Time tracking module, system and method for the implementation thereof

Abstract

The present invention relates to a radiolocation and time-tracking module (10), comprising: a phase-locked loop (PLL), which receives radio-frequency signals (S1A, S1B) from at least one transmitting base (4A, 4B), the signals having a general period (GP) and being synchronized with the absolute date (DA); the phase-locked loop (PLL) then locks phase feedback to the signals (S1A, S1B); the phase-locked loop (PLL) then transmits signal time data (DS) to a high-speed counter (HSC), the phase-locked loop (PLL) taking into account the general period (GP) and the synchronized signal (S1A, S1B); the high-speed counter (HSC) receiving the signal time data (DS) transmitted by the phase-locked loop (PPL), the high-speed counter (HSC) transmitting time data (DH) comprising an ambiguity with respect to the general period (GP), and therefore with respect to the date of the received signal (S1A, S1B); a real-time clock (RTC) providing a signal (SRTC) conveying a real-time datum (DRT); a low-speed counter (LSC) receiving the real-time datum (DRT) from the real-time clock (RTC), the low-speed counter (LSC) transmitting time data (DL) capable of removing the ambiguity with respect to the general period (GP), and therefore with respect to the date of the received signal (S1A, S1B); a date generator (DG), which receives the time data (DH; DL) from the counters (HSC; LSC); determines a date (DATE) on the basis of these time data (DH, DL); and controls a pulse generator (PG), which generates an output signal (S2) with a given frequency (FP).

Description

[0001] Time tracking module, system and implementation method

[0002] [1] Technical field

[0003] [2] The present invention relates to a time-tracking module. The invention also relates to a system, which may be either a time-tracking system or a radio-location and time-tracking system, comprising such a time-tracking module. The invention further relates to a method of implementing such a time-tracking module.

[0004] [3] The field of the invention is that of radio frequency communication devices.

[0005] [4] Prior art

[0006] [5] The localization of receiver modules in outdoor environments saw a significant technological leap with the deployment of the GPS (Global Positioning System) in the 1980s. GPS also enables precise time tracking thanks to GPSDOs (GPS-disciplined oscillators). However, GPS technology does not work in indoor environments, typically inside buildings, and performs relatively poorly in urban environments.

[0007] [6] There is therefore a need for radiolocation and time tracking systems of receiver modules which have both a long range (typically greater than 10 km) and which work equally well in outdoor and indoor environments.

[0008] [7] As is known, a location and time tracking system in an outdoor or indoor environment most often comprises, in addition to the module to be positioned or on which absolute time must be reproduced, a set of at least three beacons. These beacons are characterized by their known position and their synchronization with absolute time. Furthermore, they are usually fixed. In such a system configuration, the beacons control the transmissions: a beacon transmits to a module, and the module responds by retransmitting to the beacon. Measuring the transmission time, by taking the difference between the transmission time and the reception time, allows the distance between the beacon and the module to be determined.However, such a system requires the receiver module to retransmit signals to the beacons so that a remote server can deduce the module's position, thus preventing the module from performing its own positioning.[8] Radiolocation systems also use modulated radio frequency signals, emitted by fixed beacons or antennas, to transmit, for example, positioning and time data or random data to a receiver. Such random data, for example, data known in advance to the receiver, helps the receiver synchronize with the random data by performing signal correlations. However, such systems require a large frequency transmission bandwidth, typically several tens or hundreds of MHz for radiolocation systems with meter or sub-meter accuracy.The extensive use of the spectral band forces the manufacturer to use high carrier frequencies (>GHz). These waves do not penetrate walls. Such radio-location and time-tracking systems do not allow for dual-use operation, whether outdoors or indoors.

[0009] [9] US2006244661 describes a terminal location system, illustrating the general technological background. The receiver and transmitter use a phase-locked loop (PLL) to generate the modulation and demodulation frequencies.

[0010]

[0010] EP 4323789 A1 describes a system and method for radio-locating at least one receiver module, by the module itself, in both outdoor and indoor environments. By overcoming the drawbacks of the prior art, this technology constitutes a particularly advantageous solution, which can be further improved.

[0011]

[0011] In particular, it is important that the receiver module be able to track time to 10ns, especially in environments without GPS signals.

[0012]

[0012] Description of the invention

[0013]

[0013] The object of the present invention is to remedy the above problem.

[0014]

[0014] To this end, the invention relates to a time-tracking module, comprising:

[0015] - a closed-loop control system, configured for:

[0016] to receive radio frequency signals from at least one transmitting base, the signals received from each base comprising at least two unmodulated pure carrier signals of distinct frequencies, each pure carrier signal being in the form of an unmodulated sustained wave, preferably sinusoidal, the signals received from each base having a general period and being synchronized with the absolute date; then

[0017] o lock in phase feedback on said signals; then o transmit signal time data, taking into account the general period and the synchronized signal, to a high-speed counter; the high-speed counter configured to receive the signal time data transmitted by the phase-locked loop and to output time data, including an ambiguity on the general period and therefore on the date of the received signal;

[0018] - a real time clock (known as RTC Real Time Clock in English) configured to provide a signal carrying real time data, in normal operation or during a period of autonomy of the module, even when the module is turned off during this period of autonomy;

[0019] - a low-speed counter configured to receive real-time data from the real-time clock and emit time data, capable of removing ambiguity on the general period and therefore on the date of the received signal;

[0020] - a date generator configured for:

[0021] to receive the time data from the high-speed counter and the time data from the low-speed counter;

[0022] to determine a date from this temporal data; and

[0023] o to control a pulse generator producing an output signal of defined frequency.

[0024]

[0015] Thus, the invention enables time tracking accurate to within 10 ns, thanks to signal reception and the phase-locked loop integrated into the module. However, this signal alone contains an ambiguity regarding the overall period, and therefore the date. This ambiguity can be resolved by means of the integrated real-time clock (RTC), which, although much slower, is sufficiently precise to determine the period in which the measurement takes place. The date generator generates the date, while the pulse generator generates the output signal.

[0025]

[0016] The output signal can be used for various applications requiring precise date information. The module is particularly useful in environments without GPS signal coverage, whether indoors or outdoors.

[0026]

[0017] The invention applies to any system requiring synchronization of less than 10 ns between devices not connected by cable: geolocation, sensor networks and smart grids, high-speed telecommunications, high-frequency trading, etc.

[0027]

[0018] According to other advantageous features of the module according to the invention, taken individually or in combination:

[0028]

[0019] The module includes an external communication system, configured to transmit the date according to a predefined communication protocol, for example an NMEA protocol via UART, the date being synchronized with the absolute date.

[0029]

[0020] The module includes an external communication system, configured to transmit the output signal.

[0030]

[0021] The external communication system includes a device configured to transmit the date and a device configured to transmit the output signal, these two devices being separate.

[0031]

[0022] The pulse generator is configured so that the output signal is generated at a frequency adjustable by a user.

[0032]

[0023] The pulse generator is configured so that the output signal is generated at a default frequency, which is not adjustable by a user.

[0033]

[0024] The pulse generator driven by the date generator is configured so that the output signal is generated at a defined frequency of 1 Hz (by default or at the user's choice) and synchronized with the absolute date.

[0034]

[0025] The real-time clock includes a quartz crystal, having a preferred frequency of 32.768 kHz, corresponding to the frequency of the signal emitted by the real-time clock.

[0035]

[0026] The time data transmitted by the low-speed counter to the date generator conveys the absolute date.

[0036]

[0027] The invention also relates to a time tracking system, characterized in that it comprises at least one module as described above.

[0037]

[0028] According to a particular embodiment, the time tracking system comprises:

[0038] at least one time tracking module;

[0039] at least one fixed transmitting base, each transmitting base being configured to transmit radio frequency signals, the transmitting bases being synchronized with each other to transmit their respective signals, each transmitting base being configured to transmit a sum of at least two unmodulated pure carrier signals of distinct frequencies, each pure carrier signal being in the form of an unmodulated sustained wave, preferably sinusoidal;

[0040] the time tracking module being configured to receive and process said radio frequency signals and deduce the absolute time.

[0041]

[0029] According to another particular embodiment, the system is a radiolocation and time tracking system, comprising:

[0042] at least one time tracking module to be located;

[0043] at least two transmitting bases, each transmitting base being configured to emit radio frequency signals, the transmitting bases being synchronized with each other to emit their respective signals, each transmitting base being configured to emit a sum of at least two unmodulated pure carrier signals of distinct frequencies, each pure carrier signal being in the form of an unmodulated sustained wave, preferably sinusoidal;

[0044] the module being configured to receive and process said radio frequency signals and to deduce its position and absolute time by calculating pseudo-distances between the module and the transmitting bases, the module comprising means for storing position data of the fixed transmitting bases, the module further comprising:

[0045] Measurement means, for each given signal frequency and for each respective transmitting base, of the phase and amplitude of the signal consisting of the different signals originating from said base and exhibiting said frequency; and computing means connected to the measurement means and storage means, and configured to:

[0046] to apply, for each transmitting base, a high-resolution spectral analysis algorithm on a signal consisting of the different frequencies with a measured amplitude and phase of the radio frequency signals from said base;

[0047] to determine, for each emitting base, from the spectral analysis carried out for said base, a pseudo-distance between the module and said base;

[0048] to determine the date and position of the module, from the calculated pseudo-distance(s) and the position data of the transmitting base(s).

[0030] The invention also relates to a method for implementing a module as described above, comprising the following steps:

[0049] The input is the phase-controlled loop:

[0050] o receives radio frequency signals from at least one base; then o latches in-phase feedback onto said signals; then

[0051] o transmits signal time data, taking into account the overall period and the synchronized signal, to a high-speed counter; the high-speed counter receives the signal time data transmitted by the phase-locked loop and emits time data;

[0052] the real-time clock provides a signal carrying real-time data, in normal operation or during a period of autonomy of the module, even when the module is turned off during this period of autonomy;

[0053] The low-speed counter receives real-time data from the real-time clock and outputs time data;

[0054] the date generator:

[0055] o receives the time data from the high-speed counter and the time data from the low-speed counter; then

[0056] o determines a date from this temporal data; and

[0057] o pilots a pulse generator which produces an output signal of a defined frequency.

[0058]

[0031] According to other advantageous features of the method according to the invention, taken individually or in combination:

[0059]

[0032] The method includes an external communication step, consisting of transmitting the date according to a predefined communication protocol, for example NMEA via UART, the date being synchronized with the absolute date.

[0060]

[0033] The module is located in an area where GPS signal reception is degraded or even impossible.

[0061]

[0034] The module is located indoors, in particular in a building or basement.

[0062]

[0035] The module is located outdoors, in particular in an area of ​​electronic jamming.

[0063]

[0036] Description of the figures

[0037] The invention will be better understood upon reading the following description, given solely by way of non-limiting example and made with reference to the accompanying drawings in which:

[0064]

[0038] Figure 1 is a schematic representation of a radiolocation and time tracking system according to the invention, comprising a receiver module and transmitting bases, the receiver module being configured as a time tracking module also according to the invention.

[0065]

[0039] Figure 2 is a graph representing two Fourier transforms as a function of the pseudo-distance, each Fourier transform corresponding to a distinct transmitting basis and having been applied by the receiving module to a signal consisting of the different frequencies with a measured amplitude and phase of the radio frequency signals from that basis.

[0066]

[0040] Figure 3 is a graph illustrating the ambiguity on the date over a general period, for the signals received by the radiolocation module.

[0067]

[0041] Figure 4 is a schematic representation of the radiolocation module and its constituent elements.

[0068]

[0042] Detailed description of the invention

[0069]

[0043] Figure 1 illustrates a radiolocation and time-tracking system (1) according to the invention, comprising transmitting bases (4) and at least one module (10) according to the invention. The system (1) is configured for positioning the module (10) relative to the transmitting bases (4). The module (10) is a radio frequency signal receiver module, configured to perform a radiolocation function and a time-tracking function.

[0070]

[0044] The module (10) is configured to receive and process radio frequency signals from the transmitting bases (4) and to deduce its position and absolute time by calculating pseudo-distances between the module (10) and the transmitting bases (4). The module (10) includes means for storing position data of the fixed transmitting bases (4).

[0071]

[0045] Each transmitting base (4) is configured to transmit a sum (SIA, S1B) of at least two unmodulated pure carrier signals of distinct frequencies, each pure carrier signal being in the form of an unmodulated continuous wave, preferably sinusoidal.

[0072]

[0046] The module (10) further comprises: means for measuring, for each given signal frequency and for each respective transmitting base (4), the phase and amplitude of the signal consisting of the various radio frequency signals originating from said transmitting base (4) and exhibiting said frequency; and

[0073] computing resources connected to measurement and storage resources, and configured for:

[0074] to apply, for each transmitting base (4), a high-resolution spectral analysis algorithm on a signal consisting of the different frequencies with a measured amplitude and phase of the radio frequency signals from said transmitting base (4);

[0075] to determine, for each emitting base (4), from the spectral analysis carried out previously, a pseudo-distance between the module (10) and said emitting base (4);

[0076] to determine the date and position of the module (10), from the calculated pseudo-distance(s) and the position data of the emitting base(s) (4).

[0077]

[0047] Advantageously, the radiolocation and time tracking system (1) can be configured as follows:

[0078] - For each transmitting base (4), the frequency difference between the minimum frequency and the maximum frequency of the pure carrier signals emitted by said base (4) is greater than 50 MHz.

[0079] Each pure carrier signal emitted by a transmitting base station (4) has a frequency in the very high frequency band, that is, a frequency in the range from 30 MHz to 300 MHz. - The transmitting bases (4) are configured to emit the same number of unmodulated pure carrier signals.

[0080] - The transmitting bases (4) are configured so as to transmit their sums (SIA, S1B) of unmodulated pure carrier signals in a frequency-shifted manner, with a predetermined frequency shift between two successive transmitting bases (4).

[0081] - The frequency offset is within the range of 100 Hz to 1 kHz.

[0082]

[0048] Alternatively, the system (1) can be a time-tracking system without a radio-location function. In this case, the system (1) can integrate a single transmitting base (4) instead of several bases. The module (10) is then a time-tracking module without a radio-location function.

[0083]

[0049] With reference to Figure 1, the following description corresponds to the radiolocation and time tracking system (1), integrating a radiolocation and time tracking module (10), ensuring both functions.

[0084]

[0050] It is assumed that the environment in which the module (10) operates includes a first obstacle (01) and a second obstacle (02). The two obstacles (01, 02) are buildings, but could alternatively be any other type of structure without affecting the reasoning that follows. For each transmitting base station (4), the radio frequency signals received by the module (10) and originating from that base station (4) are divided into two types: the first type consists of the SdA and SdB signals arriving along line of sight, and the second type consists of the SrA and SrB signals arriving at the module (10) following a reflection off an obstacle (01, 02). The SdA and SrA signals, respectively sdB and srB, each correspond to the sum S1B and S1B, respectively, of unmodulated pure carrier signals, but they follow different paths.DA, and DB respectively, denote the line-of-sight distance between module (10) and the first transmitting base (4A), and the second transmitting base (4B respectively), traveled by signals SdA and SdB respectively. Dr A, and DrB respectively, denote the distance traveled by signals SrA and SrB respectively after bouncing off an obstacle (01) and an obstacle (02) respectively.

[0085]

[0051] For the sake of simplification, only the radio frequency signals originating from the first transmitting base (4A) and bouncing off the obstacle (01) closest to it are considered hereafter. This is because the impact of the signals originating from this base (4A) and bouncing off the other obstacle (02) is considered negligible. Similarly, only the radio frequency signals originating from the second transmitting base (4B) and bouncing off the obstacle (02) closest to it are considered hereafter. This is because the impact of the signals originating from this base (4B) and bouncing off the other obstacle (01) is considered negligible. Furthermore, for the sake of simplicity, it is assumed that the radio frequency signals bounce only once off one of the obstacles (01, 02).

[0086]

[0052] The positioning of the module (10) by the radiolocation system (1) will now be described in detail, with reference in particular to Figure 1.

[0053] The method includes an initial step of transmitting position data from the transmitting bases (4) to the storage means of the module (10). The transmission may, for example, consist of each transmitting base (4) transmitting its position coordinates to the module (10), or of pre-programming the position coordinates of the bases within the module (10) during its manufacture or configuration. Following this initial step, the storage means of the module (10) store the position data of the transmitting bases (4).

[0087]

[0054] The method includes a subsequent step in which each transmitting base (4) emits the sum (SIA, S1B) of unmodulated pure carrier signals of distinct cok frequencies. The phase shift between the signals (SIA, S1B) emitted by the different transmitting bases (4A, 4B) is constant. The sums (SIA, S1B) of pure carrier signals emitted by the bases (4A, 4B) are thus frequency-shifted by a frequency shift Aco. The different cok frequencies used by the bases (4A, 4B), as well as the frequency shift Aco, are known by the module (10), being pre-implemented in or transmitted to it.

[0088]

[0055] In a subsequent step, the module (10) receives the radio frequency signals SdA, SdB, SrA, SrB from the transmitting bases (4A, 4B). These signals SdA, SrA, and SdB, respectively, each correspond to the sum S1A and S1B, respectively, of unmodulated pure carrier signals, but they follow different paths. Because the sums S1A and S1B of signals are frequency-shifted by a predetermined frequency shift, known to the module (10), the module (10) can distinguish the SdA and SrA signals from the first transmitting base (4A) from the SdB and SrB signals from the second transmitting base (4B).

[0089]

[0056] In a subsequent step, the module (10) determines, via its measuring means, for each given cok signal frequency and for each transmitting base (4A, 4B), the phase of the signal consisting of the different signals SdA, SrA, and SdB, respectively, originating from that base (4A, 4B) and exhibiting the cok frequency. Indeed, for example, for the first base (4A) and for a given cok frequency, the two signals SdA(cok) and SrA(cok) are received by the module (10) in a mixed state. The phase measured by the module (10) for the cok frequency then corresponds to the phase of the signal consisting of the sum of the direct signal SdA and the reflected signal SrA. The same reasoning applies to the signals SdB and SrB originating from the second base (4B).

[0090]

[0057] In a subsequent step, the module (10) applies, via its computing means and for each of the transmitting bases (4A, 4B), a Fourier transform to a signal consisting of the different frequencies with measured amplitude and phase of the radio frequency signals received from that base. Indeed, the principle used by the invention is that for a given time delay, the phase shift undergone by a signal with a pure, unmodulated carrier depends on the frequency of that signal. The Fourier transform is typically a discrete Fourier transform, and in particular a discrete Fourier transform with complex coefficients.

[0091]

[0058] Alternatively, it is possible to apply a high-resolution spectral analysis algorithm, without Fourier transform.

[0092]

[0059] For each transmitting base (4A, 4B), the Fourier transform TF applied to the measured phases and amplitudes of the signals from this base is then expressed mathematically via the following function:

[0093] [Math 1] T

[0094]

[0095] F(d n ) = ^=ir(œ k ).

[0096]

[0060] In this way, by graphically representing, for each transmitting base (4A, 4B), the result of the applied Fourier transform, the computing means can in a subsequent step isolate different peaks corresponding to each SdA, SrA or SdB, SrB signal, and deduce the time of flight of each of these signals.

[0097]

[0061] This is illustrated in the graph in Figure 2, on which two graphical functions 3OA, 30B are represented. These two functions 3OA, 30B correspond respectively to the calculation of the Fourier transform for the first transmitting base (4A) and for the second transmitting base (4B), represented as a function of the time of flight (which is therefore read on the x-axis). During this step, the computing means of module (10) determine the time of flight between module (10) and each of the bases (4A, 4B). To do this, the computing means isolate the peak P1A, PIB having the shortest time of flight. This peak P1A, PIB corresponds to the SdA, SdB signal in line of sight. In the embodiment shown, for the first base (4A), the peak P1A corresponding to the SdA signal has a time of flight TVIA (or a pseudodistance) approximately equal to 230 ns. The time of flight TV1 A between module (10) and first base (4A) is therefore approximately 230 ns.For the second base (4B), the PIB peak corresponding to the SdB signal has a TV1B time of flight approximately equal to 310 ns. The TV1B time of flight between module (10) and the second base (4B) is therefore approximately 310 ns. For each of the bases (4A, 4B), the second peak P2A, P2B, which has a lower amplitude than the first peak P2A, P2B and a longer time of flight, corresponds to the SrA, SrB signal having been reflected off an obstacle (01, 02). This peak P2A, P2B can therefore be advantageously isolated from the first peak P2A, PIB, and not taken into account in the subsequent calculations.

[0098]

[0062] In a subsequent step, the module (10) solves the system of equations and unknowns arising from the measured pseudo-distances and the position data of the emitting bases (4A, 4B), to determine the position (x,y,z,t) of the module (10) relative to the bases (4A, 4B). This step is commonly called trilateration.

[0099]

[0063] From the known position data of the transmitting bases (4A, 4B), previously stored in the storage means, the absolute position of the module (10) is easily calculated. The absolute time is given by means of the clock (RTC) which will resolve the ambiguity in the period of the signal.

[0100]

[0064] Since the order of magnitude of the time-of-flight difference(s) thus determined is around the nanosecond, it is clear from the foregoing that the radio-location system (1) advantageously achieves sub-meter accuracy (less than 1 m) for positioning the module (10), even indoors or in urban environments. Furthermore, the module (10) performs its own positioning autonomously. Finally, the radio-location system (1) has both a long range (typically greater than 10 km), operates equally well in outdoor and indoor environments, and exhibits limited spectral occupancy, increased sensitivity, and a minimal equivalent noise band.

[0101]

[0065] Figures 1 and 2 illustrate the operation of the invention with two transmitting bases (4A, 4B). In practice, the invention can operate with a single transmitting base (4), or with more than two transmitting bases (4).

[0102]

[0066] We are now interested in the time tracking function of the module (10). The signals (SIB, S1B) sent by the transmitting base(s) (4) are received and processed by the module (10).

[0103]

[0067] Figure 3 shows a graph illustrating the ambiguity regarding the date over a general period for signals received by module (10). Indeed, the method described in EP 4323789 A11 allows the date to be determined within a general period of the signal with very good accuracy, but an ambiguity exists regarding the identity of the period. It is only by combining this information with a slower conventional RTC clock that the ambiguity is resolved, making it possible to determine the period in which the measurements are performed. Thus, module (10) makes it possible to overcome this problem.

[0104]

[0068] Figure 4 shows a time tracking module (10) according to the invention, with its constituent elements. The module (10) includes a phase-locked loop (PLL), a high-speed counter (HSC), a real-time clock (RTC), a low-speed counter (LSC), a date generator (DG), a pulse generator (PG), and an external communication system (CS).

[0105]

[0069] The phase-locked loop (PLL) is configured to:

[0106] receive radio frequency (SIA, S1B) signals from at least one transmitting base (4A, 4B), the (SIA, S1B) signals received from each base (4A, 4B) comprising at least two unmodulated pure carrier signals of distinct frequencies, each pure carrier signal being in the form of an unmodulated continuous wave, preferably sinusoidal, the (SIA, S1B) signals received from each base (4A, 4B) having a general period (GP) and being synchronized with absolute time (DA); then

[0107] - lock in phase feedback on said signals (SIA, S1B); then - transmit time-signal data (DS), taking into account the general period (GP) and the synchronized signal (SIA, S1B), to a high-speed counter (HSC);

[0108]

[0070] The high-speed counter (HSC) is configured to receive signal time data (DS) transmitted by the phase-locked loop (PPL) and to output time data (DH) to the date generator (DG). The time data (DH) transmitted by the high-speed counter (HSC) to the date generator (DG) contains an ambiguity in the overall period (GP), and therefore in the date of the received signal (SIA, S1B).

[0109]

[0071] The real-time clock (RTC) is configured to provide a signal (SRTC) carrying real-time data (RTD) during normal operation or during a standby period (PA) of the module (10), even when the module (10) is switched off during this standby period (PA). The real-time clock (RTC) comprises a quartz crystal having a frequency of 32.768 kHz, corresponding to the frequency of the signal (SRTC) emitted by the real-time clock (RTC).

[0110]

[0072] The low-speed counter (LSC) is configured to receive real-time data (RTD) from the real-time clock (RTC) and to transmit time data (DL) to the date generator (LSC). The time data (DL) transmitted by the low-speed counter (LSC) to the date generator (DG) carries the absolute date (DA).

[0111]

[0073] The date generator (DG) is configured to:

[0112] receive time data (DH) from the high-speed counter (HSC) and time data (DL) from the low-speed counter (LSC);

[0113] determine a date (DATE) from these time data (DH, DL); and drive the pulse generator (PG) generating an output signal (S2) of defined frequency (FP).

[0114]

[0074] The communication system (CS) is configured to transmit the date (DATE) to the outside, according to a predefined communication protocol, for example an NMEA protocol (the protocol applicable in marine communications defined and controlled by the National Marine Electronics Association NMEA in English) via UART (Universal Asynchronous Receiver Transmitter UART in English), the date (DATE) being synchronized with the absolute date (DA).

[0115]

[0075] The pulse generator (PG), driven by the date generator (DG), is configured so that the output signal (S2) is generated at a defined frequency (FD) of 1 Hz and synchronized with the absolute date (DA). The pulse generator (PG) is, for example, a field-programmable gate array (FPGA) logic circuit. The pulse generator (PG) can be integrated into the date generator (DG) or separate from it. The pulse generator (PG) is configured to output the signal (S2) externally, synchronous with the absolute date (DA), to within 10 ns. The signal (S2) is a synchronous square wave signal of a defined frequency (FP), for example, 1 Hz for a pulse-per-second (PPS) signal. The signal (S2) can then be used for various applications requiring precise date information. Module (10) is particularly useful in environments deprived of GPS signals, whether indoors or outdoors.

[0116]

[0076] The invention enables time tracking accurate to within 10 ns, thanks to the reception of signals (SIA, S1B) and the phase-locked loop (PPL) integrated into the module (10). The date generator (DG) generates a date (DATE), while the pulse generator generates the signal (S2). The ambiguity regarding the date to within 1 / PG(freq) = 1 ms can be resolved by means of the integrated real-time clock (RTC).

[0077] Furthermore, the system (1), the module (10), and the method (100) can be configured differently from Figures 1 to 4 without departing from the scope of the invention, which is defined by the claims. In addition, the technical features of the various embodiments and variants mentioned above can be combined, in whole or in part. Thus, the system (1), the module (10) and the method (100) can be adapted in terms of cost, functionality and performance.

Claims

Demands 1) Time tracking module (10), comprising: - a phase-locked loop (PLL), configured for: to receive radio frequency (SIA, S1B) signals from at least one transmitting base (4A, 4B), the (SIA, S1B) signals received from each base (4A, 4B) comprising at least two unmodulated pure carrier signals of distinct frequencies, each pure carrier signal being in the form of an unmodulated continuous wave, preferably sinusoidal, the (SIA, S1B) signals received from each base (4A, 4B) having a general period (GP) and being synchronized with absolute time (DA); then o lock in phase feedback on said signals (SIA, S1B); then o transmit time-signal data (DS), taking into account the general period (GP) and the synchronized signal (SIA, S1B), to a high-speed counter (HSC); - the high-speed counter (HSC) configured to receive signal time data (DS) transmitted by the phase-locked loop (PPL) and to emit time data (DH), including an ambiguity on the general period (GP) and therefore on the date of the received signal (SIA, S1B); - a real-time clock (RTC) configured to provide a signal (SRTC) carrying real-time data (DRT), in normal operation or during a period of autonomy (PA) of the module (10), even when the module (10) is turned off during this period of autonomy (PA); - a low speed counter (LSC) configured to receive real-time data (DRT) from the real-time clock (RTC) and emit time data (DL), capable of removing the ambiguity on the general period (GP) and therefore on the date of the received signal (SIA, S1B); - a date generator (DG) configured for: o receive the time data (DH) from the high-speed counter (HSC) and the time data (DL) from the low-speed counter (LSC); to determine a date (DATE) from these time data (DH, DL); and to drive a pulse generator (PG) generating an output signal (S2) of defined frequency (FP).2) Module (10) according to claim 1, characterized in that it comprises an external communication device (CD), configured to transmit the date (DATE) according to a predefined communication protocol, the date (DATE) being synchronized with the absolute date (DA). 3) Module (10) according to any of the preceding claims, characterized in that the pulse generator (PG) driven by the date generator (DG) is configured so that the output signal (S2) is generated at a defined frequency (FD) of 1 Hz and synchronized with the absolute date (DA). 4) Time tracking system (1), characterized in that it comprises at least one time tracking module (10) according to any one of claims 1 to 3. 5) Time tracking system (1) according to claim 4, comprising: at least one module (10) to be located; at least two transmitting bases (4, 4A, 4B), each transmitting base (4, 4A, 4B) being configured to transmit radio frequency signals (SIA, SI B, SdA, SdB, SrA, SrB), the transmitting bases (4, 4A, 4B) being synchronized with each other to transmit their respective signals, each transmitting base (4, 4A, 4B) being configured to transmit a sum (SIA, S1B) of at least two unmodulated pure carrier signals of distinct frequencies, each pure carrier signal being in the form of an unmodulated continuous wave, preferably sinusoidal; the module (10) being configured to receive and process said radio frequency signals (SIA, S1B, SdA, SdB, SrA, SrB) and to deduce its position and absolute time by calculating pseudo-distances between the module (10) and the transmitting bases (4, 4A, 4B), the module (10) comprising means for storing position data of the fixed transmitting bases (4, 4A, 4B), Module (10) also includes: Measurement means, for each given signal frequency and for each respective transmitting base (4A, 4B), of the phase and amplitude of the signal consisting of the different signals (SIA, S1B, SdA, SrA; SdB, SrB) originating from said base and exhibiting said frequency; and computing means connected to the measurement means and the storage means, and configured to: to apply, for each transmitting base (4A, 4B), a high-resolution spectral analysis algorithm on a signal consisting of the different frequencies with a measured amplitude and phase of the radio frequency signals from said base (4A, 4B); to determine, for each emitting base (4 A, 4B), from the spectral analysis carried out for said base, a pseudo-distance between the module (10) and said base (4 A, 4B); to determine the date and position of the module (10), from the calculated pseudo-distance(s) and the position data of the transmitting base(s) (4A, 4B). 6) Method (100) of implementing a module (10) according to any one of claims 1 to 3, comprising the following steps: - at the input, the phase-locked loop (PLL): o receives radio frequency signals (SIA, S1B) from at least one base (4A, 4B); then o locks in phase feedback on said signals (SIA, S1B); then o transmits time-domain signal (DS) data, taking into account the general period (GP) and the synchronized signal (SIA, S1B), to a high-speed counter (HSC); - the high-speed counter (HSC) receives the signal time data (DS) transmitted by the phase-locked loop (PPL) and emits time data (DH), including an ambiguity on the general period (GP) and therefore on the date of the received signal (SIA, S1B); - the real-time clock (RTC) provides a signal (SRTC) carrying real-time data (DRT), in normal operation or during a period of autonomy (PA) of the module (10), even when the module (10) is turned off during this period of autonomy (PA); - the low speed counter (LSC) receives the real time data (DRT) from the real time clock (RTC) and emits time data (DL), capable of removing the ambiguity on the general period (GP) and therefore on the date of the signal (SIA, S1B) received; - the date generator (DG): - receives time data (DH) from the high-speed counter (HSC) and time data (DL) from the low-speed counter (LSC); then determines a date (DATE) from these time data (DH, DL); and - drives a pulse generator (PG) generating an output signal (S2) of defined frequency (FP). 7) Method (100) according to claim 6, characterized in that it comprises an external communication step, consisting of transmitting the date (DATE) according to a predefined communication protocol, the date (DATE) being synchronized with the absolute date (DA). 8) Method (100) according to any one of claims 6 or 7, characterized in that the module (10) is disposed in an area where the reception of GPS signals is degraded, or even impossible. 9) Method (100) according to any one of claims 6 to 8, characterized in that the module (10) is arranged indoors, in particular in a building or basement. 10) Method (100) according to any one of claims 6 to 8, characterized in that the module (10) is disposed outdoors, in particular in an electronic jamming zone.

Images