Frequency Modulated Radio Signal Processing

Abstract

Examples illustrate a method for processing multiplexed, frequency-modulated radio signals received by a first and a second antenna, a radio receiver enabling the implementation of the signal processing method, a radio set comprising the radio receiver, and a motor vehicle comprising a radio receiver or a radio set. Figure from the abstract: [Fig. 4]

Description

Title of the invention: Frequency-modulated radio signal processing technical field

[0001] This disclosure relates to the field of receiving frequency-modulated radio signals. Previous technique

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

[0003] Methods exist to aid in the detection of cochannel interference. These methods determine the probability of cochannel interference's presence based on various parameters. However, these are probabilistic methods that cannot definitively determine whether cochannel interference is actually present. Furthermore, no solution is known to mitigate or eliminate cochannel interference once it is detected.

[0004] The present 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 proposed, the method comprising: - select, in a multiplexed radio signal received by the first antenna, a first frequency band of the radio signal belonging to a specific channel; - select, in a multiplexed radio signal received by the second antenna, a second frequency band of the radio signal belonging to the specific channel; - decode a first radio station identifier of the specific channel from the radio signal included in the first selected frequency band; - decode a second radio station identifier of the specific channel from the radio signal included in the second selected frequency band; - compare the first and second radio station identifiers; and - detect a co-channel jamming situation from the comparison.

[0006] Optionally, the method further includes a reduction of a quality coefficient linked to a radio station associated with the specific channel, when a co-channel interference situation is detected.

[0007] Optionally, the method further includes broadcasting an audio signal obtained exclusively from the radio signal received by either the first or second antenna, when a co-channel interference situation is detected.

[0008] Optionally, the method further includes a deactivation of a so-called phase diversity method which recombines 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.

[0009] Optionally, the method is implemented when a probability of existence of a co-channel jamming 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 one or the other of the first or second selected frequency band.

[0011] The application also relates to a radio receiver comprising at least one first tuner and one second tuner, at least one first and one second decoder, a calculator and a memory; wherein the first and second tuners, the first and second decoders, the calculator and the memory are configured to implement any of the methods presented in this 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 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 station comprising a radio receiver according to any of the options presented in this disclosure.

[0014] The application also relates to a motor vehicle comprising a radio unit or radio receiver according to any of the options presented in this disclosure.

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

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

[0017] The method according to this disclosure thus 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 considering exclusively the radio signal from one or the other of the first or second antenna, for example by disabling the implementation of a so-called phase diversity method. Brief description of the drawings

[0018] Other features, details and advantages will become apparent upon reading the detailed description below and analyzing the accompanying drawings, in which: Fig. 1

[0019] [Fig.1] schematically represents an example of a radio receiver. Fig. 2

[0020] [Fig.2] schematically represents an example of a radio set. Fig. 3

[0021] [Fig.3] schematically represents an example of a vehicle including a radio station. Fig. 4

[0022] [Fig.4] represents an example of a method for processing radio signals multi- teplexed, frequency modulated. Description of the implementation methods

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

[0024] The radio receiver 1 includes 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 a processor, microprocessor, microcontroller, FPGA, etc. The memory 12 can, for example, include ROM (Read-Only Memory), RAM (Random Access Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), or any other suitable type of storage medium. The memory can, for example, include optical, electronic, or magnetic storage. The computer 11 and the memory 12 are configured to implement any one of the processing methods described in this disclosure, and in particular the example processing method shown 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 is a device for selecting a specific frequency band from a radio signal. This frequency band can then be processed, for example, to extract an audio signal. The first tuner 13 is configured to select frequency bands from radio signals received by a first antenna 33. The second tuner 14 is configured to select frequency bands from radio signals received by a second antenna 34. The first antenna 33 and the second antenna 34 are separate.

[0026] The radio receiver 1 also includes at least one first decoder 15 and a second decoder 16. A decoder is a device for decoding the signals contained in a radio signal after demodulation. The decoders 15 and 16 may, in particular, be parts of the computer 11, or may, for example, be computers separate from the computer 11.

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

[0028] In some examples, and in particular those shown in [Fig. 3], the first 33 and the second 34 antennas are arranged on a motor vehicle 3. In these examples, the motor vehicle 3 may include a radio unit 2 comprising a radio receiver 1. In these examples, the radio unit 1 therefore corresponds to a car radio, that is to say, a radio unit intended to be integrated into a motor vehicle such as a car, truck, or motorcycle. In some examples, the motor vehicle 3 may include a radio receiver 1.

[0029] With reference to [Fig. 4], an example of a method 100 for processing frequency-modulated multiplexed radio signals received by the first 33 and second 34 antennas is shown 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 [Fig. 4] is merely an illustration of the example of process 100, representing, by means of blocks, the various operations that may be included in the process and described later in this document. As such, this illustration does not imply any sequence between the operations. In other words, the operations described with reference to [Fig. 4] are not necessarily carried out sequentially and may, in particular, be carried out in a different order than that shown in [Fig. 4], or be carried out in parallel. Similarly, it is not necessary for each operation to be carried out once before the same operation is repeated a second time. An operation may be carried out 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 those 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, in addition to the audio signal intended for playback by the listener, it contains digital information, including a radio station identifier. The radio station identifier of a radio signal makes it possible to determine which radio station transmitted the signal. In some examples, the radio station identifier is transmitted according to the "RDS" radio protocol, for "Radio Data System." This protocol is well known to those skilled in the art and is defined in the IEC 62106 standard.In these examples, the station identifier is transmitted in accordance with the RDS protocol via the PI code (“Program Identification”f.

[0032] As shown in [Fig. 2], the process 100 comprises an operation 110 of Selection, within a multiplexed radio signal received by the first antenna 33, of 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 for transmitting audio content. The first frequency band of the radio signal is selected in order 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 under consideration, or is included within that 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, within a multiplexed radio signal received 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 so that a radio station identifier can be determined from the radio signal received by the second antenna. For example, the second frequency band corresponds to the entire radio frequency range of the specific channel under consideration, or is included within said radio frequency range. The selection 120 of the second frequency band can, for example, be carried out by the second tuner 14.

[0034] In both operations, the two tuners, each associated with a respective antenna, are used to process a radio signal transmitted on the same channel but received differently by the two antennas, due in particular to their respective sensitivity and orientation. The first and second frequency bands must both allow the determination of a radio station identifier from the radio signals received by the first and second antennas, respectively. In some examples, the first and second frequency bands may be identical.

[0035] As shown in [Fig. 2], the method 100 includes an operation 130 of decoding a first radio station identifier of the specific channel from the radio signal contained in the first selected frequency band. This operation involves identifying which radio station is transmitting the radio signal received by the first antenna. The decoding 130 of the first radio station identifier of the specific channel can, for example, be performed 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. The aim of this operation is to identify which radio station is broadcasting the radio signal received by the second antenna. The decoding of the second radio station identifier for the specific channel can, for example, be performed by the second decoder.

[0037] As shown in [Fig.2], the method 100 includes an operation 150 of comparing the first and second radio station identifiers.

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

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

[0040] Method 100 according to this disclosure thus cleverly uses the signal received by two antennas to compare whether, on the same channel, the radio signal received by each antenna 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 incorporated into process 100 and are described later in this disclosure. These operations may be incorporated into process 100 in combination with each other unless expressly stated otherwise.

[0042] In examples, and as shown in [Fig. 2], the method 100 may further include an operation 170 for reducing a quality coefficient associated with a radio station on the specific channel when a co-channel interference situation is detected. This improves the audio signal of the radio station delivered to the listener. Indeed, radio receivers are configured to deliver audio corresponding to the radio station selected by the listener. Therefore, radio receivers are configured to choose the channel broadcasting the radio station selected by the listener that offers the best audio signal quality among the various available channels broadcasting that radio station.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 eventually use another available channel broadcasting the radio station selected by the listener, particularly when the quality coefficient associated with this channel is higher than that of the specific channel.

[0043] In examples, the method 100 includes an operation 180 of broadcasting an audio signal obtained exclusively from the radio signal received by either the first or second antenna. This operation 180 is implemented when a co-channel interference situation is detected. This involves se The system selects only 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 interfere with the audio signal broadcast to the listener. Furthermore, this also allows the tuner associated with the antenna not being used for broadcasting the audio signal to be used for another task, for example, to search for a more advantageous channel than the one being used for which co-channel interference has been detected.

[0044] In examples, and as shown in [Fig. 2], the method 100 may further include an operation 190 for deactivating a so-called "phase diversity" method when a co-channel interference situation is detected. This method recombines the radio signals received from the two antennas to obtain a recombined radio signal. The audio signal to be broadcast to the listener is then 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 and is generally referred to by the English term "phase diversity."These examples thus avoid recombining samples extracted from the radio signal received by the first antenna and corresponding to a first radio station with samples extracted from the radio signal received by the second antenna and corresponding to a second radio station. The aim of these examples is therefore to avoid contaminating the audio signal to be broadcast to the listener.

[0045] In examples, the method 100 is implemented when the probability of co-channel interference, determined by a probabilistic method, exceeds a predetermined threshold. Examples of such probabilistic methods are presented in particular in patent documents FR 3064853 and US 8064857. These examples limit the use of the method 100 to situations in which the probabilities of encountering co-channel interference exceed a predetermined threshold. More specifically, this limits 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 originates from a recombined radio signal.These examples therefore make it possible to preserve the resources of the radio receiver 1, in particular its computer 11 when the decoders correspond to integral parts of this computer 11, and to reduce its power consumption.

[0046] In examples, the decoding of the first and second radio station identifiers is carried out as follows: - The first radio station identifier is decoded from a recombination of the radio signal included in the first selected frequency band and of the radio signal included in the second selected frequency band; and - the second radio station identifier is decoded from the radio signal contained exclusively in one or the other of the first or second selected frequency band.

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

[0048] In this case, in case a), 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 antenna. In this case, the two radio station identifiers are each 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 the recombined signal via a third decoder. Thus, the audio signal broadcast to the listener during the implementation of method 100 is a good quality audio signal since it always results from the recombination of the radio signals received by the two antennas.However, it is not necessary to dedicate three decoders to implementing method 100 to maintain the transmission of the audio signal extracted from the recombined radio signal and to determine if radio receiver 1 is experiencing co-channel interference. Indeed, it is possible to directly use the radio station identifier decoded from the recombined radio signal and compare it with the identifier decoded from either of the radio signals received by either antenna to detect co-channel interference. Therefore, only two decoders are required to implement 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 needed to implement operation of the process, but the quality of the audio signal broadcast to the listener during the implementation of the process is reduced because 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 a good quality audio signal for broadcasting during the implementation of process 100 using two decoders, are particularly advantageous and do not obviously derive from the rest of the teaching shared by this disclosure.

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

[0052] Finally, the application relates to a non-transient computer-readable recording medium on which is recorded a program for the implementation of any of the processes presented in this disclosure when that program is executed by a processor.

[0053] Method 100 according to this disclosure thus 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 Method 100 also make it possible to reduce, or even eliminate, the inconvenience caused by co-channel interference by considering exclusively the radio signal from either the first or second antenna, for example by disabling the implementation of a so-called phase diversity method.

Claims

Claims

1. Method (100) for processing multiplexed, frequency-modulated radio signals picked up by a first antenna (33) and a second antenna (34), the method (100) comprising: - selecting (110), in a multiplexed radio signal picked up by the first antenna, a first frequency band of the radio signal belonging to a specific channel; - selecting (120), in a multiplexed radio signal picked up 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 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 selected frequency band; and - the second radio station identifier is decoded from the radio signal comprised exclusively in one or other of 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 the

9.

10. second radio station IDs and to detect co-channel jamming situation from the comparison. Radio station (2) comprising a radio receiver (1) according to any one of claims 7 or 8. Motor vehicle (3) comprising a radio station (2) according to the preceding claim or a radio receiver (1) according to any one of claims 7 or 8.

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