployed. In addition, the additional data derived from the much higher sampling rate, when converted to the digital form, requires substantial computational capacity. A major disadvantage of the digital oscilloscope is the loss of data that usually occurs after the conversion from logo to digital. The intei--mitent.es faults that occur on the signal are generally captured by the conversion, but not all of the captured data is displayed. Another difficulty with the prior art sampling systems is that they use complicated electronic components to trigger the capture of analog signal events of short duration. Prior art devices have typically used trip level circuits and trip delay circuitry. The trigger level circuit will allow the detection of an event if its voltage potential rises above a certain preset level. The trigger delay circuit will delay the detection of an event for a preset period after the trigger level circuit has noticed an event with a voltage potential above its preset level. Although these two techniques allow very accurate detection of the voltage potential and time of occurrence, the information obtained is superfluous if all that really needs to be known is that a particular event has occurred during a particular period. An additional difficulty with the prior art sampling systems is that if the prior art sampling system uses a single analog-to-digital converter on a multi-channel input device, the sampling rate is reduced by 1. / n for n channels, subsequently reducing the probability of detecting a burst.

Therefore, there is a need for relatively simple means to detect and indicate the occurrence of intermittent faults in electrical circuits. In addition, there is a need for a device that "latches" an intermittent fault and displays its occurrence in one of several selective histographic formats so that the user does not have to look carefully at the indicator to observe the transient occurrence of a termitent fault. .

BRIEF DESCRIPTION OF THE INVENTION Therefore, an object of the present invention is to provide an improved apparatus for monitoring electrical signals to detect and indicate the occurrence of rapidly changing anonymous events, commonly known as failures mter-mitent.es. Another objective of the present invention is to provide an intermittent fault detection and display apparatus that is simple to use and relatively inexpensive. Another object of the present invention is to provide an apparatus of the type described which allows workers not experienced in the use of complex test instruments to observe short-term faults. Another object of the present invention is to provide an apparatus of the type described which is not based on the use of fast sample rates to detect and display faults, and is not based on the observation of the user of the fault in the instant. what happens Still another object of the present invention is to provide a system of the type described for detecting rapidly changing analog events using limited computing capability by sampled at a relatively low speed compared to the analogous event to be detected. Briefly, the present invention is embodied in the form of a hand-held instrument that includes circuits for detecting maximum and minimum signal values to capture the ends of an analogue signal of rapid change. by an analog-to-digital converter to generate data that can be stored and subsequently read from memory and displayed in the form of a histogram that demonstrates the occurrence or lack of occurrence of a particular type of signal event. The present invention is that it indicates the occurrence of otherwise difficult to detect events in an easily discernible form.Another advantage of the present invention is that it provides a histographic display of the occurrence of events over time. of the present invention is that it can be used by workers without experience in the use of sophisticated test equipment. The advantages and advantages of the present invention will undoubtedly be apparent to those skilled in the art upon reading the following detailed description of the preferred embodiment illustrated in the various figures of the drawings.

IN THE DRAWINGS Fig. 1 is a diagram illustrating a typical voltage waveform including intermittent faults of the type found in automotive diagnostics; Figure 2 is a diagram illustrating a typical oxoscope type display of a portion of the waveform illustrated in Figure 1; Figure 3 is a display in real time or near the actual time of the waveform illustrated in Figure 1 during a particular sampling period; Figure 4 is a diagram that generally illustrates the operational concept of the present invention; Figure 5 is a block diagram illustrating the main fusion components of a signal measurement and display apparatus in accordance with the present invention; Figure 6 is an illustration of a graphic deployment type provided by the apparatus in accordance with the present invention; and Figure 7 is a schematic circuit diagram illustrating peak and valley detection circuits in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED MODALITY Referring now to Figure 1 of the drawings, which illustrates with the number 10 an alternative signal trace typical of the type of signal that could be detected in an automotive circuit. Nos. 12 and 14 illustrate intermittent signal sizes of the aforementioned type, i.e., very short duration random voltage spikes normally indicative of some short component or condition malfunction. If you were going to use an <; Type of instrument oxiloscope to detect intermittent faults 1? and 14, could one choose to display one or two cycles of the waveform, as illustrated in 16 in the figure? . fll use an oscilloscope, the user can choose to update the display in each cycle or every n cycles of the signal. r_? choose to update each cycle, the change from deployment to deployment will be substantially unpredictable to the observer's eye, with the main waveform appearing simply as having a slight abrupt movement due to the signal variations illustrated in figure 1. When the cycle has the intermittent fault 12 appears, will appear rapidly and then disappear, usually at a speed that would make the spike or intermittent failure 12 irrepressible. One way to make a visible intermittent fault is to show a much slower speed and wait for the intermittent failure to occur during a sampling period. However, in understandable form, if the intermittent failure does not occur during the sampling period, it will not be detected. On the other hand, the sophisticated electronic detection circuit could be used to display only those cycles that had voltage that exceeded a certain minimum value, in which case it could be discriminated-in favor of displaying only those signal cycles that had intermittent faults. However, unless the particular waveform of the intermittent fault is of particular importance, such information would normally be of little interest to a technician. What you really want is to know if an intermittent failure occurs, if it was random or repetitive and maybe its occurrence is related to some other event. Another alternative would be to display -actively in real time or near real time all the cycles within a given period, as illustrated in figure 3. However, for one that sees intermittent failures such as those illustrated in 12 ' and 14 'would be problematic. Even if the sampling period covered a number of cycles, in the usual case the duration of each intermittent failure would be extremely short, and to visually detect the occurrence of the intermittent failure it would be necessary to concentrate the attention of the technician to notice the signal transition. In addition, if it were noticed, the value of said information would be questionable.

Referring again to Figure 1 of the drawings, a solution to the problem in accordance with the present invention will be described concept to the entity. In an embodiment of the invention which will be described below, means are provided to monitor and detect the minimum voltage excursion Vm.n and the maximum voltage excursion Vma? of the signal 10 during periods of sampling P of arbitrarily chosen predetermined duration but preferably including at least 180 ° of the input signal cycle. These voltage excursions are maintained and re-sampled for digitization as described below. By connecting the respective Vnax and Vm? N values as indicated in Fig. 4, it is suggested that a histographic illustration of the minimum and maximum voltage excursions would be useful in revealing the occurrence and frequency of occurrence of the intermittent faults 12 and 14. Note, for example, the prominence of pulses 13 and 15 corresponds to the momentary signal excursions represented by pins 12 and 14 in figure 1. Vanas deployment options other than the continuously moving histogram are available in the illustration of values of Vmax and mm including? n histograrna envelope drawing on histograrnas of previous periods, and a histogram to lightning that unfolds on the screen at a time of place of the histogram bars with time. It is important to note that the present invention is not limited to the type of deployment format or deployment means. Also note that the sampling periods do not need to respond directly to the sampling cycles. The periods P may be longer or shorter. The only criterion of importance is that the periods P are of such duration that the spikes are sampled and detected. If chosen, each intermittent or spike failure in the signal voltage will be drastically visible. For example, if the sampling period P 'has been chosen as P' = 4P, the Vma? and corresponding Vmm will be as indicated by the dashed lines of Figure 4, and the Vma? 17 and 19 indicate the occurrences of intermittent faults 13 and 15; the point being that the intend of the present invention is simply to indicate that one or more abnormalities have occurred during the sampling period, not to provide qualitative or quantitative information regarding the anomalies. Turning now to Figure 5 of the drawings, which is a simplified block diagram illustrating one embodiment of the present invention, the device is shown as comprising an input stage 20, an attenuation and gain stage 22, a detection stage. and maximum signal storage 24, a minimum signal detection and storage stage 26, an analog-to-digital conversion stage 28, a computing and control stage 30 (microprocessor), a random access memory (RAMl 31, means for user input 33, means for displaying graphics 32, and a time base reference generator 34. With or in other related types of measuring devices, a row of test probes 36 and 38 are provided having contact tips, suitable clamps or transducers 35 and 37 for hooking selected tips in a circuit that is going to be tested in such a way that a voltage difference appears through the selected points, evidencing the flow of current or potential levels that are going to be detected or supervised. The probes 36 and 38 can have any suitable configuration, and normally the probe 36 will be considered the positive or hot probe while the probe 38 can be considered the common or ground probe. The step of entering 20 is active with rods 36 and 38 to develop a signal at number 40, which is also the voltage difference felt between the contact points of the probe. The signal 40 is subsequently passed through a gain and attenuation step 22 where its signal level is adjusted up or down to be compatible with the remaining circuit elements. The improved signal is then emitted on line 42 for its input to maximum detector 24 and minimum detector 26, which detect Vmax and Vmin for output lines 48 and 50 respectively. These analog signals are then coupled in the analog to digital converter 28 when they are digitalized and emitted in the bus bar 52. The control and computing step (microprocessor) 30 then causes the signal values to be stored in RAM 31. The microprocessor 30 subsequently reads the stored values and generates signals on the busbar 54 to drive the graphical display device 22. The mi croprocessor 30 also periodically generates retry signals on line 49 for the input on the 46 and 47 and re-metering the detectors 24 and 26, causing them to send the maximum and minimum signals to the analog-to-digital converter 28 for their conversion to digital signal values. The time-based reference generator 34 provides a time-regulating input at 50 to the icr-oprocessor 30, wherein the microprocessor generates the reuse signals periodically in accordance with the user input or in accordance with a range that is a function of the period as detected from the entry signals. It will then be appreciated that by detecting the minimum and minimum signal values that occur during predetermined time intervals P (or P ') to generate ma? and V m for each sample period, and subsequently digitize and store these values, such values can be subsequently read in RAM31 (and deviated in time) at a selected rate and used to drive a display in a histographic style as illustrated in Figure 6, each intermittent fault being illustrated in an easily perceivable form, as indicated by 62 and 64. By histological display it is meant that, using and repeatedly deviating the stored data, the polished signal can simulate appearing to move to through screen 66 from left to right, creating a rolling display of a strip chart recorder in which the recording medium moves from left to right. Highlighting the unfolded signal between Vma? and Vfflln as indicated by the number 60, the information content of the display can be improved. It should be understood that other display formats can be used, as well as to facilitate observations of intermittent faults. The stored Vmax and vmin can be manipulated in a variety of ways. For example, the average of consecutive joint spans of max and min can be taken and displayed, or the highest and lowest values of consecutive joint spans can be rotated and displayed, even the number of sets of values Vma? and Vm? n taken from the above calculations can change to vary the speed of deployment. Turning now to Figure 7, a schematic circuit diagram illustrating a preferred embodiment of the maximum and minimum signal storage and detection stages 24 and 26 will be provided. As illustrated, the entry in line 42 of the Gain stage 22 (FIG. 5) is fed through a volatile memory amplifier 70,? n blocking diode 71, a transistor connected to a diode 72, and a current limiting resistor 74 to a storage capacity 76? It charges up to and sustains the maximum voltage input during the sampling period P. This voltage is subsequently output to terminal 48 through a volatile memory amplifier 78, to be sampled by the 0 / D. At the end of each period P, the stage is reimaged by a frame reset signal 46 generated by the microprocessor 30 (FIG. 5), which turns on the analog switch 80 to discharge the capacitor 76 to the negative power supply rail. Motar q? E because the diodes 71 and 72 prevent the discharge of the capacitor 76 to the amplifier 70, the period P can be understood over any number of cycles of the input signal (any time loss selected) and is therefore not determined by the type of input waveform. The tracking diode 73 serves to cause the output signal 48 to respond quickly to the largest input signal changes, diverting the storage capacity / b. The minimum detection / storage stage 26 includes a volatile memory amplifier 82, a blocking diode 84, a tracking diode 85, a polarized diode transistor 86, a current limiting resistor 90 and a storage capacitor 92. Step 26 further includes means for looping (recharging) the capacitor 92 through an analog switch 94, and a volatile memory amplifier 98 for coupling the Vm? n out at 50. Stage 26 operates to capture on the capacitor 92 the minimum voltage excursion d? r-before each sampling period of the waveform input at 42. Capacitor 92 is initial and positively charged ( so that it is negatively charged as in circuit 24) by the reset signal applied in 46, and its load is reduced by the signal input in 42. The corresponding min value is subsequently output through an amplifier of volatile memory 98 in 50, and step 26 is relayed by the frame recall input from the microprocessor in line 46. The digital-to-digital converter 28 and microprocessor stage 30 are of a standard configuration. In the preferred embodiment, they are respectively implemented using an ADC10158 converter manufactured by National Semiconductor and an M37451 microprocessor manufactured by Mitsubishi Electric. The graphic display device 32 in the preferred embodiment is an LCD display of the type manufactured by Seiko Instruments. As it is actually implemented, the present invention is part of a diagnostic and digital data base and graphical instrument manufactured by Baleo, a division of Snap-on Incorporated. However, it will be appreciated that the invention may be in the form of an individual unit or a component part of another indicator or diagnostic system. Moreover, although the present invention has been described in terms of a preferred embodiment, it is anticipated that alterations and modifications of the ism will undoubtedly be apparent to those skilled in the art. Therefore, it is desired that the following claims be understood to cover all such alterations and modifications that fall within the true spirit and scope of the invention.

Claims (20)

NOVELTY OF THE INVENTION CLAIMS

1. - A short-term analogue signal acquisition deployment system consisting of: input means to acquire an analogous signal; maximum signal detection means for detecting and sustaining the maximum values of said analog signal «During predetermined periods of time; means of detecting a minimum signal to detect and sustain the minimum values of said analog signal during said predetermined periods of time; conversion means analogous to digital to convert the maximum values and the minimum values to digital signals; means for storing said digital signals; graphic display means; and microprocessor means for sampling the stored digital signals and for transferring the sampled signals to said deployment means for deployment.

2. A system for displaying and acquiring analog signal events of short duration according to claim 1, further characterized in that said microprocessor means rnuest repetitively revive and deviate stored digital signals in time so that the displayed signal values appear move from one side of the deployment media to another.

3. A system for displaying and acquiring events of analog signal of short duration in accordance with claim 2, further characterized in that said means of maximum signal detection include a first capacitor, means to enter said signal analogous to said capacitor causing it to charge at the maximum voltage that occurs during each said predetermined period, and means for generating an output voltage corresponding to the maximum load stored in said first capacitor means during each said predetermined period.

4. A system for displaying and acquiring short-term anonymous signal events according to claim 3, further characterized in that said means of maximum signal detection also include means that respond to a reset signal generated by said means of microprocessor to download said first capacitor means.

5. A system for displaying and acquiring short-duration anonymous signal events according to claim 4, further characterized in that said means of minimum potential detection include a second capacitor means, interrupting means responsive to a reimage signal supplied by said microprocessor means and operable to cause said second capacitor means to be recharged, means for coupling said analogous signal to said second capacitor means for discharging said capacitor means at a level proportional to the minimum value of said an-dur-ante signal each said predetermined period, and output means for generating an output signal proportional to the minimum load stored in said second capacitor means during each said predetermined period.

6. A system for displaying and acquiring short-term anonymous signal events in accordance with claim 5, further characterized in that said graphic display means includes an LOD display screen.

7. An electronic detection and signal display unit consisting of: first means for detecting the maximum excursions of an analog input voltage during predetermined periods of time and for recording first signals proportional to it; second means for detecting the minimum excursions of said analog input voltage during said predetermined periods of time and for generating second signals proportional to the ism; means for storing said first signals and said second signals; and means of visual display to read repetitively, divert time and display at least the first stored signals to produce a histogrammatic display of them.

8. An electronic signal detection and display device according to claim 7, further characterized in that said visual display means also read repetitively the time deviations and displays of the stored second signals for inclusion in said histogrammatic display.

9. - An electronic signal detection and display device according to claim 7, further characterized in that said means includes first capacitor means for receiving and storing charge proportional to the maximum voltage level obtained by said input signal during each period predetermined time, and means which respond to the maximum charges stored by said first capacitor means and which operate to generate corresponding digital data that report said black signals.

10. An electronic signal detection and display device according to claim 9, further characterized in that said means includes second capacitor means for receiving and storing charge proportional to the minimum voltage level obtained by said analog input signal during each predetermined period of time, and means responsive to the minimum charges stored by said second capacitor means and q? e operate to generate corresponding data forming said second signals.

11. An electronic device for detecting and displaying a signal according to claim 7, further characterized in that said visual display means include an LDC screen and an associated microprocessor to control the reading, time deviation and deployment of the first stored signals.

12. An electronic device for detecting and displaying a signal according to claim 10, further characterized in that said visual display means include an LCD screen and an associated microprocessor to control the reading, time deviation and deployment of the first and second ones. second stored signals.

13. A system for displaying and acquiring analog signal events of short duration according to claim 1, which also includes means for user input to said microprocessor means.

14. A system for displaying and acquiring analog signal events of short duration according to claim 13, further characterized in that said initiator means repetitively sample and deviate stored digital signals in time.

15. - A system of display and acquisition of events of analog signal of short duration according to claim 13, further characterized in that said microprocessor means repetitively sampled said analog signal to a range of compliance with an input signal of the user from said user input means.

16. A method for detecting and displaying short-term signal events consisting of the steps of; receive an analog signal that has maximum values and minimum values over time; detecting the maximum values of said analog signal and the minimum values of said analogous signal at specific time intervals; store the maximum values and the minimum values of said analog signal; process the maximum value stored and the minimum values stored for deployment; and display the maximum values processed and the minimum values processed. 17.- A method according to the claim 16, further characterized because the maximum values processed and the minimum values processed are displayed in a histogramic format. 18. A method according to claim 16, further characterized in that the specified time intervals are variable. 19. A method in accordance with the claim 16, further characterized in that after the processing step, the stored maximum values and the stored minimum values are grouped and the maximum group values and the minimum group values are calculated for their deployment. 20.- A method in accordance with the claim 16, further characterized in that the stored maximum values and the stored minimum values are displayed at a specific speed.