WO2013044399A1

WO2013044399A1 - Automatic flight mode

Info

Publication number: WO2013044399A1
Application number: PCT/CH2011/000229
Authority: WO
Inventors: Ruud Riem-Vis; Bertrand SPÄTH; Philipp TOMÉ; Youssef TAWK; Aleksandar Jovanovic; Jérôme LECLÈRE; Cyril Botteron
Original assignee: Swisscom AG
Current assignee: Swisscom AG
Priority date: 2011-09-29
Filing date: 2011-09-29
Publication date: 2013-04-04
Anticipated expiration: 2014-03-29

Abstract

The invention relates to an electronic device which is capable of being transported on an airplane and includes a radio transmitter. The invention comprises: a) collecting acceleration data and/or precession data from the electronic device; b) estimating parametric data from the acceleration data and/or precession data; c) comparing the parametric data with reference data in order to determine a comparison result; and d) controlling the radio transmitter based on the comparison result.

Description

Automatic Flight Mode

Technical Field

The invention relates to a method for controlling an electronic device and to an electronic device, wherein the electronic device is capable of being transported on an airplane, and wherein the electronic device includes a radio transmitter. Background Art

During flight, the use of mobile communication devices, such as cell-phones according to the GSM (GSM: Global System for Mobile Communications) standard, is not allowed, mainly because of the risk of radio interference with flight instruments, in particular during take-off and landing. Accordingly, mobile communication devices have to be turned off during the flight at all times, except if it has been proven that they cannot adversely affect the airplane. Many cell-phones or portable computers come with a feature wherein the cellular module like the GSM module is turned off during the flight, but other features of the cell-phone or portable computer, like for example a music or video player, may be used after take-off and before landing. However, particularly because of manipulation errors or misunderstanding, it can happen that the flight mode of a cell-phone or portable computer is not correctly enabled.

In order to track the current geographic location of shipments such as parcels, shipping containers or the like during transportation from an originator to a recipient, tracking devices may be employed, wherein one variant of tracking devices includes a cellular module designed to interact with a cellular network, for example a GSM or UMTS network (UMTS: Universal Mobile Telecommunications System). When transporting the parcel, shipping container or the like, the cellular module may connect on a regular basis to a cell of the cellular network, whereby an identifier, for example the MSISDN (MSISDN: Mobile Subscriber Integrated Services Digital Network Number), is used. Accordingly, during transportation of the parcel, shipping container or the like, it may be determined on a regular basis to which cell the cellular module is currently connected, if at all. This also determines the approximate location of the cellular module, as the location of a cell is stored in a cell plan, whereby each cell is assigned a coverage area. In other solutions, the location of the tracking device is determined by means of, for example, GPS (Global Positioning System) and submitted to the tracking service using a cellular module.

For transportation of the parcels, shipping containers or the like, vehicles as for example cars, vans, trains, vessels, or airplanes may be used. According to certification requirements and aviation regulations, cellular phones may have to be turned off during some flight phases, as interference with aircraft systems may disturb safe operation.

A cellular module of a tracking device can be turned off, for example, manually before loading a container and manually turned on again after unloading. However, such manual operation is error prone and requires personnel resources in order to provide a high reliability, as required by some present regulations.

WO 01 /75472 (Marconi) relates to a tracking device that is associated with a cargo container used for shipping goods with a vessel. The tracking device includes a GPS and is adapted to transmit its location remotely. Sensors associated with the tracking device sense information concerning the surroundings of the container. The tracking device is deactivated when the container is inside, or in proximity to, an aircraft. Environmental sensors may receive information concerning the surrounding of the container like positioning information, acoustics, frequencies, pressure, altitude, motion, vibration, capacitance, and imaging data. Cooperative markers may be placed proximate to the vessel, which may be read by sensors associated with the container. Acoustic signals unique to a particular type of vessel may be sensed. Frequency detection may sense aircraft power systems operating at around 400 Hz. Pressure readings can determine height above sea level. Movement of the container in a certain way/angle or unique vibrations may signify proximity to a vessel. Cargo holds of a vessel may couple with the container at a predetermined capacitance. An imaging sensor may determine certain shapes of a vessel.

WO 97/22049 (Motorola) relates to inhibiting the operation of an electronic device during take-off and landing of an aircraft. A sensor determines when take-off or landing occurs, such that operation of the electronic device may be inhibited either by switching off power supply for the device or sending a signal to the device initiating a shutdown procedure. The sensor may e. g. detect lateral acceleration; when the control circuit determines that the lateral acceleration is outside a predetermined range, it is implied that a take-off or landing takes place. In addition to the lateral acceleration, vibration characteristics or an absolute rate of ascent may be sensed. Alternatively, the sensor may be a receiver for picking up a signal that is broadcast by a transmitter when the aircraft is taking off or landing. Different operational phases of an aircraft flight can be distinguished based on factors such as movement, location, altitude, purpose etc. These operational phases may comprise, for example, "park", "taxi", "departure", and "arrival". An exemplary definition of flight phases may be found in the document "Guidance for the Use of Portable Electronic Devices on Board Aircraft", ED-130, December 2006, European Organisation for Civil Aviation Equipment. Aviation Authorities may regulate how cellular radio devices, such as GSM or UMTS devices, may be used in different flight phases, based on how hazardous the cellular operations are deemed to during specific flight phases. How hazardous cellular operations are, may also depend on the level of activity by the cellular device. For example, near-constant cellular activity resulting from e.g. an active data connection or a call in progress may be more hazardous than merely keeping a cellular device registered on the network while no user communication is occurring via the cellular device. Without loss of generality, high levels of cellular network activity will be referred to as "constant interaction" or "constant transmission", and low levels of cellular network activity will be referred to as "short time interaction" or "short transmission". According to some regulations, portable electronic devices and/or cellular devices must be switched off with a defined reliability as soon as the airplane moves under its own force. Solutions currently known are not usable because disabling the radio module occurs too late. Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.

Summary of the invention

A method for controlling an electronic device and an electronic device, wherein the electronic device is capable of being transported on an airplane and includes a radio transmitter, providing automatic control of the radio transmitter during flight phases, substantially as shown in and/or described in connection with at least one of the figures, as set forth more completely in the claims. These and other advantageous aspects and novel features of the present invention, as well as details of an illustrated embodiment thereof, will be more fully understood from the following description and drawings.

Brief description of the drawings The drawings, used to explain a possible embodiment, show:

Fig. 1 a flow diagram of a mechanical acceleration monitor (MAM), in accordance with various embodiments of the invention;

Fig. 2 an exemplary V-point moving variance architecture and an exemplary /V-point moving average architecture; Fig. 3 an exemplary /V-point RRS (RRS: recursive running sum) architecture;

Fig. 4 an implementation of an exemplary exponential moving variance (EMV) block;

Fig. 5 an exemplary exponential average block (EA);

Fig. 6 an architecture of an exemplary automatic flight mode detector (AFM);

Fig. 7 a flow diagram of an exemplary watchdog Fig. 8 a fault tree analysis for exemplary constant transmission;

Fig. 9 a fault tree analysis for exemplary short transmission;

Fig. 10 an exemplary comparison circuit of the mechanical acceleration monitor (MAM);

Fig. 1 1 an exemplary location update timer (LUT);

Fig. 12 an exemplary radio energy monitor (REM); Fig. 13 a block diagram of an exemplary validation part of a MAM;

Fig. 14 an exemplary time window limiter (TWL); and

Fig. 15 an exemplary RF amplifier with output control. Detailed description of the invention

A method according to the invention comprises: a) collecting acceleration data and/or precession data from the electronic device; b) estimating parametric data from the acceleration data and/or precession data; c) comparing the parametric data with reference data in order to determine a

comparison result; and d) controlling the radio transmitter based on the comparison result.

To collect acceleration data and/or precession data, i.e. inertial sensor data, any device for measuring acceleration may be used, for example a highly miniaturized accelerometer based on MEMS technology (MEMS: Micro-Electro-Mechanical Systems) that may directly provide acceleration data and/or precession data in a digital format. However, it is possible to use a gyroscope or any other device for collecting acceleration data and/or precession data. Moreover, acceleration data may relate to rotational data, which may be collected using a specially designed device for measuring rotation or using any other device for measuring acceleration. Precession is a change in the orientation of the rotation axis of a rotating body and allows detecting a circular movement at constant angular speed when no acceleration is detectable.

The collected data may be stored, for example, in memory associated with a microprocessor for further processing, wherein estimation of parametric data, comparison with reference data, and control of a radio transmitter, for example a cellular transmitter, may be performed by a software module executable on the micro-processor. Estimation of parametric data may be based on current acceleration and on past acceleration, which may be collected during an observation window and stored in memory for further processing. On the other hand, estimation of parametric data may result from computations that may be performed on the basis of acceleration data and/or precession data and previously estimated parametric data. As soon as acceleration and/or precession indicate that the electronic device has moved, the electronic device can be controlled. Accordingly, components of an electronic device which should not be operated during certain flight phases can be disabled, or switched into an operation mode without radio interference to flight instruments. Such device components may include a cellular module designed for interaction with a cellular network, such as a GSM radio module, or a wireless radio module designed for interaction with other electronic devices, such as a WLAN module or a Bluetooth module.

In accordance with various embodiments of the invention, the estimated parametric data may comprise a first parameter, a second parameter, and a third parameter. For example, multi-dimensional acceleration data and/or precession data may be collected, wherein three parameters are estimated from the collected acceleration data and/or precession data, which are compared with reference data. Accuracy can be improved when acceleration values and/or precession values in more than one spatial direction are taken into account. Furthermore, the accuracy of the determination of a comparison result will be substantially independent from the orientation of the acceleration measuring device. Accordingly, a parameter in an x-direction, in a y-direction, and in a z-direction of a spatial system may be estimated. It is possible to compare these parameters to reference data composed of, for example, a single xyz-threshold, of an xy-threshold and a z-threshold, an xz-threshold and a y-threshold, or of an x-threshold, y-threshold, and z-threshold. The reference data may include one or more thresholds or a lookup table. A threshold may be determined according to a calibration performed in specific conditions, for example any movement of an aircraft. A lookup table may include several entries, wherein the comparison results may relate to various flight phases of an aircraft, for example "park/gate", "taxi-out", "cruise", "landing", or any other flight phase. The parametric data may include a normal moving variance (NMV) or an exponential moving variance (EMV). Exemplary details for calculating the NMV and EMV are given below. The moving variance may enable a counter with a threshold comparison for accurate control of the radio transmitter when transported in an airplane. The step of estimating parametric data may be performed more than once and a parameter based on the plurality of parametric data estimates may be compared with reference data. For example, parametric data may be estimated a number of times. In a first scenario, the radio transmitter may be controlled only in case the comparison with a threshold gives the same result for each estimation. In another scenario, the radio transmitter may be controlled in case a certain percentage of the comparisons give similar results.

Communication of the radio transmitter may be disabled for a period of time. In an exemplary embodiment, if a specific activity like activation of the radio transmitter takes place, a timer may be started and the radio transmitter may be disabled until a time interval has lapsed. For example, if a location update takes place, a further location update may occur after a certain time has passed.

Radio frequency energy may be measured, wherein the radio transmitter is disabled if the measured radio frequency energy exceeds an energy threshold. For example, an antenna measures the energy of radiated electromagnetic waves of the environment in a certain frequency range, and the radio transmitter may be stopped or paused for a time period in case the emitted electromagnetic energy exceeds some energy threshold. For example, if multiple radio transmitters are placed close to each other, the maximum transmitted radio energy will be limited. Communication of the radio transmitter may be disabled after a period of time has expired. The period of time may be initiated, for example, upon transmission of a communication packet, for example a location update, through the radio transmitter. The period of time may be defined such that sufficient time is provided to perform necessary functions, such as, for example, a location update. In accordance with various embodiments of the invention, the period of time may be defined such that the overall emission of radio energy remains limited.

A counter of a clock circuit may be activated, wherein the counter may be reset after a period of time, or wherein the electronic circuit may be reset if the counter reaches a threshold. For example, the counter may be reset at certain time intervals and a reset of the electronic circuit may be generated for example when the counter reaches a threshold value.

The controller may actuate one or more switches arranged between a radio amplifier and an antenna. For example, in order to disable the radio transmitter, both an input signal can be disabled and one or more of the switches can be opened, thereby avoiding to rely on further complex components.

The electronic device may be implemented as, or in, a chipcard. The chipcard may be any electronic card with embedded integrated circuits. For example, the chipcard may contain memory and microprocessor components. The chipcard may be implemented, for example, as a SIM card (SIM: subscriber identification module)

Fig. 1 shows schematically a flow diagram of an exemplary mechanical acceleration monitor (MAM), which may, for example, be implemented as a software module executable on a microprocessor system. In step 1 , the mechanical acceleration monitor (MAM) is started. In step 2, a flight-mode detector is reset. In step 3, samples x_n , y_n , z_n of a three dimensional accelerometer are collected for multiple spatial axes, wherein the subscript n denotes the sample index.

Acceleration data is collected on the basis of any suitable accelerometer. Digital acceleration data may be provided at suitable sampling frequencies and with suitable resolutions. Additionally or alternatively, precession data may be collected using any suitable gyroscope or any other inertial sensor. In this case, the following description of the estimation of parametric data has to be adapted accordingly.

In step 4, a parameter is estimated based on acceleration data collected during an observation window. A normal moving variance (NMV) or an exponential moving variance (EMV) may be estimated for each of the axes as follows, in accordance with an exemplary embodiment of the invention. The normal moving variance (NMV) may be estimated according to the following formula, for example:

where N is the number of samples taken in an observation window. To lower the computational load, suitable data processing can be applied. For example, a regression approach may be used.

The EMV may be useful when there is little available memory for collecting measurements, or when costs of memory access dominate those of computation, or when using a weighting approach for different acceleration samples. The exponential moving variance (EMV) may be estimated according to the following formulas, for example: x_n = (l - «)*„_, + a x_n

EMV_n = σ = (1 - « ²-, + a{x„ - x_n f

Where n is the sample index, a is a weighting factor, x₀ = 0 , and

= 0 . In Fig. 1 , step 4, the EMV may be estimated for multiple acceleration axes, for example EMV( xJ,

In step 5, the EMV values may be compared with a threshold o,_h ²:

EMV( x_n ) < o_th ² AND EMV( y_n ) < σ*² AND EMV( z„ ) < o_th ²

Where "AND" denotes a logic AND function. The formula applies similarly when NMV is used. When the result of the comparison is false, the aircraft is considered in flight (dynamic condition) in step 6 and the MAM continues at step 3, and another sample may be collected for one or more axes. Otherwise, the aircraft is considered in a non-flight condition (stationary condition) in step 7. In step 8, multiple comparison results may be considered together; for example, if a certain number of comparisons are true, the aircraft is considered stationary in step 9. Otherwise, the aircraft is considered in flight in step 6.

To distinguish a stationary condition from a dynamic condition, data obtained from the accelerometer of a stationary aircraft may be analysed, for example. Often, the acceleration data may be distributed normally in each of the axes according to a similar power spectral density. Hence, for such types of accelerometers, it may be sufficient to define a single threshold value for each of the axes.

The following table shows exemplary raw measurements of a particular accelerometer:

In accordance with various embodiments of the invention, a suitable threshold o,_h ^z may be selected, for example based on a desirable probability of a wrong detection of whether the airplane is in stationary condition (non-flight) or dynamic condition (flight).

In step 8, multiple NMV/EMV based decisions on the stationary condition of the airplane may be compared, and a further decision on the stationary condition may be generated, corresponding to a longer observation interval. The longer interval may be, for example, several seconds.

The power spectral density of the acceleration measurement on each axis generally varies during different stages of the flight (takeoff, flight and landing). The amplitude spectrum noise may increase when the engines are on (e.g. when movement starts), comparing to the case when the sensor is stationary. The landing phase of the flight may result in more elevated noise levels. A peak component, often around 10 Hz, during the stages of the flight where the engines are on may exist due to engine vibration. Large power spectrum components may also occur due to turbulence during a flight. The power spectrum density characteristics may depend on the type of transport vehicle, and the motorization, for example. In many cases, the main spectral components are below approximately 20 Hz. Therefore, sampling frequencies of about 40 to 60 Hz are often practical.

In Fig. 2, and Fig. 3, the reference signs 201 and 301 denote an RRS (RRS: recursive running sum) architecture. The reference signs 202 and 302 denote multipliers and reference signs 203 and 303 denote summers. Reference sign 304 denotes delay elements. Fig. 3 shows schematically the AApoint RRS, which forms a building block of the architecture shown in Fig. 2. x_n may denote an average at time n, of samples x_n over a certain observation period, see also below.

Fig. 2 shows schematically the A point moving variance CT„² and AApoint moving average „ architecture, which implement the following exemplary formula for calculating the NMV, in accordance with an exemplary embodiment of the invention:

where x_n denotes an average and is defined as:

The formula to compute the EMV may be written as: where k is equal to the weighting factor a _j and x_n corresponds to the mean average and is equal to: x_n = (l - a)x₍ + ax n

To make a relationship with the NMV, when we set k =— , then we obtain:

N

Fig. 5 shows schematically the implementation of an exemplary exponential average block (EA), which forms a building block of Fig. 4 and is denoted with reference sign 401 and 501 in Fig. 5. In Fig. 5, reference sign 502 refers to a multiplier, reference signs 503 refer to summers, reference sign 504 refers to a delay element. y_n is the output signal of the EA

10 501.

The implementation of the EMV is composed of two exponential averager blocks EA, and is shown in Fig. 4, which shows the mechanical acceleration monitor (variance part). In Fig. 4, reference sign 402 denotes a multiplier, reference sign 403 denotes a summer, and reference signs 401 denote exponential averager blocks ΕΑ(α, ) and EA( <2₂ ) .

15 Fig. 6 shows schematically the architecture of an automatic flight mode detector (AFM).

The architecture includes elements that enable a radio transmitter to interact with a GSM network upon positive detection. The architecture shown in Fig. 6 includes the following elements:

- a mechanical acceleration monitor (MAM) 61 1 , comprising: 0 o a mechanical acceleration monitoring algorithm, for example using sensor 610; and o a watchdog mechanism that will restart the MAM under certain conditions. 201

14

- a time-energy monitor (TEM) 612, comprising: o a radio energy monitor (REM) that monitors the transmitted radio energy, for example using antenna 613; o a location update timer (LUT) that limits the use of the GSM module in time, for example on the basis of a timer 614. The LUT restricts the time window; o a time window limiter (TWL) that limits the transmission time, for example on the basis of timer 614; and o a watchdog mechanism that will restart the TEM under certain conditions.

- a user application (UA), denoted with reference sign 615, - a GSM signal processing module ("GSM Module"), denoted with reference sign 616,

- a GSM RF amplifier, denoted with reference sign 620.

In Fig. 6, RF-switches S_A and S_B are denoted with reference signs 617, 618. RF-switches S_A and S_B are controlled based on the MAM 61 1 output and the TEM 612 output. The RF- switches S_A, S_B are connected in series between the GSM RF amplifier 620 and the antenna 619. Hence, if one of the RF-switches S_A, S_B is open, transmission of RF energy is inhibited. Moreover, the TX-enable signal, which is connected between the GSM module 616 and the TEM 612, is further connected to a first input of logic AND gate 621. The output signals of the outputs of TEM 612 and of MAM 61 1 are combined in a logic AND gate 623, whose output is connected to a second input of logic AND gate 621. The result is that the RF-switches S_A and S_B are blocked, and the GSM RF amplifier 620 may be disabled.

The user application (UA) 615 may run any user application independently of the flight mode detection through interface 670, for example.

In addition to the accelerometer-related functions, a watchdog function may be added to monitor the execution of the algorithm. Such a watchdog function may be implemented as a counter with an independent clock signal which generates a global system reset when the counter reaches a threshold value. During normal operation, this counter will be reset regularly so it may not reach the threshold value. In case of an algorithmic or system failure, the software cannot reset the watchdog clock, eventually leading to a global reset.

Fig. 7 shows the flow diagram of an exemplary watchdog. At step 700, the counter of an independent clock is reset. In step 701 , the counter increments. In step 702, the counter is compared with a threshold value. If the threshold value is reached, in step 703, a global system reset is performed. The watchdog is then restarted and returns to step 700. If the threshold value of the counter is not reached, step 702, it is checked in step 704 if the system has requested a reset of the counter. If a reset of the counter has been requested, the watchdog is restarted and returns to step 700. If no reset of the counter has been requested, which may occur in case the system does not function correctly, the watchdog returns to step 701.

Fig. 8 shows a first fault tree analysis for exemplary constant transmissions.

As the GSM module 616 may be implemented in software, it is not considered for error probability certification. Its error probability is assumed to be 1 and has been eliminated from the analysis.

The user application UA 615 is controlling the GSM module 616. As the error probability of the GSM module 616 is assumed to be 1 , the influence of the user application (UA) 615 is not accounted for either. The AFM, Fig. 6, then adds functionality to reduce the probability of a constant transmission during flight.

In Fig. 8, reference sign 839 denotes the case of a MAM detection failure during flight, that is, the MAM algorithm detecting a non-flight condition while in flight, is denoted with reference sign 831 , or the RF-switch S_A being on but its control signal from the MAM being off, which is denoted with reference sign 832. As indicated by the OR gate 833 there is a MAM detection failure if at least one the events 831 , 832 occurs. Accordingly, the probabilities of these events add to a total probability of the order of 10^"5. Reference sign 849 denotes the case of a TEM allowing radio transmission when it should not. This condition occurs a) if there is a failure of the timer functions Tmr of the LUT, and/or the TWL, based on the timer 614, for example, denoted with reference sign 841 in combination with a failure of the REM in detection of radio energy RE, which is denoted with reference sign 842, the requirement of both occuring at the same time indicated by the AND gate 844 (accordingly, the two probabilities multiply); and/or b) the RF-switch S_B being on but its control signal according to the TEM being off, denoted with reference sign 843. If either event a) or b) is present, TEM allows for radio transmission when it should not. The corresponding probability is the sum of the probabilities of the two events, i. e. of the order of 10^"2.

Reference sign 800 denotes constant transmission, which is a result of a MAM detection failure and TEM detection failure during flight, indicated by the AND gate 801. The failure rates are multiplied as denoted in Fig. 8, wherein a failure rate of 10^~7 is achieved for constant transmission, for example. Fig. 9 shows a second fault tree analysis for short transmissions, i.e. transmissions which occur during a flight with the authorized time window enabled and while not exceeding the RF-energy level (both controlled by the REM and TWL, respectively). In this case, the fault classification in aviation safety terms is minor and the rate should not exceed 10^~3 per flight hour, for example. In Fig. 9, reference sign 939 denotes the case when flight-mode detection has failed. Reference sign 949 denotes the case when the TEM could not react because of the short time window. The corresponding failure probability is therefore 1. Reference sign 900 denotes the case of a short transmission. Reference signs 931 , 932, 941 , 942, 943 denote the same cases 831 , 832, 841 , 842, and 843, similar to Fig. 8. The failure rates are combined as denoted in Fig. 9 (OR gates 933, 945; AND gates 944, 901 ), wherein an exemplary failure rate of 10^"3 is achieved for a short transmission. The requirement for the short-duration transmission during flight enforces the exemplary acceptable fault level for the MAM to 10^"3 per flight hour. To reduce interference, it may be desirable to utilize connection-less GSM modes of data transfers because they may generate less interference than connection-oriented GSM modes of data transfers.

Fig. 10 shows a block diagram of an exemplary comparison circuit of the MAM, which provides a logic signal 'Notjnjlight' based on the EMV( x_n ), EMV( .y_n ), EMV( z_n ) of the axes taken into consideration, and which may be combined and passed through a limiter 1050 which generates a clock enable signal of a counter circuit 1051 . The role of the limiter 1050 is to stop the counter 1051 when it reaches a threshold value (indicated by 'Max') and a new "up-count" condition occurs. It also stops the counter 1051 when the counter 1051 reaches zero and a "count-down" condition occurs. The EMV algorithm allows for an efficient implementation in both hardware and software. Its basic structure contains a running sum of mean values and variance values. A delayed decision mechanism to generate the logical signal 'Notjnjlight', and therefore a stationary condition, may be performed in logic circuitry and based on relevant samples. The role of the time energy monitor (TEM) shown in Fig. 6 is to limit GSM transmissions by adding time and RF-energy constraints. This may be achieved with the help of three units: a location update time (LUT), a radio energy monitor (REM), and a time window limiter (TWL), see also Figs 1 1 , 12, and 13.

Fig. 1 1 shows a location update timer (LUT), which limits the number of location requests that may occur in a certain period of time.

The principle of the LUT is to disable the GSM output for a certain time interval in the event of a location update.

Hence, as shown in Fig. 1 1 , the 'Event' signal, which is denoted with reference sign 1 150, may initiate the process. If a location update is requested and the location update counter 1 151 is not running, the request will be accepted and a 'Loc_ok' signal will be set.

Once the location update has finished, i.e. the 'Event' signal 1 150 has been reset, the location update counter 1 151 may be loaded with a timeout value 'Max interval' and the 'Event' request flag may be reset as well as the 'Loc_ok' signal. The location update counter 1 151 will then start a countdown.

If a new request for a location update is generated before the location update counter has reached zero, the 'Event' request flag may be set, but the 'Loc_ok' signal may not be set. When the location update counter 1 151 reaches zero and the 'Event' request flag is set, the 'Loc_ok' signal will be set.

The 'Event' signal 1 150 should remain in a set state as long as the location update has not been treated. When more than one event occurs, the 'Event' signal 1 150 should remain in a set state. When the 'Event' signal 1 150 is released, for example in case a location update has been performed, a new time interval will be triggered during which a location update is prevented. Timestamps of pending requests for location updates are not handled by the LUT.

The LUT may, for example, be implemented on a dedicated MCU (MCU: Micro Controller Unit). In another implementation, as shown in Fig. 10, a 'Maxjnterval' value may be provided, together with counter circuit 1 151 and a latch 1 152 in order to implement the LUT functionality.

Fig. 12 shows an exemplary radio energy monitor (REM), which may monitor radiated RF energy of a radio transmitter and disable a radio amplifier as well as deliver a corresponding signal to the GSM-unit if emissions exceeded a threshold,. A controller may be provided to disable the radio transmitter or suspend transmission for a certain period of time.

RF-energy is detected through an antenna, labelled "RF-in", which, for example, is not physically connected to the antenna of the GSM-unit. In addition, the placement of the REM antenna is desirably as far as possible from the GSM main antenna. REM may be enabled whenever the TEM is enabled. When TEM is not enabled, a signal may be set to false in order to disable GSM communications. Hence, REM and TEM operate in parallel, which may have the following consequences: - The GSM communication may be only enabled when the REM is enabled.

- The RF-power level may be limited via a pre-set limit.

- The probability of a non-functioning REM is determined by the reliability of the REM circuitry. When the REM operates on UHF signals, it may be implemented in analogue hardware, for example. The basic functionality may be implemented, for example, using a diode and a capacitor plus some filtering circuitry, wherein, for example, a matching filter (MF) circuit may be used in order to maximize the signal to noise ratio. An 'RF_ok' signal is generated according to a comparison of measured radio frequency energy with a threshold 'RF_max_limit'.

The implementation of the REM detection circuitry may be made in dedicated hardware, wherein the reliability substantially depends on the following elements:

- Reliability of the individual components;

- Structure of the filtering and matching circuitry; - Number of interconnections and the reliability of the interconnections.

Fig. 13 shows the time window limiter (TWL), which provides, as described earlier, that the duration of the GSM transmissions does not exceed a certain period of time. As shown in Fig. 13, the TWL includes a counter circuit 1351 , which may be connected to the power amplifier enable 'TXEN' signal of the GSM radio amplifier circuit. This signal controls the power amplifier circuit and is enabled in case of GSM transmission. As the GSM protocol is based on a TDMA access scheme (TDMA: Time Division Multiple Access), each transmission corresponds to a time slot and the corresponding power amplifier enable signal is enabled during this slot.

The TWL will set the 'Window_ok' signal high as long as the counter value remains below a certain threshold value 'Max_cnt'. This threshold value is determined depending on the effective number of frames to be transmitted for registering to the GSM network and transmitting an SMS or performing a location update, for example. The 'Window_ok' signal may be asserted low when the counter value exceeds this limit.

The 'Event' signal may enable the time window limiter (TWL) before a transmission request. When asserted low, the counter value is reset and the output signal 'Window_ok' is kept low.

The time window limiter (TWL) may be implemented on a dedicated MCU in assembler. The power amplifier enable signal 'TXEN' may be used as a clock enable signal for a software counter, and the counter may be reset when the 'Event' input signal is reset.

The effect of the time window limiter (TWL) is to reduce transmissions. While the LUT already reduces transmissions, the time window limiter (TWL) reduces transmissions further by limiting the effective transmission duration.

Fig. 14 shows an exemplary time energy monitor (TEM), which combines the location update timer LUT, the radio energy monitor (REM), and the time window limiter (TWL) into a single output signal. As shown in Fig. 14, the signals 'Loc_ok', 'RF_ok', and 'Window_ok' are combined through a logic AND circuit to provide the 'GSM_allow' signal used for enabling or disabling the radio transmitter.

Moreover, as described earlier, a watchdog may be provided, to increase robustness of the circuitry shown in Fig. 10 - Fig. 14. The watchdog monitors the time energy monitor (TEM). Its function is to generate a global system reset when a counter reaches a threshold value. The counter may be reset regularly so it will not reach this threshold value and a global reset will not occur. If, however, a system failure occurs, a system reset may be generated, thus preventing the circuit from remaining in an error condition.

In accordance with various embodiments of the invention, the watchdog verifies two aspects for the location update timer (LUT): 1 ) That the 'Loc_ok' signal is disabled if the 'Event' signal is disabled; and 2) That the counter counts down at a regular interval if the 'Event' signal is disabled and the counter is not O.For the radio energy monitor (REM), the watchdog verifies that a changing energy level is detected on its input when the GSM module is transmitting. For the time window limiter (TWL), the watchdog verifies that the 'TXEN' signal does not remain enabled. When this occurs, a watchdog reset may be generated. For the complete time energy monitor (TEM), the watchdog verifies that the 'GSM_allow' signal is only enabled if the 'Loc_ok' AND the 'RF_ok' AND the 'Window_ok' signals are enabled. The GSM RF amplifier part of the GSM circuit is responsible for the amplification of the GSM signal that is generated by the GSM module. The automatic flight mode AFM may use a control input to enable/disable the power output amplifier.

Fig. 15 shows a basic structure of an exemplary GSM amplifier. Using two RF-switches in series reduces the reliability constraints on the RF-switches and performs a logic AND- function at the same time. The input 'txin' of the power amplifier 'Power amp' is amplified. It is only amplified when the signals 'Notjnjlight', 'GSM_allow', and 'Power amp enable' are enabled. Additionally, switches 'S_A' and 'S_B' are serially connected between the output of the power amplifier 'Power amp' and the output 'txout, as shown in Fig. 6, for example. Switch 'S_A' is closed in case the 'GSM_allow' signal is enabled and switch 'S_B' is closed in case the 'Not_in_f light' signal is enabled.

For most electronic components, a constant failure rate hypothesis is assumed. This means that the error probability is assumed to be constant over time as wear out or ageing effects are expected to be very small.

According to the present invention, an automatic flight mode (AFM) detector is provided that is composed of multiple items each contributing to the reduction of the probability of a false positive authorization.

It is to be noted that the invention is not restricted to the embodiment described above. Other embodiments may feature a smaller or higher number of circuits for excluding false positive authorizations. Furthermore, the invention is not restricted to controlling GSM or other cellular network devices but is applicable to other purposes as well. The detailed aspects of the embodiment presented above represent a possible and preferred way of embodying the invention, however different solutions are possible. In summary, it is to be noted that the invention provides for a method and an electronic device having a radio transmitter and being transportable in an airplane, which provides reliable automatic control of the radio transmitter during a flight. The invention is applicable for any airplane or helicopter, as well as any vessel referring to small or big airplanes, cargo or passengers, big or small helicopters.

Claims

1. A method for controlling an electronic device that is capable of being transported on an airplane, wherein the electronic device includes a radio transmitter, comprising: a) collecting acceleration data and/or precession data from the electronic device; b) estimating parametric data from the acceleration data and/or precession data; c) comparing the parametric data with reference data in order to determine a comparison result; and d) controlling the radio transmitter based on the comparison result.

2. The method according to claim 1 , characterized in that the estimated parametric data comprises a first parameter, a second parameter, and a third parameter.

3. The method according to claim 1 or 2, characterized in that the reference data includes one or more thresholds or a lookup table, and/or that the parametric data includes a normal moving variance (NMV) or an exponential moving variance (EMV).

4. The method according to one of claims 1 to 3, characterized in that the step of estimating parametric data is performed more than once and a parameter based on the plurality of parametric data estimates is compared with reference data.

5. The method according to one of claims 1 to 4, characterized in that communication of the radio transmitter is disabled for a period of time.

6. The method according to one of claims 1 to 5, characterized in that radio frequency energy is measured, wherein the radio transmitter is disabled if the measured radio frequency energy exceeds an energy threshold.

7. The method according to one of claims 1 to 6, characterized in that communication of the radio transmitter is disabled after a period of time has expired.

8. The method according to one of claims 1 to 7, characterized in that a counter of a clock circuit is activated, wherein the counter is reset after a period of time has expired, or wherein the electronic circuit is reset if the counter value reaches a threshold.

9. An electronic device that is capable of being transported on an airplane, wherein the electronic device includes a controllable radio transmitter, further comprising: a) an accelerometer and/or a gyroscope for collecting acceleration data and/or precession data of the electronic device; b) an estimator for estimating parametric data from the collected acceleration data and/or precession data; c) a comparator for comparing the parametric data with reference data in order to determine a comparison result; and d) a controller for controlling the radio transmitter based on the comparison result.

10. The electronic device according to claim 9, characterized in that the estimator estimates parametric data composed of a first parameter, a second parameter, and a third parameter.

1 1. The electronic device according to claim 9 or 10, characterized in that the reference data includes one or more thresholds or a lookup table, and/or that the parametric data includes a normal moving variance (NMV) or an exponential moving variance (EMV).

12. The electronic device according to one of claims 9 to 1 1 , characterized in that the estimator estimates parametric data more than once and a parameter based on the plurality of parametric data estimates is compared with reference data.

13. The electronic device according to one of claims 9 to 12, characterized in that an update timer module defines a period of time, wherein the radio transmitter is disabled for the period of time.

14. The electronic device according to one of claims 9 to 13, characterized in that a radio energy monitor measures the radio frequency energy of the radio transmitter, wherein the radio transmitter is disabled if the measured radio frequency energy exceeds an energy threshold.

15. The electronic device according to one of claims 9 to 14, characterized in that a window limiter module defines a period of time, wherein the radio transmitter is disabled after the period of time has expired.

16. The electronic device according to one of claims 9 to 15, characterized in that a watchdog initiates a counter of an independent clock circuit, wherein the counter is reset after a period of time has expired, or wherein the electronic circuit is reset if the counter value reaches a threshold.

17. The electronic device according to one of claims 9 to 16, characterized in that the controller actuates one or more switches arranged between a radio amplifier and an antenna.

18. The electronic device according to one of claims 9 to 17, characterized in that the electronic device is implemented as or into a chipcard.