JPS60194636A - Carrier regenerating device - Google Patents

Abstract

PURPOSE:To generate a stable regenerated carrier even in an atmosphere where an S/N ratio is inferior by allowing a spectrum spread communication device to impose two- phase modulation and suppress and transmit a carrier at the transmission side, and to remove a carrier frequency component and remove the same frequency component with the carrier frequency of a noise. CONSTITUTION:A balanced modulator 21 spreads a receive wave reversely with a spread code from a spread code generator 24 and outputs a signal 3. A synchronism detector 22 detects the synchronism between the signal 3 and a local oscillation wave from a local oscillator 36. A removing filter 30 for the carrier frequency component, on the other hand, removes the carrier frequency component of the carrier-suppressed receive signal 3, and a squaring circuit 31 squares the output of the filter 30 and generates a frequency component twice as high as the carrier from the two-phase modulated reception wave; and this generated frequency component is passed through a band-pass filter 32 and a frequency divider 33 to generate a reference carrier frequency component. A phase detector 34 detects the phase of the reference carrier frequency component and the phase of the oscillation frequency of the local oscillator 36 as a voltage-controlled oscillator and controls the local oscillator 36 through a low-pass filter 35 to obtain a local oscillation wave as the regenerated carrier.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a carrier regeneration device for spread spectrum communication that performs wide-bandwidth transmission by phase modulation.

[Background of the invention]

The configuration of a conventional spread spectrum communication device will be explained. The configuration diagram of the transmitter is shown in Figure 1, and the configuration diagram of the receiver is shown in Figure 2.
In the transmitter shown in FIG.
0 spreads the transmission information 1 with the spreading code from the spreading code generator 12 and outputs it to the balanced modulator 11. This balanced modulator 11 performs two-phase phase modulation on the carrier wave from the carrier wave oscillator 13 using the output from the balanced modulator 10, and outputs it as a transmission wave. In the receiver shown in FIG. 2, a received wave from an antenna is amplified by an amplifier 20 and input to a balanced modulator 21.

The balanced modulator 21 despreads the received wave using a spreading code from the same spreading code generator 24 as that on the transmitting side, and outputs the despread signal to the phase detector 22 . The phase detector 22 compares which phase of the local oscillation wave from the voltage controlled oscillator 25 and the signal 3 from the balanced modulator 21 and outputs the result to the low-pass filter 23 . Furthermore, the voltage controlled oscillator 25 is controlled by the output of the low-pass filter. At this time, as the signal-to-noise ratio (S/N ratio) decreases, the carrier-to-noise ratio (C
/N ratio) may decrease, and the recovered carrier wave from the voltage controlled oscillator may become unstable.

[Purpose of the invention]

An object of the present invention is to reduce deterioration of the C/N ratio in an environment with a poor S/N ratio and provide a stable reproduced carrier wave.

[Summary of the invention]

In order to achieve the above object, the present invention performs two-phase phase modulation on the transmitting side, suppresses the carrier wave, and transmits the signal.

On the receiving side, since there is no carrier frequency component in the received wave, if this frequency component is removed, the same frequency component as the carrier frequency of the noise will be removed. By squaring this signal, a frequency component twice that of the carrier wave appears from the two-phase phase modulation signal. This is passed through a band pass filter and then frequency-divided to obtain a carrier wave frequency component, from which the carrier wave is reproduced.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 3 and 4. FIG. 3 shows the configuration of a receiver of a spread spectrum communication device including an example of the device of the present invention.
Components with the same reference numerals as those in the figure are the same parts. FIG. 4 shows a spectrum diagram of each signal.

Balanced modulator 21 despreads the received wave using the spreading code from spreading code generator 24 and outputs signal 3.

Signal 3 is shown in FIG. 4(,) and enters a synchronous detector 22 and a carrier frequency component removal filter 30. Synchronous detector 2
2 performs synchronous detection with the signal 3 and the local oscillation wave from the local oscillator 36, that is, the regenerated carrier wave.

On the other hand, the carrier frequency component removal filter 30 removes the carrier frequency component of the carrier-suppressed received signal 3 (mainly a noise component since the carrier component of the received wave is suppressed) and outputs it to the squaring circuit 31.

The spectral pass characteristics of the filter 30 are shown in FIG. 4(b).
The output is shown in FIG. 4(c). The squaring circuit 31 squares the output of the carrier frequency component removal filter 30 to create a frequency component twice that of the carrier wave from the received wave that has been subjected to two-phase phase modulation, and further filters the frequency component twice the frequency component of this carrier wave into a band-pass filter. Take out by 32. The signal is shown in Figure 4 (
Shown in d). Further, this signal is frequency-divided by a frequency divider 33 to obtain a reference carrier wave frequency component. This is shown in FIG. 4(e).

The phase detector 34 detects the phase of this reference carrier wave frequency component and the oscillation number of the local oscillator 36 which is a voltage controlled oscillator, outputs the detection signal to the low pass filter 35, and uses the output of the low pass filter 35 to operate the voltage controlled oscillator. control to obtain a local oscillation wave that is a regenerated carrier wave.

According to this embodiment, the frequency component twice the carrier wave obtained by squaring is reproduced only from the target signal of the received wave, and the noise component in the carrier wave frequency component is removed. , C/N in the reference carrier component
The improvement of the ratio is expected.

〔Effect of the invention〕

According to the present invention, deterioration of the C/N ratio can be reduced even when the S/N ratio is poor, so it is effective in improving operational stability and reliability of the communication device.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a transmitter of a conventional spread spectrum communication device, FIG. 2 is a configuration diagram of its receiver, and a third spectrum diagram. 21... Balanced modulator, 22... Synchronous detection circuit, 23
...Low pass filter, 24...Spreading code generator,
30... Carrier frequency component removal filter, 31... Square circuit, 32... Frequency component passing filter twice the carrier wave, 33... Frequency divider, 34... Phase detector, 35
... Ropa 1st Figure 2 Figure 5 (/ , l/ jl 3j 4th mouth

Claims (1)

[Claims] 1. A transmitter that spreads transmission information with a spreading code having a wide bandwidth, further phase-modulates it, and transmits it; and a receiver that obtains the transmission information by despreading it with the same spreading code as the transmitting side. In a direct sequence spread spectrum communication device equipped with a receiver,
A circuit that removes the carrier frequency component in the signal before or after despreading the received wave, and a circuit that squares the output of the circuit that removes the carrier frequency component and passes the frequency component twice that of the carrier wave. What is claimed is: 1. A carrier wave reproducing device comprising: a frequency component of a frequency component twice that of the carrier wave; and a divider that divides the output of a circuit that passes a frequency component twice that of the carrier wave. 2. In the carrier wave regeneration device according to claim 1, a circuit for detecting the phase of the regenerated carrier wave and an oscillation wave from a voltage-controllable local oscillator provided in the receiver is provided, and a circuit for detecting the phase is provided. The output of Rerono (Sfilt =
;ii. A carrier wave regeneration device characterized in that a local oscillator is controlled by the output of the l-ronos filter, and the oscillation wave is used as a regenerated carrier wave.