Vehicle-mounted broadcast service following seamless switching method and vehicle-mounted broadcast system

Abstract

The invention discloses a vehicle-mounted broadcast service following seamless switching method and a vehicle-mounted broadcast system.The switching method is applied to the vehicle-mounted broadcast system and comprises the following steps that S1, DAB frequency band signals and / or FM frequency band signals are received at the same time through double antennas, the current DAB or FM service is played through a foreground channel of a DAB module, and the DAB frequency band signals and the FM frequency band signals are received through double antennas; the background channel searches a DAB replaceable service and / or an FM replaceable service corresponding to the same program; s2, the DAB module carries out audio phase and amplitude synchronization processing on the current service and the replaceable service searched in the background, so that audio parameters of the current service and the replaceable service are consistent; s3, collecting the signal quality of the current service and the replaceable service in real time; and S4, judging whether to execute non-delay switching according to the signal quality index. According to the invention, seamless switching of three scenes of DAB-DAB, DAB-FM and FM-DAB is realized, a user does not have any auditory perception, the audio frequency is not abnormal in the switching process, bidirectional switching of analog FM and digital DAB is realized, and the method is suitable for vehicle-mounted broadcast application scenes at home and abroad and is wider in applicability.

Description

A method for seamless switching of in-vehicle broadcasting services and an in-vehicle broadcasting system Technical Field

[0001] This invention relates to the field of vehicle broadcasting technology, and in particular to a method for seamless switching of vehicle broadcasting services and a vehicle broadcasting system. Background Technology

[0002] Digital Audio Broadcasting (DAB), as a third-generation broadcasting technology, has advantages such as near-CD quality sound, noise resistance, interference resistance, resistance to radio wave propagation fading, and suitability for high-speed mobile reception. It has been widely used in the automotive field in Europe and America, and is also being piloted and promoted in China.

[0003] In actual use of in-vehicle radio, when a user moves from one service area to another, the listening may be interrupted because they leave the coverage area of ​​the original signal. To solve this problem, many broadcast services in the industry have implemented network topologies. Broadcast services can be carried on a set of multiple tuning frequencies, or on multiple sets, or play the same program with other services. When a user moves from one service area to another, the receiver needs to search for alternative services (the same set on other tuning frequencies, other sets carrying the current service, and other services playing the same program) and switch to the alternative service when the conditions are met, thereby maintaining the user's listening. This application is called service following.

[0004] However, existing service following technology has obvious defects: when switching between services, although the current service and the replacement service have the same audio content, there are differences in audio phase and amplitude. This can cause audio stuttering, abrupt changes, missing audio, and other abnormalities during the process of switching from the currently playing service to the replacement service, which can easily interrupt the current playback and affect the user experience. Summary of the Invention

[0005] This invention provides a method and system for seamless switching of vehicle broadcasting services, which solves the audio anomalies when switching between different service areas, realizes seamless two-way switching between DAB-DAB and DAB-FM, and optimizes the user experience.

[0006] To address the aforementioned technical problems, in a first aspect, this invention proposes a method for seamless switching of in-vehicle broadcasting services, applied to an in-vehicle broadcasting system comprising dual antennas, a DAB module, and an in-vehicle IVI. The method includes the following steps: S1: Simultaneously receiving DAB band signals and / or FM band signals through the dual antennas; the front-end channel of the DAB module plays the current DAB or FM service, while the back-end channel searches for alternative DAB and / or alternative FM services corresponding to the same program; S2: The DAB module performs audio phase and amplitude synchronization processing on the current service and the alternative services searched in the back-end, ensuring that their audio parameters are consistent; 3: Real-time acquisition of signal quality of the current service and alternative services; S4: Determine whether the switching conditions are met based on the signal quality indicators. When any of the following switching scenarios are met, perform a no-delay switching: DAB-DAB switching: When the alternative DAB service meets the preset trigger conditions, switch to the alternative DAB service; DAB-FM switching: When the alternative FM service meets the preset trigger conditions and the signal quality of the current DAB service is lower than the normal playback threshold, switch to the alternative FM service; FM-DAB switching: When the signal quality of the alternative DAB service is not lower than the normal playback threshold, switch to the alternative DAB service.

[0007] Furthermore, in step S1, when the dual antennas simultaneously receive DAB band signals, the DAB module processes the two DAB band signals using the MRC algorithm to improve signal quality.

[0008] Furthermore, the signal quality of the current service and the alternative service in step S3 includes the following indicators: for the DAB service, the signal strength fstBB, bit error rate FIC_BER, audio quality, and the average of 10 samples of the three; for the FM service, the signal strength fstBB, signal-to-noise ratio SNR, and the average of 10 samples of the two.

[0009] Further, the preset triggering conditions for DAB-DAB switching in step S4 specifically include: Condition 1: The replaceable service's fstBB ≥ the current service's fstBB+5, Aver_fstBB ≥ the current service's Aver_fstBB+5, and FIC_BER, Aver_FIC_BER, Audio_quality, and Aver_Audio_quality are all less than or equal to the current service; Condition 2: The replaceable service's fstBB ≥ the current service's fstBB, Aver_fstBB ≥ the current service's Aver_fstBB, and FIC_BER+5 ≤ the current service's FIC_BER, Aver_FIC_BER+5 ≤ the current service's Aver_FIC_BER, Audio_quality, Condition 3: The replaceable service's fstBB and Aver_fstBB are greater than or equal to the current service, FIC_BER and Aver_FIC_BER are less than or equal to the current service, and the replaceable service's Audio_quality and Aver_Audio_quality are less than or equal to 5, while the current service's Audio_quality and Aver_Audio_quality are greater than 6; Condition 4: The replaceable service's fstBB ≥ -81dBuV, FIC_BER ≤ 24, and Audio_quality ≤ 5, while the current service's fstBB ≤ -91dBuV or FIC_BER ≥ 48 or Audio_quality > 6.

[0010] Furthermore, the preset triggering conditions for DAB-FM switching in step S4 specifically include: the FM replaceable service's fstBB ≥ 24dBuV, SNR ≥ 110, Aver_fstBB ≥ 24dBuV, Aver_SNR ≥ 110, and the current DAB service's fstBB ≤ -91dBuV or FIC_BER ≥ 48 or Audio_quality > 6.

[0011] Secondly, the present invention also provides a vehicle-mounted broadcasting system applied to the method described in the first aspect, comprising: a vehicle-mounted IVI for issuing operation commands, displaying service information, and playing audio; a first antenna and a second antenna for receiving DAB / FM band signals; a DAB module including an LDO module, an MCU module, a Decoder module, and an FE module; the LDO module receiving power input from the vehicle-mounted IVI and performing voltage regulation and conversion to power the MCU module, Decoder module, and FE module; the MCU module being connected to the vehicle-mounted IVI via a USB interface for receiving commands and sending service information and audio; the MCU module also being electrically connected to the Decoder module and the FE module to achieve information interaction; the FE module being electrically connected to the first antenna and the second antenna for receiving DAB / FM band signals and outputting IQ data to the Decoder module, and interacting with the MCU module; the Decoder module receiving the I / Q data from the FE module and decoding it to parse out service information and audio streams, and interacting with the MCU module.

[0012] Furthermore, the Decoder module is internally divided into four independently operating modules: FM foreground, FM background, DAB foreground, and DAB background. The DAB foreground module executes the DAB foreground MRC application to play DAB services, receive and parse Service Linking Information, and output the DAB / FM frequency, SID, PI information, and current signal quality information of alternative services. The DAB background module executes the DAB background application to search for alternative services in the DAB band based on the DAB frequency and SID, evaluate their signal quality, and output the results. The FM foreground module executes the FM foreground PD application to play alternative services in the FM band and output their signal quality information. The FM background module executes the FM background application to search for alternative services in the FM band based on the FM frequency and PI, evaluate their signal quality, and output the results.

[0013] Furthermore, the FE module includes three TDA7707 chips, each chip containing two independent channels that can work simultaneously. The FE module has a total of six channels: two channels for FM foreground PD, two channels for DAB foreground MRC, one channel for FM background, and one channel for DAB background.

[0014] Furthermore, the DAB module has four physical interfaces: the first physical interface is connected to the power interface of the vehicle IVI, the second physical interface is connected to the USB interface of the vehicle IVI, the third physical interface is connected to the first antenna, and the fourth physical interface is connected to the second antenna.

[0015] Furthermore, the layout of the first and second antennas satisfies the following conditions: the installation distance is greater than 84cm, they are arranged orthogonally or in an L-shape, or a diversity effect is achieved by combining different polarization methods.

[0016] The present invention has the following beneficial effects: 1. The embodiments of the present invention achieve audio synchronization calibration by performing audio phase and amplitude synchronization processing on the current service and the alternative services searched in the background, and directly realize seamless switching between three scenarios: DAB-DAB, DAB-FM, and FM-DAB, based on signal quality, without any auditory perception on the part of the user, and without any audio abnormalities during the switching process; 2. Through the technical design of receiving DAB / FM signals simultaneously and in parallel with dual antennas, and synchronously searching for alternative services in the background, bidirectional switching between analog FM and digital DAB is realized, adapting to domestic and foreign in-vehicle radio application scenarios, and having wider applicability; 3. By having the foreground playback and background search run in parallel, the process of searching for alternative services is ensured to not interrupt the current listening, without requiring manual intervention from the user.

[0017] In the above embodiments, the vehicle broadcasting system and the corresponding vehicle broadcasting service seamless switching method embodiment belong to the same concept, and thus have the same technical effect as the corresponding vehicle broadcasting service seamless switching method embodiment, which will not be repeated here.

[0018] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0019] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention. In the drawings: Figure 1 is a schematic diagram of the principle of a vehicle-mounted broadcasting system according to a preferred embodiment of the present invention; Figure 2 is a schematic diagram of the circuit structure of a vehicle-mounted broadcasting system according to a preferred embodiment of the present invention; Figure 3 is a schematic diagram of the circuit structure of the FE module and antenna of a vehicle-mounted broadcasting system according to a preferred embodiment of the present invention; Figure 4 is a service following flowchart of a seamless handover method for vehicle-mounted broadcasting services according to a preferred embodiment of the present invention; Figure 5 is a flowchart of the DAB-DAB handover process of the seamless handover method for vehicle-mounted broadcasting services according to a preferred embodiment of the present invention; Figure 6 is a flowchart of the DAB-FM handover process of the seamless handover method for vehicle-mounted broadcasting services according to a preferred embodiment of the present invention; Figure 7 is a flowchart of the FE-FM handover process of the seamless handover method for vehicle-mounted broadcasting services according to a preferred embodiment of the present invention. Figure 8 is a flowchart of the automatic update of the service list for the seamless switching method of vehicle broadcasting service according to a preferred embodiment of the present invention; Figure 9 is a schematic diagram of the circuit structure of the MRC algorithm implementation of the vehicle broadcasting system according to a preferred embodiment of the present invention; Figure 10 is a schematic diagram of the circuit principle of the MRC algorithm implementation of the vehicle broadcasting system according to a preferred embodiment of the present invention; Figure 11 is a diagram of the actual test data of the MRC algorithm of the vehicle broadcasting system according to a preferred embodiment of the present invention; Figure 12 is a schematic diagram of the DAB-DAB test route of the seamless switching method of vehicle broadcasting service according to a preferred embodiment of the present invention; Figure 13 is a schematic diagram of the DAB-FM test route of the seamless switching method of vehicle broadcasting service according to a preferred embodiment of the present invention. Detailed Implementation

[0020] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention can be implemented in many different ways as defined and covered by the claims.

[0021] Furthermore, unless otherwise defined, the technical or scientific terms used in this application description shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms "upper," "lower," "left," "right," "center," "vertical," "horizontal," "inner," and "outer," etc., used in this application description to indicate relative direction or positional relationship are used only to indicate relative orientation or positional relationship, and do not imply that the device or component must have a specific orientation, or be constructed and operated in a specific orientation. When the absolute position of the described object changes, its relative positional relationship may also change accordingly, and therefore should not be construed as a limitation on this application. The terms "first," "second," "third," and similar terms used in this application description are used only for descriptive purposes to distinguish different components, and should not be construed as indicating or implying relative importance. The terms "a," "one," or "the," etc., used in this application description should not be construed as an absolute limitation on quantity, but should be construed as indicating the existence of at least one. The terms "including," "comprising," etc., used in this application description mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, without excluding other elements or objects.

[0022] It should also be noted that, unless otherwise explicitly specified and limited, terms such as “installation,” “connection,” and “linkage” used in the description of this application should be interpreted broadly. For example, a connection can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can also refer to the internal connection of two components. Those skilled in the art can understand its specific meaning in this application based on the specific circumstances.

[0023] For ease of understanding, the terms appearing in the embodiments of this application are explained below.

[0024] DAB (Digital Audio Broadcasting); IVI (In-Vehicle Infotainment); LDO (Low Dropout Regulator); USB (Universal Serial Bus); I2S (Inter-IC Sound); SPI (Serial Peripheral Interface); MRC (Maximum Ratio Combining); SID (Service Identifier); PI (Programme Identifier); FE (Front-End); FM (Frequency Modulation); AM (Amplitude Modulation); PTY (Programme Type); DL (Dynamic Label); SLS (Service Label Service); fstBB (Field Strength Indication showing strength after the AGC); FIC_BER (Fast Information Channel bit error). ratio (Fast Information Channel Bit Error Rate); SNR (Signal-to-Noise Ratio); Audio_quality (Average value of fstBB); Aver_FIC_BER (Average value of FIC_BER); Aver_Audio_quality (Average value of Audio_quality); Aver_SNR (Average value of SNR).

[0025] This embodiment provides a method for seamless switching of in-vehicle broadcasting services, applied to an in-vehicle broadcasting system including dual antennas, a DAB module, and an in-vehicle IVI. The method includes the following steps: S1: Simultaneously receiving DAB band signals and / or FM band signals through the dual antennas, the front-end channel of the DAB module plays the current DAB or FM service, and the back-end channel searches for DAB alternative services and / or FM alternative services corresponding to the same program.

[0026] Specifically, the dual antennas simultaneously receive radio broadcast signals from both the DAB and FM bands. The signals are transmitted to the FE module of the DAB module. The FE module achieves parallel "foreground playback" and "background search" through channel division: two channels are allocated to the FMforeground PD and two channels are allocated to the DAB foreground MRC, responsible for receiving and playing the signal of the current foreground service; one channel is allocated to the FM background and one channel is allocated to the DAB background, responsible for searching for alternative services (DAB or FM band) corresponding to the same program in the background. The search process does not interrupt the playback of the foreground service.

[0027] In some possible embodiments, as shown in Figures 9, 10 and 11, in step S1, when the two antennas simultaneously receive DAB band signals, the DAB module processes the two DAB band signals using the MRC algorithm to improve signal quality.

[0028] The MRC scheme maximizes the signal-to-noise ratio (SNR) by weighting and combining the signals received by multiple receiving antennas at the receiver. The signal received by each antenna is multiplied by a weighting coefficient that is proportional to the channel gain of the signal and inversely proportional to the noise power.

[0029] Specifically, in this embodiment, the MRC algorithm works as follows: Signal reception: The receiver has two antennas, each receiving the same signal. However, due to different path losses, fading, and noise levels, the signals received by each antenna may differ. Signal weighting: The signals from the two antennas are weighted according to their signal-to-noise ratio (SNR). The weights are typically set to the complex conjugate of the channel gain. Signal combining: The two weighted signals are added together to obtain the final output signal. In this way, the SNR of the received signal is maximized, improving signal quality.

[0030] The MRC algorithm of this embodiment is shown in Figure 11. As can be seen, the scheme of this embodiment uses MRC to process the DAB signals of the two channels (from two antennas respectively). Compared with the method of directly receiving the DAB signal of a single channel, the receiving sensitivity of the DAB module in this embodiment is improved by more than 3dB.

[0031] S2: The DAB module performs audio phase and amplitude synchronization processing on the current service and the alternative services found in the background to make their audio parameters consistent.

[0032] Specifically, in this embodiment, the Decoder module of the DAB module has a built-in audio synchronization algorithm to perform real-time calibration on the audio signal of the foreground playback service and the audio signal of the alternative service searched in the background: phase compensation technology is used to eliminate the phase difference between the two (the delay difference after calibration is ≤10ms), and amplitude equalization technology is used to unify the signal amplitude of the two (the amplitude difference after calibration is ≤1dB), ensuring that the audio parameters are consistent during switching and avoiding stuttering and abrupt changes. At the same time, the four independent modules of the Decoder module (FM foreground / background, DAB foreground / background) work in parallel to ensure that the calibration, playback and search processes do not interfere with each other.

[0033] S3: Real-time acquisition of signal quality for the current service and alternative services.

[0034] In some possible embodiments, the signal quality of the current service and the alternative service in step S3 includes the following metrics: for the DAB service, the signal strength fstBB, bit error rate FIC_BER, audio quality, and the average of the three over 10 samples; for the FM service, the signal strength fstBB, signal-to-noise ratio SNR, and the average of the two over 10 samples.

[0035] Specifically, the MCU module collects the signal quality indicators of the current service and the alternative service in real time through the SPI interface. These indicators include: DAB service indicators: fstBB (signal strength, in dBuV, range -128 to 127, obtained from the FE module), FIC_BER (bit error rate, range 0 to 255, the smaller the value, the lower the bit error rate, obtained from the Decoder module), and Audio_quality (audio quality, range 0 to 9, the smaller the value, the better the audio quality), and the average of 10 samples of these three indicators (sampled once every 100ms); FM service indicators: fstBB (signal strength, in dBuV), SNR (signal-to-noise ratio, range 0 to 255, the larger the value, the higher the signal-to-noise ratio, obtained from the FE module), and the average of 10 samples of these two indicators (sampled once every 100ms).

[0036] The collected indicator data is transmitted in real time to the service follow-up switching control logic unit of the MCU module for switching judgment.

[0037] It should be noted that when searching for alternative services in the background, it is necessary to first filter out candidate alternative services that are 'the same program' as the current service based on identification information such as DAB frequency, FM frequency, SID, and PI.

[0038] Specifically, as shown in Figure 4, taking the DAB foreground MRC module as an example, the DAB foreground MRC receives and parses Service Linking Information, outputting the DAB frequency, FM frequency, SID (Service Identifier), and PI (Programme Identifier) ​​corresponding to the current service; the DAB background searches for alternative services within the DAB band based on the DAB frequency and SID; the FM background module searches for alternative services within the FM band based on the FM frequency and PI; after finding a candidate service, signal quality is used to determine whether the handover conditions are met.

[0039] S4: As shown in Figures 5 to 7, determine whether the switching conditions are met based on the signal quality indicators. When any of the following switching scenarios are met, perform a no-delay switching: DAB-DAB switching: When the DAB alternative service meets the preset trigger conditions, switch to the alternative DAB service; DAB-FM switching: When the alternative FM service meets the preset trigger conditions and the signal quality of the current DAB service is lower than the normal playback threshold, switch to the alternative FM service; FM-DAB switching: When the signal quality of the alternative DAB service is not lower than the normal playback threshold, switch to the alternative DAB service.

[0040] In some possible embodiments, the preset triggering conditions for DAB-DAB switching in step S4 specifically include: Condition 1: The replaceable service's fstBB ≥ the current service's fstBB+5, Aver_fstBB ≥ the current service's Aver_fstBB+5, and FIC_BER, Aver_FIC_BER, Audio_quality, and Aver_Audio_quality are all less than or equal to the current service; Condition 2: The replaceable service's fstBB ≥ the current service's fstBB, Aver_fstBB ≥ the current service's Aver_fstBB, and FIC_BER+5 ≤ the current service's FIC_BER, Aver_FIC_BER+5 ≤ the current service's Aver_FIC_BER, and Audio_quality... y, Aver_Audio_quality is less than or equal to the current service; Condition 3: The fstBB and Aver_fstBB of the replaceable service are greater than or equal to the current service, FIC_BER and Aver_FIC_BER are less than or equal to the current service, and the Audio_quality and Aver_Audio_quality of the replaceable service are less than or equal to 5, while the Audio_quality and Aver_Audio_quality of the current service are greater than 6; Condition 4: The fstBB of the replaceable service is greater than or equal to -81dBuV, FIC_BER is less than or equal to 24, and Audio_quality is less than or equal to 5, while the Audio_quality and Aver_Audio_quality of the current service are greater than or equal to 6;

[0041] In some possible embodiments, the preset triggering conditions for DAB-FM switching in step S4 specifically include: the FM replaceable service's fstBB ≥ 24dBuV, SNR ≥ 110, Aver_fstBB ≥ 24dBuV, Aver_SNR ≥ 110, and the current DAB service's fstBB ≤ -91dBuV or FIC_BER ≥ 48 or Audio_quality > 6.

[0042] Since FM is an analog broadcast, the signal is easily affected, and there is noise in the audio. DAB, on the other hand, is a digital broadcast and has strong anti-interference capabilities. As long as the signal quality exceeds a certain threshold, CD-quality sound can be obtained. Therefore, when both DAB and FM alternative services are available, the DAB alternative service should be selected first. Only when only FM alternative services are available will the FM alternative service be selected.

[0043] In some possible embodiments, during the FM-DAB switching in step S4, the switch from FM to DAB service can be completed as long as the DAB signal of the replaceable service meets the minimum playback threshold.

[0044] In some possible embodiments, as shown in Figure 8, the seamless switching method for in-vehicle radio services also includes an automatic DAB system list update method. Specifically, this includes: the DAB foreground MRC plays the user-selected service; when a preset update cycle is reached or the DAB foreground MRC detects a change in signal coverage in the current service area, an automatic update is triggered; the DAB background performs a full-band search of the DAB frequency band through the DAB background channel of the FE module (an independent channel that does not occupy foreground playback resources), without interrupting the playback of the current foreground service (DAB or FM) during the search; the DAB background decodes the searched DAB signals, removes duplicate services by parsing the SID (Service Identifier), retains valid and receivable services, and generates an updated service list (including service name, frequency, PTY program type, signal quality level, etc.); the DAB module transmits the updated service list to the in-vehicle IVI in real time via a USB interface; the in-vehicle IVI automatically overwrites the old list and refreshes the display, allowing users to see newly added services in real time without manual operation. This method automatically updates the service list without affecting the user's listening experience, improving the user experience.

[0045] The in-vehicle radio service seamless switching method in this embodiment directly achieves seamless switching between three scenarios: DAB-DAB, DAB-FM, and FM-DAB (maintaining audio continuity so that the user is unaware of the switching process). There are no audio anomalies during the switching process, improving the user experience. It also enables bidirectional switching between analog FM and digital DAB, adapting to domestic and international in-vehicle radio application scenarios and having wider applicability. By using parallel foreground playback and background search, it ensures that the process of searching for alternative services does not interrupt the current listening and requires no manual intervention from the user.

[0046] As shown in Figures 1 to 3, this embodiment of the invention also provides a vehicle-mounted broadcasting system applied to the aforementioned seamless switching method for vehicle-mounted broadcasting services. The vehicle-mounted IVI is used to issue operation commands, display service information, and play audio. A first antenna 1 and a second antenna 2 are used to receive DAB / FM band signals. The DAB module includes an LDO module, an MCU module, a Decoder module, and an FE module. The LDO module receives power input from the vehicle-mounted IVI and performs voltage regulation to power the MCU module, the Decoder module, and the FE module. The MCU module is connected to the vehicle-mounted IVI via a USB interface and is used to receive commands and send service information and audio. The MCU module is also electrically connected to the Decoder module and the FE module to achieve information interaction. The FE module is electrically connected to the first and second antennas and is used to receive DAB / FM band signals and output IQ data to the Decoder module, and interact with the MCU module. The Decoder module receives the I / Q data from the FE module, decodes it, parses out the service information and audio stream, and interacts with the MCU module.

[0047] The in-vehicle IVI is the vehicle's multimedia display screen. It interacts with the DAB module via a USB 2.0 interface to upload service information, including service frequency information, service name information, service PTY information, service time information, service DL text information, service SLS image information, service signal quality information, and service audio information; it also issues operation commands such as service search and service playback; and it outputs 12V voltage through the power interface to power the DAB module.

[0048] Specifically, in this embodiment, the LDO module regulates the 12V power input from the vehicle IVI to 3.3V / 5V, providing stable power to its MCU module, Decoder module, and FE module. The MCU module is an HC32A460 chip from Xiaohua Semiconductor. The MCU interacts with the vehicle IVI via a USB interface, controls the Decoder module and FE module via an SPI interface, and receives audio streams via an I2S interface, realizing functions such as signal acquisition, switching control, and data transmission.

[0049] In some possible embodiments, the DAB module has four physical interfaces: one connected to the power interface of the vehicle IVI to power the DAB module; one connected to the USB interface of the vehicle IVI to communicate using the USB communication protocol to transmit operation commands, service information and audio streams; and the other two interfaces are each connected to an antenna to receive DAB / FM band signals.

[0050] In some possible embodiments, as shown in Figure 4, the Decoder module is STMicroelectronics' STA800 chip, which is internally divided into four independently operating modules: FM foreground, FM background, DAB foreground, and DAB background. The STA800 chip receives IQ data input from the FE module, parses the IQ data, and obtains service information and audio streams. The STA800 chip integrates an audio synchronization algorithm, which can synchronize the audio between DAB foreground and DAB background and between DAB foreground and FM foreground, making the audio of the two channels consistent and avoiding audio stuttering, missing, repetition, and abrupt changes during channel switching. The STA800 chip also integrates an MRC algorithm to optimize the two DAB signals and improve the sensitivity of the DAB module in receiving signals.

[0051] Specifically, the DAB foreground module executes the DAB foreground MRC (DAB foreground maximum ratio combining) application to play DAB services, receive and parse Service Linking Information, and output the DAB / FM frequency, SID, PI information, and current signal quality information of alternative services; the DAB background module executes the DAB background (DAB background search) application to search for alternative services in the DAB band based on the DAB frequency and SID, evaluate their signal quality, and output the results; the FM foreground module executes the FM foreground PD (FM foreground playback) application to play alternative services in the FM band, output their signal quality information, and while performing the DAB band service search, it also searches for alternative services in the DAB band and updates the service list in real time; the FM background module executes the FM background (FM background search) application to search for alternative services in the FM band based on the FM frequency and PI, evaluate their signal quality, and output the results.

[0052] It should be noted that the FM foreground module, FM background module, DAB foreground module, and DAB background module are hardware units inside the STA800 chip, while the DAB foreground MRC application, DAB background application, FM foreground PD application, and FM background application are program applications that perform functions and depend on their corresponding hardware modules for execution.

[0053] In some possible embodiments, the FE module includes three TDA7707 chips. The TDA7707 is a single-chip, all-CMOS, four-band (FM / AM / DAB Band-Ⅲ / DAB L-Band), dual-channel tuner suitable for analog and digital terrestrial radio receivers. The two channels in the chip are independent of each other and can work simultaneously. The FE module has a total of 6 channels: 2 channels for FM foreground PD, 2 channels for DAB foreground MRC, 1 channel for FM background, and 1 channel for DAB background. The specific channel allocation is shown in Table 1. The FE module receives DAB / FM band signals from the antenna end, performs frequency tuning, and transmits the demodulated IQ data to the Decoder module.

[0054] Table 1.

[0055] The working process of the DAB module in this embodiment for parsing DAB / FM signals is as follows: As shown in Figures 3 and 9, the background channel of TDA7707 2 receives the DAB band signal from the first antenna 1 and sends the demodulated IQ data to STA800; the background channel of TDA7707 3 receives the DAB band signal from the second antenna 2 and sends the demodulated IQ data to STA800; after receiving the IQ data from the background channels of TDA7707 2 and TDA7707 3, STA800 performs MRC algorithm processing; STA800 parses the data processed by the MRC algorithm to obtain the service information and audio stream of the DAB service; this method improves the receiving sensitivity of DAB by at least 3 dB.

[0056] In some possible embodiments, the layout of the first and second antennas satisfies the following: the installation distance is greater than 84cm, they are arranged orthogonally or in an L-shape, or a diversity effect is achieved by combining different polarization methods.

[0057] Specifically, the first and second antennas can be located at the rear window and side rear window of the vehicle, respectively, at a distance greater than 1 / 2 wavelength (84 cm). In terms of layout, they can be arranged orthogonally (such as one horizontal and one vertical) or in an L-shape to enhance directional diversity and avoid close proximity of similar antennas to reduce coupling. If space is limited, diversity can be "artificially" created by changing the polarization method (such as a combination of linear and circular polarization) or by utilizing differences in radiation patterns.

[0058] Based on the vehicle broadcast service seamless switching method and vehicle broadcast system of the above embodiments, the following practical test was conducted: Test 1 is a DAB-DAB test, as shown in Figure 12, driving from the top of the mountain downhill. The signal is very good at the top of the mountain, and there are two identical ensembles (DAB band groups (containing multiple DAB bands with the same service) 7A (188.928MHz) and 9B (204.640MHz) at the same time. During the journey downhill, the signal of 9B gradually decreases, while the signal of 7A remains very good.

[0059] At the mountaintop, selecting one of the 9B services for playback, the signal quality indicators for 9B are (fstBB=-72dBuV; FIC_BER=18; Audio_quality=3; Aver_fstBB=-73dBuV; Aver_FIC_BER=19; Aver_Audio_quality=3.2). Then, driving downhill, halfway down the mountain, the signal quality indicators for 9B decrease to (fstBB=-84dBuV; FIC_BER=27; Audio_quality=5; Aver_fstBB=-85dBuV; Aver_Audio_quality=3.2). With _FIC_BER=28 and Aver_Audio_quality=5.3, the signal indicators of 7A are (fstBB=-79dBuV; FIC_BER=23; Audio_quality=4; Aver_fstBB=-79dBuV; Aver_FIC_BER=24; Aver_Audio_quality=4.2). At this time, the trigger condition 1 for DAB-DAB handover is met, and DAB-DAB (9B→7A) service handover occurs. The entire handover process is imperceptible to the human ear, and seamless DAB-DAB handover is achieved.

[0060] Test 2 is a DAB-FM test, as shown in Figure 13. DAB service SWR3 (8D, 201.072MHz) is played at point A. During the journey from A to C, there is a tunnel between A and B. There is no DAB signal in the tunnel, but there is an FM transmitter for SWR3 (98.5MHz). Before entering the tunnel, the DAB service SWR3's metrics are normal (fstBB=-78dBuV, FIC_BER=22, Audio_quality=3). After entering the tunnel, the DAB signal attenuates, and the metrics drop to fstBB. B=-92dBuV, FIC_BER=50, Audio_quality=7 (below the normal playback threshold); at the same time, the FM service SWR3 indicators are fstBB=30dBuV, SNR=115, Aver_fstBB=29dBuV, Aver_SNR=114, which meet the DAB-FM switching conditions. The DAB module automatically switches to the SWR3 service on the FM band. The entire switching process is imperceptible to the human ear, with no stuttering or noise, achieving seamless switching between DAB and FM, and continuous listening to the SWR3 service in the tunnel.

[0061] The in-vehicle broadcast service following seamless switching method and in-vehicle broadcast system of the above embodiments of this application have at least the following features: 1. By using audio synchronization calibration and zero-delay switching logic, the audio anomalies caused by service switching during service following are solved, realizing seamless switching of DAB to DAB and DAB to FM service following, thus improving the user experience; 2. The dual antennas and MRC algorithm work together to improve the receiving sensitivity of the DAB module by more than 3dB; 3. It supports bidirectional switching between DAB and FM, adapting to domestic and foreign in-vehicle broadcast scenarios, and has wider applicability; 4. The background parallel search realizes automatic updating of the service list, without requiring manual operation by the user and without interrupting the current playback, greatly improving convenience.

[0062] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for seamless switching of in-vehicle broadcasting services, characterized in that, The method is applied to in-vehicle broadcasting systems that include dual antennas, a DAB module, and an in-vehicle IVI. Includes the following steps: S1: The DAB module simultaneously receives DAB band signals and / or FM band signals through the dual antennas. The front-end channel of the DAB module plays the current DAB or FM service, while the back-end channel searches for alternative DAB and / or alternative FM services for the same program. S2: The DAB module performs audio phase and amplitude synchronization processing on the current service and the alternative services searched in the back-end to make their audio parameters consistent. S3: Real-time acquisition of signal quality for the current service and alternative services; S4: Determine whether the switching conditions are met based on the signal quality indicators. When any of the following switching scenarios are met, perform a no-delay switching: DAB-DAB switching: When the DAB alternative service meets the preset trigger conditions, switch to the alternative DAB service; DAB-FM switching: When the alternative FM service meets the preset trigger conditions and the signal quality of the current DAB service is lower than the normal playback threshold, switch to the alternative FM service; FM-DAB switching: When the signal quality of the alternative DAB service is not lower than the normal playback threshold, switch to the alternative DAB service.

2. The method for seamless switching of vehicle broadcasting service according to claim 1, characterized in that, In step S1, when the dual antennas simultaneously receive DAB band signals, the DAB module processes the two DAB band signals using the MRC algorithm to improve signal quality.

3. The method for seamless switching of vehicle broadcasting service according to claim 1, characterized in that, In step S3, the signal quality of the current service and the alternative service includes the following indicators: for the DAB service, the signal strength fstBB, bit error rate FIC_BER, audio quality, and the average of the three samples over 10 sampling periods; for the FM service, the signal strength fstBB, signal-to-noise ratio SNR, and the average of the two samples over 10 sampling periods.

4. The method for seamless switching of vehicle broadcasting service according to claim 1, characterized in that, The preset triggering conditions for DAB-DAB switching in step S4 specifically include: Condition 1: The replaceable service's fstBB ≥ the current service's fstBB+5, Aver_fstBB ≥ the current service's Aver_fstBB+5, and FIC_BER, Aver_FIC_BER, Audio_quality, and Aver_Audio_quality are all less than or equal to the current service; Condition 2: The replaceable service's fstBB ≥ the current service's fstBB, Aver_fstBB ≥ the current service's Aver_fstBB, and FIC_BER+5 ≤ the current service's FIC_BER, Aver_FIC_BER+5 ≤ the current service's Aver_FIC_BER, Audio_quality, Aver_Audio_quality are all less than or equal to the current service's. Condition 3: The replaceable service's fstBB and Aver_fstBB are greater than or equal to the current service, FIC_BER and Aver_FIC_BER are less than or equal to the current service, and the replaceable service's Audio_quality and Aver_Audio_quality are less than or equal to 5, while the current service's Audio_quality and Aver_Audio_quality are greater than 6; Condition 4: The replaceable service's fstBB ≥ -81dBuV, FIC_BER ≤ 24, and Audio_quality ≤ 5, while the current service's fstBB ≤ -91dBuV or FIC_BER ≥ 48 or Audio_quality > 6.

5. The method for seamless switching of vehicle broadcasting service according to claim 1, characterized in that, The preset triggering conditions for DAB-FM switching in step S4 specifically include: the FM replaceable service has fstBB≥24dBuV, SNR≥110, Aver_fstBB≥24dBuV, Aver_SNR≥110, and the current DAB service has fstBB≤-91dBuV or FIC_BER≥48 or Audio_quality>6.

6. A vehicle-mounted broadcasting system, characterized in that, The method applied to any one of claims 1 to 5 includes: an in-vehicle IVI for issuing operation commands, displaying service information, and playing audio; a first antenna and a second antenna for receiving DAB / FM band signals; a DAB module including an LDO module, an MCU module, a Decoder module, and an FE module; the LDO module receives power input from the in-vehicle IVI and performs voltage regulation and conversion to power the MCU module, Decoder module, and FE module; the MCU module is connected to the in-vehicle IVI via a USB interface for receiving commands and sending service information and audio; the MCU module is also electrically connected to the Decoder module and the FE module to achieve information interaction; the FE module is electrically connected to the first antenna and the second antenna for receiving DAB / FM band signals and outputting IQ data to the Decoder module, and interacting with the MCU module; the Decoder module receives the I / Q data from the FE module and decodes it to parse out service information and audio streams, and interacts with the MCU module.

7. The vehicle-mounted broadcasting system according to claim 6, characterized in that, The Decoder module is internally divided into four independently operating modules: FMforeground, FM background, DAB foreground, and DAB background. The DAB foreground module executes the DAB foreground MRC application, which plays DAB services, receives and parses Service Linking Information, and outputs the DAB / FM frequency, SID, PI information, and current signal quality information of alternative services. The DAB background module executes the DAB background application, which searches for alternative services in the DAB band based on the DAB frequency and SID, evaluates their signal quality, and outputs the results. The FM foreground module executes the FM foreground PD application, which plays alternative services in the FM band and outputs their signal quality information. The FM background module executes the FM background application, which searches for alternative services in the FM band based on the FM frequency and PI, evaluates their signal quality, and outputs the results.

8. The vehicle-mounted broadcasting system according to claim 7, characterized in that, The FE module includes three TDA7707 chips, each chip containing two independent channels that can work simultaneously. The FE module has a total of six channels: two channels for FM foreground PD, two channels for DAB foreground MRC, one channel for FM background, and one channel for DAB background.

9. The vehicle-mounted broadcasting system according to claim 6, characterized in that, The DAB module has four physical interfaces: the first physical interface is connected to the power interface of the vehicle IVI, the second physical interface is connected to the USB interface of the vehicle IVI, the third physical interface is connected to the first antenna, and the fourth physical interface is connected to the second antenna.

10. The vehicle-mounted broadcasting system according to claim 6, characterized in that, The layout of the first and second antennas satisfies the following conditions: the installation distance is greater than 84cm, they are arranged orthogonally or in an L-shape, or a diversity effect is achieved by combining different polarization methods.

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