JPH11215036A - Voice transmitting device, voice receiving device, and voice communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure a satisfactory speech quality by eliminating effects on a modulation rate, a voice compression ratio, etc., and effectively transmitting a teaching signal to make a waveform equalizer follow changed in circuit characteristics. SOLUTION: A transmitting station outputs voice modulation signals 1' which are generated at a voice generation part in a voiced talker mode, while in a voiceless talker mode, outputs teaching signals 2, which are generated at a teaching signal generation part to be used for learning by an adaptive waveform equalization part of a receiving station. Upon the receipt of the signals 1', the receiving station outputs voices which are generated at a voice demodulating part, and when the signals 2 are received from the adaptive waveform equalization part, performs learning by the adaptive waveform equalization part and also turns the output voices into silent voices.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information communication technology using digital modulation and demodulation, and more particularly to a voice transmitting device, a voice receiving device, and a voice communication device using a line whose line characteristics fluctuate, such as a radio line.

[0002]

2. Description of the Related Art Generally, a waveform equalizer is positioned as a very important element in data communication. Waveform equalizers are generally used to correct distortions that occur in transmission waveforms due to non-ideal line characteristics, and are important in this sense.

A device called a modem for performing data communication using a general telephone line has a built-in adaptive waveform equalizing function for correcting distortion of a transmission waveform according to line characteristics.
The adaptive waveform equalization function in the modem transmits a teacher signal known from the transmitting side to the transmitting side and the receiving side prior to data communication because the line characteristics differ every time (each call) depending on the connection path of the line. The waveform equalizer is trained using the teacher signal received by the side, and the distortion of the received signal is corrected by the trained waveform equalizer during data communication. Normal,
When using a wired line, once the connection path is determined, it can be said that the line characteristics of the connection path hardly fluctuate.
Once the waveform equalizer has been trained, there is almost no need to learn the waveform equalizer in the call thereafter. In addition,
The details of the adaptive waveform equalization function are described in various documents and will not be described here.

However, when a wireless line is used as a line, the line characteristics fluctuate with time, so that it is necessary to make the characteristics of the waveform equalizer follow the fluctuations of the line characteristics. For this reason, it is necessary to insert a teacher signal not only at the start of communication but also during communication so that the waveform equalizer learns.

FIG. 8 is a diagram for explaining a data transmission method according to the prior art, in which a teacher signal is inserted even during communication and a waveform equalizer learns. This will be described below. In FIG. 8, 1 is a transmission data modulation signal, and 2 is a teacher signal.

When digital wireless communication is performed using a wireless line, as shown in FIG.
Is inserted between the transmission data modulation signals 1, and the waveform equalizer periodically performs learning.

[0007]

When the above-described method according to the prior art is applied to voice communication, moving image communication, or the like, the modulation necessary for transmitting information of the information source by the amount of insertion of the teacher signal 2 is required. A modulation speed higher than the speed (communication speed) is required. If the modulation speed is increased, the occupied bandwidth becomes wider. Therefore, if there is no margin in the allowable bandwidth of the used line, it is necessary to compress information to be transmitted. For voice communication,
In general, when the compression rate of the audio encoding is increased, the audio quality at the time of reproduction deteriorates. For this reason, the prior art described above has a problem that the insertion of the teacher signal 2 to improve the call quality by applying to voice communication creates a factor that lowers the call quality. .

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to use a waveform equalizer to change line characteristics in voice communication using a line such as a wireless line whose line characteristics fluctuate with time. In transmitting a teacher signal in order to follow, the effect on modulation rate, voice compression ratio, etc. is eliminated, and the teacher signal is transmitted efficiently, and good voice quality can be obtained. A device, a voice receiving device, and a voice communication device are provided.

[0009]

According to the present invention, an object of the present invention is to provide a voice transmitting apparatus for a voice communication apparatus using modulation and demodulation. , A voice modulator for modulating voice, and a teacher signal generator for generating a teacher signal used for learning of the adaptive waveform equalizer of the receiving station. This is achieved by outputting a voice modulation signal generated by the modulation unit and outputting a teacher signal generated by the teacher signal generation unit when the voice of the sender is silent.

[0010] The object of the present invention is to provide a voice communication apparatus using modulation and demodulation, wherein the voice reception apparatus is opposite to the voice transmission apparatus and determines whether a received signal is a voice modulation signal or a teacher signal for an adaptive waveform equalizer. A modulation signal / teacher signal determination unit for determining, a voice demodulation unit for demodulating the voice modulation signal to generate voice, and an adaptive waveform equalization unit for learning with the teacher signal and waveform equalizing the received signal; When receiving a signal,
This is achieved by outputting a voice generated by the voice demodulation unit, learning the adaptive waveform equalization unit when receiving the teacher signal for the adaptive waveform equalization unit, and making the output voice silent.

Further, according to the present invention, it is attained by integrally configuring the voice transmitting device and the voice receiving device as a voice communication device.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a voice transmitting device, a voice receiving device, and a voice communication device according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a diagram for explaining a transmission state of a voice signal and a teacher signal for explaining the basic principle of the present invention, and FIGS.
FIG. 1 is a block diagram illustrating a schematic configuration of first to fourth embodiments of the present invention. 1 to 5, reference numeral 1 'denotes an audio modulation signal, reference numeral 2 denotes a teacher signal, reference numeral 3 denotes a sound / non-speech determination unit, reference numeral 4 denotes an audio modulation unit, reference numeral 5 denotes a teacher signal generation unit, and reference numeral 6 denotes a modulation signal / teacher signal determination unit. , 7 are an adaptive waveform equalizer, 8 is a voice demodulator, 9 is an identification information modulator, 10 is an identification information demodulator, 11 is a delay unit, 12 is a voice communication device, and 13 is a radio.

The basic principle of the present invention is as shown in FIG.
Focusing on the voice signal having a sound section and a silent section,
A voice modulated signal 1 'corresponding to a signal in a voiced section of the voice input signal is generated, and a silent section is used as a section for transmitting the teacher signal 2.

FIGS. 2A and 2B show a schematic configuration of a voice transmitting apparatus and a voice receiving apparatus according to the first embodiment of the present invention using the basic principle shown in FIG. ing. The voice transmitting device learns a voiced / silent determining unit 3 for determining whether the voice of a sender is voiced or silent, a voice modulating unit 4 for modulating voice, and an adaptive waveform equalizing unit of the receiving station. And a teacher signal generation unit 5 for generating a teacher signal 2 used for the purpose. The voice / silence determination unit 3 outputs the voice modulation signal 1 'generated by the voice modulation unit 4 when the voice of the sender is voice, and outputs the teacher signal generation unit when the voice of the speaker is silent. The switch SW is controlled so as to output the teacher signal 2 generated by the switch 5.

The voice receiving apparatus further includes a modulation signal / teacher signal determination unit 6 for determining whether the received signal is the voice modulation signal 1 'or the teacher signal 2 for the adaptive waveform equalization unit 7, and a demodulation of the voice modulation signal 1'. And an adaptive waveform equalizer 7 that learns with the teacher signal 2 and equalizes the waveform of the received signal. The modulation signal / teacher signal determination unit 6 causes the audio demodulation unit 8 to output the audio generated by demodulating the waveform-modulated audio modulation signal from the adaptive waveform equalization unit 7 when receiving the audio modulation signal 1 ′. , When receiving the teacher signal 2,
Control is performed to output silence. The modulation signal /
When receiving the teacher signal 2 to the adaptive waveform equalizer 7, the teacher signal determiner 6 controls the adaptive waveform equalizer 7 to perform learning using the teacher signal 2.

According to the above-described first embodiment of the present invention, when the adaptive waveform equalization technique is applied to voice communication using a line whose line characteristics fluctuate with time, such as a wireless line, an adaptive equalization technique is used. To send the teacher signal for the
It is not necessary to set the modulation speed higher than originally required for transmitting voice information, and it is not necessary to compress the information of the information source more than necessary, and to effectively use the allowable bandwidth of the communication line. It is possible to efficiently transmit the teacher signal and make the adaptive equalizer follow the line characteristics at the receiving station to obtain good communication quality.

FIGS. 3A and 3B show a schematic configuration of a voice transmitting apparatus and a voice receiving apparatus according to a second embodiment of the present invention using the basic principle shown in FIG. ing. As shown in FIG. 3A, the voice transmitting device
In the configuration shown in (a), identification information for identifying whether the audio modulated signal 1 ′ is being transmitted or the teacher signal 2 to the adaptive waveform equalizer 7 is being transmitted is composed of the audio modulated signal 1 ′ and the teacher signal 2. It is configured by adding an identification information modulating section 9 that modulates and transmits the data by another frequency band. And on the receiving station side,
The audio modulation signal 1 'generated by the audio modulation unit 4 or the teacher signal 2 generated by the teacher signal generation unit 5 is output,
The identification information modulation signal generated by the identification information modulation section 9 is output.

Further, as shown in FIG. 3B, the audio receiving apparatus adds the teacher signal 2 to the adaptive waveform equalizer 7 while receiving the audio modulated signal 1 'to the configuration shown in FIG. An identification information demodulation unit 10 for demodulating an identification information modulation signal in which identification information for identifying whether or not reception is being performed is added.
Then, based on the identification information obtained by demodulation by the identification information demodulation unit 10, the modulation signal / teacher signal determination unit 6 determines whether the received signal is the voice modulation signal 1 ′ or the teacher signal of the adaptive waveform equalization unit 7. 2
The audio demodulator 8 and the adaptive waveform equalizer 7 are controlled in the same manner as described with reference to FIG.

According to the above-described second embodiment of the present invention, the modulation signal / teacher signal according to the first embodiment is added by adding a channel having an extremely low information communication rate at which stable and good communication quality can be expected. The determination can be easily performed, and the size of the circuit can be reduced and the cost of the device can be reduced.

FIGS. 4A and 4B show a schematic configuration of a voice transmitting apparatus and a voice receiving apparatus according to a third embodiment of the present invention using the basic principle shown in FIG. ing. As shown in FIG. 4A, the voice transmitting apparatus
The configuration is the same as the configuration shown in FIG. And FIG.
The audio apparatus shown in FIG. 1A is configured such that the teacher signal generation unit 5 is configured to generate a teacher signal whose output becomes silent when demodulated as the teacher signal 2 to the adaptive waveform equalization unit 7. This is different from the device shown in FIG.

In the audio receiving apparatus, in the configuration shown in FIG. 2B, a delay unit 11 is provided in the adaptive waveform equalizing unit 7, and the audio demodulating unit 8 generates a sound output or no sound. It has a function of determining whether Then, the audio demodulation unit 8 determines whether the output audio generated by the own demodulation unit is sound or no sound, and determines the result of the determination as the modulation signal /
The signal is given to the teacher signal determination unit 6. The modulation signal / teacher signal determination unit 6 determines that the received signal is the teacher signal 2 for the adaptive waveform equalization unit 7 when the given determination result is silent, and adds the delay signal to the adaptive waveform equalization unit 7. The output of 11 is used as the teacher signal 2 to instruct to delay learning.

The third embodiment of the present invention described with reference to FIGS. 4 (a) and 4 (b) corresponds to FIGS. 3 (a) and 3 (b).
The present invention can be applied to the second embodiment of the present invention described with reference to FIG. 2 to 4,
Although the configurations of the voice transmitting device and the voice receiving device have been described, the voice communication device can be configured by integrally combining the voice transmitting device and the voice receiving device in these drawings.

According to the above-described third embodiment of the present invention, the modulation signal / modulation signal according to the first and second embodiments of the present invention is used.
Even when the teacher signal determination unit makes an erroneous determination and determines that the teacher signal is a modulated signal, the reproduced sound can be silenced, thereby avoiding the adverse effect of giving the user an unusual sound. it can. Further, according to the third embodiment, the information transmission required for the modulation signal wave / teacher signal determination in the first embodiment of the present invention does not increase the amount of information generated for that purpose. It is possible to achieve effective use of frequency without requiring additional equipment or the like.

FIG. 5 shows the configuration of a wireless communication apparatus using the voice transmitting apparatus and the voice receiving apparatus described above as a fourth embodiment of the present invention. The example illustrated in FIG. 5 includes the voice confidential communication device 12 and the wireless device 13. In the fourth embodiment of the present invention, the voice confidential communication device 12 includes the confidential function together with the confidential function. The voice transmitting device and the voice receiving device described in (1) are incorporated.
This makes it possible to create a wireless voice communication device having a secret function. The configuration shown in FIG. 5 can be applied to a portable telephone terminal or its base station device.

According to the above-described fourth embodiment of the present invention, it is possible to realize wireless voice private communication capable of obtaining good communication quality, and to realize a portable telephone capable of obtaining good communication quality. Service can be provided.

FIG. 6 is a block diagram showing a detailed configuration of a wireless voice communication device having a secret function according to a fifth embodiment of the present invention using the voice transmitting device and the voice receiving device described above. . In FIG. 6, reference numeral 4a denotes a voice coding unit, 4b denotes an encryption unit, 4c denotes an amplitude / phase modulation unit, 4d denotes a pilot tone generation unit, 4e denotes a frequency division multiplexing unit A,
8a is an amplitude / phase demodulation unit, 8b is a reference amplitude generation unit, 8c is a decryption unit, 8d is a silence code generation unit, 8e and 16 are switching units, 8f is a voice decoding unit, 13a is a wireless transmitter, 13b
Is a wireless receiver, 14 is a microphone, 15 is an input amplifier, 17
Is a frequency division multiplexing unit B, 18 is a transmission filter, 19 is a transmission amplifier, 20 is a reception amplifier, 21 is a reception filter,
22 is a Doppler frequency shift correction unit, 23 is an audio channel filter, 24 is an identification channel filter, 25 is an output amplifier, 26 is a headset, and other symbols are those in FIG.
Is the same as

In the fifth embodiment of the present invention shown in FIG. 6, the voice transmitting apparatus and the voice receiving apparatus described with reference to FIG.
This is applied to a wireless voice communication device having a confidential function described above. In the fifth embodiment of the present invention, a transmission system and a reception system described below can be configured as separate devices. The fifth embodiment of the present invention is preferably applied to, for example, confidential communication between an aircraft and a ground station. The transmission frequency band of the wireless device is HF band, and the modulation method is the SSB method. The allowable bandwidth is the voice band.

In the fifth embodiment of the present invention shown in FIG. 6, the transmitting system includes an input amplifier 15 to which a microphone 14 is connected, a voice encoding unit 4a, an encryption unit 4b, an amplitude / phase modulation unit 4c, Pilot tone generating section 4d, frequency division multiplexing section A4e, teacher signal generating section 5, switching section 16,
It comprises a silence determination section 3, a BPSK modulation section 9, a frequency division multiplexing section B17, a transmission filter 18, and a transmission amplifier 19 connected to the wireless transmitter 13a.

In the above description, the voice signal of the sender is input to the microphone 14 and amplified by the input amplifier 15 to an appropriate input level to the voice encoding unit 4a. It is input to the determination unit 3. The audio encoding unit 4a performs well-known CELP audio encoding using a processing unit of 40 ms, and converts an input audio signal to A / A.
D / D conversion, and A / D for the past 40 ms every 40 ms
The input audio signal after the conversion is information-compressed to 4800 b / s
It shall be converted into a corresponding digital code string and output.

The encryption section 4b encrypts the digital code string output from the audio coding section 4a and outputs the encrypted digital code string. The amplitude / phase modulation unit 4c modulates the digital code string output from the encryption unit 4b and outputs a modulated signal. The modulation method here is a frequency division multiplexing 16-value QAM method that applies modulation in the amplitude direction and phase direction called well-known 16-value QAM to sine waves of 16 kinds of frequencies in the voice band, and modulates in the amplitude direction. Is performed using the amplitude of the pilot tone generated by the pilot tone generation unit 4d as a reference amplitude, and the modulation in the phase direction is performed by differential phase modulation using the immediately preceding phase as the reference phase. The modulation speed is 75 baud. As a result, the total information transmission rate of the 16 types of modulated signals becomes 4800 b / s, and
It is possible to transmit the information generated by a.

The pilot tone generating section 4d has a frequency whose amplitude is a reference amplitude of the modulation in the amplitude direction of the frequency division multiplexing 16-value QAM system, and a frequency within a voice band, and A sine wave having a frequency that does not match any of the 16 types of sine waves that are modulated in the QAM system and that has not been modulated at all is generated and output as a pilot tone.
This pilot tone is also used by the receiving station to detect the Doppler frequency shift amount received by the received signal by the Doppler frequency shift amount detection unit 25.
The 16 types of modulated signals output from the amplitude and phase modulator 4c and the pilot tones output from the pilot tone generator 4d are frequency division multiplexed by the frequency division multiplexing unit A4e, and are switched as voice modulated signals. 16 is input.

It should be noted that, in the above description, the speech encoding unit 4a,
The combination of the encryption unit 4b, the amplitude / phase modulation unit 4e, and the pilot tone generation unit 4d corresponds to the voice modulation unit 4 in FIG.
The method can be implemented almost in the same way even if the method of voice coding and the method of modulation are replaced with methods other than the above. However, in this case, the sine wave to be modulated is adjusted so that the information transmission rate is equal to or higher than the transmission rate at which the digital code string generated by voice encoding can be transmitted, and the occupied bandwidth is within the allowable bandwidth. It is necessary to determine the frequency and the modulation speed.

The teacher signal generating unit 5 is a composite wave of 16 kinds of sine waves used for the modulation of the frequency division multiplexing 16QAM system and the same sine wave as the pilot tone, and the amplitude and initial phase of each sine wave are The transmitting station and the receiving station both generate a known signal, and output this signal to the switching unit 16 as a teacher signal 2 for learning of the adaptive waveform equalizing unit 7 in the receiving station.

It should be noted that the teacher signal 2 is not limited to the above-described synthesized wave, but may be another signal as long as the signal is within a permissible band known at the transmitting station and the receiving station. In this case, in order to increase the learning accuracy of the adaptive waveform equalizer 7, it is desirable to use a signal having as many frequency components as possible within the allowable band as the teacher signal.

The voice modulated signal 1 ′ output from the frequency division multiplexing unit A 4 e and the teacher signal 2 output from the teacher signal generator 5 are used to determine whether the voice The switching unit 16 is controlled to output the voice modulation signal 1 'when the input voice signal to the encoding unit 4a is sound, and to output the teacher signal 2 when the input voice signal is silent. Frequency division multiplexing section B17 via
Is input to

As described above, the sound / non-sound determining unit 3 determines whether the input audio signal is sound or no sound. This determination is performed using the same 40 ms as the processing unit in synchronization with the processing unit of the audio encoding unit 4a.
a) to determine whether the input audio signal of the past 40 ms being processed in step a.
The power of the input audio signal is calculated for each processing unit of s, and a determination result is obtained by comparing the calculated power values of the past several times with a preset threshold value. Furthermore, the output of the determination result includes the time required from the input of the input audio signal of the processing unit to the audio encoding unit 4a to the modulation of the digital code string by the amplitude / phase modulation unit 4c, and the presence / absence of sound / non-speech determination. The output is delayed so that the time required from the input of the processing unit input audio signal to the output of the determination result becomes equal. In the fifth embodiment of the present invention described, the processing unit of the sound / non-sound determining unit 3 is set to 40 m.
Although it is set to s, it can be set within a range of an integral multiple of the processing unit of the audio encoding method of the audio encoding unit 4a to be used.

The judgment output from the sound / non-speech judging section 3 is input to the switching section 16 and also to the BPSK modulating section 9, where it is modulated by a well-known binary differential phase modulation method to perform frequency division multiplexing. It is input to the section B17. The sine wave used for the above-mentioned binary differential phase modulation has a frequency that does not match any of the 16 types of sine waves used in the amplitude and phase modulator 4c and the frequency of the pilot tone generated by the pilot tone generator 4d. used. In this case, another modulation scheme can be used, but a modulation scheme in which the occupied bandwidth is as small as possible and the bit error rate is as small as possible is desirable.

The frequency division multiplexing unit B17 is provided with a switching unit 16
Signal 1 'or teacher signal 2 output from
The modulated signal of the determination output of the sound / non-sound determination unit 3 output from the PSK modulation unit 9 is frequency division multiplexed and output.
Then, the output of the frequency division multiplexing unit B17 is input to the transmission filter 18 having the audio band as the pass band, band-limited, and then amplified by the transmission amplifier 19 to an appropriate input level of the audio input of the wireless transmitter 13a. And the wireless transmitter 1
It is input to the voice input of 3a and transmitted. The synchronization method according to the fifth embodiment of the present invention is an initial synchronization method using a preamble, transmits a preamble signal at the start of communication, and establishes synchronization at a receiving station while receiving the preamble signal. Hereinafter, this shall be followed. However, the present invention can be similarly implemented by adopting another synchronization method.

In the fifth embodiment of the present invention shown in FIG. 6, the receiving apparatus includes a receiving amplifier 20 to which a radio receiver 13b is connected, a receiving filter 21, a Doppler frequency shift correcting section 22, and a voice CH filter 23. , Identification CH filter 24, adaptive waveform equalizer 7, reference amplitude generator 8b, amplitude / phase demodulator 8a, decryption unit 8c, silence code generator 8
d, BPSK demodulation unit 10, modulation signal / teacher signal determination unit 6, switching unit 8e, audio decoding unit 8f, headset 26
Is connected to the output amplifier 25.

In the above configuration, the reception signal output from the radio receiver 13b is amplified by the reception amplifier 20 to an appropriate level for the subsequent processing, and the reception filter 21
Is input to The reception filter 21 is a filter whose pass band is an audio band, and a reception signal output from the reception filter 21 is a well-known Doppler frequency shift correction unit 22.
And frequency-shifted. This frequency shift is caused by the frequency error of the transmitter of the voice confidential communication device and the radio transceiver between the transmitting station and the receiving station, the frequency shift peculiar to the use of the SSB system for mobile communication, and the HF band radio wave. It is necessary to correct the frequency shift due to the ionospheric movement peculiar to the propagation, so that the error between the frequency equivalent to the pilot tone generated inside the receiving station and the frequency of the received pilot tone is as small as possible. , The entire received signal is frequency shifted.

The received signal frequency-shifted by the Doppler frequency shift corrector 22 is a sound CH filter 23 which is a filter for passing the sound modulation signal 1 ′ and the teacher signal 2, and a binary differential phase modulated sound / silence. The signal is input to an identification CH filter 24, which is a filter that allows the modulated signal of the determination output to pass. The output of the identification CH filter 24 is B
Demodulated by the PSK demodulation unit 10. A method for demodulating a binary differential phase modulation signal is well known. Further, when a signal is modulated by a modulation method other than binary differential phase modulation at the transmitting station, it is necessary to match the demodulation method to the transmitting station.

The result of the demodulation by the BPSK demodulation unit 10 is input to the modulation signal / teacher signal determination unit 6, whether the voice modulation signal 1 ′ is being received, or whether the teacher signal 2
Is determined, and the output of the determination is input to the adaptive waveform equalizer 7 and the switch 8e. The output of the audio CH filter 23 is input to the adaptive waveform equalizer 7.

The adaptive waveform equalizer 7 has a filter capable of learning, and the input signal is BPSK
After a delay equivalent to the time required from when the signal is input to the demodulation unit 10 until the modulation signal / teacher signal determination unit 6 outputs the determination output is given, the delay signal is input to the learnable filter. This filter capable of learning operates as a filter with a fixed filter coefficient based on the determination output of the modulation signal / teacher signal determination unit 6 to correct distortion of a received wave when receiving the voice modulation signal 1 ′. Then, the filter coefficient is changed by learning while receiving the teacher signal 2. Note that the learning method in the adaptive waveform equalizing unit 7 is well known, and a description thereof will be omitted.

The output of the adaptive waveform equalizer 7 is input to an amplitude / phase demodulator 8a and a reference amplitude generator 8b. The reference amplitude generator 8b detects the amplitude of the pilot tone from the output of the adaptive waveform equalizer 7, and inputs the detected amplitude of the pilot tone to the amplitude / phase demodulator 8a. Amplitude / phase demodulation unit 8
a is the above-mentioned 16Q included in the output of the adaptive waveform equalizer 7.
It demodulates each of the 16 types of sine waves modulated by the AM method and outputs a digital code string. The amplitude / phase demodulation unit 8a uses the amplitude of the pilot tone input from the reference amplitude generation unit 8b as the reference amplitude at the time of demodulation. Note that the demodulation of the 16QAM system is well known and the description thereof is omitted here. In the transmitting station, 1
When a modulation method other than the 6QAM method is used, it is necessary to match the demodulation method to the transmitting station.

The decryption section 8c decrypts the demodulated digital code string output from the amplitude / phase demodulation section 8a, and inputs the decrypted digital code string to the switching section 8e. On the other hand, the silence code generation unit 8d includes a speech decoding unit 8f
A digital code string is generated such that the audio output becomes silent when the signal is decoded in step (1), and this digital code string is input to the switching unit 8e (4).

The switching unit 8e responds to the input of the judgment signal from the modulation signal / teacher signal judgment unit 6 by inputting the reception signal to the filter that can learn the adaptive waveform equalization unit 7 and then decrypting the signal. Gives a delay equivalent to the time it takes for the decrypted digital code string to be output. Then, based on the judgment output from the modulated signal / teacher signal judging unit 6 to which the delay has been given, the switching unit 8e decodes the decryption unit 8c when the audio modulated signal 1 'is being received.
And outputs a digital code string which is silent and is output from the silent code generator 8d when the teacher signal 2 to the adaptive waveform equalizer 7 is being received.

The audio decoding section 8f decodes the digital code string output from the switching section 8e to generate reproduced audio, and D / A converts and outputs the reproduced audio. It is assumed that the decoding method is the CELP method described above. In the transmitting station, C
When encoding using an encoding method other than the ELP method is performed, it is necessary to match the decoding method to the transmitting station. The D / A converted reproduced audio output from the audio decoding unit 8f is amplified by the output amplifier 25 to an appropriate input level of the headset and output to the headset.

According to the fifth embodiment of the present invention shown in FIG. 6 described above, in the transmitting station, a pilot tone is generated by the pilot tone generating section 4d and transmitted to the receiving station. 16 amplitude
Since the reference amplitude is used for modulation and demodulation in the amplitude direction in the QAM system, good demodulation accuracy can be obtained in wireless communication in which the received signal level fluctuates easily.

According to the fifth embodiment of the present invention,
Since the synthesized signal of the 16 sine waves used for the frequency division multiplexing 16QAM system and the same sine wave as the pilot tone is transmitted from the transmitting station as the teacher signal 2 of the adaptive waveform equalizer 7 to the receiving station, 16Q frequency division multiplexing at the station
It is possible to perform adaptive waveform equalization that is sufficient for performing the demodulation of the AM system well.

The reason for this is that the occupied band of the voice modulation signal 1 'and the occupied band of the teacher signal 2 are substantially equal, so that there is no loss in capturing the line characteristics at the required frequency. For example, if the modulated signals of 1 kHz and 2 kHz are frequency-division multiplexed to produce an audio modulated signal 1 ′ and only the sine wave of 1 kHz is used as the teacher signal 2, the line characteristics around 2 kHz are insufficiently captured, so that the frequency of 2 kHz is insufficient. Although the distortion of the modulation signal cannot be completely corrected, if the synthesized signal of the sine waves of 1 kHz and 2 kHz is used as the teacher signal 2, the distortion of both the 1 kHz and 2 kHz modulation signals can be corrected well.

According to the fifth embodiment of the present invention,
Since the unit of processing time of the sound / non-speech determining unit 3 is the same as the unit of processing of the audio encoding unit 4a at the transmitting station and is synchronized, abnormal noise is generated when audio decoding is performed at the receiving station. This can be easily prevented from occurring. That is, at the time of speech decoding, even if a part of the digital code string for the processing unit is partially input, if the other digital code strings are not input, the speech for the processing unit is not generated correctly and the difference is generated. Highly likely to generate sound. Therefore, if the switching between the audio modulation signal 1 'and the teacher signal 2 is not synchronized with the processing unit of the audio encoding method, an abnormal sound is generated as described above. If the processing unit of the sound / non-speech determining unit 4a is the same as the processing unit of the audio coding system in the receiving station and synchronized, the switching between the audio modulation signal 1 'and the teacher signal 2 can be easily performed by the audio coding. It can be synchronized with the processing unit of the system.

In the fifth embodiment of the present invention,
The switching between the voice modulation signal 1 'and the teacher signal 2 and the synchronization with the processing unit of the voice coding method are performed by outputting the determination result of the voice / non-voice determination unit 3 to the voice coding unit 4a. The time required from the input of the input audio signal to the modulation of the digital code string by the amplitude / phase modulation section 4c, and the determination result after the input audio signal of the processing unit is input to the sound / non-speech determination section 3. Are output with a delay so that the time required until the output is equal.

Further, in the switching unit 8e of the receiving station, a digital code string decrypted by the decryption unit 8c is output after the reception signal is input to the learnable filter of the adaptive waveform equalization unit 7. A similar purpose is to provide a delay equivalent to the time required until the determination output of the modulation signal / teacher signal determination unit 6.

In the fifth embodiment of the present invention,
After the adaptive waveform equalizer 7 gives the input signal a delay equivalent to the time required from when the signal is input to the BPSK demodulator 10 to when the modulation signal / teacher signal determiner 6 outputs the determination output. Since this signal is input to a filter capable of learning, it is possible to accurately identify whether the input to the filter capable of learning is the voice modulation signal 1 'or the teacher signal 2, and The accuracy of learning of possible filters can be increased.

FIG. 7 is a block diagram showing a detailed configuration of a wireless voice communication device having a secret function according to a sixth embodiment of the present invention using the voice transmitting device and the voice receiving device described up to FIG. is there. In FIG. 7, 5 'is a silence code generation unit, 27 is a frequency division multiplexing unit, 28 is an amplitude and phase modulation unit, 29 is a pilot tone generation unit, 30 is a code storage unit, and the other codes are those in FIG. Is the same as

In the sixth embodiment of the present invention shown in FIG. 7, the voice transmitting apparatus and the voice receiving apparatus described with reference to FIG.
This is applied to a wireless voice communication device having a confidential function described above. In the sixth embodiment of the present invention, the transmission system and the reception system described below can be configured as separate devices. The sixth embodiment of the present invention is suitable for, for example, confidential communication between an aircraft and a ground station, as in the case of the fifth embodiment described above. , The transmission frequency band is the HF band, the modulation method is the SSB method, and the allowable bandwidth is the voice band.

In the sixth embodiment of the present invention shown in FIG. 7, the transmitting apparatus includes an input amplifier 15 to which a microphone 14 is connected, a voice coding unit 4a, a silence code generation unit 5 ', a sound / no sound. Determination unit 3, switching unit 16, encryption unit 4b, amplitude and phase modulation unit 4c, pilot tone generation unit 4d, frequency division multiplexing unit A4e, transmission filter 18, radio transmitter 13a
Is connected to the transmission amplifier 19.

In the sixth embodiment of the present invention configured as described above, the voice signal from the sender is
Is amplified by the input amplifier 15 to an appropriate input level to the audio encoding unit 4a.
And the sound / non-speech determination unit 3. Voice encoding unit 4
“a” performs CELP-based speech encoding with a processing unit of 40 ms, and outputs a digital code string equivalent to 4800 b / s. Silence code generator 8d
Generates and outputs a digital code string whose output is silent when decoded by the audio decoding unit 8f of the receiving station. The sound / silence determination unit 3 determines whether the input audio signal is sound or silence.

The switching section 16 outputs a digital code string output from the speech encoding section 4a when the input speech is speech based on the judgment output of the speech / non-speech judgment section 3, and the input speech is When there is no sound, a digital code string output from the silent code generation unit 5 is output. The encryption unit 4b encrypts the digital code string output from the switching unit 16 and outputs the encrypted digital code string to the amplitude / phase modulation unit 4c.

The amplitude and phase modulator 4c modulates the digital code string output from the encryption unit 4b and outputs a modulated signal. The modulation method used here is a frequency division multiplexing 16-value QAM method in which sine waves of 16 kinds of frequencies in a voice band are modulated in amplitude and phase directions called 16-value QAM. Is not the differential phase modulation but the phase modulation that always refers to the phase of the reference phase carrier.
The modulation speed is 75 baud. Thereby, the above 1
The total information transmission rate of each of the six types of modulated signals is 4800 b
/ S.

[0062] Pilot tone generator 4d generates and outputs a pilot tone. Frequency division multiplexing unit A4
In e, frequency-division multiplexing is performed on each of the above-described 16 types of modulated signals output from the amplitude / phase modulation unit 4c and the pilot tone output from the pilot tone generation unit 4d, and input to the transmission filter 18.

It should be noted that the sixth embodiment of the present invention can be implemented almost in the same manner even if the voice coding method and the modulation method are replaced with methods other than those described above. The silence code generator 5 'corresponds to the teacher signal generator 5 in FIG. When the digital code sequence output from the voice coding unit 4a is modulated, the transmission signal becomes a voice modulation signal 1 '. When the digital code sequence output from the silent code generation unit 5 is modulated, this transmission signal is transmitted to the receiving station. Becomes the teacher signal 2 for the adaptive waveform equalizing section 7 of FIG.

The output of the frequency division multiplexing unit A 4 e is input to a transmission filter 18 having a voice band as a pass band, and is band-limited.
The signal is amplified to an appropriate input level of the voice input to a, input to the voice input of the wireless transmitter 13a, and transmitted.

In the sixth embodiment, the synchronization system of the voice confidential communication device is an initial synchronization system based on a preamble. A preamble signal is transmitted at the start of communication, and a synchronization is performed while the receiving station receives the preamble signal. Shall be established and will be followed thereafter. However, the present invention can be similarly implemented by adopting another synchronization method.

In the sixth embodiment of the present invention shown in FIG. 7, the receiving apparatus includes a receiving amplifier 20, a receiving filter 21, a Doppler frequency shift correcting section 22, and a delay section 11 connected to a radio receiver 13b. Adaptive waveform equalizer 7 having
Reference amplitude generation unit 8b, amplitude / phase demodulation unit 8a, decryption unit 8c, voice decoding unit 8f, modulation signal / teacher signal determination unit 6, code storage unit 30, amplitude / phase modulation unit 28, pilot tone generation unit 29, frequency It comprises a division multiplexing unit A27 and an output amplifier 25 to which a headset 26 is connected.

In the above configuration, the reception signal output from the radio receiver 13b is amplified by the reception amplifier 20 to an appropriate level for the subsequent processing, and the reception filter 21b
Is input to The reception filter 21 is a filter whose pass band is an audio band, and a reception signal output from the reception filter 21 is a well-known Doppler frequency shift correction unit 22.
And frequency-shifted. The received signal whose frequency has been shifted by the Doppler frequency shift correction unit 22 is input to the adaptive waveform equalization unit 7.

The adaptive waveform equalizing section 7 has a waveform equalizing filter / delay section 11 and a learning filter. The above-mentioned filter for waveform equalization corrects the distortion of the received signal and outputs it as an output of the adaptive waveform equalizer 7. In addition, the above-described learning filter, based on the determination output from the modulation signal / teacher signal determination unit 6, when the teacher signal 2 is being received, the delay unit 11
The learning is performed using the signal delayed by, that is, the teacher signal. Note that the delay amount of the delay unit 11 is set to a delay amount equivalent to the time required from when a received signal is input to the waveform equalization filter to when the modulation signal / teacher signal determination unit 6 switches the determination output. I have. Further, at the time of the above-described learning, a signal output from the frequency division multiplexing unit A27 is learned as a prototype of the teacher signal 2. After the above learning,
The filter coefficient of the filter for waveform equalization is changed to a filter coefficient of a learning filter obtained by learning.

The output of the adaptive waveform equalizer 7 is input to an amplitude / phase demodulator 8a and a reference amplitude generator 8b. The reference amplitude generator 8b detects the amplitude of the pilot tone from the output of the adaptive waveform equalizer 7, and inputs the amplitude of the pilot tone to the amplitude / phase demodulator 8a. Amplitude / phase demodulator 8a
Demodulates each of the 16 types of sine waves modulated by the 16QAM method included in the output of the adaptive waveform equalizer 7 and outputs a digital code string. The transmitting station is 1
When a signal is modulated by a modulation method other than the 6QAM method, it is necessary to match the demodulation method to the transmitting station.

The decryption unit 8c decrypts the digital code sequence output from the amplitude / phase demodulation unit 8a, and inputs the decrypted digital code sequence to the voice decoding unit 8f. The audio decoding unit 8f decodes the digital code string output from the decryption unit 8c to generate a reproduced audio,
/ A conversion and output. This decoding method is the CELP method described above. Note that the transmitting station is the CEL
When encoding is performed using an encoding method other than the P method, it is necessary to match the decoding method to the transmitting station. Further, the speech decoding unit 8f has a function of determining whether or not the input digital code sequence is a digital code generated by the silent code generation unit 5, and determines the result of this determination as a modulation signal / teacher signal determination. Input to section 6.

The modulation signal / teacher signal judging section 6 judges whether the received wave is the sound modulation signal 1 'or not based on the judgment input from the past several times of the sound decoding section 8f. Is determined, and the determination result is output to the adaptive waveform equalization unit 7. The code storage unit 30
Is the time from when the digital code sequence is input to the decryption unit 8c to when the modulation signal / teacher signal determination unit 6 switches the determination output, and the frequency division multiplexing after the digital code sequence is input to the code storage unit 30. Teacher signal 2 from section A27
The delay is given to the input digital code string so that the time required until the prototype is output is output to the amplitude / phase modulation unit 28.

The amplitude / phase modulation unit 28 to which the digital code string output from the code storage unit 30 is input performs amplitude / phase modulation on the input signal, and outputs the output from the frequency division multiplexing unit A27.
Give to. The frequency division multiplexing unit 27A multiplexes the output signals from the amplitude / phase modulation unit 28 and the pilot tone generation unit 29 and inputs the multiplexed signal to the adaptive waveform equalization unit 7 as a prototype of the teacher signal 2 to the adaptive waveform equalization unit 7. Voice decoding unit 8
The D / A-converted reproduced sound output from f is amplified to an appropriate input level for the headset 36 by the output amplifier 25 and output to the headset 36.

In the above description, the amplitude / phase modulation unit 2
8, the pilot tone generation unit 29 and the frequency division multiplexing unit A27 have the same configuration as the amplitude / phase modulation unit 4c, the pilot tone generation unit 4d and the frequency division multiplexing unit 4e in the transmitting station.

According to the above-described sixth embodiment of the present invention shown in FIG. 7, the delay amount of the delay unit 11 in the adaptive waveform equalization unit 7 is calculated after the reception signal is input to the waveform equalization filter. The delay amount is equal to the time required for the modulation signal / teacher signal determination unit 6 to switch the determination output, and the code accumulation unit 3
The delay amount of 0 is determined by the time from when the digital code sequence is input to the decryption unit 8c to when the modulation signal / teacher signal determination unit 6 switches the determination output, and after the digital code sequence is input to the code storage unit 30. The delay required for learning the learning filter of the adaptive waveform equalizing unit 7 is set by setting the delay amount so that the time required until the prototype of the teacher signal 2 is output from the frequency division multiplexing unit A27 is equal. Since the teacher signal 2 and the prototype of the teacher signal 2 are given to the learning filter at the same time, the learning accuracy of the learning filter can be improved.

Further, in the sixth embodiment of the present invention, the code obtained by demodulation is modulated by the same modulation scheme as that of the transmitting station and input to the adaptive waveform equalizer as a prototype of the teacher signal 2. Then, even if the audio modulation signal 1 'is always transmitted without transmitting the teacher signal 2, the received audio modulation signal 1' can be treated as the teacher signal 2, so that learning of the adaptive waveform equalization unit is in principle required. Becomes possible. However, in this case, if a code error occurs, the prototype of the generated teacher signal 2 and the voice modulated signal 1 'transmitted as the teacher signal 2 become different signals, and the adaptive waveform equalizer learns correctly. Adverse effects occur.

In order to avoid the above-mentioned adverse effects, the sixth embodiment of the present invention employs a special code generated by the silent code generation unit 5 when the signal used for learning of the adaptive waveform equalization unit 7 is silent. And the modulation signal / teacher signal determination unit 6 makes a determination by using the determination output of the audio decoding unit 8f for the past several times, so that the likelihood of the determination that the modulation signal has been received is determined. I try to raise it.

The voice secret communication devices according to the fifth and sixth embodiments of the present invention can be applied to a portable telephone terminal and a base station device thereof.

[0078]

As described above, according to the present invention, when the adaptive waveform equalization technique is applied to voice communication using a line whose line characteristics fluctuate with time such as a radio line, the adaptive equalization technique is applied. In order to transmit a dexterous teacher signal, there is no need to set the modulation speed higher than the modulation speed originally required for transmitting voice information, and it is not necessary to compress the information of the information source more than necessary. The allowable bandwidth of the line can be used effectively, the teacher signal can be transmitted efficiently, and the adaptive equalizer can follow the line characteristics at the receiving station to obtain good speech quality.

Further, according to the present invention, a modulation signal / teacher signal determination can be easily realized by adding a channel having an extremely low information communication rate at which stable and good communication quality can be expected. The size and the cost of the device can be reduced.

Further, according to the present invention, even when the modulation signal / teacher signal determination unit makes an erroneous determination and determines that the teacher signal is a modulation signal, the reproduction sound is made silent and the user is made to hear abnormal noise. Adverse effects such as the

Further, according to the present invention, the information transmission required for the modulation signal / teacher signal determination can be realized without increasing the amount of information generated for that purpose, so that it is not necessary to add a line or the like. The frequency can be used effectively.

Further, by utilizing the present invention, it is possible to realize wireless voice private communication capable of obtaining good call quality, and to provide a portable telephone service capable of obtaining good call quality. it can.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a state of transmission of an audio signal and a teacher signal for explaining a basic principle of the present invention.

FIG. 2 is a block diagram illustrating a schematic configuration of the first embodiment of the present invention.

FIG. 3 is a block diagram illustrating a schematic configuration of a second embodiment of the present invention.

FIG. 4 is a block diagram illustrating a schematic configuration of a third embodiment of the present invention.

FIG. 5 is a block diagram illustrating a schematic configuration of a fourth embodiment of the present invention.

FIG. 6 is a block diagram illustrating a detailed configuration of a wireless voice communication device having a secret function according to a fifth embodiment of the present invention.

FIG. 7 is a block diagram showing a detailed configuration of a wireless voice communication device having a secret talk function according to a sixth embodiment of the present invention.

FIG. 8 is a diagram for explaining a data transmission method according to a conventional technique in which a teacher signal is inserted even during communication and a waveform equalizer learns.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transmission data modulation signal 1 'Voice modulation signal 2 Teacher signal 3 Voice / non-speech determination part 4 Voice modulation part 4a Voice coding part 4b Encryption part 4c Amplitude phase modulation part 4d Pilot tone generation part 4e Frequency division multiplexing part A Reference Signs List 5 teacher signal generation unit 5 'silence code generation unit 6 modulation signal / teacher signal determination unit 7 adaptive waveform equalization unit 8 audio demodulation unit 8a amplitude phase demodulation unit 8b reference amplitude generation unit 8c decryption unit 8d silence code generation unit 8e Reference Signs List 16 switching unit 8f voice decoding unit 9 identification information modulation unit 10 identification information demodulation unit 11 delay unit 12 voice secret communication device 13 radio 13a radio transmitter 13b radio receiver 14 microphone 15 input amplifier 17 frequency division multiplexing unit B 18 Transmit filter 19 Transmit amplifier 20 Receive amplifier 21 Receive filter 22 Doppler frequency shift correction unit 23 Voice channel Filter 24 identification channel filter 25 output amplifier 26 headset 27 frequency division multiplexing unit 28 amplitude / phase modulation unit 29 pilot tone generation unit 30 code storage unit

Claims (10)

[Claims] 1. A voice transmitting apparatus for a voice communication apparatus using modulation / demodulation, comprising: a voice / silence determining unit for determining whether a voice of a sender is voiced or silent; a voice modulating unit for modulating voice;
A teacher signal generation unit that generates a teacher signal used for learning of the adaptive waveform equalization unit of the receiving station, and when the voice of the sender is sound, outputs a voice modulation signal generated by the voice modulation unit,
A speech transmission device, wherein a teacher signal generated by the teacher signal generation unit is output when a voice of a sender is silent. 2. An audio communication apparatus using modulation and demodulation, wherein the modulation signal determines whether a received signal is an audio modulation signal or a teacher signal for an adaptive waveform equalizer in an audio receiving apparatus opposed to the audio transmitting apparatus according to claim 1. / Teacher signal determination unit, an audio demodulation unit that demodulates the audio modulation signal to generate audio, and an adaptive waveform equalization unit that learns from the teacher signal and equalizes the waveform of the received signal. An audio receiving apparatus for outputting an audio generated by an audio demodulating unit and, upon receiving a teacher signal for the adaptive waveform equalizing unit, learning the adaptive waveform equalizing unit and making the output audio silent. 3. An identification information modulating section for modulating identification information indicating whether a voice modulated signal is being transmitted or a teacher signal to the adaptive waveform equalizer is being transmitted in a frequency band different from that of the voice modulated signal and the teacher signal. 2. The voice transmitting apparatus according to claim 1, wherein an identification information modulation signal generated by the identification information modulation unit is output. 4. An audio communication apparatus using modulation and demodulation, wherein an audio receiving apparatus opposed to the audio transmitting apparatus according to claim 3 identifies whether an audio modulated signal is being transmitted or a teacher signal of the adaptive waveform equalizer is being transmitted. An identification information demodulation unit for demodulating an identification information modulation signal in which information is modulated, and a modulation signal / teacher signal determination unit converts a received signal to a voice modulation signal based on identification information obtained by demodulation by the identification information demodulation unit. 3. The voice receiving apparatus according to claim 2, wherein it is determined whether the signal is a teacher signal for an adaptive waveform equalizer. 5. The audio transmitting apparatus according to claim 1, wherein the teacher signal generation unit generates a signal whose output becomes silent when demodulated, as a teacher signal for the adaptive waveform equalization unit. 6. An audio communication apparatus using modulation and demodulation, wherein the audio demodulation unit determines whether the output audio to be generated is sound or silence. The modulation signal / teacher signal determination unit determines that the received signal is a teacher signal of the adaptive waveform equalization unit when the output voice is silent, and the adaptive waveform equalization unit delays And an adaptive waveform equalizer that learns an output of the delay unit as a teacher signal when the modulation signal / teacher signal determiner determines that the received signal is a teacher signal of the adaptive waveform equalizer. A feature according to claim 2 or claim 4.
An audio receiving device as described in the above. 7. The voice transmitting device according to claim 1, and a voice transmitting device according to claim 2.
A voice communication device, wherein the voice reception device according to any one of the preceding claims is integrally formed. 8. The voice transmitting apparatus according to claim 3, and claim 4.
A voice communication device, wherein the voice reception device according to any one of the preceding claims is integrally formed. 9. The voice transmitting device according to claim 5, and a voice transmitting device according to claim 6.
A voice communication device, wherein the voice reception device according to any one of the preceding claims is integrally formed. 10. A voice communication device connected to voice input / output of a wireless device, wherein the voice communication device according to claim 7, 8 or 9 is provided with a secret function.