Low-cost airborne audio and other data sharing transmission method and system

Abstract

The invention relates to an airborne audio and other data multiplexing transmission scheme. The scheme comprises the following steps: receiving audio data and decoding the audio data; judging whether the received audio data is analog audio or digital audio, and if the audio data is analog audio, converting the audio data into digital audio through analog-to-digital conversion; selecting a corresponding coding and decoding standard to code the digital audio; according to the coding and decoding standard used by the digital audio, selecting a corresponding ARINC429 encapsulation data format to encapsulate the digital audio into an ARINC429 frame so as to generate an audio ARINC429 frame; the audio ARINC 429 frame is stored in an audio buffer; the method comprises the following steps: receiving non-audio service data, and carrying out ARINC 429 framing on the received non-audio service data to generate a non-audio ARINC 429 frame; the non-audio ARINC 429 frame is stored in a non-audio buffer; and reading the data from the audio buffer and the non-audio buffer in sequence according to a sending period sequence corresponding to the multiplexing combination mode, and forwarding the data to an ARINC429 sending chip for outward sending.

Description

Technical Field

[0001] The present application belongs to the field of aircraft avionics system design, and in particular, relates to the design of airborne avionics equipment with external audio interaction. Background Art

[0002] Currently, the audio systems of most mainstream civil aircraft are analog audio systems, such as the Boeing 737 series and the Airbus 320 series. With the development of digital audio technology, digital audio systems have gradually replaced analog audio systems.

[0003] The processing of analog audio is relatively simple. It does not require analog-to-digital, digital-to-analog, or digital signal processing. It is low-cost and has low latency. However, the disadvantages of analog audio are also obvious. Distortion and noise are easily generated during recording, transmission, processing, and amplification. In addition, since the audio system has many cross-linked devices, the crosstalk interference between the cross-linked devices will affect the system's signal-to-noise ratio and dynamic range. In particular, the on-board cables are long, the electromagnetic environment is complex and harsh, and the shortcomings of weak noise resistance are magnified. In order to avoid interference with the analog audio signal, the cables need to be spatially isolated from other cables, which brings difficulties to the laying of on-board cables. In addition, analog audio is not easy to perform complex editing and processing, such as editing, mixing, and filtering. It is also not easy to store and copy for a long time, and is easily affected by environmental factors and degraded.

[0004] Digital audio is high-fidelity and high-definition, overcoming the defects of analog audio technology, improving the signal-to-noise ratio and dynamic range, and digital audio can use mature and advanced digital signal processing algorithms, which is easy to perform complex editing and processing, such as editing, mixing, filtering, compression and transmission, etc. Digital audio is also easy to store and copy for a long time, and is not degraded by environmental factors.

[0005] Airborne audio applications are mainly various types of communication and navigation radio stations, and digital signal transmission involves bus selection. For communication and navigation radio RF voice links, audio bandwidth and modulation depth are limited and defined by ITU and ICAO rules and conventions to maximize the use of allocated frequency channels for air-to-ground communications. In order to meet these requirements, the audio response curve used for RF voice links is usually limited to a passband of 300Hz to 2500Hz, and the general onboard audio processing system limits the audio frequency band of the radio station to between 300Hz and 3000Hz. The audio codec involved in airborne audio digitization, the bit rate of commonly used audio codec standards are all 64kbps and below.

[0006] Most mainstream airborne radio stations use the ARINC429 bus to exchange data externally, and the high-speed ARINC429 bus rate is 100Kbps. Considering that the transmission interval of the ARINC429 frame is generally 40μs, the actual bit rate is 100Kbps*320 / 360=88.889kbps, which is not only greater than the digital audio bit rate of 64kbps, but also has a surplus.

[0007] Therefore, there is a demand to utilize the abundant bandwidth of the ARINC429 bus to help transmit more data to save communication resources and costs. Summary of the invention

[0008] The present application provides a solution for multiplexing transmission of airborne audio and other data, which can fully utilize the bandwidth resources of the ARINC429 bus without increasing the cost and cable weight.

[0009] According to a first aspect of the present application, a method for transmitting airborne audio and other data multiplexed transmission is provided, comprising:

[0010] Phase 1:

[0011] Receive audio data and decode it;

[0012] Determine whether the received audio data is analog audio or digital audio, and if the audio data is analog audio, convert it into digital audio by analog-to-digital conversion;

[0013] Select a corresponding codec standard to encode the digital audio;

[0014] According to the codec standard used by the digital audio, select a corresponding ARINC429 encapsulation data format to encapsulate the digital audio into an ARINC429 frame to generate an audio ARINC429 frame;

[0015] Storing the audio ARINC429 frame in an audio buffer;

[0016] Phase 2:

[0017] Receiving non-audio service data, and performing ARINC429 framing on the received non-audio service data to generate non-audio ARINC429 frames;

[0018] storing the non-audio ARINC429 frame into a non-audio buffer; and

[0019] Phase 3:

[0020] Data is read from the audio buffer and the non-audio buffer in sequence according to the transmission cycle sequence corresponding to the multiplexing combination mode and forwarded to the ARINC429 transmission chip for external transmission.

[0021] According to a second aspect of the present application, a method for receiving airborne audio and other data multiplexed transmission is provided, comprising:

[0022] Receiving data sent by the sending method according to any one of claims 1 to 5 from the ARINC429 bus;

[0023] Parsing the data, buffering the audio ARINC429 frames into an audio buffer, and buffering the non-audio ARINC429 frames into a non-audio buffer;

[0024] (a) reading the audio ARINC429 frame from the audio buffer and de-framing it into digital audio;

[0025] Decoding the digital audio into uncompressed linear PCM digital audio based on the digital audio codec standard;

[0026] Determine whether the device audio function module is a digital audio processing module or an analog audio processing module:

[0027] If the device audio function module is a digital audio processing module, directly processing the unencoded digital audio;

[0028] If the device audio function module is an analog audio processing module, the unencoded digital audio is converted into corresponding analog audio through a digital-to-analog converter before being processed;

[0029] (b) reading the non-audio ARINC429 frame from the non-audio buffer and de-framing it into non-audio service data;

[0030] The non-audio service data is processed by the non-audio function module.

[0031] According to a third aspect of the present application, there is provided an airborne audio and other data multiplexing and sending system, comprising:

[0032] an analog-to-digital converter configured to convert the received audio data into uncompressed linear PCM digital audio;

[0033] An encoder configured to compress and encode the digital audio;

[0034] The audio data ARINC429 framing module is configured to select a corresponding ARINC429 encapsulation data format according to the codec standard used by the digital audio to encapsulate the digital audio into an ARINC429 frame to generate an audio ARINC429 frame;

[0035] A non-audio data ARINC429 framing module, configured to encapsulate received non-audio service data into ARINC429 frames to generate non-audio ARINC429 frames;

[0036] An audio buffer configured to buffer the audio ARINC429 frame;

[0037] A non-audio buffer configured to buffer the non-audio ARINC429 frame;

[0038] A multiplexer configured to read data from the audio buffer and the non-audio buffer in sequence according to a transmission cycle sequence corresponding to a multiplexing combination mode and provide the data to an ARINC429 transmission chip; and

[0039] The ARINC429 transmitting chip is configured to transmit data on the ARINC429 bus.

[0040] According to a fourth aspect of the present application, there is provided an airborne audio and other data multiplexing receiving system, comprising:

[0041] An ARINC429 receiving chip configured to receive data sent by the airborne audio and other data multiplexing transmission system according to claim 8 from an ARINC429 bus;

[0042] A demultiplexer configured to parse audio ARINC429 frames and non-audio ARINC429 frames from the received data and buffer them into an audio buffer and a non-audio buffer respectively;

[0043] An audio buffer configured to buffer the audio ARINC429 frame;

[0044] A non-audio buffer configured to buffer the non-audio ARINC429 frame;

[0045] An audio data ARINC429 de-framing module, configured to de-frame the audio ARINC429 frames from the audio buffer into digital audio;

[0046] A decoder configured to decode the digital audio accordingly based on a determined codec standard to generate decoded uncompressed linear PCM digital audio;

[0047] a digital-to-analog converter configured to convert the decoded digital audio into analog audio;

[0048] The non-audio data ARINC429 de-framing module is configured to de-frame the non-audio ARINC429 frames from the non-audio buffer into non-audio service data.

[0049] This Summary is provided to introduce some concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to describe the manner in which the above and other advantages and features of the present invention can be obtained, a more particular description of the invention briefly described above will be presented by reference to specific embodiments of the invention shown in the accompanying drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings, in which:

[0051] Figure 1 A schematic flow chart of a method for transmitting multiplexed transmission of airborne audio and other data according to an embodiment of the present application is shown.

[0052] Figure 2 Several transmitted ARINC429 audio data formats are shown.

[0053] FIG3( a ) shows three audio transmission formats in one ARINC429 frame in a multi-channel audio, single bus scenario.

[0054] FIG3( b ) shows a schematic diagram of data multiplexing on an ARINC429 bus in a multi-channel audio, single bus scenario.

[0055] Figure 4 An example block diagram of a system for multiplexing and transmitting airborne audio and other data according to an embodiment of the present application is shown.

[0056] Figure 5 An example block diagram of an airborne audio and other data multiplexing receiving system according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0057] As mentioned above, the actual bit rate of the high-speed ARINC429 bus (hereinafter referred to as "ARINC429 bus" or "429 bus") is generally greater than the digital audio bit rate of 64kbps, so there is enough bandwidth to do other things. This means that without adding other technically complex and costly buses, the ARINC429 bus widely used on aircraft and radio stations can be used to transmit audio to reduce communication costs.

[0058] In general, this application makes full use of the high-speed ARINC429 bus to multiplex digital audio transmission during the idle time of non-audio data transmission. The airborne device does not need to add a transmission interface for audio data, does not increase the number of device interface pins, and does not increase the interface chip. The aircraft does not need to increase the number of buses, so there is no increase in cost and weight of onboard cables.

[0059] In order to realize the multiplexing of the high-speed ARINC429 bus, the present application provides a solution for multiplexing transmission of airborne audio and other data, and the solution can be divided into two parts: sending and receiving.

[0060] exist Figure 1 A schematic flow chart of a method for multiplexing and transmitting airborne audio and other data (eg, non-audio service data) according to an embodiment of the present application is shown.

[0061] As shown in the flow chart, in general, the scheme is to first perform ARINC429 framing on the audio data and the non-audio service data, respectively, and then transmit them together on the ARINC429 bus after multiplexing. Specifically, the method can be divided into three stages:

[0062] Stage 1: ARINC429 framing of audio data, including:

[0063] In step 202, it is determined whether the audio data received by the system is analog audio or digital audio:

[0064] If the audio data is analog audio, then the process proceeds to step 204 to perform analog-to-digital conversion on the audio data, for example, the analog audio may be converted into uncompressed 14-bit linear PCM digital audio, and then the process proceeds to step 206;

[0065] If the audio data itself is digital audio, the analog-to-digital conversion process of step 204 can be skipped, and the digital audio can be decoded into digital audio in an uncompressed linear PCM format as needed. Specifically, if the digital audio is originally in an uncompressed linear PCM format, then the process directly proceeds to step 206. If the digital audio is encoded (i.e., compressed), it needs to be decoded into an uncompressed linear PCM format before proceeding to step 206.

[0066] At step 206, a corresponding codec standard is selected to encode the digital audio. In the method flow, for the purpose of illustration, the audio codec scheme uses two standards (royalty-free) of ITU-T G.711 and G.726. Both G.711 and G.726 are speech waveform coding (PCM) standards, and their sampling rates are 8KHz, that is, one audio waveform sampling point is 0.125ms. The G.711 standard uses 8-bit quantization for each sampling point, and the bit rate is 64kbps; the G.726 standard uses ADPCM technology, and the number of quantization bits for each sampling point is 5 / 4 / 3 / 2 bits, and the corresponding bit rates are 40kbps / 32kbps / 24kbps / 16kbps (that is, G.726 has four bit numbers and bit rates to choose from). Therefore, these two standards can provide five encodings with different compression rates.

[0067] As for which codec standard to choose for encoding, it can actually be adaptively selected based on the load and scenario of non-audio service data, that is, the audio data compression rate can be dynamically adjusted according to the non-audio service traffic of different devices to meet the multiplexing transmission. This selection needs to meet a basic principle, that is, when the encoded digital audio and non-audio service data are multiplexed together, the maximum bit rate of the ARINC429 bus cannot exceed 100kbps.

[0068] For example, if the amount of non-audio service data to be transmitted is small, we can choose G.711 (bit rate of 64kbps) with a low compression rate to encode digital audio. The higher the bit rate, the lower the compression rate, and therefore the better the sound quality.

[0069] On the contrary, if the amount of non-audio service data to be transmitted is large, we can choose the 2-bit / 16kbps scheme in G.726 with a high compression rate to encode digital audio. The lower the bit rate, the greater the compression, so the worse the sound quality, but this ensures that the total bit rate multiplexed together does not exceed the maximum bit rate of 100kbps.

[0070] It should be understood that the above audio codec standards are provided as examples and are not limited thereto. In fact, other audio codec standards can also be applied to the solution of the present application, as long as the subsequent format and processing are modified accordingly according to the standards to meet the multiplexing requirements. Due to space considerations, they will not be repeated here.

[0071] After the encoding of the digital audio is completed, the process proceeds to step 208. In this step, according to the codec standard used by the digital audio, the corresponding ARINC429 encapsulation data format is selected to encapsulate the digital audio into the ARINC429 frame to generate the audio ARINC429 frame. This step can also be called the ARINC429 framing step of the digital audio data.

[0072] This application designs the corresponding ARINC429 encapsulation data format for digital audio encoded at different bit rates. For specific examples, please refer to Figure 2 .

[0073] exist Figure 2 The data formats of several transmitted audio ARINC429 frames are shown in FIG.

[0074] The standard ARINC429 data format is shown at the top, which is a commonly used format in the art and will not be further described here.

[0075] The following audio ARINC429 frame data formats are new data formats designed for different encoding and decoding standards based on this.

[0076] The first bit position of the audio data (hereinafter referred to as "bit") is "1", indicating that the ARINC429 frame is digital audio data (i.e., audio ARINC429 frame). If the bit is "0", it means that the ARINC429 frame is non-audio service data (i.e., non-audio ARINC429 frame). Bits 31 to 29 identify the digital audio coding method, and their specific meanings are shown in Table 1:

[0077] No. 31 No. 30 No. 29 meaning Compression 0 spare spare G711, 64Kbps audio 57.14％ 1 0 0 G726, 40Kbps audio 35.71％ 1 0 1 G726, 32Kbps audio 28.57％ 1 1 0 G726, 24Kbps audio 21.43％ 1 1 1 G726, 16Kbps audio 14.29％

[0078] Table 1: Digital audio coding method identification

[0079] According to the above Figure 2 According to the correspondence between the coding and decoding standards and the data formats in Table 1, the digital audio data is filled into the corresponding bits in the ARINC429 frame to implement the ARINC429 framing of the digital audio.

[0080] Finally, in step 210, the audio ARINC429 frame from step 208 is stored in an audio buffer, preferably a FIFO (first in first out) buffer, for transmission.

[0081] At this point, the ARINC429 framing stage of the audio data is completed.

[0082] Phase 2: ARINC429 framing of non-audio service data, namely:

[0083] In step 220, data from non-audio services is received and the received non-audio service data is framed by ARINC429. The non-audio service data is the data originally transmitted on the traditional ARINC429 bus. Therefore, the ARINC429 framing of the non-audio service data is the same as the steps of transmitting the non-audio service data on the traditional ARINC429 bus. For example, Figure 1 The standard ARINC429 data format is used for encapsulation to generate non-audio ARINC429 frames, which will not be described in detail here.

[0084] Subsequently, in step 222, the non-audio ARINC 429 frame from step 220 is stored in a non-audio buffer, preferably a FIFO (first in first out) buffer, for transmission.

[0085] At this point, the ARINC429 framing stage of non-audio service data is completed.

[0086] It should be understood that the steps in stage 1 and stage 2 can be performed simultaneously without any order of precedence, that is, the audio data and non-audio service data can be received, processed and packaged simultaneously, or received, processed and packaged one after another without any clear order.

[0087] Stage 3: Multiplexing of audio data and non-audio service data:

[0088] In step 230, data is read from the audio FIFO buffer and the non-audio FIFO buffer in sequence according to the transmission cycle sequence corresponding to the multiplexing combination mode and forwarded to the ARINC429 transmission chip for external transmission. The specific implementation of the steps will be described in detail in the following scenario-based example application.

[0089] At this point, the sending method of multiplexing and transmitting the onboard audio and other data is completed.

[0090] The following further describes a corresponding receiving method for multiplexed transmission of airborne audio and other data according to the solution of the present application.

[0091] Generally speaking, the receiving method is the reverse process of the sending method.

[0092] Specifically, after the receiving end receives the data (all ARINC429 frames) sent by the sending method from the ARINC429 bus, first, the first bit of the received ARINC429 frame is parsed. If it is 1, it represents digital audio data (audio ARINC429 frame), and the data is cached in the audio FIFO buffer; if the first bit is 0, it represents non-audio service data (non-audio ARINC429 frame), and the data is cached in the non-audio FIFO buffer.

[0093] The device audio function module (for processing audio data) and other non-audio function modules (for processing non-audio service data) at the receiving end respectively request to read data from the two FIFO buffers for subsequent processing.

[0094] Specifically, in step (a), if the audio ARINC429 frame is read from the audio FIFO buffer, the audio ARINC429 frame is deframed according to the aforementioned ARINC429 encapsulation data format and restored to a digital audio format. Subsequently, the codec standard used by the digital audio is determined (G.726 standard or G.711 standard), and corresponding decoding (i.e. G.726 decoding or G.711 decoding) is performed based on the determined codec standard to generate the corresponding decoded uncompressed linear PCM format digital audio (14-bit PCM digital audio in this example) data. If the device audio function module is a digital audio processing module, it can be directly processed. If the device audio function module is an analog audio processing module, the decoded digital audio is converted into the corresponding analog audio through a digital-to-analog converter before being processed.

[0095] In step (b), if the non-audio ARINC429 frame is read from the non-audio FIFO buffer, the non-audio ARINC429 frame is deframed according to the aforementioned ARINC429 encapsulation data format and restored to non-audio service data. Subsequently, the non-audio function module processes it. It should be understood that the steps (a) and (b) do not have a sequential order and can be performed simultaneously.

[0096] Since the process of the receiving method is basically the same as that of the sending method, which is just a reverse engineering, the specific processing can refer to the corresponding steps in the process of the sending method, which will not be repeated here.

[0097] After understanding the basic process of the sending and receiving method of the multiplexed transmission of airborne audio and other data in the solution of the present application, a specific description is given below in conjunction with an example scenario.

[0098] In this solution, there are three scenarios according to the number of audio channels and the number of buses, and each scenario corresponds to a time division multiplexing solution.

[0099] Scenario 1: Mono audio, single bus:

[0100] In this scenario, the device has one audio transmission channel and only one high-speed ARINC429 interface. The audio data stream is real-time and continuous. To ensure that the audio data is not congested and flows continuously, the following conditions must be met:

[0101] T / Δt≥(T+t) / 125

[0102] Wherein, T represents the time for transmitting audio ARINC429 frames, t represents the time for transmitting non-audio ARINC429 frames, 125 represents the audio data interval of 125us (corresponding to 8KHz sampling rate) sent by the front end; Δt represents the average time consumption of one sampling point in the audio ARINC429 frame, and its value is 360us / the number of sampling points in one ARINC429 frame, and 360us is 320us of one ARINC429 frame plus a 40us protection interval.

[0103] According to sending one non-audio ARINC429 frame after every N audio ARINC429 frames, the above formula can be rewritten as:

[0104] N / Δt≥(N+1) / 125

[0105] Table 2 describes the sending cycle arrangement when audio ARINC429 frames and non-audio ARINC429 frames are transmitted in time division multiplexing on an ARINC429 bus. For different audio formats, the data is sent using different data multiplexing sending cycles.

[0106] According to the sending cycle in Table 2, it can be ensured that the rate at which the back-end ARINC429 sends audio is greater than the front-end audio stream, and the audio data will not be interrupted.

[0107]

[0108] Table 2 Mono audio single bus multiplexing transmission cycle

[0109] Subsequently, at the transmitting end, according to the above different multiplexing combinations, audio ARINC429 frames and non-audio ARINC429 frames are sent alternately. Specifically, if the multiplexing combination indicates that the audio ARINC429 frame should be sent currently, the audio ARINC429 frame is read from the audio FIFO buffer and sent to the ARINC429 transmitting chip to send the audio ARINC429 frame on the ARINC429 bus.

[0110] Similarly, if the multiplexing combination indicates that a non-audio ARINC429 frame should be sent currently, the non-audio ARINC429 frame is read from the non-audio FIFO buffer and sent to the ARINC429 transmitting chip to send the non-audio ARINC429 frame on the ARINC429 bus.

[0111] In order to ensure the time division multiplexing of different data streams and continuous control, the data multiplexing transmission cycle must be strictly carried out according to the description in Table 2.

[0112] If there is no buffered data to be sent in the FIFO buffer, it will immediately switch to the dedicated transmission of another data until the empty FIFO buffer is re-stored with data, and then continue to perform time division multiplexing according to the multiplexing cycle. In this way, time division multiplexing transmission of digital audio and other non-audio service data on an ARINC429 high-speed bus is realized.

[0113] After receiving the data sent by the ARINC429 bus, the receiving end first parses the first bit of the received ARINC429 frame. If it is 1, it represents audio data, which is cached in the audio FIFO buffer. If the first bit is 0, it represents non-audio service data, which is cached in the non-audio FIFO buffer. The audio function module and other non-audio function modules of the receiving end device take out data from the two FIFO buffers for subsequent processing (framing decoding).

[0114] The above is a multiplexing transmission scheme for a single audio on a single bus. In it, while ensuring the transmission interval of non-audio service data, try to use a high-bitrate digital audio format to maximize the audio quality (the higher the audio bit rate, the better the sound quality).

[0115] Scenario 2: Multi-channel audio, single bus:

[0116] In this scenario, the device has multi-channel audio transmission and only one high-speed ARINC429 interface (i.e., one ARINC429 bus). In this scenario, a high-compression audio format can be used. Referring to Table 1, considering the need to multiplex and transmit other non-audio data and the 40us protection interval between two adjacent ARINC429 frames, the audio formats available for multi-channel transmission are shown in Table 3:

[0117]

[0118] Table 3 The number of multi-channels and total bit rate supported by a single bus

[0119] Generally, most airborne electronic devices transmit 1-channel audio (multiple audio signals are mixed into one channel inside the device for transmission), and the most common multi-channel is left and right dual channels. The scenario with more than 2 channels is the audio broadcast sent to different devices, which is generally transmitted using multiple buses, one-to-one transmission, see the multi-bus multi-channel audio transmission scenario below; if multiple audio channels are broadcasted through a single bus, each receiving device needs to identify whether the audio is sent to itself when receiving it, which rarely occurs.

[0120] The following only describes the most commonly used dual-channel method; the principles for multiple channels are the same.

[0121] According to the scheme of sending one non-audio ARINC429 frame after sending N audio ARINC429 frames, the condition for audio not to be congested and disconnected is:

[0122] N / Δt≥2*[(N+1) / 125]

[0123] In the above formula, 2 represents dual channels, and Δt represents the average time consumed by one sampling point in the audio ARINC429 frame.

[0124] The dual-channel audio single bus multiplexing transmission cycle is shown in Table 4:

[0125]

[0126]

[0127] Table 4 Dual-channel audio single bus multiplexing transmission cycle

[0128] The mixed transmission of left and right channels requires strict time alignment, so the left and right sampling points with the same sequence number should be encapsulated in one ARINC429 frame for transmission.

[0129] As shown in FIG. 3( a ), three audio transmission formats in one ARINC429 frame in a multi-channel audio (two-channel in example) and single bus scenario are shown.

[0130] As shown in FIG3( b ), a schematic diagram of data multiplexing on an ARINC429 bus in a multi-channel audio (two-channel for example) single-bus scenario is shown.

[0131] Here, bits 28-26 in the ARINC429 frame can be used as identification bits to identify how many channels are multiplexed and transmitted in one audio ARINC429 frame, as shown in Table 5. After parsing the received ARINC429 frame, the receiving end parses the audio data into corresponding channels according to these identification bits.

[0132] No. 28 No. 27 No. 26 meaning 0 spare spare Mono 1 0 0 2 channels 1 0 1 3 channels 1 1 0 4 channels 1 1 1 5 channels

[0133] Table 5 Meaning of channel number identification

[0134] Scenario 3, multi-channel audio, multiple buses:

[0135] In this scenario, the device has multiple ARINC429 buses and multi-channel audio, so the audio traffic load should be balanced and the multiple channels of audio should be transmitted in parallel on these multiple buses. That is, try to arrange the transmission of one channel of audio data on one ARINC429 bus, and the transmission method on each bus is based on the single-channel audio single bus multiplexing solution of scenario 1.

[0136] However, if the number of channels is greater than the number of buses, it is inevitable that multi-channel audio data needs to be transmitted on some buses. In the case of a mono-channel single bus, the mono-channel audio single bus multiplexing scheme of scenario 1 is used for transmission, and in the case of a multi-channel single bus, the multi-channel audio single bus multiplexing scheme of scenario 2 is used for transmission.

[0137] After introducing the schematic flow of the sending and receiving method of the multiplexing transmission of airborne audio and other data according to the solution of the present application, the following is combined with Figure 4 and 5 The following is an example block diagram of an onboard audio and other data multiplexing transmission / reception system according to an embodiment of the present application.

[0138] like Figure 4 As shown, the multiplexing transmission system mainly includes an analog-to-digital converter 402, an encoder 404, an audio data ARINC429 framing module 406, a non-audio data ARINC429 framing module 408, an audio (FIFO) buffer 410, a non-audio (FIFO) buffer 412, a multiplexer 414 and an ARINC429 transmission chip 416, etc.

[0139] Specifically,

[0140] The analog-to-digital converter 402 is configured to perform analog-to-digital conversion on the received audio data, for example, to convert the received audio data into uncompressed 14-bit linear PCM format data. As mentioned above, if the received audio data is digital audio, the conversion may not be performed and the audio data may be directly output.

[0141] The encoder 404 is configured to encode the digital audio according to the codec standard. As mentioned above, the encoder 404 can use the ITU-T G.711 and G.726 standards to implement encoding. Of course, other codec standards can also be used, depending on actual needs.

[0142] The audio data ARINC429 framing module 406 is configured to select a corresponding ARINC429 encapsulation data format according to the coding and decoding standard used by the digital audio to encapsulate the digital audio into an ARINC429 frame to generate an audio ARINC429 frame.

[0143] The non-audio data ARINC429 framing module 408 is configured to encapsulate the received non-audio service data into ARINC429 frames to generate non-audio ARINC429 frames.

[0144] The audio (FIFO) buffer 410 is configured to buffer audio ARINC 429 frames.

[0145] The non-audio (FIFO) buffer 412 is configured to buffer non-audio ARINC 429 frames.

[0146] The multiplexer 414 is configured to read data from the audio (FIFO) buffer 410 and the non-audio (FIFO) buffer 412 in sequence according to the transmission cycle sequence corresponding to the multiplexing combination mode and provide the data to the ARINC429 transmission chip 416.

[0147] The ARINC429 transmitting chip 416 is configured to transmit the data from the multiplexer on the ARINC429 bus.

[0148] Similarly, if Figure 5 As shown, the multiplexed receiving system mainly includes a digital-to-analog converter 502, a decoder 504, an audio data ARINC429 deframing module 506, a non-audio data ARINC429 deframing module 508, an audio (FIFO) buffer 510, a non-audio (FIFO) buffer 512, a demultiplexer 514, and an ARINC429 receiving chip 516, etc. The functions of these component modules are opposite to those of the corresponding component modules of the multiplexed transmitting system, namely:

[0149] The ARINC429 receiving chip 516 is configured to receive data from the ARINC429 bus. The data may be ordinary data or data sent by the aforementioned airborne audio and other data multiplexing transmission system. For ordinary data, it is directly processed according to the traditional processing method, and only the data sent by the aforementioned airborne audio and other data multiplexing transmission system needs to be processed by the corresponding receiving system of the present application.

[0150] The demultiplexer 514 is configured to parse the audio ARINC429 frames and non-audio ARINC429 frames from the received data if the received data is sent by an airborne audio and other data multiplexing transmission system, and buffer them into the audio (FIFO) buffer 510 and the non-audio (FIFO) buffer 512 respectively.

[0151] The audio (FIFO) buffer 510 is configured to buffer audio ARINC429 frames.

[0152] The non-audio (FIFO) buffer 512 is configured to buffer non-audio ARINC429 frames.

[0153] The audio data ARINC429 de-framing module 506 is configured to de-frame the audio ARINC429 frames from the audio (FIFO) buffer 510 into digital audio.

[0154] The decoder 504 is used to decode the digital audio according to the coding standard used by the digital audio to generate uncompressed digital audio in linear PCM format.

[0155] The digital-to-analog converter 502 is configured to convert the decoded linear PCM format digital audio into analog audio. As mentioned above, if the device audio function module that processes data is a digital audio processing module, the digital-to-analog conversion can be skipped and the digital audio is directly output to the device audio function module. Only when the device audio function module is an analog audio processing module, the digital-to-analog converter 502 is required to perform the conversion.

[0156] The non-audio data ARINC429 de-framing module 508 is configured to de-frame the non-audio ARINC429 frames from the non-audio (FIFO) buffer 512 into non-audio service data. The non-audio service data is output to the non-audio function module for processing.

[0157] So far, the onboard audio and other data multiplexing transmission scheme of the present application has been introduced.

[0158] It should be understood that although specific digital audio formats and ARINC429 frame formats are shown in the drawings and tables, the examples are only given for illustrative purposes and are not intended to be limiting. Other modifications (such as changes in bit order) are within the scope of protection of this application.

[0159] The multiplexing transmission scheme of the present application can provide the following advantages:

[0160] 1. Transmit digital audio data and other data through ARINC429 bus time division multiplexing, saving device external interface pins and airborne connection weight;

[0161] 2. Multiple ARINC429 digital audio formats designed for data multiplexing;

[0162] 3. The audio data compression rate can be dynamically adjusted according to the non-audio service traffic of different devices to meet the needs of multiplexed transmission.

[0163] Although various embodiments are described above, it should be understood that they are intended to be exemplary rather than limiting. Those skilled in the relevant art(s) will appreciate that various modifications may be made in form and detail without departing from the spirit and scope of the present invention as defined in the appended claims. Therefore, the breadth and scope of the present invention disclosed herein should not be limited by the exemplary embodiments disclosed above, but should only be defined in accordance with the appended claims and their equivalents.

Claims

1. A method for transmitting airborne audio and other data multiplexed transmission, comprising: Phase 1: Determine whether the received audio data is analog audio or digital audio: If the audio data is analog audio, convert it into uncompressed digital audio in linear PCM format by analog-to-digital conversion; If the audio data is digital audio, decoding the digital audio into uncompressed linear PCM digital audio as required; Selecting a codec standard to encode the digital audio; According to the codec standard used by the digital audio, select a corresponding ARINC429 encapsulation data format to encapsulate the digital audio into an ARINC429 frame to generate an audio ARINC429 frame; Storing the audio ARINC429 frame in an audio buffer; Phase 2: Receiving non-audio service data, and performing ARINC429 framing on the received non-audio service data to generate non-audio ARINC429 frames; storing the non-audio ARINC429 frame into a non-audio buffer; and Phase 3: Data is read from the audio buffer and the non-audio buffer in sequence according to the transmission cycle sequence corresponding to the multiplexing combination mode and forwarded to the ARINC429 transmission chip for external transmission.

2. The sending method according to claim 1, characterized in that: There is no chronological order for the steps in stage 1 and stage 2.

3. The sending method according to claim 1, characterized in that: The coding and decoding standards include ITU-TG.711 and G.

726. The G.711 standard uses 8-bit quantization for each sampling point and a bit rate of 64kbps. The G.726 standard uses ADPCM technology, with 5 / 4 / 3 / 2 bits of quantization for each sampling point, and a corresponding bit rate of 40kbps / 32kbps / 24kbps / 16kbps.

4. The sending method according to claim 1, characterized in that: In the ARINC429 encapsulation data format, the first bit indicates whether the ARINC429 frame is an audio ARINC429 frame or a non-audio ARINC429 frame, and the meanings of bits 31 to 29 are shown in the following table:

5. The sending method according to claim 1, characterized in that: The transmission period corresponding to the multiplexing combination mode satisfies the following formula: T / Δt≥(T+t) / 125 T represents the time for transmitting the audio ARINC429 frame, t represents the time for transmitting the non-audio ARINC429 frame, 125 represents the audio data interval 125us sent by the front end; Δt represents the average time consumption of one sampling point in the audio ARINC429 frame, and its value is 360us / the number of sampling points in one ARINC429 frame, and 360us is 320us of one ARINC429 frame plus a 40us protection interval; According to sending one other ARINC429 frame for every N digital audio ARINC429 frames, the above formula can be rewritten as: N / Δt≥(N+1) / 125.

6. A method for receiving airborne audio and other data multiplexed transmission, comprising: Receive data from the ARINC429 bus; If the data is data sent by the sending method according to any one of claims 1 to 5, then: Parse the data, buffer the audio ARINC429 frames into the audio buffer, and buffer the non-audio ARINC429 frames are buffered into non-audio buffers; (a) reading the audio ARINC429 frame from the audio buffer and de-framing it into digital audio; Decoding the digital audio into uncompressed linear PCM digital audio based on the codec standard used by the digital audio; Determine whether the device audio function module is a digital audio processing module or an analog audio processing module: If the device audio function module is a digital audio processing module, directly Process the decoded linear PCM digital audio; If the device audio function module is an analog audio processing module, the decoder The linear PCM digital audio is converted into analog audio by a digital-to-analog converter and then processed. (b) reading the non-audio ARINC429 frame from the non-audio buffer and de-framing it into non-audio service data; The non-audio service data is processed by the non-audio function module.

7. The receiving method according to claim 6, characterized in that: There is no order of precedence for steps (a) and (b).

8. An airborne audio and other data multiplexing and sending system, comprising: an analog-to-digital converter configured to convert the received analog audio into digital audio in an uncompressed linear PCM format; An encoder configured to encode the digital audio according to a codec standard; An audio data ARINC429 framing module is configured to select a corresponding ARINC429 encapsulation data format according to the codec standard used by the digital audio to encapsulate the digital audio into an ARINC429 frame to generate an audio ARINC429 frame; A non-audio data ARINC429 framing module, configured to encapsulate received non-audio service data into ARINC429 frames to generate non-audio ARINC429 frames; An audio buffer configured to buffer the audio ARINC429 frame; A non-audio buffer configured to buffer the non-audio ARINC429 frame; a multiplexer configured to read data from the audio buffer and the non-audio buffer in sequence according to a transmission cycle sequence corresponding to a multiplexing combination mode and provide the data to an ARINC429 transmission chip; and The ARINC429 transmitting chip is configured to transmit data on the ARINC429 bus.

9. An airborne audio and other data multiplexing receiving system, comprising: The ARINC429 receiving chip is configured to receive data from the ARINC429 bus; a demultiplexer configured to parse audio ARINC429 frames and non-audio ARINC429 frames from the received data and buffer them into an audio buffer and a non-audio buffer respectively if the data is data transmitted by the airborne audio and other data multiplexing transmission system as claimed in claim 8; An audio buffer configured to buffer the audio ARINC429 frame; A non-audio buffer configured to buffer the non-audio ARINC429 frame; An audio data ARINC429 de-framing module configured to de-frame the audio ARINC429 frames from the audio buffer into digital audio; A decoder configured to decode the digital audio accordingly based on the coding standard used by the digital audio to generate digital audio in an uncompressed linear PCM format; A digital-to-analog converter, configured to convert the decoded linear PCM digital audio into analog audio; The non-audio data ARINC429 de-framing module is configured to de-frame the non-audio ARINC429 frames from the non-audio buffer into non-audio service data.

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