JPH08265296A - Radio multiplex transmission system and multiplex modulation circuit and multiplex demodulation circuit applying the system - Google Patents

Abstract

PURPOSE: To compress a transmission band and to improve the utilization efficiency of a carrier wave frequency by simultaneously transmitting digital signals and analog signals just by using one carrier wave signal. CONSTITUTION: In this multiplex modulation circuit on a transmission side, after the digital signals DS are spread spectrum modulated in a mixer 13a, the carrier wave signal CS is 2-phase PSK modulated in a BPSK modulator 13c by the spread modulation signal, quadrature modulation wave signals whose frequency is the same as the carrier wave signal CS and phase is different for π/2 are amplitude modulated in an amplitude modulator 14 by the analog signals AS and the phase modulation wave signals and amplitude modulation wave signals are synthesized by a hybrid circuit 15 and transmitted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless multiplex transmission system for simultaneously transmitting a digital signal and an analog signal between a communication satellite and a ground station, and a multiplex modulation circuit and multiplex demodulation circuit to which this system is applied. Regarding

[0002]

2. Description of the Related Art Between a communication satellite and a ground station, an analog signal for distance measurement may be transmitted at the same time as transmitting a command, telemetry or the like by a digital signal. As a signal transmission method in this case, conventionally, for example, first and second carrier signals having different frequencies are generated, and the first carrier signal is digitally modulated by a digital signal and transmitted, and the second carrier signal is transmitted. A method has been considered in which a signal is analog-modulated by an analog signal and transmitted.

[0003]

However, in such a conventional system, separate carrier signals must be prepared for digital signal transmission and analog signal transmission. Therefore, there is a problem that the transmission bandwidth of the signal becomes wide and the utilization efficiency of the carrier frequency is lowered.

The present invention has been made in view of the above circumstances. An object of the present invention is to enable simultaneous transmission of a digital signal and an analog signal by using only one carrier signal so that the transmission band can be reduced. It is an object of the present invention to provide a wireless multiplex transmission system that improves compression and utilization efficiency of carrier frequencies, and a multiplex modulation circuit and multiplex demodulation circuit to which this system is applied.

[0005]

In order to achieve the above object, the wireless multiplex transmission system of the present invention is designed so that when a digital signal and an analog signal are simultaneously wirelessly transmitted from a transmitting side to a receiving side, a predetermined signal is transmitted at the transmitting side. A carrier signal having a frequency and a frequency equal to the carrier signal and having a phase of π
/ 2 different quadrature carrier signals are generated, the digital signal is subjected to spread spectrum processing by a spread signal, the spread carrier modulated signal is subjected to two-phase phase modulation, and the analog signal is used for the quadrature. A carrier signal is amplitude-modulated, and the phase-modulated carrier signal and the amplitude-modulated quadrature carrier signal are combined and transmitted. On the other hand, on the receiving side, the received signal is subjected to spectrum despreading processing with a spread signal and then the inverse signal is applied. A carrier signal is regenerated from the spread-processed received signal, and the regenerated carrier signal has the same frequency and phase of π.
/ 2 different orthogonal regenerated carrier signals are generated, the despread received signal is phase demodulated by the regenerated carrier signal to output a digital demodulated signal, and the received signal before the despread process is the orthogonal regenerated carrier signal. The signal is amplitude-demodulated and an analog demodulated signal is output.

The multiplex modulation circuit of the present invention further comprises a carrier signal generating means for generating a carrier signal having a predetermined frequency and an orthogonal carrier signal having the same frequency as the carrier signal and a phase difference of π / 2, and a digital signal. And a spread modulation means for performing spread spectrum processing with a spread signal to output a spread modulation signal, and a direct spread modulation signal output from this spread modulation means for two-phase phase modulating the carrier signal to output a phase modulation signal. And a phase modulation signal for amplitude-modulating the quadrature carrier signal with an analog signal to output an amplitude-modulated signal. The phase-modulated signal output from the phase-modulating means and the amplitude-modulated signal are provided. The amplitude-modulated signal output from the means is combined and transmitted.

Further, the multiplex demodulation circuit of the present invention reproduces a carrier signal from the despreading processing means for despreading the received signal by spectrum despreading processing with the spread signal and the received signal despread by the despreading processing means. Carrier reproduction means for generating an orthogonal reproduction carrier signal having the same frequency as the reproduced carrier signal and a phase difference of π / 2, and the received signal despread by the despreading processing means are reproduced by the carrier reproducing means. Phase demodulation means for phase demodulating the reproduced carrier signal to output a digital demodulated signal, and amplitude demodulation of the received signal before despreading by the orthogonal reproduced carrier signal generated by the carrier reproducing means for analog demodulated signal And an amplitude demodulating means for outputting

[0008]

As a result, according to the present invention, the digital signal is
After being spread-spectrum-modulated by the spread signal, the carrier signal is transmitted by performing two-phase phase modulation by the spread-modulated signal. On the other hand, the analog signal is an orthogonal carrier having the same frequency as the carrier signal but different in phase by π / 2. It is transmitted by amplitude-modulating the signal. That is, the digital signal and the analog signal are transmitted so that they can be separated and demodulated on the receiving side by utilizing the phase orthogonality between the carrier signal and the orthogonal carrier signal and by utilizing the correlation of the spread signal. Therefore, it becomes possible to transmit a digital signal and an analog signal at the same time by using only one carrier wave, whereby the transmission bandwidth can be compressed and the frequency utilization efficiency can be improved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A wireless multiplex transmission system according to an embodiment of the present invention will be described below with reference to the drawings. 1 and 2 are circuit block diagrams showing configurations of a multiplex modulation circuit and a multiplex demodulation circuit for implementing the wireless multiplex transmission system of the present embodiment, respectively.

First, the multiple modulation circuit includes a carrier wave oscillator 11
, The hybrid circuit 12, the direct spread modulator 13,
The amplitude modulator 14 and the hybrid circuit 15 are provided. The carrier wave oscillator 11 generates a carrier wave signal CS having a predetermined frequency. The hybrid circuit 12 has a π / 2 phase shifter, divides the carrier signal CS generated from the carrier oscillator 11 into two, supplies one of them directly to the spread spectrum modulator 13, and shifts the other by π / 2. The quadrature carrier signal QCS is generated by phase shifting by π / 2 in the modulator and is supplied to the amplitude modulator 14.

The direct spread modulator 13 includes a pseudo random signal generator 13a for generating a spread signal PN and a mixer 13b.
And a BPSK modulator 13c. And
The mixer 13b multiplies the digital signal DS by the spread signal PN to spread-spectrum-modulate the digital signal DS, and the BPSK modulator 13c further spreads the carrier signal CS supplied from the hybrid circuit 12 by the spread-spectrum modulated signal. Phase PSK modulation.

The amplitude modulator 14 amplitude-modulates the quadrature carrier signal QCS output from the hybrid circuit 12 with the analog signal AS. The hybrid circuit 15 is
The phase modulation wave signal output from the direct spread modulator 13 and the amplitude modulation wave signal output from the amplitude modulator 14 are combined, and the combined modulation wave signal MCS is transmitted to a transmission circuit (not shown) for transmission. Supply.

On the other hand, the multiple demodulation circuit is the hybrid circuit 2
1, a mixer 22, a spread signal generator 23, a spread signal acquisition / tracking circuit 24, a carrier recovery circuit 25, a phase demodulator 26, and an amplitude demodulator 27.

The hybrid circuit 21 bifurcates the reception signal RS output from a reception circuit (not shown) and supplies one to the mixer 22 and the other to the amplitude demodulator 27. The spread signal acquisition / tracking circuit 24 acquires and tracks the spread signal PN included in the received signal RS '. Spread signal generator 23
Generates a spread signal PN according to the acquisition and tracking result of the spread signal acquisition and tracking circuit 24. The mixer 22 spreads the spectrum of the received signal RS by multiplying the received signal RS by the spread signal PN and outputs the result.

The carrier wave regenerating circuit 25 has, for example, a PLL circuit and a π / 2 phase shifter. In the PLL circuit, the carrier wave signal is regenerated from the despread reception signal RS 'and the π / 2 phase shifter is also used. This reproduced carrier signal C
A quadrature reproduced carrier signal QCS 'having the same frequency as S'and a phase shifted by .pi. / 2 is generated.

The phase demodulator 26 is the carrier recovery circuit 2 described above.
The despread reception signal RS 'is phase-demodulated by using the reproduced carrier signal CS' output from the signal 5, thereby outputting the digital demodulation signal DS '. The amplitude demodulator 27 is
The reception signal RS supplied from the hybrid circuit 21 is amplitude demodulated by using the quadrature reproduction carrier signal QCS 'generated from the carrier recovery circuit 25, and the analog demodulated signal AS' obtained by this is output.

Next, the wireless multiplex transmission system of this embodiment using the multiplex modulation circuit and multiplex demodulation circuit configured as described above will be explained. In the terrestrial radio station on the transmitting side, the digital signal DS representing the command or telemetry of the satellite is spread-spectrum-modulated by the spread signal PN generated from the pseudo random signal generator 13a in the multiple modulation circuit, and then is transmitted to the BPSK modulator 13c. It is input as a modulation signal. Then, this BPSK modulator 13
In c, the carrier signal CS is two-phase PSK-modulated by the spread modulation signal.

On the other hand, the analog signal AS for distance measurement is directly input to the amplitude modulator 14 as a modulation signal, and the amplitude modulator 14 has a quadrature carrier signal having the same frequency as the carrier signal CS but different phase by π / 2. The QCS is amplitude-modulated by the analog signal AS. And the BPS
The phase modulated wave signal output from the K modulator 13c and the amplitude modulated wave signal output from the amplitude modulator 14 are combined by the hybrid circuit 15 to be a combined modulated wave signal MCS.
Is transmitted to a communication satellite from a transmission circuit (not shown).

On the other hand, in the communication satellite, the modulated wave signal arriving from the terrestrial radio station is received by the receiving circuit (not shown) and then input to the multiplex demodulating circuit. To be done.
One of the two branched reception signals RS is inversely spread and modulated by the spread signal PN generated from the spread signal generator 23, and then input to the carrier recovery circuit 25. And
In the carrier recovery circuit 25, the carrier signal is reproduced from the received signal RS 'after the despreading modulation, and the reproduced carrier signal CS' thus obtained and the phase of the reproduced carrier signal CS 'are .pi. /. Two different quadrature reproduced carrier signals QCS 'are generated respectively, and the phase demodulator 2
6 and the amplitude demodulator 27.

In the phase demodulator 26, the received signal RS 'after the despreading modulation is phase-demodulated based on the reproduced carrier signal CS', whereby the digital signal DS 'is demodulated. The digital demodulated signal DS 'is input to, for example, a control circuit (not shown), and the control circuit executes control relating to the communication satellite according to the content of the digital demodulated signal DS'.

On the other hand, in the amplitude demodulator 27, the other of the received signals RS branched into two in the hybrid circuit 21 is amplitude-modulated by using the quadrature reproduced carrier signal QCS ', whereby the analog signal AS' is obtained. Demodulated.
This analog demodulated signal AS 'is provided to arithmetic processing for measuring the distance between the communication satellite and the ground radio station, for example.

As described above, in the transmission system of this embodiment, the multiple modulation circuit on the transmission side performs the spread spectrum modulation of the digital signal DS and then the two-phase PSK modulation of the carrier signal CS by the BPSK modulator 13c by the spread modulation signal. Along with the analog signal AS, the carrier signal C
The quadrature carrier signal QCS having the same frequency as S and different in phase by π / 2 is amplitude-modulated by the amplitude modulator 14, and the phase-modulated wave signal and the amplitude-modulated wave signal are combined by the hybrid circuit 15 and transmitted. On the other hand, in the receiving side multiplex demodulation circuit, the received signal RS is despread-modulated, the carrier is regenerated from the despread received signal RS ', and the regenerated carrier signal CS' is used to perform the despread received signal. The phase of RS 'is demodulated to demodulate the digital signal DS', and the phase of the reproduced carrier signal CS 'is π.
/ 2 different quadrature reproduced carrier signals QCS 'are used to amplitude demodulate the received signal RS to demodulate the analog signal AS'.

Therefore, according to this embodiment, the digital signal DS and the analog signal AS are the same as the digital signal DS.
Of the spread signal PN that spread-modulates the carrier signal CS, which is two-phase PSK modulated by the digital signal DS, and the quadrature carrier signal Q which is amplitude-modulated by the analog signal AS.
Using the orthogonality with CS, it is wirelessly transmitted by a carrier signal of one frequency. For this reason, the digital signal DS and the analog signal AS can be simultaneously wirelessly transmitted by using only one carrier wave signal, whereby separate carrier wave signals are used for digital signal transmission and analog signal transmission. The transmission band is 1 /
It can be compressed to 2. In addition, by using only one carrier wave, it is possible to increase the frequency utilization rate.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the case where the digital signal DS for transmitting a command or telemetry and the analog signal AS for distance measurement are simultaneously transmitted has been described as an example, but the digital signal for data transmission and the pilot signal are described. It may be applied when transmitting an analog signal for transmission at the same time. In addition, regarding the circuit configuration of the multiple modulation circuit and multiple demodulation circuit, the modulation method, etc.,
Various modifications can be implemented without departing from the scope of the present invention.

[0025]

As described above in detail, in the wireless multiplex transmission system of the present invention, when the digital signal and the analog signal are simultaneously wirelessly transmitted from the transmitting side to the receiving side, the transmitting side has a carrier signal having a predetermined frequency. And orthogonal carrier signals having the same frequency as the carrier signal and different phases by π / 2 are generated, the digital signal is subjected to spread spectrum processing by the spread signal PN, and then the carrier signal is converted by the spread modulated signal subjected to the spread processing. The two-phase phase modulation is performed, the quadrature carrier signal is amplitude-modulated by the analog signal, and the phase-modulated carrier signal and the amplitude-modulated quadrature carrier signal are combined and transmitted, while one is received at the receiving side. The signal is subjected to spectrum despreading with a spread signal and then carried from this despread received signal. A signal is regenerated, an orthogonal regenerated carrier signal having the same frequency as the regenerated carrier signal and a phase different by π / 2 is generated, and the despread reception signal is phase demodulated by the regenerated carrier signal to obtain a digital demodulated signal. In addition to the output, the received signal before the despreading process is amplitude-demodulated by the quadrature reproduced carrier signal to output an analog demodulated signal.

Further, in the multiplex modulation circuit of the present invention, a carrier signal generating means for generating a carrier signal having a predetermined frequency and an orthogonal carrier signal having the same frequency as the carrier signal and a phase difference of π / 2, and a digital signal. Spread spectrum processing is performed with a spread signal to output a spread modulation signal, and the carrier signal is two-phase phase modulated with the direct spread modulation signal output from the spread modulation means to output a phase modulation signal. And a phase modulation signal for amplitude-modulating the quadrature carrier signal with an analog signal to output an amplitude-modulated signal, and the phase-modulated signal output from the phase-modulating means and the amplitude-modulated signal The amplitude-modulated signal output from the means is combined and transmitted.

Further, in the multiplex demodulation circuit of the present invention, the despreading processing means for despreading the received signal by the spread signal, and the carrier signal is reproduced from the received signal despread by the despreading processing means. Carrier reproduction means for generating an orthogonal reproduction carrier signal having the same frequency as the reproduced carrier signal and a phase difference of π / 2, and the received signal despread by the despreading processing means are reproduced by the carrier reproducing means. Phase demodulation means for phase demodulating the reproduced carrier signal to output a digital demodulated signal, and amplitude demodulation of the received signal before despreading by the orthogonal reproduced carrier signal generated by the carrier reproducing means for analog demodulated signal And an amplitude demodulation means for outputting

Therefore, according to the present invention, the digital signal and the analog signal can be simultaneously transmitted by using only one carrier signal, whereby the compression of the transmission band and the utilization efficiency of the carrier frequency can be improved. It is possible to provide a possible wireless multiplex transmission system, a multiple modulation circuit and a multiple demodulation circuit to which this system is applied.

[Brief description of drawings]

FIG. 1 is a circuit block diagram showing a configuration of a multiplex modulation circuit for realizing a wireless multiplex transmission system according to an embodiment of the present invention.

FIG. 2 is a circuit block diagram showing a configuration of a multiplex demodulation circuit for realizing a wireless multiplex transmission system according to one embodiment of the present invention.

[Explanation of symbols]

11 ... Carrier oscillator 12 ... Hybrid circuit 13 ... Quadrature spread modulator 13a ... Pseudo random signal generator 13b ... Mixer 13c ... BPS
K modulator 14 ... Amplitude modulator 15 ... Hybrid circuit 21 ... Hybrid circuit 22 ... Mixer 23 ... Spreading signal generator 24 ... Spreading signal capturing / tracking circuit 25 ... Carrier regeneration circuit 26 ... Phase demodulator 27 ... Amplitude demodulator DS ... Digital Signal AS ... Analog signal CS ... Carrier signal QCS ... Quadrature carrier signal PN ... Spread signal DS '... Digital demodulation signal AS' ... Analog demodulation signal CS '... Regenerated carrier signal QCS' ... Orthogonal regenerated carrier signal MCS ... Synthetic modulated wave signal RS ... Received signal RS '... Received signal after despreading

Claims (3)

[Claims] 1. When a digital signal and an analog signal are simultaneously wirelessly transmitted from a transmitting side to a receiving side, the transmitting side has a carrier signal having a predetermined frequency, and the carrier signal has the same frequency and a phase difference of π / 2. After each of the orthogonal carrier signals are generated and the digital signal is subjected to spread spectrum processing with a spread signal,
The spread carrier modulated signal subjected to the spread processing is subjected to two-phase phase modulation, and the quadrature carrier signal is amplitude-modulated by the analog signal to obtain the phase-modulated carrier signal and the amplitude-modulated quadrature carrier signal. On the other hand, on the receiving side, the received signal is subjected to spectrum despreading processing with a spread signal and then a carrier signal is reproduced from this despread processed received signal and the frequency and frequency are equal and phase with this reproduced carrier signal. π / 2 different orthogonal reproduction carrier signals are generated, the despread processing reception signal is phase-demodulated by the reproduction carrier signal to output a digital demodulation signal, and the reception signal before the despread processing is orthogonal reproduction. A wireless multiplex transmission characterized in that an amplitude demodulation is performed by a carrier signal and an analog demodulation signal is output. Method. 2. Carrier generation means for respectively generating a carrier signal having a predetermined frequency and an orthogonal carrier signal having the same frequency as the carrier signal and a phase different by π / 2, and spread spectrum processing of a digital signal by a spread signal. And a spread modulation means for outputting a spread modulation signal, and a phase modulation means for performing a two-phase phase modulation of the carrier signal by the direct spread modulation signal output from the spread modulation means and outputting a phase modulation signal. An amplitude modulation unit for amplitude-modulating the quadrature carrier signal with an analog signal to output an amplitude modulation signal; a phase modulation signal output from the phase modulation unit and an amplitude modulation signal output from the amplitude modulation unit; And a signal synthesizing means for synthesizing the signals for transmission. 3. A despreading processing unit for performing a spectrum despreading process on a received signal with a spread signal, and a carrier signal is reproduced from the received signal subjected to the despread processing by this despreading processing unit. Carrier demodulation means for generating orthogonal reproduction carrier signals having the same phase but different in phase by π / 2, and phase demodulation of the reception signal despread by the despreading processing means by the reproduction carrier signal reproduced by the carrier reproduction means. And a phase demodulation means for outputting a digital demodulation signal, and an amplitude for outputting an analog demodulation signal by amplitude demodulating the reception signal before the despreading processing by the orthogonal reproduction carrier signal generated by the carrier reproduction means. A multiplex demodulation circuit comprising: a demodulation means.