JP2008182393A - Baseband signal generation apparatus, baseband signal generation method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a baseband signal generator or the like for surely transmitting data at high speed without increasing the total amount of the data to be transmitted or without adding redundant data. <P>SOLUTION: A transmitter T generates a speech communication channel and a high-speed accompanying control channel, generates the dibit of 4-valued FSK for which a bit inside the speech communication channel is made a high-order bit and a bit inside the high-speed accompanying control channel is made a low-order bit, and generates baseband signals indicative of the dibit. However, when significant additional data to be included in the high-speed accompanying control channel are not present, the high-speed accompanying control channel is generated so that the value of the entire bits becomes "1". In the meantime, for the dibit for which the value of the low-order bit is "1", the baseband signal is generated so that the symbol value becomes the highest value or the lowest value among four convergence values that the symbol value can take. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a baseband signal generation device, a baseband signal generation method, and a program.

  In recent years, digital communication using a four-value FSK (Frequency Shift Keying) modulation wave has been accelerated. For example, conventionally, data communication with a bandwidth of 12.5 kHz and a communication speed of 4800 bps was performed by transmitting and receiving a 384-bit frame having the data structure shown in FIG. 7 in 80 milliseconds. By transmitting and receiving two 384-bit frames each having the data structure shown in FIG. 8 every 40 milliseconds, digital communication at a communication speed of 9600 bps is achieved while keeping the bandwidth at 12.5 kHz. The communication channels shown in FIGS. 7 and 8 are usually made up of data representing voice, and the high-speed associated control channel may be used for transmission of data used by GPS (Global Positioning System). In some cases, it does not contain significant data.

On the other hand, the data structure of the frame shown in FIG. 8 is the same as the frame shown in FIG. 7 for the one including the communication channel, so that the communication speed is increased as described above for the communication channel in the frame of FIG. As a result, the signal-to-noise ratio decreases. As a technique for solving this problem, a redundant bit is added to each bit constituting the main part of the data to be transmitted, thereby forming a dibit corresponding to an FSK symbol. The maximum value or the minimum value of the four possible values is set (see, for example, Patent Document 1 to Patent Document 3).
JP 2005-197830 A JP 2005-295225 A JP 2005-295277 A

  However, in the above method, the total amount of data to be transmitted increases by the amount of redundant bits. Therefore, if the total amount of data to be transmitted is to be suppressed, the portion to which redundant bits are added is narrowed down. It will have to be.

  The present invention has been made in view of such problems, and is a base for transmitting data at high speed and reliably without increasing the total amount of data to be transmitted or without adding redundant data. An object is to provide a band signal generation device, a baseband signal generation method, and a program.

In order to achieve this object, a baseband signal generation device according to the first aspect of the present invention provides:
Baseband signal generating means for converting data consisting of main data and additional data into a baseband signal representing a sequence of symbols composed of 2 bits;
Main data acquisition means for acquiring the main data;
Additional data acquisition and generation means for acquiring or generating the additional data,
The baseband signal generation means includes
At least some of the symbols belonging to the symbol column include, as upper bits, bits belonging to the main data acquired by the main data acquisition unit, and lower bits belonging to the additional data acquired or generated by the additional data acquisition generation unit Converting the data into the baseband signal to include as bits,
When the value of the low-order bits constituting the symbol is a predetermined value, the instantaneous value of the point representing the symbol in the baseband signal is the highest value of the four convergence values that the instantaneous value can converge or Always converges to the lowest value,
It is characterized by that.

  The additional data acquisition and generation means determines whether or not the additional data already exists, acquires the additional data when determining that the additional data exists, and determines that the predetermined data does not exist There may be provided means for generating a bit string composed only of bits having a value as additional data.

  The main data may include a part of a bit string obtained by encoding speech.

  The baseband signal generation device may further include a modulation unit that generates a modulated wave using the baseband signal generated by the baseband signal generation unit and sends the modulated wave to a transmission path. .

A baseband signal generation method according to the second aspect of the present invention includes:
A baseband signal generation step of converting data consisting of main data and additional data into a baseband signal representing a symbol string composed of 2 bits;
A main data acquisition step of acquiring the main data;
An additional data acquisition and generation step for acquiring or generating the additional data, and
In the baseband signal generation step,
At least some of the symbols belonging to the symbol column include bits belonging to the main data acquired in the main data acquisition step as upper bits and bits belonging to the additional data acquired or generated in the additional data acquisition generation step as lower bits. Converting the data into the baseband signal to include as bits,
When the value of the low-order bits constituting the symbol is a predetermined value, the instantaneous value of the point representing the symbol in the baseband signal is the highest value of the four convergence values that the instantaneous value can converge or Always converge to the lowest value,
It is characterized by

A program according to the third aspect of the present invention is:
Processor,
Baseband signal generating means for converting data consisting of main data and additional data into a baseband signal representing a sequence of symbols composed of 2 bits;
Main data acquisition means for acquiring the main data;
A program for functioning as additional data acquisition and generation means for acquiring or generating the additional data,
The baseband signal generation means includes
At least some of the symbols belonging to the symbol column include, as upper bits, bits belonging to the main data acquired by the main data acquisition unit, and lower bits belonging to the additional data acquired or generated by the additional data acquisition generation unit Converting the data into the baseband signal to include as bits,
When the value of the low-order bits constituting the symbol is a predetermined value, the instantaneous value of the point representing the symbol in the baseband signal is the highest value of the four convergence values that the instantaneous value can converge or Always converges to the lowest value,
It is characterized by that.

  According to the present invention, a baseband signal generation device, a baseband signal generation method, and a baseband signal generation method for transmitting data at high speed and reliably without increasing the total amount of data to be transmitted or without adding redundant data The program is realized.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings, taking a voice and data transmitting / receiving apparatus as an example.
FIG. 1 shows the configuration of voice and data transceivers TR1 and TR2 according to an embodiment of the present invention. As shown in the figure, the voice and data transceivers TR1 and TR2 have substantially the same configuration, and are constituted by a transmission device T, a reception device R, and an antenna A, respectively. The transceivers TR1 and TR2 transmit and receive voice and data between each other wirelessly.

  The transmission device T of the transceiver TR1 generates an FSK (Frequency Shift Keying) modulated wave representing sound, transmits the modulated wave to the reception device R of the transceiver TR2, and transmits the modulated wave from the antenna A of the transceiver TR1. R receives this FSK modulated wave from the antenna A of the transceiver TR2 and reproduces the sound. Similarly, the transmitter T of the transceiver TR2 generates an FSK modulated wave representing sound and transmits it to the receiver R of the transceiver TR1 from the antenna A of the transceiver TR2, and the receiver R of the transceiver TR1 The FSK modulated wave is received from the antenna A of the transceiver TR1 to reproduce the sound.

The transmitters T of the transceivers TR1 and TR2 have substantially the same configuration, and the receivers R of the transceivers TR1 and TR2 have substantially the same configuration.
However, it is assumed that the transceivers TR1 and TR2 each have a configuration in which the FSK modulated wave transmitted by the own transmission device T is not received by the own reception device R. Specifically, for example, it is conceivable that the transmission frequency of the transmission device T of the transceiver TR1 (or TR2) is different from the reception frequency of the reception device R. Alternatively, the transceivers TR1 and TR2 attach the identification code of the transmission source and / or the destination to the FSK modulated wave transmitted by the respective transmission device T, while the respective reception device R identifies itself as the destination. Only the FSK modulated wave to which the code is attached or the FSK modulated wave to which the self identification code is not attached as the transmission source may be handled as a target for reproducing the sound. Alternatively, PTT (Press To Talk) in which each of the transceivers TR1 and TR2 stops the operation of receiving the FSK modulated wave by the receiving apparatus R while the transmitting apparatus T is transmitting the FSK modulated wave. You may make it have a well-known mechanism which performs these functions.

  As shown in FIG. 2, each of the transmission devices T of the transceivers TR1 and TR2 includes a voice input unit T1, a voice encoding processing unit T2, an additional data input unit T3, a frame generation unit T4, and a baseband signal. A generation unit T5, a modulation unit T6, and a high-frequency output unit T7 are included.

  The audio input unit T1 includes, for example, a microphone, an AF (Audio Frequency) amplifier, an A / D (Analog-to-Digital) converter, and the like.

  For example, the audio input unit T1 collects audio, generates an analog audio signal representing the audio, amplifies the audio signal, performs sampling and A / D conversion, and thereby converts the audio data in digital format. Is generated.

  The audio encoding processing unit T2 performs predetermined audio encoding processing and error correction-detection encoding processing on the digital audio data supplied from the audio input unit T1, and the digital audio data after processing is fixed. Are divided into a plurality of audio data strings representing audio having a time length of (for example, 20 milliseconds) and sequentially supplied to the frame generation unit T4.

  The additional data input unit T3 obtains arbitrary additional data including a code string from the outside, performs a predetermined error correction-detection encoding process, and sequentially supplies 144-bit data to the frame generation unit T4. Additional data should just be comprised from the positioning data which GPS (Global Positioning System) produces | generates, for example.

  Assuming that the additional data input unit T3 is composed of a processor that performs the function of the frame generation unit T4, the data generated by the processor or read from an arbitrary storage device is used as additional data to the processing of the frame generation unit T4. You may hand over. Alternatively, the additional data input unit T3 may acquire data serially transmitted from the outside via an interface or the like, and deliver it to the processing of the frame generation unit T4 as additional data.

  Each of the frame generation unit T4 and the baseband signal generation unit T5 includes a processor such as a DSP (Digital Signal Processor) or a CPU (Central Processing Unit), a memory that stores a program to be executed by the processor, and the like. ing. A single processor may perform a part or all of the functions of the frame generation unit T4 and the baseband signal generation unit T5. Further, a processor that performs a part or all of the functions of the frame generation unit T4 and the baseband signal generation unit T5 may further perform the function of a logic circuit for generating audio data of the audio input unit T1.

  For example, the frame generation unit T4 generates a frame having a data structure to be described later by performing the processing shown in FIG.

That is, when audio data is supplied from the audio input unit T1 (FIG. 3, step S1), the audio encoding processing unit T2 obtains the audio represented by the audio data for each supplied audio data. Encoded audio data is generated (step S2). Note that the speech encoding method in step S2 is arbitrary, and the speech encoding processing unit T2 may perform this encoding using a method such as linear predictive encoding.
Next, the speech encoding processing unit T2 performs error correction by a known method on the encoded speech data generated in step S2 (step S3). The 72-bit encoded voice data generated by the process of step S3 constitutes one speech channel (step S4).

  On the other hand, the additional data input unit T3 determines whether or not additional data is supplied (step S5). If it is determined that the additional data is not supplied (step S5; NO), the additional data input unit T3 uses the 144-bit data whose bit values are all “1” as one high-speed associated control channel. It produces | generates as what comprises (step S6).

  On the other hand, if it is determined in step S5 that additional data is supplied (step S5; YES), the additional data input unit T3 performs error correction by a known method on the supplied additional data (step S7). ). The 144-bit additional data created by the process in step S7 constitutes one high-speed associated control channel (step S8).

  When two call channels are generated in step S4 and one high-speed associated control channel is generated in step S6 or S8, the frame generation unit T4 interleaves the two call channels and the high-speed associated control channel. 288-bit data (hereinafter referred to as interleaved data) is generated (step S9).

That is, in step S9, the frame generation unit T4 combines the total 144 bits constituting the two speech channels and the 144 bits constituting the high-speed associated control channel in a one-to-one manner, thereby 144 pieces of 2-bit data (dibits) corresponding to symbols in FSK are generated. However, these 144 pieces of data are all combined so that the bit constituting the high-speed associated control channel becomes the lower bit and the bit constituting the speech channel becomes the upper bit. In other words, the bits that make up the speech channel are combined so that the bits that form the interleaved data are odd-numbered from the beginning of the interleaved data, and the bits that make up the high-speed associated control channel are even-numbered from the beginning of the interleaved data Shall be. Therefore, in the dibit generated by the frame generation unit T4 in step S9, when the additional data is not supplied from the additional data input unit T3, the lower one digit is “1” in all cases.
Note that the upper bit and the lower bit here are relative, and the left bit of the bit string constituting the dibit may be the upper bit and the right bit may be the upper bit. In the former case, for example, the upper bit of the bit string “01” is “0” on the left side and the lower bit is “1” on the right side. In the latter case, the upper bit of the bit string “01” is “1” on the right side, and the lower bit is “0” on the left side.

  Next, the frame generation unit T4 generates a frame synchronization word composed of 20-bit data having a predetermined data format and a low-speed associated control channel composed of 76-bit data having a predetermined data format. Are combined with each other in the order of the frame synchronization word, the low-speed associated control channel, and the interleaved data from the beginning, so that a 384-bit frame having the data structure shown in FIG. ") Is completed (FIG. 3, step S10). Then, the completed frame is supplied to the baseband signal generation unit T5.

  When the frame is supplied from the frame generation unit T4, the baseband signal generation unit T5 converts the frame into a baseband signal in quaternary FSK and supplies the baseband signal to the modulation unit T6.

  FIG. 5 is a diagram illustrating an example of an eye pattern of a baseband signal generated by the baseband signal generation unit T5. As shown in the figure, this baseband signal has a constant phase point (Nyquist point) in one symbol interval (an interval representing information for one dibit), and the instantaneous value becomes one of four values. Converge. Of these four values (hereinafter referred to as symbol values), assuming that the second value from the largest value is (+1), for example, as shown in FIG. ), (-1), and (-3) are taken at equal intervals.

  Then, for example, as shown in FIG. 5, the baseband signal generation unit T5 converts the dibit “11” (that is, the dibit having the value “11”) included in the frame into a symbol section whose symbol value is (−3). And the dibit “10” is converted into a symbol interval whose symbol value is (−1), the dibit “00” is converted into a symbol interval whose symbol value is (+1), and the dibit “10” is converted. It is assumed that 01 ″ is converted into a symbol interval whose symbol value is (+3).

  As a result of the conversion from the frame to the baseband signal according to the above-mentioned rule, the dibit whose lower one digit is “1” is converted into the symbol interval whose symbol value is (−3) or (+3). Therefore, when the additional data is not supplied from the additional data input unit T3, any dibit representing the interleaved data included in the frame is converted into a symbol section having a symbol value of (+3) or (-3). Will be. On the other hand, when additional data is supplied, the dibit representing the interleaved data is converted into a symbol interval that takes any symbol value of (+3), (+1), (-1), or (-3). Can be done.

  As is clear from the above, when the conversion from the frame to the baseband signal is performed according to the above-mentioned rules, these four types of dibits are arranged in a gray code sequence when arranged in the order of higher symbol values (or lower order). (That is, the hamming distance between adjacent dibits in this array is 1).

  The modulation unit T6 includes a known frequency modulation circuit, an oscillation circuit that generates a carrier wave, and the like, and is obtained by frequency-modulating the carrier wave using the baseband signal supplied from the baseband signal generation unit T5. A quaternary FSK modulated wave is supplied to the high-frequency output unit T7.

  Note that the modulation unit T6 may also include a processor, a memory that stores a program to be executed by the processor, and the like. Further, a processor that performs some or all of the functions of the audio input unit T1, the frame generation unit T4, and the baseband signal generation unit T5 may further perform the function of the modulation unit T6.

  The high-frequency output unit T7 includes a high-frequency amplifier circuit and the like, amplifies the modulated wave supplied from the modulation unit T6, and transmits the amplified wave from the antenna A to free space.

By performing the operation described above, the transmission device T generates and transmits a quaternary FSK modulated wave representing the sound collected by itself.
Of the dibits represented by the baseband signal of the quaternary FSK modulated wave, the symbol value of the symbol section representing the dibit composed of the bit belonging to the speech channel and the bit belonging to the high speed associated control channel is When there is no additional data to be transmitted by T, it is the highest value or the lowest value among the four symbol values that can be taken by the symbol period of the baseband signal. As a result, while the number of possible symbol values is two, the interval between the symbol values is substantially enlarged, and as a result, the signal-to-noise ratio is improved.

  In addition, since (+3) is the maximum value of the symbol value, even if noise in the positive direction is superimposed on the symbol interval having the symbol value (+3), the symbol in the symbol interval is received by a device or the like that has received the FSK modulated wave. There is little risk of misjudging the value. Similarly, since (-3) is the lowest symbol value, even if a negative noise is superimposed on the symbol section having the symbol value (-3), the symbol value in the symbol section is erroneously determined. There is little danger.

Also, due to noise superposition that only changes the value of the lower bit of the dibit, the symbol value in the symbol section where the original symbol value is (+3) is erroneously determined as (+1), or the original symbol value Even if the symbol value of the symbol interval in which (+1) is (+1) is erroneously determined as (+3), no error occurs in the data of the speech channel restored on the side of the device that has received the FSK modulated wave. Similarly, even if the symbol value of the symbol section whose original symbol value is (−1) is erroneously determined as (−3), the symbol value of the symbol section whose original symbol value is (−3) is also determined. Even if it is erroneously determined as (-1), no error occurs in the data of the restored call channel.
On the other hand, the symbol value in the symbol interval where the original symbol value is (+1) is erroneously determined as (−1), or the symbol value in the symbol interval where the original symbol value is (−1) is (+1). Even if erroneous determination is made, no error occurs in the data of the high-speed associated control channel restored on the side of the device that has received the FSK modulated wave.

  Next, the description of the receiving device R will be made. As shown in FIG. 6, the receiving devices R of the transceivers TR1 and TR2 respectively include a high frequency input unit R1, a demodulation unit R2, a symbol determination unit R3, a channel restoration unit R4, and a speech decoding processing unit R5. , An audio output unit R6 and an additional data output unit R7.

  The high-frequency input unit R1 includes a tuning circuit, a high-frequency amplifier circuit, and the like. The FSK modulated wave transmitted from the transmitting device T or the like to free space is received from the free space via the antenna A, amplified, and demodulated. Supply to part R2.

  The demodulator R2 includes a known detection circuit that detects a frequency modulation wave, and restores the baseband signal by detecting the quaternary FSK modulation wave supplied from the high frequency input unit R1. Then, the restored baseband signal is supplied to the symbol determination unit R3. Note that the demodulator R2 may include a processor, a memory that stores a program to be executed by the processor, and the like.

  Each of the symbol determination unit R3, the channel restoration unit R4, and the speech decoding processing unit R5 includes a processor and a memory that stores a program to be executed by the processor. A single processor may perform a part or all of the functions of the symbol determination unit R3, the channel restoration unit R4, and the speech decoding processing unit R5. Further, a processor that performs a part or all of the functions of the demodulation unit R2 and the receiving device R may further perform a part or all of the functions of the symbol determination unit R3, the channel restoration unit R4, and the speech decoding processing unit R5. Good.

  The symbol determination unit R3 determines the dibit value represented by the symbol section including each Nyquist point based on the instantaneous value at each Nyquist point of the baseband signal supplied from the demodulation unit R2, and based on the determination result, Data corresponding to the frame generated by the frame generation unit T4 of the transmission device T is reproduced. Then, the reproduced data is supplied to the channel restoration unit R4.

Specifically, for example, for each Nyquist point included in the baseband signal supplied from the demodulation unit R2, the symbol determination unit R3 first sets the instantaneous value of the baseband signal at the Nyquist point to the first threshold (Th + ) Or more, a second threshold (Th0) or more and less than (Th +), a third threshold (Th−) or more and less than (Th0), or less than (Th−). Determine.
However, the value of (Th +) is greater than (+1) and less than (+3), the value of (Th0) is greater than (−1) and less than (+1), and the value of (Th−) is (−3) And less than (-1). Therefore, specifically, the value of (Th +) may be (+2), the value of (Th0) may be (0), for example, and the value of (Th−) may be (−2), for example.

If the symbol determination unit R3 determines that the instantaneous value of the baseband signal at the Nyquist point is equal to or greater than (Th +), the symbol value of the symbol section including the Nyquist point is (+3). It is determined that it represents the dibit “01”.
Similarly, if it is determined that it is greater than or equal to (Th0) and less than (Th +), the symbol value of the symbol section including the Nyquist point is (+1), and therefore, the symbol section represents the dibit “00”. judge. If it is determined that it is greater than or equal to (Th−) and less than (Th0), the symbol value of the symbol section including the Nyquist point is (−1), and thus the symbol section represents the dibit “10”. Is determined. If it is determined that it is less than (Th−), it is determined that the symbol value of the symbol section including the Nyquist point is (−3), and therefore the symbol section represents the dibit “11”.

  When all symbols for one frame are determined, the symbol determination unit R3 supplies these dibit strings to the channel restoration unit R4 as data corresponding to one reproduced frame.

  The channel restoration unit R4 restores the speech channel and the high-speed associated control channel using the frame supplied from the symbol determination unit R3. Then, the restored call channel is supplied to the voice decoding processing unit R5. On the other hand, the restored high-speed associated control channel is output to the additional data output unit R7.

  Specifically, when the data corresponding to the frame is supplied from the symbol determination unit R3, the channel restoration unit R4 receives an odd number from the top of the 288-bit data out of the 288 bits excluding the top 96 bits. A total of 144th bit and 144 even-numbered bits are extracted from the head of the frame. Then, the voice decoding processing unit converts the data consisting of the first 72 bits of the 144-bit data consisting of 144 odd-numbered bits and the data consisting of the remaining 72 bits as data corresponding to the two restored speech channels. Supply to R5. On the other hand, 144-bit data composed of 144 even-numbered bits is output to the additional data output unit R7 as the restored high-speed associated control channel.

The additional data output unit R7 may include an interface circuit for outputting the restored high-speed associated control channel to the outside as additional data. For example, the interface circuit may be substantially the same as that included in the additional data input unit T3 of the transmission device T.
Alternatively, the data constituting the content of the high-speed associated control channel may be delivered to an arbitrary process executed by the processor that performs the function of the additional data output unit R7.

  When the speech decoding processing unit R5 acquires the data corresponding to the call channel supplied from the channel restoration unit R4, the encoded speech data constituting the call channel is converted into the encoded speech data by a known method. It converts into the audio | voice data of the digital format showing the waveform of the audio | voice shown, and supplies to the audio | voice output part R6.

The audio output unit R6 includes, for example, a D / A (Digital-to-Analog) converter, an AF amplifier, and a speaker.
When the audio output unit R6 is supplied with the audio data in the digital format from the audio decoding processing unit R5, for example, the audio output unit R6 generates an analog audio signal by D / A converting the audio data. Then, the audio signal is amplified and the speaker is driven by the amplified audio signal, thereby reproducing the audio represented by the audio signal.

The receiving device R receives the quaternary FSK modulated wave transmitted by the transmitting device T and the like, and reproduces the sound represented by the quaternary FSK modulated wave by performing the operation described above.
As described above, the quaternary FSK modulated wave transmitted by the transmitting apparatus T has a symbol interval representing a dibit composed of a combination of a bit belonging to a speech channel and a bit belonging to a high-speed associated control channel. When it does not represent additional data, the number of possible symbol values is two, while the interval between the symbol values is substantially expanded. For this reason, the receiving apparatus R can restore these dibits satisfactorily.

In addition, the structure of this audio | voice transmission / reception system is not restricted to the above-mentioned thing.
For example, a portion configured by the processor among the units of the transmission device T and the reception device R may be configured by a dedicated electronic circuit instead of the processor. Further, the number of bits of the speech channel, the high-speed associated control channel, the low-speed associated control channel, and the frame synchronization word are all arbitrary.

  Further, the data constituting the call channel does not necessarily represent voice, and is arbitrary as long as it can be represented as a code string. Therefore, for example, data representing an image may be used.

  Moreover, the rule by which the frame generation unit T4 generates a frame is also arbitrary, and the frame generation unit T4 may further perform processing such as scramble processing on the generated frame.

  Further, the voice input unit T1 may acquire data to be transmitted by an arbitrary method. For example, the voice input unit T1 includes an interface circuit, and data serially transmitted from the outside via an interface or the like. You may get it. Alternatively, the voice input unit T1 may include a recording medium drive device, and the data may be read from a recording medium on which data to be transmitted is recorded.

Also, the interleaving mode between the speech channel and the high-speed associated control channel, the value of each bit of the high-speed associated control channel when there is no additional data to be transmitted by the transmission device T, and the correspondence between the dibit and the symbol value are as follows: It is not restricted to what was mentioned above.
So, for example,
(A) When the frame generation unit T4 determines that the additional data is not supplied from the additional data input unit T3, in step S6, the frame generation unit T4 converts 144-bit data in which each bit value is “0” to 1 Shall be generated as constituting a number of high-speed associated control channels,
(B) Further, for example, the baseband signal generation unit T5 converts the dibit “00” included in the frame into a symbol section whose symbol value is (−3), and converts the dibit “01” into a symbol value ( -1) is converted to a symbol interval, and dibit "11" is converted to a symbol interval whose symbol value is (+1), and dibit "10" is converted to a symbol interval whose symbol value is (+3). And convert,
You may take the structure of. Even with this configuration shown as (a) and (b) above, of the dibits represented by the baseband signal of the FSK modulated wave generated by the transmitter T, the bits belonging to the speech channel and the bits belonging to the high-speed associated control channel are The symbol value of the symbol interval representing the combined dibit is the highest value of the four symbol values that can be taken by the symbol interval of the baseband signal when there is no additional data to be transmitted by the transmitter T or Minimum value.

Further, when there is no additional data to be transmitted by the transmitting apparatus T (that is, when the high-speed associated control channel does not represent additional data and the values of all the bits constituting the high-speed associated control channel are the same). The symbol value of a dibit consisting of a combination of a bit belonging to a speech channel and a bit belonging to a high-speed associated control channel does not necessarily have to be the highest value or the lowest value among a plurality of possible values. The minimum value of the difference between the symbol values of two different dibits only needs to be larger than the minimum value when additional data to be transmitted by the transmitting apparatus T exists.
Also, the dibits represented by the baseband signal do not necessarily have to be determined so as to form a Gray code sequence when the symbol values are arranged in the order of higher (or lower) symbol values.

  The modulated wave transmitted and received between the transmission device T and the reception device R may have, for example, a root Nyquist characteristic, a Gaussian characteristic, and other arbitrary characteristics. The modulated wave only needs to represent the baseband signal generated by the baseband signal generation unit T5 in some form, and thus may be, for example, a PSK (Phase Shift Keying) modulated wave.

  Each processing performed by the speech encoding processing unit T2, the additional data input unit T3, the frame generation unit T4, and the baseband signal generation unit T5 of the transmission device T is realized by a general-purpose microprocessor or DSP (Digital Sigal Processor). It is also possible to do. In this case, you may make a processor run the program for implement | achieving said each process.

It is a block diagram which shows the structure of the transmitter / receiver of the audio | voice and data which concern on embodiment of this invention. It is a block diagram which shows the structure of a transmitter. It is a flowchart which shows the flow of the process which produces | generates a frame. It is a figure which shows the data structure of a flame | frame. It is a graph which shows an example of the eye pattern of a baseband signal. It is a block diagram which shows the structure of a receiver. It is a figure which shows the data structure of the flame | frame in a prior art. It is a figure which shows the data structure of two frames in a prior art.

Explanation of symbols

TR1, TR2 Transceiver T Transmitter T1 Audio input unit T2 Audio encoding processing unit T3 Additional data input unit T4 Frame generation unit T5 Baseband signal generation unit T6 Modulation unit T7 High frequency output unit R Reception device R1 High frequency input unit R2 Demodulation unit R3 Symbol determination unit R4 Channel restoration unit R5 Audio decoding processing unit R6 Audio output unit R7 Additional data output unit A Antenna

Claims (6)

Baseband signal generating means for converting data consisting of main data and additional data into a baseband signal representing a sequence of symbols composed of 2 bits;
Main data acquisition means for acquiring the main data;
Additional data acquisition and generation means for acquiring or generating the additional data,
The baseband signal generation means includes
At least some of the symbols belonging to the symbol column include, as upper bits, bits belonging to the main data acquired by the main data acquisition unit, and lower bits belonging to the additional data acquired or generated by the additional data acquisition generation unit Converting the data into the baseband signal to include as bits,
When the value of the low-order bits constituting the symbol is a predetermined value, the instantaneous value of the point representing the symbol in the baseband signal is the highest value of the four convergence values that the instantaneous value can converge or Always converges to the lowest value,
A baseband signal generator characterized by the above. The additional data acquisition and generation means determines whether or not the additional data already exists, acquires the additional data when determining that the additional data exists, and determines that the predetermined data does not exist Means for generating a bit string composed only of bits having a value as additional data;
The baseband signal generation device according to claim 1. The main data includes a part of a bit string obtained by encoding speech.
The baseband signal generation device according to claim 1 or 2. Further comprising modulation means for generating a modulated wave using the baseband signal generated by the baseband signal generating means and sending the modulated wave to a transmission line;
The baseband signal generation device according to any one of claims 1 to 3. A baseband signal generation step of converting data consisting of main data and additional data into a baseband signal representing a symbol string composed of 2 bits;
A main data acquisition step of acquiring the main data;
An additional data acquisition and generation step for acquiring or generating the additional data, and
In the baseband signal generation step,
At least some of the symbols belonging to the symbol column include bits belonging to the main data acquired in the main data acquisition step as upper bits and bits belonging to the additional data acquired or generated in the additional data acquisition generation step as lower bits. Converting the data into the baseband signal to include as bits,
When the value of the low-order bits constituting the symbol is a predetermined value, the instantaneous value of the point representing the symbol in the baseband signal is the highest value of the four convergence values that the instantaneous value can converge or Always converge to the lowest value,
And a baseband signal generation method. Processor,
Baseband signal generating means for converting data consisting of main data and additional data into a baseband signal representing a sequence of symbols composed of 2 bits;
Main data acquisition means for acquiring the main data;
A program for functioning as additional data acquisition and generation means for acquiring or generating the additional data,
The baseband signal generation means includes
At least some of the symbols belonging to the symbol column include, as upper bits, bits belonging to the main data acquired by the main data acquisition unit, and lower bits belonging to the additional data acquired or generated by the additional data acquisition generation unit Converting the data into the baseband signal to include as bits,
When the value of the low-order bits constituting the symbol is a predetermined value, the instantaneous value of the point representing the symbol in the baseband signal is the highest value of the four convergence values that the instantaneous value can converge or Always converges to the lowest value,
A program characterized by that.

Images