JPH03230635A - Digital privacy call radio relay station - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a digital confidential wireless relay station that wirelessly relays digital data subjected to confidential communication processing between terminals.

[Prior Art] Digital confidential wireless relay stations that perform confidential wireless relay of digital data between terminals have been known.

FIG. 2 shows a schematic configuration of a wireless system using this relay station.

This figure shows terminals 10 and 12 that transmit and receive continuously using BreathTalk, and a relay station 14. The relay station 14 receives a radio signal (hereinafter referred to as an RF multiplied signal) from the terminal 10. and a transmitter 18 that takes in the output of the receiver 16 and transmits it to the RF multiplied signal terminal 12.

For example, the terminal 10 receives audio input from a microphone, etc.
DM (Adaptive Delta Modula
tion; adaptive delta modulation), etc.
D conversion is performed to generate digital data, this digital data is subjected to confidential processing according to predetermined rules, and then GMSK (Gaussian-rilter
ed MinimuIIIShj('t Keying
), etc., and transmits the RF multiplied signal.

The receiver 16 of the relay station 14 receives and demodulates this RF multiplied signal, and transmits the digital data obtained by demodulation ta1.
Output to 8. The transmitter 18 modulates the digital data supplied from the receiver 16, performs predetermined processing such as amplification, and then transmits the RF-multiplied signal to the terminal 2.

Terminal 12 receives and demodulates this RF multiplied signal, cancels the confidential communication processing in terminal 10, and reproduces the digital data. This digital data is, for example, D/A converted and output as audio from a speaker.

FIG. 3 shows the configuration of the relay station 14 in more detail, and in this figure, a receiver 16, a transmitter 18,
An antenna 20 for receiving an RF multiplied signal of frequency fR and transmitting an RF multiplied signal of frequency f1, and a duplexer 22 for sharing the antenna 20 with the receiver 16 and the transmitter 18 are shown.

Further, the receiver 16 connects to the antenna 20 via the duplexer 22.
A high frequency circuit (hereinafter referred to as RF circuit) 24 performs processing such as amplification of the RF doubled signal supplied from the RF circuit 24, and receives the RF doubled signal from the RF circuit 24 and converts it into an intermediate frequency signal (hereinafter referred to as IF doubled signal); It includes an inter-frequency circuit (hereinafter referred to as an IF circuit) 26, and a demodulation circuit 28 that demodulates the IF signal and reproduces digital data that has been subjected to confidential communication processing.

The demodulation circuit 28 is connected to a signal processing section (not shown), and the IF circuit 26 is similarly connected to a control section (not shown).

That is, when the RF multiplied signal is received by the antenna 2o and supplied to the RF circuit 24 via the duplexer 22, the RF circuit 2
4 performs predetermined processing and then outputs it to the engineering F circuit 26.

The IP circuit 26 receives an I signal having a lower frequency than the supplied RF multiplied signal.
It converts the F-fold signal and outputs it to the demodulation circuit 28, and also issues a squelch signal (hereinafter referred to as the SQ-fold signal) indicating the arrival of the RF-fold signal to the control section.

The demodulation circuit 28 demodulates the IF multiplied signal and outputs the digital data, which has undergone confidential communication processing in the terminal 10, to the signal processing section. The control unit causes the signal processing unit to execute processing related to monitoring and the like in response to the SQ multiplied signal.

On the other hand, the demodulation circuit 28 is connected to the modulation circuit 30 of the transmitter 18. The transmitter 18 includes a modulation circuit 3o that generates an IF multiplied signal modulated with digital data output from the demodulation circuit 28, a transmitting circuit 32 that takes in the IF multiplied signal from the modulation circuit 30 and generates an RF multiplied signal, and a transmitting circuit 32 A power amplifier 34 amplifies the output of the antenna 20 and supplies the amplified output to the antenna 20 via the duplexer 22.

That is, the digital data output from the demodulation circuit 28 is supplied to the signal processing section and also to the modulation circuit 30. The modulation circuit 30 modulates a local oscillation signal (generated by, for example, a local oscillator within the modulation circuit 30) using this digital data, and outputs the IF multiplied signal.

The transmitting circuit 32 converts the IF multiplied signal into an RF multiplied signal, which is further amplified by the RF multiplied signal power amplifier 34.

Then, the RF multiplied signal is sent to the antenna 20 via the duplexer 22.
and transmitted to the terminal 12. At the terminal 12, RF signal demodulation and deprivation will be performed as described above.

Note that the receiving frequency fR and the transmitting frequency fT are set to different values.

In this way, in the past, it was possible to modulate and demodulate confidentially processed digital data and relay it wirelessly, and it was possible to perform digital data communication without the communication content being intercepted by a third party. .

[Problems to be Solved by the Invention] However, in the past, when a relay station performs continuous transmission in a so-called silent state in which no RF multiplied signal is transmitted from a terminal, noise is generated at the receiving terminal. there were.

That is, when the relay station is not receiving the RF multiplied signal, the transmitter of the relay station modulates digital data indicating a silent state and transmits it to the terminal.

The terminal on the receiving side performs deconfidential processing cancellation processing on this message. As a result, the digital data played by the receiving terminal in the silent state is digital data in which the confidential processing has been removed from the unencrypted digital data indicating the silent state, and is not the digital data indicating the silent state. , which becomes noise for the receiving terminal.

Particularly in a system in which audio is digitized and transmitted/received as digital data, such noise generation becomes noise in the speaker output at the receiving terminal. In order to suppress the noise in the speaker output, it is possible to add a signal such as an RF multiplied signal, selector signal, etc., detect silence and turn off the speaker output, but this method increases the size and complexity of the device. Put it away. Therefore, it is difficult to use it in a general-purpose digital radio system.

The present invention has been made with the aim of solving these problems, and it is possible to reproduce digital data without generating noise related to deconfidential processing in the terminal device on the receiving side even in a silent state. The purpose of the present invention is to provide a digital confidential communication wireless relay station having a small size and simple configuration that enables the communication.

[Means for Solving the Problems] In order to achieve the above object, the present invention detects whether a receiver receives an RF multiplied signal from a receiving terminal, and generates pattern data that cancels confidential communication processing at the transmitting terminal. When the transceiver detects that the RF multiplied signal is not being received from the transmitting terminal, the pattern generator is connected to the transmitter, and at other times, the receiver is connected to the transmitter. A modulation data switching circuit for switching.

[Operation] In the present invention, when digital data that has been subjected to decryption processing is modulated and transmitted as an RF multiplied signal from the transmitting terminal, the receiver receives and demodulates this.

At this time, the arrival of the RF multiplied signal is detected in the receiver, the modulation data switching circuit is switched, and the receiver and transmitter are connected via the modulation data switching circuit. The output of the receiver, that is, the encrypted digital data, is again transmitted as an RF signal to the receiving terminal by the transmitter. Then, the receiving terminal demodulates the RF signal, cancels the confidential communication processing, and reproduces the digital data.

On the other hand, in a silent state where the RF multiplied signal transmitted from the transmitting terminal is not being received, the receiver switches the modulation data switching circuit to connect the pattern generator to the transmitter. Therefore, the pattern data generated by the pattern generator is modulated in the transmitter and transmitted as an RF multiplied signal to the receiving terminal. Here, the pattern data is data that offsets the confidential conversation processing, and therefore, noise generated due to cancellation of the confidential conversation processing by the receiving terminal in a silent state is prevented.

[Embodiments] Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 1 shows the configuration of a digital confidential radio relay station according to an embodiment of the present invention.

In this embodiment, a modulation data switching circuit 36 according to the characteristics of the present invention is provided between the demodulation circuit 28 and the modulation circuit 30, and this modulation data switching circuit 36 has an IF
An SQ multiplied signal output from the circuit 26 is supplied. Further, the modulation data switching circuit 36 is a switch that switches and connects the demodulation circuit 28 and the pattern generator 38, which is also a feature of the present invention, to the modulation circuit 30 in accordance with the SQ multiplied signal, and the pattern generator 38 is controlled by controls (not shown). The parts are connected.

Next, the operation of this embodiment will be explained.

In this embodiment, for example, 150 MH
When the z-band RF multiplied signal is being transmitted, the arrival of this RF multiplied signal is detected in the IF circuit 26, and is notified to the control section as an SQ multiplied signal.

At this time, the modulation data switching circuit 36
is placed on the side of the demodulation circuit 28 and connected to either the demodulation circuit 28 or the modulation circuit 30, and RF multiplied signal relay is performed as in the conventional case.

On the other hand, when the RF multiplied signal is not being transmitted from the terminal 10, the SQ signal is sent from the IF circuit 26 to the modulation data switching circuit 36.
Double signal not supplied. Accordingly, the modulation data switching circuit 36 is moved to the pattern generator 38 side, and is connected to either the pattern generator 38 or the modulation circuit 30. Further, the control unit starts the operation of the pattern generator 38 in response to the fact that the SQ multiple signal does not arrive.

The pattern generator 38 generates digital data of a predetermined pattern and supplies it to the modulation circuit 30 via the modulation data switching circuit 36.

Here, the pattern generated by the pattern generator 38 is a pattern that offsets the secret processing performed at the terminal 10. That is, when the pattern supplied from the pattern generator 38 to the modulation circuit 30 via the modulation data switching circuit 36 is transmitted from the antenna 20 to the terminal 12 after being subjected to the above-described processing, the terminal 12 receives this R.
For the F-fold signal, in addition to processing such as demodulation, processing for canceling confidential speech processing is performed.

For example, when ADM is used as the A/D conversion method, silence is expressed by 101010...
In this embodiment, the pattern generator 38 generates data of a pattern that becomes data indicating silence when the confidential conversation processing is canceled.

When the terminal 12 cancels confidential communication processing for such a pattern, digital data indicating silence will be reproduced.

For example, when the digital data involved in transmission and reception is data obtained by digitizing audio, when there is no transmission wave from the transmitter, that is, when there is no relay wave, the reception side terminal that receives the transmission wave from the relay station that is continuously transmitting The speaker output has reduced noise, which is closer to the ideal silent state.

Note that the present invention does not depend on the RF multiplication signal band or modulation method.

The above explanation concerns the case of RF multiplied signal analog signal processing, and the SQ multiplied signal is used for switching of the modulation data switching circuit 36. When digitally processing the RF multiplied signal, the RF multiplied signal input to the receiver is demodulated and frame synchronization is detected.

If frame synchronization is detected, a frame synchronization signal is generated, and it is determined from this that the wireless line is in use. Therefore, if the modulation data switching circuit 36 is switched by the frame synchronization signal, even in this case,
It is possible to eliminate malfunctions due to noise and the like.

[Effects of the Invention] As explained above, according to the present invention, when the RF multiplied signal does not arrive from the transmitting terminal, a pattern for canceling the secret processing is modulated, and the RF multiplied signal is transmitted to the receiving terminal. As a result, it is possible to suppress the generation of noise at the receiving terminal due to cancellation of confidential communication processing, and it is possible to perform suitable relaying of digital data. Furthermore, such effects can be achieved with a small and simple configuration.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a relay station according to an embodiment of the present invention, FIG. 2 is a configuration diagram of a wireless system using the relay station, and FIG. 3 is a block diagram showing the configuration of a conventional relay station. FIG. 10.12 ... Terminal 14 ... Relay station 16 ... Receiver 18 ... Transmitter 28 ... Demodulator 0 32 6 8 Q Modulator transmission circuit switch pattern generator squelch signal

Claims (1)

[Scope of Claims] A transmitting terminal that performs decryption processing and modulation on digital data and transmits it as a wireless signal; a receiving terminal that performs demodulation on the received wireless signal and canceling the decryption processing to reproduce the digital data; A receiver that is wirelessly connected to the transmitting terminal, receives and demodulates the wireless signal from the transmitting terminal, and outputs confidentially processed digital data, and a receiver that modulates this digital data and transmits it as a wireless signal to the receiving terminal. In a digital confidential wireless relay station that has a transmitter and performs confidential wireless relay between a transmitting terminal and a receiving terminal, the receiver detects whether a wireless signal has arrived from the transmitting terminal, and a pattern generator that generates pattern data that offsets confidential communication processing at the terminal; and a pattern generator connected to the transmitter when the receiver detects that no wireless signal has arrived from the transmitter terminal;
A digital confidential radio relay station comprising: a modulation data switching circuit that switches the receiver to the transmitter at other times.