JPS60178727A - Communication system for intermittent signal - Google Patents

Abstract

PURPOSE:To always attain transmission/reception of digital signals by using an intermittent signal transmission means which can transmit the intermittent signal which is produced during transmission of the end code of transmission signal to inform the end of a transmission signal to the receiver side from the transmitter side. CONSTITUTION:An output signal 12 of a sound detector 1 is set at logic ''1'' (121) when a sound input 11 exists and at logic ''0'' (122) when the input 11 does not exist respectively. For a transmission signal 18, the control information 176 is added after a fixed code EOB (end of Bovst) 175. The information 176 shows with a code whether or not the signal 12 decided again the existence of the input 11 within a period occupied by the EOB175. Then CONT1 and CONT2 are decided with the absence of sounds and the presence of sounds respectively. If the output 11 exists during transmission of the EOB175, the signal 12 is set again at logic ''1''. Then the control signal 176 is transmitted under the control of a control signal generating circuit 3 so that the sound information to be transmitted continuously is transmitted after the code CONT2 and then the 2nd hang-over bit 174 are set.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an intermittent signal communication system, and more particularly to an intermittent signal communication system in which digital information is intermittently communicated via an artificial satellite for communication relay.

[Prior art]

Satellite communication systems, in which multiple ground stations communicate with each other via repeaters mounted on artificial satellites, are becoming increasingly popular these days. This satellite communication system uses a repeater to amplify the weak i-waves received by the satellite, increase the output, and send it back to the ground. In this case, the greater the power output from the satellite, the greater the power that reaches the ground, and the conditions imposed on the receiver at the ground station are relaxed. In order to increase the satellite output, it is necessary to increase the power of the output amplifier built into the repeater, and this increase in power requires the expansion of the power supply scale in addition to the output amplifier, which increases the weight of the repeater. Satellite launches will result in a significant increase in costs.

Voice activation technology is commonly used as an effective means of increasing satellite output without significantly increasing launch costs. This voice acting technology is based on SCPC (8ingle Channel 4), a well-known satellite communication system.

This is used in the Per Carrier) system. In the 8CPC system, this is modulated into one audio channel for each transmission channel, and the satellite repeater multiplexes the above modulated waves transmitted from each ground station by frequency division, and transmits them again to each ground station. I'll go. Is the audio signal used in this case a normal telephone signal? However, as is well known, telephone audio is transmitted in both directions between the local station and the other station, and while one of these two stations is talking, the other station is usually not talking.
Furthermore, the audio during the conversation often includes silent sections.

In communication using normal telephone signals, there is a lot of invalid time during the communication time, and in general, the ratio of the transmission time required for each station to the total call time is often at most 50 channels or more. For this reason, it is extremely uneconomical for the satellite repeater to continue transmitting power over the entire call time, as the size and weight of the satellite repeater must be minimized. Therefore, voice activation technology is usually used to solve this problem.

This voice activation technology uses an audio detector that detects the presence of call voices in the transmitted image to determine the presence or absence of a voice signal through a gold film, and transmits the signal only in the time domain where it is determined that there is a voice signal. In the time domain where it is determined that there is no
This technology reduces the simultaneous call rate of the 80 PC signal group processed by the satellite repeater to approximately 50% or less, saving power for the amplifier in the repeater. Satellite launch cost) (D) can be significantly reduced.

As mentioned above, the 5CPC method commonly used in satellite communications generally uses voice activation technology to reduce power consumption and launch costs, and the transmitted signal is sent to the receiver intermittently depending on the presence or absence of voice. An intermittent signal communication method is often adopted. Then, is there an intermittent signal like this on the receiving side? Receive and demodulate audio signals? I will do it, but
The demodulator cannot perform complete production and demodulate the audio signal ft at the same time as the intermittent signal arrives, and always requires some processing time. For example, in the digital format 8CPC Manshiki, if the receiver uses synchronous detection as the demodulation method, processing time is required for the reproduction time of the reference carrier wave, the reproduction time of the black signal, etc., and the elapsed processing time is Correct signal demodulation is then possible. For this reason, a method has been considered in which, on the transmitting side, prior to the audio signal to be transmitted, all signals suitable for demodulator processing are added and transmitted.

In the normal 8CPC system, intermittent signals are transmitted and received in this way, but this intermittent signal communication system originally uses a transmission path that has nonlinearity when the C/N (Carrier to Noise, signal-to-noise power ratio) is low. In a satellite communication system targeted at It is necessary to keep on/off switching to a minimum.

In this kind of conventional intermittent signal transmission method, even if the audio section in which it is determined that there is an audio signal ends, the signal indicating the status as the audio section remains unchanged for a preset period of time. This problem is dealt with by providing a so-called hangover time for continuous transmission. That is, if a voice signal is input again during this hangover time period, it will continue to transmit it, and will not respond to a silent period that is shorter than the hangover time, thereby reducing the on/off operation on the transmitting side. It's suppressed.

10,000, a receiver that receives an intermittent signal needs to know the start and end points of this intermittent signal. For this purpose, for example, a fixed code 80M (Start A fixed code indicating the end of the intermittent signal EOB (End of Burst) f
(One possible method is to add the EO
As B, in addition to the above-mentioned fixed code, various other transmission signal tail signals having similar effects are also used. On the receiving side, as mentioned above, in the case of the fc80M and EOB, signals other than voice signals, mainly noise, are received, and demodulated signals? If it is output as is, extremely harsh noise will be input. To avoid this problem, the receiver output t is usually turned on in response to SUM and turned off in response to EOB. Therefore, 80M like this.

and 80M and EOB in a system that transmits and receives audio signal information using EOB or an equivalent transmission signal tail signal.
Although it has the characteristic that noise reception outside the interval due to OB is impossible, even if an audio signal transmission state occurs again during this EOB transmission, part or all of the EOB is output from the transmitting side, and the receiving side Since the receiver output is turned off once this EOB t- is detected, there is a drawback that it becomes impossible to correctly receive the following audio data from the beginning.

[Purpose of the invention]

The purpose of the present invention is to eliminate the above-mentioned drawbacks, and to provide an intermittent signal communication system in which all satellites are used to transmit and receive digital signals. An object of the present invention is to provide an improved intermittent signal communication system that is equipped with an intermittent signal transmitting means that can transmit even an intermittent signal generated in the process, and is capable of constantly transmitting and receiving digital signals.

[Structure of the invention]

The system of the present invention is an intermittent signal communication system that transmits and receives digital signals intermittently via an artificial satellite. Even if there is a transmission signal to be transmitted even when there is a transmission signal to be transmitted, the apparatus is configured to include an intermittent signal transmission means that enables the transmission of the transmission signal at all times.

〔Example〕

Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the basic configuration of a satellite communication system based on the 5CPC system via artificial satellites.

A transmitting station a serving as an earth station sends a transmission signal of 8 CPCs to an artificial satellite C, and the artificial satellite C amplifies this signal by an on-board repeater and transmits it to the receiving station of the earth station. In addition, in this 5ere system, as described below, the transmission signal sent from transmitting station a is divided into multiple channel frequencies, so-called 8 CPC frequency components, and the corresponding transmission channels/channels by dividing the transmission frequency band into preset frequency steps. It has a so-called channel unit configuration and can transmit to multiple receiving stations.

FIG. 2 is a block diagram showing the basic configuration of a transmitting station in the satellite communication system shown in FIG. 1.

A conventional 5cpc transmitting station has N channel units 1001-1 to 1001-N that transmit N IP (intermediate frequency) signals at frequency steps that can be set in advance based on the transmission bit rate of data to be transmitted, etc. , a synthesizer 1002 that combines the outputs of these channel units,
It is configured to include a frequency converter 1003 for increasing the frequency of the IP synthesized output frequency of the synthesizer 1002 to all transmission frequencies, a power amplifier 1004, and the like.

Each channel unit is equipped with almost the same digital data forming circuit that converts the input signal into digital data with a predetermined code formation, and a modulator that converts the input digital data into IP of a preset frequency. Each of the modulators modulates the built-in carriers with a preset frequency difference based on the bit rate of the digital data, the modulation method of the modulator, etc., and modulates them with digital data. Outputs IP times signal.

The digital data forming circuit in each channel unit receives an input signal such as an audio signal and converts it to a predetermined bit rate by Korg or the like.

An input data sequence is formed by performing encoding using a code format. This input data series is further added with bits for carrier and clock reproduction, or bits for frame synchronization, such as the above-mentioned SOM, and then supplied as digital data.

The N IP signal outputs obtained through the basic operation of the channel unit as described above are outputted via a combiner 1002, a frequency converter 1003, and a power amplifier 1004.
80 PC transmission signals, each of which is transmitted to a pre-designated receiving station.

Furthermore, in the transmission operation of satellite communications based on the 5CPC method, it is assumed that voice activation is applied in order to effectively utilize satellite power, and a voice detector for this purpose is installed in each channel unit. The digital data forming circuit is equipped with 5CP.
The C method ensures voice communications and the like via satellites.

However, such communication via satellite has the above-mentioned drawbacks, and the present invention attempts to solve this problem as follows.

FIG. 3 is a block diagram showing the basic configuration of the transmitting side according to the intermittent signal communication system of the present invention.

The configuration of the transmitting side shown in Fig. 3 is a voice detector 1, a delay circuit 2,
．． Control signal generation circuit 3. Multiplexing circuit 4 and transmitter 5?
Except for the configuration of the control signal generation circuit 3, which is directly related to the present invention, this is a substantially basic configuration on the transmitting side of an intermittent audio signal communication system.

The audio detector 1 receives an input audio signal 11, generates an audio detection signal 12 every time it detects the presence or absence of audio contained therein, and sends this to the control signal generation circuit 3. This voice detection signal 12 is indicated by a binary logical value 11'' level when there is voice, and by wO'' level when there is no voice, but generally it is an arbitrary code corresponding to the presence or absence of voice. When the setting is made, the control signal generating circuit 3 generates an additional signal 13t- as a first control signal and sends it to the multiplexing circuit 4. The additional signal 13 consists of the time required for the receiver to be able to normally receive and process intermittent signals on the receiving side, and 80M indicating the beginning of the audio information signal, and the audio signal follows this additional signal. Set in chronological order as sent. Time information regarding this additional signal 13 is also sent to the delay circuit 2, and the audio detection signal 1
2, when it is determined that there is audio, the input audio signal 11 is given a delay equal to the time length of the additional signal 13 and is supplied as a delayed audio signal 14 to the multiplexing circuit 4, where it is multiplexed with the additional signal 13. , and is supplied to the transmitter 5 as a transmission information signal 16.

Further, under the control of the control signal generating circuit 3 and the audio detector 1, the signal to be transmitted by the transmission information signal 16, that is, the above-mentioned additional signal and the delayed audio signal, is turned on for a time interval, and is turned off for other intervals. Open/close signal 15t-
It is generated as a second control signal and is supplied to the transmitter 5 as an on/off signal for the transmission output. In this way, the transmitter 5 generates an audio modulation signal based on the transmitted transmission information signal 16, and the transmitted open/close signal 15 is used as a transmission on/off signal for setting transmission on/off of the transmitter 5. Ru. In this way, the transmission signal sent out from the transmitter 5 becomes an intermittent signal that exists only during the time when it is determined that there is a voice signal, and the 8CPC universal operation using the voice actuation page 7 described above is performed. It has been realized.

When transmitting and receiving such intermittent signals, in order to prevent the on/off frequency from increasing more than desired, the preset period of time is normally maintained even after the period in which the voice detector l determines that the voice level is low. As described above, the hangover time is provided. Also, does it take intermittent signals? As mentioned above, when receiving, it is necessary for the receiving side to know the start and end points of this intermittent signal, and for this purpose, for example, a fixed code EOB is added to indicate the end of the signal. Aha Also in the embodiment shown in FIG. 3, the hangover time as described above is 80M.
and EOB are set.

However, when intermittent communication is performed using the transmission frame format configured in this manner, noise is mainly received in frames other than the frame period from 150M to EOB, which significantly deteriorates the quality of the received signal. To solve this problem, the receiver is normally controlled so that it starts outputting every 80M reception and stops outputting when EOB is received.As a result, the audio detection timing by the audio detector l overlaps with the EOB transmission. As mentioned above, if the EOB is stored away, part or all of the EOB is output from the transmitting side, and the receiving side becomes unable to receive the following audio data from the beginning, as described above.

Therefore, in this embodiment, this problem is solved as follows.

4 and 5 respectively show the audio detection signal waveform (5) and transmission output timing chart (B) in the embodiment of FIG. 3, and FIG.
In the general case where there is no voice input again immediately after c, FIG. 5 shows the case where there is voice input again immediately after the voice signal ends (during EOB transmission). The embodiment shown in FIG. 3 will be described below with reference to FIGS. 4 and 5.

FIGS. 4 and 5 (6) show the waveform of the voice detection signal 12, and when it is determined that there is voice input by the voice detector I, the logic value 11'' level 121 is reached.

If it is determined that there is no audio input, a logical value of 10'' level 122 is output. In the case of nest 4 < AI, the 11'' level will not return to 11'' level again after the interval of 121 ends. The waveform of the voice detection signal in a general case is shown. FIG. 4 (I3) is a timing chart of the transmission signal 18 output from the transmitter 5 under the conditions of FIG. 4 (5). Signal 18 is a reception processing signal 9 to bring the receiving side into a normal reception processing state.In this embodiment, the receiving side performs all synchronous detection, so it is a code suitable for carrier wave regeneration for synchronous demodulation and clock regeneration for instantaneous detection. Signal for reception processing as bits 171.50M172.Audio information 1
In addition to the conventional transmission signal consisting of 73, hangover bit 174, and EOB 175, control information 176 k is further added, and the control information 176 is a third control signal from the control signal generation circuit 3 as described below. In response to the signal 17', in the same manner as the additional signal 13 which is the second control signal, the hangover pictogram 174, EOB 175 and control information 176 are superimposed on the delayed sound P signal 14 through multiplexing processing and sent to the transmitter 5. do.

In the m4 diagram, reception processing signals 171 and 80M172
Assuming that the transmission frame interval kT (seconds) is τ seconds from the moment when the voice detection signal 12 reaches the logical value "H1e level 121," that is, from the moment when the voice detector l determines that the input voice signal 11 contains voice M. Audio information 17 after the elapsed time
3 is transmitted for a time equal to the 11'' level 121. This τ second is therefore required by the delay time of the delay circuit 2.Audio information 1
Immediately after the transmission of 73 is completed, the preset no. 174 is transmitted (hang over within the time interval), and then EOB 175 is transmitted to the end of 174 to notify the end of the intermittent signal. is,
Control information 176 is further added after this EOB 175.

Control information 176 indicates that during the time occupied by EOB 175, the output of audio detection circuit l again
Whether or not it is determined that there is sound is indicated by a pre-specified code, and in the case of this embodiment, if there is no sound, C0NTl,
Is there a code like C0NT 2 for audio? We are using.

Therefore, as shown in FIG. 4, under the condition that the voice detection signal 12 remains at the high level 121 @ indicating the presence of voice, it does not take the a1'' level again and remains at the 50'' level, the control information 176 C0NTl is selected and this control information 176 becomes the last of the intermittent transmission signals.

Furthermore, the audio detection signal 12 shown in FIG. 5(5) is as shown in FIG.
Different from case 5), all cases where the audio detection output becomes high level 121 again during DEOB 175 transmission are shown.

As shown in FIGS. 4 and 5, the intermittent transmission signal is a reception processing signal 171 and 80M for 1 second immediately after the voice detection signal 12 reaches the tll" level 121 at fc.
172 is transmitted, immediately after that audio information 173 is transmitted, followed by hangover bit 174, EOB 1
75 will be sent. However, in the case of Fig. 5, unlike the case of Fig. 4, the sound sending button signal 12 is
becomes “1” again and becomes bell 121, so EOB175
The code C0NT2 is set to the control signal 176 that follows
Furthermore, after the second hangover message (174) is set, the process is executed under the control of the first to third control signals of the control signal generating circuit 3 so that the continuous multiplication voice information is sent out. Ru. The time from the moment the second half reaches the ul'' level shown in Figure 5 (4) to the start of transmitting the audio information in the second half is τ seconds, as in the first half; The time to from the bit to the second hangover bit is set equal to the time for the 10'' level 122 shown in the fifth country.

In this way, even if it is detected that the EOB transmission loudness audio signal is input, the audio signal will not be detected. Can be transmitted without any abnormality If the receiving side receives the above-mentioned fc transmission signal shown in Figure 4 (B) or Figure 5 (B), the receiver will transmit the signal as shown in Figure 4 (B).
) and the transmission signal shown in FIG. 5(B) are received in the same way, and in either case, it is fully known that there is a possibility that the received intermittent signal will soon end upon reception of EOB 175. After this, further control signal 1'7t3 fc
Is this the code of CUNTl? If so, the data after EOB175 that has already been received will not be recognized as audio information and this output will be deleted. Also, the control signal 176 is C0N
If it is T2, it is known that the received intermittent signal will continue, and the input information is continuously outputted, thus making it possible to stably transmit and receive audio data even if the EOB transmission audio signal is input. can.

In addition, although the above-mentioned embodiment is explained using the case where two consecutive voice detections occur as an example, it is clear that the present invention can be similarly implemented no matter how many times the voice detection occurs consecutively. It is.

Furthermore, in this embodiment, the control signal 176 is EOB1750@
Although the configuration of the transmission signal up to EOB175 cannot be changed for the purpose, the transmission signal after that can be arbitrarily selected as long as it does not conflict with the overall system operation.For example, EOB175 and control ( It is also clear that the zfc transmission control signal can be easily implemented by sending and setting appropriate information or a hangover bit between the t[lI multiplication signal 176 and the zfc transmission control signal.

Furthermore, in this embodiment, EOB175 is a fixed code set in advance, but it is also possible to use other transmission signal tail codes that have the same effect, such as frame synchronization that is inserted into the audio information 173 for each encoded frame length of the audio signal. There is no problem in replacing it by continuously sending out a plurality of bits, and all of the above can be easily implemented without detracting from the spirit of the present invention.

〔Effect of the invention〕

As explained above, according to the present invention, intermittent signal transmission and reception via a satellite? In the intermittent signal communication system that uses intermittent signal transmission, by providing communication with a means that enables transmission at all times even when transmitting the final code of the intermittent signal, it is possible to always accurately determine the completion of the intermittent signal on the receiving side. This has the effect of realizing an intermittent signal communication system that can always ensure stable transmission and reception of necessary signals with low noise.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the complete basic configuration of a satellite communication system based on the 8CPC system via artificial satellites, and Figure 2 is a block diagram showing the basic configuration of a transmitting station in the satellite communication system shown in Figure 1. , FIG. 3 is a block diagram showing the basic configuration of the transmitting side of the intermittent signal communication system according to the present invention, and FIG. 4 is a block diagram showing the basic configuration of the transmitting side of the intermittent signal communication method according to the present invention. FIG. Audio detection signal waveform (5) and transmission output timing chart) (B),
FIG. 5 shows a voice detection signal waveform (5) and a transmission output timing chart (B) in a communication state in which a voice detection signal is subsequently generated in the embodiment of FIG. l...Audio detector, 2...Delay circuit,
3... Control signal generation circuit, 4... Multiplexing circuit, 5... Transmitter, 11... Input audio signal, 12...・Audio detection signal, 13...
...Additional signal, 14...Delayed audio signal, 15
...Opening/closing signal, 16...Transmission information signal, 17...Audio presence/absence signal, 18...Transmission signal, 121...Logic value 11" level (with audio input), 122... logical value "'0" level (no audio input), 171... signal for reception processing, 17
2...80M, 173...Audio fHl
i% 174...Hangover Biv), 175
No. 17 Foil Z Circle 3 Figure

Claims (1)

[Claims] In an intermittent signal communication system that transmits and receives digital signals intermittently via an artificial satellite, the transmission signal to be sent is An intermittent signal communication system characterized by comprising an intermittent signal transmission means that enables the transmission at all times.