JP5221271B2 - Transmitter, receiver, transmission / reception system and method - Google Patents

Description

  The present invention relates to an improvement in technology for transmitting and receiving audio as digital data, and more particularly to a technology having an error correction function.

  In recent years, with the advancement of digital technology, the digitization of voice transmission is also progressing rapidly in the field of wireless communication. Here, in digital data transmission such as voice, error detection / correction technology that detects and corrects errors without requesting additional information on the transmission side on the reception side by adding redundancy to the transmission data on the transmission side Is used.

For example, in this technique, a redundant bit called a checksum or the like is added to transmission data on the transmission side, and error detection or correction of reception data is performed on the reception side (see, for example, Patent Document 1). Typical examples include vertical parity check method, horizontal parity check method, Hamming code method, CRC method, Reed-Solomon code method, convolutional code method, Viterbi decoding method, turbo code method, etc. It is suitable for applications that not only detect but also correct.
JP 2000-353968 A

  By the way, the rate of error that can be corrected in the transmission data is related to the size of the redundant data rate with respect to the transmission data body. For example, a unit amount of data transmission in a wireless microphone system is called a symbol, but how many symbols can be error-corrected within a certain amount of data is proportional to the amount of redundant data added to that amount of data. .

  However, since the number of symbols that can be transmitted per unit time is limited due to the limit of the data transmission rate (bandwidth), the amount of redundant data that can be added is also limited. In the conventional wireless microphone system, a predetermined ratio of redundant data, that is, a checksum is equally allocated to any part of transmission data, so that sufficiently effective error correction processing is performed on all symbols. There was a problem that I could not.

  For example, when a wireless microphone is used as a transmitter, the radio wave condition of the carrier wave is likely to change due to the usage frequency band and the usage that the user walks around on the platform, etc. If there are too many errors in the portion and the correction cannot be made, there will be inconveniences in the sound such as extreme noise and sound quality deterioration including sound interruption.

  The present invention solves the above-described problems of the prior art, and an object of the present invention is a digital data transmission / reception technique having an error correction function. An object of the present invention is to provide a transmitter, a receiver, a transmission / reception system, and a method capable of effectively reducing deterioration in sound quality during communication by performing error correction processing in accordance with the degree of influence on the communication.

To achieve the above object, a first receiving means for wirelessly receiving voice first transmission data, a second receiving means for wirelessly receiving voice second transmission data, and a computer or electronic An error correction decoding means for restoring digital audio data by using error correction redundant bits added to the first and second transmission data, and a digital audio data from the computer or electronic circuit In a receiver comprising D / A conversion means for converting to a signal and means for outputting the sound of the converted analog audio signal to the outside, the error correction decoding means preliminarily classifies the data for each bit. Redundancy for restoring the error correction redundant bits added to the first and second transmission data, which are added at a high rate in order from the higher bit position. And the redundant bit restoring means add the corrected redundant bits added to the first transmission data to the first digital audio data restored to the second transmission data. And selecting means for selecting data with good sound quality by comparing the sound quality of the second digital sound data from which the error correction redundant bits have been restored, wherein the selecting means includes the first digital sound data. When it is determined that the deterioration of the sound quality of the digital audio data exceeds a predetermined threshold, it is determined whether the deterioration of the sound quality of the second digital sound data exceeds a predetermined threshold, and the second digital sound When it is determined that the voice quality degradation of the data exceeds a predetermined threshold, the first digital voice data and the second digital voice data are compared to reduce the voice quality degradation. And selects a free digital audio data.

According to a second aspect of the present invention, in the receiver according to the first aspect, the selection means is within a usable range for the selected digital audio data with little deterioration of the voice quality. It is characterized by judging .

According to a third aspect of the invention, in the receiver according to the first or second aspect, the deterioration of the voice quality corresponds to the number of bits in which an error occurs .

According to a fourth aspect of the present invention, a microphone for voice input, an A / D conversion means for converting an analog voice signal input from the microphone into digital voice data by a computer or an electronic circuit, and the digital voice data are used. In a transmitter comprising: an error correction encoding means for creating transmission data by processing including redundant bit addition for error correction by a computer or electronic circuit; and a transmission means for wirelessly transmitting the transmission data by a carrier wave. The error correction coding means includes a quality classifying means for classifying the digital audio data for each bit, and corresponding to each bit classified by the quality classification means, and the higher percentage of the bit positions in descending order. A transmitter comprising: means for adding redundant bits for error correction; and any one of claims 1 to 3 Characterized in that a combination of a receiver according to (1).

  The present invention is a concept that encompasses the above-described invention from the viewpoint of a method, and includes a transmission method using a transmitter, a reception method using a receiver, and a transmission / reception method using a transmitter and a receiver. .

  As described above, according to the present invention, voice data to be transmitted is collected for each bit, and error correction processing is performed according to the degree of influence on voice quality, thereby effectively reducing sound quality degradation during communication. Furthermore, by receiving a plurality of audio data and comparing the degree of deterioration, it is possible to select and output audio data with good audio quality even when an error has occurred.

[This embodiment]
Next, the best mode for carrying out the present invention will be described in detail below with reference to FIGS. In addition, the structure of the transmitter in a transmission / reception system is shown in FIG. 1, and the structure of a receiver is shown in FIG. Further, the processing procedure in the transmitter is shown in the flowchart of FIG. 4, and the processing procedure in the receiver is shown in the flowchart of FIG.

[1. Constitution]
First, main elements constituting the present embodiment will be described, but some components will be described later in the section of action.

[1.1. overall structure]
In the transmission / reception system according to the present embodiment, as shown in FIGS. 1 and 2, for example, a transmitter 1 that is a wireless microphone and a receiver 2 are combined to realize error correction by a Hamming code method or the like. The present embodiment can also be grasped as a data transmission method in the transmitter 1, a data reception method in the receiver 2, and a data transmission / reception method in the transmitter 1 and the receiver 2.

[1.2. Configuration of transmitter]
The transmitter 1 is configured as shown in the functional block diagram of FIG. That is, the microphone (microphone) 11 is for voice input, and the A / D converter 13 is an A / D for converting an analog voice signal input from the microphone 11 and amplified by the amplifier 12 into digital voice data by a computer or an electronic circuit. It is a conversion means.

  The audio codec 14a (CODEC) processes the compressed data by performing audio compression encoding processing based on the digital audio data converted by the A / D conversion unit 13. The tens of sample buffers 14b accumulates the compressed data in a predetermined number, that is, tens of samples at a time as unit audio data for transmission.

  The voice quality classification unit 14c sorts the voice data for each degree of influence on the voice quality by collecting the accumulated unit voice data for each bit. In other words, since the audio data is collected for each bit, it corresponds to the part that has a large influence on the voice quality due to errors such as the sign bit and the upper bit of the voice data, and other parts that have a relatively small influence on the voice quality. Are classified. Here, as shown in FIG. 3, for example, 4 bits of audio data means that the audio data is grouped for each bit. For example, the audio data is divided from the upper bits to the lower bits (3 bits group, 2 bits group). 1 bit group,...).

  For example, when using PCM coding or ADPCM, a code with a large amount of change in sound is included in the upper bits, and other codes with a relatively small amount of change are included in the lower bits. This category corresponds to the degree of influence on voice quality. Note that the audio codec 14a to the audio quality classification unit 14c correspond to the audio processing unit.

  The error correction encoding unit 15 adds an error correction code such as a checksum to the digital audio data classified for each bit by the audio quality classification unit 14c after adjusting the relative ratio. In other words, depending on the degree of influence on voice quality, error correction codes are added at a relatively high rate for high-impact code bits and high-order bits, and for low-order bits with low influence Error correction codes are added at a relatively smaller rate than in the case of high data. The speech processing unit and the error correction coding unit 15 correspond to error correction coding means.

  The channel codec 16 processes a specific channel by performing channel compression encoding processing. The baseband processing unit 17 and the wireless unit 18 constitute a transmission unit that wirelessly transmits the transmission data using a carrier wave.

  The control unit 19 includes a computer or an electronic circuit, and includes an A / D conversion unit 13, an audio codec 14a, several tens of sample buffers 14b, an audio quality classification unit 14c, an error correction encoding unit 15, a channel codec 16, and baseband processing. The unit 17 is controlled, and the operation unit 20a and the display unit 20b are connected.

[1.3. Receiver configuration]
The configuration of the receiver 2 is configured as shown in the functional block diagram of FIG.
The radio unit 21A and the baseband processing unit 22A to which the antenna is connected constitute a reception unit that wirelessly receives audio transmission data.

  The channel codec 23A expands a specific channel compressed into the received transmission data, and the error correction decoding unit 24A converts the digital audio data into the digital audio data using the error correction redundant bits added to the transmission data. Restore. As shown in FIG. 2, the receiver 2 includes a radio unit 21B to a correction decoding unit 24B having the same configuration in addition to the radio unit 21A to the error correction decoding unit 24A, and the radio unit 21A to the error correction unit. It is assumed that the data passing through the decoding unit 24A is Ach and the data passing through the radio unit 21B to the correction decoding unit 24B is Bch. A separate antenna is connected to the radio unit 21B.

  The error correction decoding units 24A and 24B have a higher rate than the other parts in the audio data collected for each bit, which has a high influence on the audio quality (code bit and upper bit). Redundant error correction redundant bits are restored, and for those that have a low impact on voice quality (low order bits), redundant bits for error correction that are added at a lower rate than the high impact portions To restore.

  The selection unit 25 selects and restores data with good audio quality from the degree of deterioration of the Ach digital audio data and the Bch digital audio data decoded by the error correction decoding units 24A and 24B. This process is described in detail in the section “2. Action”. Note that the error correction decoding unit 24, the selection unit 25, and the audio codec 26 shown below correspond to the error correction decoding unit (the correction decoding unit 24 corresponds to the redundant bit restoration unit, and the selection unit 25 serves as the selection unit). Corresponding.)

  The audio codec (CODEC) 26 restores the compressed unit audio data to digital data in an uncompressed format for reproduction. The D / A converter 27 is a D / A converter that converts the digital audio data into an analog audio signal, and the amplifier 28 and the speaker 29 are means that output the audio based on the converted analog audio signal to the outside. is there.

  The control unit 30 includes a computer or an electronic circuit, and controls the error correction decoding units 24A and 24B, the selection unit 25, the audio codec 26, and the D / A conversion unit 27, and the display unit 31 is connected thereto. Yes.

[2. Action]
Next, the operation according to the present embodiment as described above will be described below with reference to the flowcharts of FIGS.

[2.1. Send]
First, in the present embodiment, a processing procedure when the transmitter 1 transmits voice is shown in the flowchart of FIG.

[2.1.1. Until digitalization]
At the time of transmission, first, the transmitter 1 converts the sound input to the microphone (microphone) 11 into an electrical analog audio signal, and the amplifier 12 amplifies the analog audio signal to a predetermined level. The amplified analog audio signal is converted into digital audio data in accordance with conditions such as a predetermined sampling frequency and the number of quantization bits by an A / D (analog-to-digital) converter 13 (step 01).

[2.1.2. compression]
First, the voice codec (CODEC) 14a performs voice compression coding processing based on the digital voice data converted by the A / D conversion unit 13 (step 02), thereby processing the compressed data. .

[2.1.3. Quality category]
The compressed data is stored in the tens of sample buffers 14b as a unit audio data for transmission in units of a predetermined number, that is, tens of samples (step 03), and the audio quality classification unit 14c stores the unit audio data for each bit. Thus, the voice data is classified according to the degree of influence on the voice quality (step 04). Specifically, the audio data has a part that has a large influence on the voice quality due to an error such as a sign bit or an upper bit, and other parts that have a relatively little influence on the voice quality, and therefore, for each bit. By collecting the audio data, it is possible to classify the audio data corresponding to the degree of influence on the audio quality.

[2.1.4. Error correction coding]
As described above, with respect to the data group classified by the voice quality classification unit 14c, the error correction encoding unit 15 uses an error correction code such as a checksum whose relative ratio is adjusted corresponding to each bit. Is added (step 05). That is, the error correction coding unit 15 adds error correction codes at a relatively high rate to code bits and higher bits having a high influence on the voice quality, and to lower bits having a low influence. Error correction codes are added at a relatively smaller rate than in the case of data with high influence.

  For example, when a total of 10 symbols can be corrected per 100 symbols of the transmission data body, the correction encoding unit 14, for example, uses 1.8 symbols for the code bits (3.6 symbols for the checksum data amount) and 1.6 bits for the 9 bits. Symbol (checksum data amount 3.2 symbols), 1.4 symbols (checksum data amount 2.8 symbols) in 8 bits,..., 0 symbols (checksum data amount 0 symbols) are assigned to 0 bits. Thereby, the reception sensitivity of an important part improves, and as a result, deterioration of sound quality can be reduced.

[2.1.5. Wireless transmission]
As described above, the audio data group to which an error correction code is attached for each bit is subjected to necessary interleaving processing (step 06), frame addition (step 07), IQ signal output, and the like, and then the baseband processing unit 17 Is carried on the carrier wave and transmitted from the radio unit 18 equipped with the antenna (steps 08 and 09).

[2.2. Receive]
Next, in the present embodiment, a processing procedure when the receiver 2 receives data for transmission is shown in the flowchart of FIG.

[2.2.1. Reception and error correction coding]
Specifically, first, from the carrier wave received by the first radio unit 21A equipped with an antenna (FIG. 2), the received data is demodulated by baseband processing (step 21 in FIG. 5) by the baseband processing unit 22A, A data group for each bit (referred to as Ach), which is transmitted transmission data, is extracted by necessary frame removal (step 22), deinterleave processing (step 23), and the like. On the other hand, the received data is demodulated from the carrier wave received by the second radio unit 21B equipped with a separate antenna by the baseband processing (step 21) by the baseband processing unit 22B, and necessary frame removal (step 22), decoding is performed. A data group for each bit (referred to as Bch), which is the transmitted data for transmission, is extracted by interleaving (step 23).

  Then, the error correction decoding unit 24A restores the digital audio data using the error correction redundant bits added to the data group extracted by Ach (step 24). Specifically, in the audio data grouped by bit, those that have a high influence on the audio quality (sign bit and upper bit), error correction added at a higher rate than other parts The redundant bits for error correction are restored, and for those having a low influence on the voice quality (lower bits), the redundant bits for error correction added at a lower rate than the part having a high influence are restored. Further, in the same manner as described above, the error correction decoding unit 24B restores digital audio data using the error correction redundant bits added to the data group extracted from Bch.

[2.2.2. Select data]
The selection unit 25 selects data with good audio quality as follows from the degree of deterioration of the Ach digital audio data and the Bch digital audio data decoded by the error correction decoding units 24A and 24B. First, it is determined whether an error has occurred in the Ach audio data after the correction processing (step 25). If no error has occurred in the Ach audio data (YES in step 25), this Ach bit by bit, that is, quality The voice data divided every time is restored (step 26).

  Here, whether or not an error has occurred is determined by, for example, whether or not the number of bits in which an error has occurred is greater than a predetermined threshold in the audio data of Ach. Restored.

  If an error has occurred in the Ach audio data (NO in step 25), it is determined whether an error has occurred in the Bch audio data (step 27). If no error has occurred in the Bch audio data (YES in step 27), the audio data divided for each Bch quality is restored (step 26).

  If an error has occurred in the Bch audio data (NO in step 27), the number of error bits generated in the Ach audio data and the Bch audio data is compared to determine which audio data. It is determined whether the data is degraded (step 28). That is, audio data with a large number of bits in which an error has occurred has a greater deterioration, and audio data having an error in which the number of bits has a small number has a small deterioration.

  If it is determined that the audio data of Ach is less deteriorated (Ach in step 28), it is determined whether the degree of deterioration of the audio data of Ach is within a usable range (step 29). Here, the usable range of the degree of deterioration of the audio data can be determined according to the bit in which an error has occurred. For example, is it within the usable range even if an error has occurred up to the 0th bit? Or, whether or not an error occurs before the first bit is set within a usable range.

  If it is determined that the deterioration level of the Ach audio data is within the usable range (YES in step 29), the audio data divided for each Ach quality is restored (step 26). If it is determined that the degree of degradation of the Ach audio data is not within the usable range (NO in step 29), no audio is output and the process ends.

  If it is determined in step 28 that the Bch audio data is less degraded than the Ach audio data (Bch in step 28), the degradation level of the Bch audio data is within the usable range. (Step 30). If it is determined that it is within the usable range (YES in step 30), the audio data divided for each Bch quality is restored (step 26). If it is determined that the deterioration level of the Bch audio data is not within the usable range (NO in step 30), the audio output is not performed and the process ends.

[2.2.3. Stretch and play]
The audio data restored in step 26 is compressed, and the audio codec (CODEC) 26 restores the compressed unit audio data to uncompressed digital data for reproduction (step 31).

  The D / A (digital-to-analog) converter 27 D / A converts this digital data into an analog audio signal according to conditions such as a predetermined sampling frequency and the number of quantization bits (step 32), and the amplifier 28 Through the speaker 29 (step 33).

[3. effect]
According to the present embodiment as described above, voice data to be transmitted is collected for each bit, and error correction processing is performed according to the degree of influence on voice quality, thereby effectively reducing sound quality degradation during communication. In addition, by receiving a plurality of audio data and comparing the degree of deterioration, it is possible to select and output audio data with good audio quality even when an error has occurred.

[Other Embodiments]
In the embodiment of the present invention, as described above, interleaving processing, addition of a frame, and the like are not essential depending on the transmission method, and the amplifier 27 and the speaker 28 are different from the receiver 2 constituting the present invention. You may make up your body.

The functional block diagram which shows the structure of the transmitter in embodiment of this invention. The functional block diagram which shows the structure of the receiver in embodiment of this invention. The figure which shows the audio | voice data example put together for every bit concerning embodiment of this invention. The flowchart which shows the process sequence of the transmission side in embodiment of this invention. The flowchart which shows the process sequence of the receiving side in embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Transmitter 2 ... Receiver 11 ... Microphone 12 ... Amplifier 13 ... A / D conversion part 14a ... Voice codec 14b ... Dozens of sample buffers 14c ... Voice quality classification part 15 ... Correction coding part 16 ... Channel codec 17 ... Base Band processing unit 18 ... radio unit 19 ... control unit 20a ... operation unit 20b ... display units 21A, 21B ... radio units 22A, 22B ... baseband processing units 23A, 23B ... channel codec 24A, 24B ... correction decoding unit 25 ... selection Unit 26 ... Audio codec 27 ... D / A converter 28 ... Amplifier 29 ... Speaker 30 ... Control unit 31 ... Display unit

Claims (8)

First receiving means for wirelessly receiving voice first transmission data;
Second receiving means for wirelessly receiving voice second transmission data;
An error correction decoding means for restoring digital audio data by using a redundant bit for error correction added to the first and second transmission data by a computer or an electronic circuit;
D / A conversion means for converting the digital audio data into an analog audio signal by a computer or electronic circuit;
Means for outputting the sound of the converted analog sound signal to the outside;
In a receiver with
The error correction decoding means includes
Redundant bit restoration that restores the error correction redundant bits added to the first and second transmission data, in which the data is divided in advance, in order from the higher bit position in order. Means,
The first digital audio data in which the correction redundant bit added to the first transmission data is restored by the redundant bit restoration means and the error correction redundancy added to the second transmission data A selection means for selecting data having good voice quality by comparing the voice quality of the second digital voice data in which bits are restored;
Equipped with a,
The selection means includes
If it is determined that the deterioration of the voice quality of the first digital audio data exceeds a predetermined threshold, it is determined whether the deterioration of the voice quality of the second digital audio data exceeds a predetermined threshold;
When it is determined that the deterioration of the sound quality of the second digital sound data exceeds a predetermined threshold, the deterioration of the sound quality is performed by comparing the first digital sound data and the second digital sound data. receiver according to claim you to select a small digital audio data with. The receiver according to claim 1 , wherein the selection unit determines whether the degradation is within a usable range for the selected digital audio data with little degradation of the voice quality. The receiver according to claim 1 or 2 , wherein the deterioration of the voice quality corresponds to the number of bits in which an error occurs. A microphone for voice input;
A / D conversion means for converting an analog audio signal input from the microphone into digital audio data by a computer or electronic circuit;
Based on the digital audio data, error correction coding means for creating transmission data by a process including redundant bit addition for error correction by a computer or electronic circuit;
Transmitting means for wirelessly transmitting the data for transmission on a carrier wave;
In a transmitter with
The error correction encoding means includes
Quality classifying means for classifying the digital audio data bit by bit;
Means for adding the error-correcting redundant bits in order from the highest bit position corresponding to each bit classified by the quality classification means;
A transmitter characterized by comprising:
A transmission / reception system comprising a combination of the receiver according to claim 1. First receiving means for wirelessly receiving voice first transmission data;
Second receiving means for wirelessly receiving voice second transmission data;
An error correction decoding means for restoring digital audio data by using a redundant bit for error correction added to the first and second transmission data by a computer or an electronic circuit;
D / A conversion means for converting the digital audio data into an analog audio signal by a computer or electronic circuit;
Means for outputting the sound of the converted analog sound signal to the outside;
In a receiving method executed using a receiver comprising:
The error correction decoding means includes
Redundant bit restoration that restores the error correction redundant bits added to the first and second transmission data, in which the data is divided in advance, in order from the higher bit position in order. Steps,
The first digital audio data in which the correction redundant bit added to the first transmission data is restored by the redundant bit restoration step, and the error correction redundancy added to the second transmission data. A selection step of selecting data with good audio quality by comparing the audio quality of the second digital audio data with bits restored;
The execution,
The selection step includes
If it is determined that the deterioration of the voice quality of the first digital audio data exceeds a predetermined threshold, it is determined whether the deterioration of the voice quality of the second digital audio data exceeds a predetermined threshold;
When it is determined that the deterioration of the sound quality of the second digital sound data exceeds a predetermined threshold, the deterioration of the sound quality is performed by comparing the first digital sound data and the second digital sound data. A receiving method characterized by selecting digital audio data with less content. 6. The receiving method according to claim 5 , wherein the selecting step determines whether or not the deterioration is within a usable range for the selected digital audio data with little deterioration of the voice quality. . The reception method according to claim 5 or 6 , wherein the deterioration of the voice quality corresponds to the number of bits in which an error has occurred. A microphone for voice input;
A / D conversion means for converting an analog audio signal input from the microphone into digital audio data by a computer or electronic circuit;
Based on the digital audio data, error correction coding means for creating transmission data by a process including redundant bit addition for error correction by a computer or electronic circuit;
Transmitting means for wirelessly transmitting the data for transmission on a carrier wave;
In a transmission method to be executed using a transmitter equipped with
The error correction encoding means includes
A quality classification step of classifying the digital audio data bit by bit;
In correspondence with each bit classified by the quality classification step, adding a high percentage of the error correcting redundant bits in order from the highest bit position,
A transmission / reception method characterized in that the transmission method is executed in combination with the reception method according to any one of claims 5 to 7 .

Images