Processing of frequency modulated radio signals

Abstract

Examples provide a method for processing multiplexed, frequency-modulated radio signals captured by a first antenna and a second antenna, a radio receiver for implementing the signal processing method, a radio station comprising the radio receiver, and a motor vehicle comprising a radio receiver or a radio station.

Description

Description Processing of frequency modulated radio signals Technical field

[0001] The present disclosure relates to the field of receiving frequency modulated radio signals. Prior art

[0002] In the field of radio, a channel refers to a range of radio frequencies allocated to a radio station to transmit audio content in a geographical area. In some cases, the same channel may be allocated to two different radio stations in two neighboring geographical areas, so that a radio receiver in a motor vehicle traveling on the border between these two geographical areas may receive, on this same channel, frequency-modulated radio signals from different radio stations. These situations result, in terms of sound, in audio content that may alternate successively between radio stations transmitting on the same channel, which degrades the listener's listening experience. These situations, well known to those skilled in the art, are referred to by the English term "co-channel interference" or "co-channel jamming" in French.

[0003] Methods exist to assist in the detection of co-channel interference (see for example US 2020 / 007248 A1, US 2010 / 151809 A1, US 2016 / 211995 A1). These methods determine a probability of the existence of co-channel interference based on various parameters. However, these are probabilistic methods and do not allow one to determine with certainty whether there is actually co-channel interference. Furthermore, no solution is known to mitigate or eliminate co-channel interference when such interference is detected.

[0004] This disclosure improves this situation. Summary

[0005] In this regard, a method for processing multiplexed, frequency-modulated radio signals received by a first antenna and a second antenna is provided, the method comprising: selecting, from a multiplexed radio signal received by the first antenna, a first frequency band of the radio signal belonging to a specific channel; selecting, from a multiplexed radio signal received by the second antenna, a second frequency band of the radio signal belonging to the specific channel; decoding a first radio station identifier of the specific channel from the radio signal included in the first frequency band selected; decoding a second radio station identifier of the specific channel from the radio signal included in the second selected frequency band; comparing the first and second radio station identifiers; and detecting a co-channel interference situation from the comparison.

[0006] Optionally, the method further comprises reducing a quality coefficient previously stored in a memory of a radio receiver, said quality coefficient being linked to a radio station associated with the specific channel, when a co-channel interference situation is detected.

[0007] Optionally, the method further comprises broadcasting an audio signal obtained exclusively from the radio signal picked up by one or other of the first or second antenna, when a co-channel interference situation is detected.

[0008] Optionally, the method further comprises deactivating a so-called phase diversity method recombining the radio signals picked up from the two antennas in order to improve the audio signal to be broadcast, when a co-channel interference situation is detected.

[0009] Optionally, the method is implemented when a probability of existence of co-channel interference determined by a probabilistic method is greater than a predetermined threshold.

[0010] Optionally, the first radio station identifier is decoded from a recombination of the radio signal included in the first selected frequency band and the radio signal included in the second selected frequency band; and the second radio station identifier is decoded from the radio signal included exclusively in either the first or second selected frequency band.

[0011] The application also relates to a radio receiver comprising at least a first tuner and a second tuner, at least a first and a second decoder, a computer and a memory; wherein the first and the second tuners, the first and the second decoders, the computer and the memory are configured to implement any of the methods presented by the present disclosure.

[0012] Optionally, the first tuner is configured to select the first frequency band; the second tuner is configured to select the second frequency band; the first decoder is configured to decode the first radio station identifier of the specific channel from the radio signal included in the first selected frequency band; the second decoder is configured to decode the second radio station identifier of the specific channel of the specific channel from the radio signal included in the second selected frequency band; and the calculator is configured to compare the first and second radio station identifiers and to detect a co-channel interference situation from the comparison.

[0013] The application further relates to a radio set comprising a radio receiver according to any of the options presented by the present disclosure.

[0014] The application further relates to a motor vehicle comprising a radio set or a radio receiver according to any of the options presented by the present disclosure.

[0015] The application further relates to a computer program product comprising instructions for implementing any of the methods presented by the present disclosure when this program is executed by a processor.

[0016] Finally, the application relates to a non-transitory recording medium readable by a computer on which is recorded a program for implementing any of the methods presented by the present disclosure when this program is executed by a processor.

[0017] The method according to the present disclosure therefore makes it possible to reliably detect co-channel interference situations by cleverly comparing the radio station identifiers decoded from the radio signals of two different antennas. Certain options of the method also make it possible to reduce or even eliminate the inconvenience caused by co-channel interference by exclusively considering the radio signal of one or other of the first or second antenna, for example by deactivating the implementation of a method known as phase diversity. Brief description of the drawings

[0018] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analyzing the attached drawings, in which:

[0019] Figure 1 schematically represents an example of a radio receiver.

[0020] Figure 2 schematically represents an example of a radio station.

[0021] Figure 3 schematically represents an example of a vehicle including a radio station.

[0022] Figure 4 represents an example of a method for processing multiplexed, frequency-modulated radio signals. Description of the embodiments

[0023] There is now described with reference to Figure 1 an example of a radio receiver 1 according to the present disclosure. A radio receiver is to be understood herein disclosure as a device for processing radio signals transmitted by radio stations, in particular for the purpose of extracting audio content therefrom, which can be broadcast to a listener.

[0024] The radio receiver 1 comprises a computer 11 and a memory 12. The memory 12 can store the code instructions executed by the computer 11. The computer 11 can for example be of the processor, microprocessor, microcontroller, FPGA, etc. type. The memory 12 can for example comprise a ROM (Read-Only Memory), a RAM (Random Access Memory), an EEPROM (Electrically Erasable Programmable Read-Only Memory) or any other type of suitable storage means. The memory can for example comprise optical, electronic or magnetic storage means. The computer 11 and the memory 12 are configured to implement any of the processing methods described in the present disclosure and in particular the example of a processing method presented with reference to FIG. 4.

[0025] The radio receiver 1 further comprises at least a first tuner 13 and a second tuner 14. A tuner designates a device for selecting, in a radio signal, a specific frequency band. This frequency band can then be processed, for example for the purpose of extracting an audio signal therefrom. The first tuner 13 is configured to select frequency bands of radio signals picked up by a first antenna 33. The second tuner 14 is configured to select frequency bands of radio signals picked up by a second antenna 34. The first antenna 33 and the second antenna 34 are distinct.

[0026] The radio receiver 1 further comprises at least a first decoder 15 and a second decoder 16. A decoder designates a device for decoding the signals contained in a radio signal after demodulation. The decoders 15 and 16 may in particular constitute parts of the computer 11, or may for example correspond to computers separate from the computer 11.

[0027] In examples, the radio receiver 1 may in particular constitute a part of a radio set 2, as shown in FIG. 2. The radio set 2 may for example further comprise loudspeakers 21 configured to broadcast an audio signal extracted from a radio signal. The radio set 2 may also comprise a screen 22 for displaying information to the listener.

[0028] In examples, and in particular those shown in figure 3, the first 33 and the second 34 antennas are arranged on a motor vehicle 3. In these examples, the motor vehicle 3 may comprise a radio station 2 comprising a radio receiver 1. In these examples, the radio station 1 therefore corresponds to a car radio station, that is to say a radio set for integration into a motor vehicle such as a car, truck, or motorcycle. In examples, the motor vehicle 3 may include a radio receiver 1.

[0029] With reference to Figure 4, an example of a method 100 for processing frequency-modulated multiplexed radio signals captured by the first 33 and second 34 antennas is presented below. The method 100 can for example be implemented by the radio receiver 1, in particular using its computer 11, its memory 12, and the first 13 and second 14 tuners.

[0030] It should be noted that Figure 4 is only an illustration of the example of the method 100 representing, by blocks, the different operations possibly included in the method and described in the remainder of the document. As such, this illustration does not reflect any sequentiality between the operations. In other words, the operations described with reference to Figure 4 are not necessarily implemented one after the other and may in particular be implemented in a different order from that shown in Figure 4, or be implemented in parallel. In the same way, it is not necessary for each operation to be implemented once before the same operation is repeated a second time. An operation may be implemented several times before the implementation of another operation. The frequency of implementation of each operation is specific to it and is not necessarily linked to the implementation of the other operations.

[0031] A frequency modulated radio signal is a principle known to the person skilled in the art. This radio signal is also called an FM radio signal, FM being the acronym for "Frequency Modulation". In this case, the frequency modulated radio signal is multiplexed since it presents, in particular, in addition to the audio signal intended to be reproduced to the listener, digital information including in particular a radio station identifier. The radio station identifier of a radio signal makes it possible to determine which radio station transmitted the radio signal. In examples, the radio station identifier is transmitted in accordance with the radio protocol known as "RDS" for "Radio Data System". This protocol is well known to the person skilled in the art and is defined in particular in the IEC 62106 standard.In these examples, the station identifier is transmitted according to the RDS protocol via the PI (“Program Identification”) code.

[0032] As shown in Figure 2, the method 100 comprises an operation 110 of selecting, in a multiplexed radio signal received by the first antenna 33, a first frequency band of the radio signal belonging to a specific channel. As indicated above, a channel designates a range of radio frequencies allocated to a radio station to transmit audio content. The first frequency band of the radio signal is selected to be able to determine a radio station identifier from the radio signal received by the first antenna. For example, the first frequency band corresponds to the entire radio frequency range of the specific channel in question, or is included in said radio frequency range. The selection 110 of the first frequency band can for example be carried out by the first tuner 13.

[0033] As shown in FIG. 2, the method 100 comprises an operation 120 of selecting, in a multiplexed radio signal picked up by the second antenna 34, a second frequency band of the radio signal belonging to the specific channel. The second frequency band of the radio signal is selected to be able to determine a radio station identifier from the radio signal picked up by the second antenna. For example, the second frequency band corresponds to the entire radio frequency range of the specific channel considered, or is included in said radio frequency range. The selection 120 of the second frequency band can for example be carried out by the second tuner 14.

[0034] These two operations involve using the two tuners, each associated with a respective antenna, to process a radio signal transmitted on the same channel, but picked up differently by these two antennas due in particular to their respective sensitivity and orientation. The first frequency band and the second frequency band must both make it possible to determine a radio station identifier from the radio signals picked up by the first antenna and the second antenna respectively. In certain examples, the first frequency band and the second frequency band may be identical.

[0035] As shown in FIG. 2, the method 100 comprises an operation 130 of decoding a first radio station identifier of the specific channel from the radio signal included in the first selected frequency band. This operation involves identifying which radio station is transmitting the radio signal picked up by the first antenna. The decoding 130 of the first radio station identifier of the specific channel can for example be carried out by the first decoder 15.

[0036] As shown in FIG. 2, the method 100 comprises an operation 140 of decoding a second radio station identifier of the specific channel from the radio signal included in the second selected frequency band. This operation involves identifying which radio station is transmitting the radio signal picked up by the second antenna. The decoding 140 of the second radio station identifier of the specific channel can for example be carried out by the second decoder 16.

[0037] As shown in Figure 2, the method 100 comprises an operation 150 of comparison of the first and second radio station IDs.

[0038] As shown in FIG. 2, the method 100 comprises an operation 160 of detecting a co-channel interference situation from the comparison.

[0039] In examples, a co-channel interference situation is detected when the first identifier and the second identifier correspond to different radio station identifiers.

[0040] The method 100 according to the present disclosure therefore cleverly uses the signal received by two antennas to compare whether, on the same channel, the radio signal received by each of the antennas is indeed transmitted by the same radio station. When this is not the case, the method therefore makes it possible to determine with certainty that the radio receiver is in a co-channel interference situation insofar as a first antenna receives a radio signal from a first station and a second antenna receives a radio signal from a second station.

[0041] Other operations may optionally be integrated into the method 100 and are presented in the remainder of this disclosure. These operations may be integrated into the method 100 in combination with each other unless expressly stated otherwise.

[0042] In examples, and as shown in FIG. 2, the method 100 may further comprise an operation 170 of reducing a quality coefficient linked to a radio station associated with the specific channel, said quality coefficient having been previously stored in a memory of the radio receiver 1, when a co-channel interference situation is detected. This makes it possible to improve the audio signal of the radio station restored to the listener. Indeed, the radio receivers are configured to restore audio corresponding to the radio station selected by the listener. The radio receivers are therefore configured to choose the channel broadcasting the radio selected by the listener having the best audio signal quality among the different available channels broadcasting this radio station, according to quality coefficients previously stored in a memory of the radio receiver 1 and associated respectively with these different available channels.Therefore, by reducing the quality coefficient linked to the radio station and associated with the specific channel for which a co-channel interference situation has been detected, the radio receiver may possibly use another available channel broadcasting the radio station selected by the listener, in particular when the quality coefficient associated with this channel is higher than that of the specific channel.

[0043] In examples, the method 100 comprises an operation 180 of broadcasting an audio signal obtained exclusively from the radio signal picked up by one or the other of the first or second antenna. This operation 180 is implemented when a co-channel interference situation is detected. This involves selecting exclusively the radio signal received by one antenna to obtain the audio signal to be broadcast to the listener. In this way, the radio signal received by the other antenna, which, in the case of co-channel interference, corresponds to another radio station, does not taint the audio signal to be broadcast to the listener. Furthermore, this also allows the tuner associated with the antenna that is not considered for broadcasting the audio signal to be used for another task, for example to search for another channel more advantageous than the specific channel used for which a co-channel interference situation has been detected.

[0044] In examples, and as shown in FIG. 2, the method 100 may further comprise an operation 190 of deactivating a method called “phase diversity” when a co-channel interference situation is detected. This method recombines the radio signals picked up from the two antennas so as to obtain a recombined radio signal. The audio signal to be broadcast to the listener is subsequently extracted from this recombined radio signal, which improves the quality of the audio signal compared to an audio signal extracted from a non-recombined radio signal. This is a method well known to those skilled in the art which is generally referred to by the English term “phase-diversity”.These examples thus make it possible to avoid recombining samples extracted from the radio signal picked up by the first antenna and corresponding to a first radio station with samples extracted from the radio signal picked up by the second antenna and corresponding to a second radio station. In these examples, the aim is therefore to avoid tainting the audio signal to be broadcast to the listener.

[0045] In examples, the method 100 is implemented when a probability of co-channel interference existence determined by a probabilistic method is greater than a predetermined threshold. Examples of such probabilistic methods are notably presented by the patent documents FR 3064853 and US 8064857. These examples make it possible to limit the use of the method 100 to situations in which the probabilities of being in co-channel interference are greater than a predetermined threshold. This makes it possible more precisely to limit the time during which the radio receiver 1 devotes two decoders to decoding the radio signals received by each of the antennas, whereas only one decoder is necessary when the signal to be decoded comes from a recombined radio signal.These examples therefore make it possible to preserve the resources of the radio receiver 1, in particular of its computer 11 when the decoders correspond to integral parts of this computer 11, and to reduce its electrical consumption.

[0046] In examples, the decoding of the first and second radio station IDs is performed as follows: the first radio station identifier is decoded from a recombination of the radio signal included in the first selected frequency band and the radio signal included in the second selected frequency band; and the second radio station identifier is decoded from the radio signal included exclusively in either of the first or second selected frequency bands.

[0047] These examples make it possible to: a) avoid dedicating three decoders of the radio receiver 1 to decoding the radio signals during the implementation of the method 100, or b) dedicate only two decoders of the radio receiver 1 to decoding during the implementation of the method 100 by reducing the quality of the audio signal broadcast to the listener.

[0048] In this case, in case a), the method 100 can be implemented by decoding the radio signals received by the first 33 and the second 34 antennas as well as the radio signal recombined from the signals of each of the antennas. In this case, the two radio station identifiers are each extracted directly from the two radio signals picked up by the antennas via a respective decoder, and the audio signal to be broadcast to the listener is extracted from the recombined signal via a third decoder. Thus, the audio signal broadcast to the listener during the implementation of the method 100 is a good quality audio signal since it always comes from the recombination of the radio signals picked up by the two antennas.However, it is not necessary to dedicate three decoders to the implementation of the method 100 to maintain the transmission of the audio signal extracted from the recombined radio signal and to determine whether the radio receiver 1 is in a co-channel interference situation. Indeed, it is possible to directly use the radio station identifier decoded from the recombined radio signal in order to compare it with the identifier decoded from one or other of the radio signals received by one or other of the antennas in order to be able to detect co-channel interference. Also, only two decoders are necessary to implement the method 100 while maintaining the quality of the audio signal extracted from the recombined radio signal during the implementation of this method.

[0049] In case b), the method 100 can be implemented by decoding only the radio signals received by the first 33 and the second 34 antennas. In this case, the radio station identifiers are extracted directly from the two radio signals received by the antennas via a respective decoder, and the audio signal to be broadcast to the listener is extracted from one of the two radio signals received by the antennas, but is not extracted from the recombined signal, which would require a third decoder. In this case, only two decoders are required to implement the method, but the quality of the audio signal broadcast to the listener during the implementation of the method loses in quality since the audio signal is no longer extracted from the recombined radio signal. It is therefore of lower quality than in case a).

[0050] It is thus understood that the examples presented above which make it possible to avoid the disadvantages of implementing cases a) and b) and thus to obtain an audio signal to be broadcast, during the implementation of the method 100, of good quality using two decoders, are particularly advantageous and do not derive in an obvious manner from the rest of the teaching shared by the present disclosure.

[0051] The application further relates to a computer program product comprising instructions for implementing any of the methods presented by the present disclosure when this program is executed by a processor.

[0052] Finally, the application relates to a non-transitory recording medium readable by a computer on which is recorded a program for implementing any of the methods presented by the present disclosure when this program is executed by a processor.

[0053] The method 100 according to the present disclosure therefore makes it possible to reliably detect co-channel interference situations by cleverly comparing the radio station identifiers decoded from the radio signals of two different antennas. Certain examples of the method 100 also make it possible to reduce or even eliminate the inconvenience caused by co-channel interference by exclusively considering the radio signal of one or other of the first or second antenna, for example by deactivating the implementation of a method known as phase diversity.

Claims

Claims

1. A method (100) for processing multiplexed, frequency-modulated radio signals received by a first antenna (33) and a second antenna (34), the method (100) comprising: selecting (110), in a multiplexed radio signal received by the first antenna, a first frequency band of the radio signal belonging to a specific channel; selecting (120), in a multiplexed radio signal received by the second antenna, a second frequency band of the radio signal belonging to the specific channel; decoding (130) a first radio station identifier of the specific channel from the radio signal included in the first selected frequency band; decoding (140) a second radio station identifier of the specific channel from the radio signal included in the second selected frequency band; comparing (150) the first and second radio station identifiers;and detecting (160) a co-channel interference situation from the comparison.;

2. Method (100) according to the preceding claim, further comprising a reduction (170) of a quality coefficient previously stored in a memory of a radio receiver, said quality coefficient being linked to a radio station associated with the specific channel, when a co-channel interference situation is detected.

3. A method according to any preceding claim, further comprising broadcasting (180) an audio signal obtained exclusively from the radio signal picked up by either the first (33) or second (34) antenna, when a co-channel interference situation is detected.

4. Method (100) according to any one of the preceding claims, further comprising a deactivation (190) of a so-called phase diversity method recombining the radio signals received from the two antennas in order to improve the audio signal to be broadcast, when a co-channel interference situation is detected.

5. A method (100) according to any preceding claim, wherein the method is implemented when a probability of existence of co-channel interference determined by a probabilistic method is greater than a predetermined threshold.

6. A method (100) according to any preceding claim, wherein: the first radio station identifier is decoded from a recombination of the radio signal comprised in the first selected frequency band and the radio signal comprised in the second frequency band selected; and the second radio station identifier is decoded from the radio signal comprised exclusively in either the first or second selected frequency band.

7. A radio receiver (1) comprising at least a first tuner (13) and a second tuner (14), at least a first (15) and a second (16) decoder, a computer (11) and a memory (12); wherein the first (13) and the second (14) tuners, the first (15) and the second (16) decoders, the computer (11) and the memory (12) are configured to implement the method according to any one of claims 1 to 6.

8. Radio receiver (1) according to the preceding claim, wherein the first tuner (13) is configured to select the first frequency band; the second tuner (14) is configured to select the second frequency band; the first decoder (15) is configured to decode the first radio station identifier of the specific channel from the radio signal included in the first selected frequency band; the second decoder (16) is configured to decode the second radio station identifier of the specific channel from the radio signal included in the second selected frequency band; and the calculator (11) is configured to compare the first and second radio station identifiers and to detect a co-channel interference situation from the comparison.

9. A radio station (2) comprising a radio receiver (1) according to any one of claims 8 or 9.

10. Motor vehicle (3) comprising a radio station (2) according to the preceding claim or a radio receiver (1) according to any one of claims 8 or 9.

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