JPS61136350A - Carrier wave recovery circuit - Google Patents

Abstract

PURPOSE:To obtain a titled circuit which is not influenced by a noise, by providing a narrow band pass filter by which only a synchronizing pattern of non- modulation positioned at the head part, among received PSK modulated waves is made to pass through, stopping a reve rse modulator by this output, and reproducing a reference carrier wave. CONSTITUTION:A band pass filter 16a of a synchronizing pattern detecting part 16 is a narrow band pass filter, and makes only a synchronizing pattern of non-modulation pass through. Also, an envelope detector 16b reproduces and outputs an envelope of an inputted synchronizing pattern, and sends it out to a voltage comparator 16c of the next stage. This comparator 16c compares its reference voltage and an output of the detector 16b, and sends out a reverse modulation stop signal to a reverse modulator 11, if said output exceeds the reference voltages. In this way, the reverse modulator stops its operation, determines a reference phase based on the synchronizing pattern of the inputted moulated wave, applies a modulation in reverse to this reference phase, and reproduces a reference carrier wave. Also, based on this reference carrier wave, the inputted modulated wave is demodulated by a demodulator 13.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a carrier regeneration circuit in a receiving device for PSK modulated waves.

P S K (phase 5hift keying
) Modulation method is generally a type of method for modulating digital signals.

For example, the phase of the carrier wave corresponding to the digital signal “1” is set to 1 for the phase of the carrier wave corresponding to the digital signal “0”.
There are cases where a modulated wave is generated with a shift of 80 degrees and a -binary signal is transmitted.

Since the PSK modulation method has good signal identification, it is used when stations on the earth communicate with each other via relay stations installed on far-off artificial satellites.

However, in the PSK modulation method described above, the receiving side reproduces a reference carrier wave with no phase fluctuation from the received PSK modulated wave, and demodulates the digital signal by comparing the phase of the reproduced reference carrier wave and the input PSK modulated wave. There is.

The present invention relates to a carrier wave regeneration circuit of a receiving device using such PSK modulation method 2.

[Conventional technology]

The conventional carrier regeneration circuit includes an inverse modulator 1, a bandpass filter 2, a demodulator 3, a UW detector 4, and a synchronization pattern part predictor 5, as shown in FIG.

In the conventional circuit described above, the UW detector 4 first detects the unique word UW from the demodulated signal a+ (FIG. 5(^)) from the demodulator 3, and sends the UW detection signal S to the pattern part predictor 5. (Figure 5(B)).

The synchronization pattern part predictor 5, which has received the above S, stops the inverse modulation operation of the inverse modulator 1 by sending the non-modulated part prediction signal S2 to the inverse modulator 1 (FIG. 5(C)).

Then, a carrier wave whose frame format has the synchronization pattern CR of the psK modulated wave inputted when the inverse modulation operation is stopped is set as a reference carrier wave.

[Problem that the invention seeks to solve]

However, the conventional circuit described above can determine the reference carrier wave and reference phase only after the demodulator 3 operates normally.

That is, as shown in FIG. 6, if the demodulated signal from the demodulator 3 is "1" or rOJ, and the demodulated signal is ``1'' or rOJ, if the signal-to-noise ratio, that is, the SN ratio is poor, it will be affected by the noise. Originally NJ
What should be expressed becomes rOJ, and the phase may differ by 180° (arrow α).

On the other hand, what should originally represent rOJ may become "1" (arrow β).

That is, the conventional circuit has a problem in that the carrier wave regeneration operation becomes unstable at low SN sinking.

Means for Solving Problem c] According to the present invention, a PSK modulated wave obtained by modulating each digital signal in correspondence with a phase-deviated sine wave is received, and a PSK modulated wave located at the beginning of the received PSK modulated wave is In the carrier wave regeneration circuit, the reference carrier wave for demodulating the PSK modulated wave is regenerated by an inverse modulator by assuming a reference phase by exposing the synchronization pattern to the input terminal of the inverse modulator. A detection section is provided, and the synchronization pattern detection section includes a filter that allows only the unmodulated synchronization pattern to pass through, and an envelope detector that inputs the synchronization pattern and reproduces and outputs its envelope. and a voltage comparator that inputs the output of the detector and outputs an inverse modulation stop signal to the inverse modulator when the output voltage is equal to or higher than the reference voltage. There is provided a carrier wave regeneration circuit characterized in that the reference carrier wave is regenerated by assuming the reference phase based on the reference pattern.

[For production]

The method of the present invention is provided with a narrow band filter that passes only the unmodulated synchronization pattern located at the head of the received PSK modulated wave, and uses the output of the filter to stop the inverse modulator and transmit the reference carrier. can be reproduced, so it is not affected by noise like conventional methods and can be applied to communication systems of any frame format.

〔Example〕

Hereinafter, the present invention will be explained by way of examples with reference to the accompanying drawings.

FIG. 1 is a configuration diagram of a carrier regeneration circuit according to the present invention, FIG. 2 is an explanatory diagram of the operation of FIG. 1, and FIG. 3 is a P
FIG. 2 is an explanatory diagram of the SK modulation method.

The circuit shown in FIG. 1 includes an inverse modulator 11, a bandpass filter 12, a demodulator 13, and a synchronization pattern detection section 16.

The carrier wave regeneration circuit is provided on the receiving side and receives the received P.
This circuit reproduces a reference carrier wave from the SK modulated wave, and demodulates the original digital signal from the input modulated wave by comparing it with the reproduced reference carrier wave.

Here, an outline of the PSK modulation method applied to the present invention is as follows.
This will be explained based on FIG.

As mentioned above, P S K (phase 5hif
The t keying) modulation method is a type of modulation method when the modulated wave is a digital signal.

Taking the two-phase modulation shown in Figure 3 as an example, if the digital signal is "0", the sine wave m+ has a certain phase, and if the digital signal is "1", the inverted phase of the waveform m is the sine wave m+. Each signal is converted into a 180° sine wave m2, and then transmitted to the receiving side on a higher radio frequency.

Although FIG. 3 shows an example of two-phase modulation, four-phase modulation in which carrier waves orthogonal to each other are modulated in two phases and added together, and eight-phase modulation in which these are combined are also similar.

On the other hand, on the receiving side, a reference carrier wave is regenerated by the carrier wave regeneration circuit shown in FIG. 1, and the phase difference between the reference carrier wave and the input modulated wave is detected to extract the original digital signal.

The inverse modulator 11 in FIG. 1 is a device that inputs the PSK modulated wave and inversely modulates it in the same manner as on the receiving side. The bandpass filter 12 is a bandpass filter for improving the signal-to-noise ratio of the recovered carrier wave. The demodulator 13 is a device that demodulates the original digital signal by comparing the input modulated wave with the reference carrier wave reproduced by the inverse modulator (FIG. 3).

The synchronization pattern detection unit 16 is a device that detects an unmodulated synchronization pattern present at the head of the received PSK modulated wave.

Furthermore, this synchronization pattern detection section 16 includes a bandpass filter 16.
4, an envelope detector 16b, and a voltage comparator 16c.

The bandpass filter 16a is a narrowband filter that passes only the synchronization pattern CR, which is a non-modulated portion, of the input modulated wave frame (FIG. 2(^)), which will be described later. The envelope detector 16b is a device that inputs the synchronization pattern CR from the filter 16a and reproduces and outputs the envelope. The voltage comparator 16c converts the voltage of the envelope of the input synchronization pattern CR into a reference voltage VL (Fig. 2 (ζ
)), this device outputs an inverse modulation stop signal when it is 71 or more.

Next, the operation of the apparatus shown in FIG. 1 having the above configuration will be explained based on FIG. 2.

First, a PSK modulated wave in the frame form shown in FIG. 2 (^) is received.

Reference symbol CR is a synchronization pattern, BTR is a bit time pattern, and DATA is data.

Only the synchronization pattern CR is a non-modulated portion, and the bit time pattern BTR to data DATA are modulated portions.

The synchronization pattern CR exists at the beginning of the PSK modulated wave and is a pattern for establishing high-speed synchronization of the carrier wave recovery circuit, and the BTR is a pattern of the bit timing recovery circuit that indicates how long the signal is divided. This is a pattern for synchronization.

The bandpass filter 16a of the synchronization pattern detection section 16 is a narrowband filter, and allows only the unmodulated synchronization pattern CR to pass (FIG. 2(B)).

Next, the envelope detector 16b reproduces the envelope of the input pattern CR and outputs it, as shown in FIG. 2 (C1), and sends it to the next stage voltage comparator 16c.

The voltage comparator 16c compares the reference voltage VL with the input output of the envelope detector 16b.
If it is greater than y L, the inverse modulation stop signal is sent to the inverse modulator 11.
Send to.

As a result, the inverse modulator 1 stops its operation, assumes a reference phase based on the synchronization pattern CR of the input modulated wave, and reversely modulates the reference phase to reproduce the reference carrier wave. The demodulator 13 demodulates the input modulated wave based on this base tjs carrier wave.

〔Effect of the invention〕

According to the present invention, a narrow band filter is provided that passes only the unmodulated synchronization pattern located at the head of the received PSK modulated wave, and the inverse modulator is stopped by the output of the first filter. Since the reference carrier wave can be regenerated, it is not affected by noise unlike conventional methods and can be applied to communication systems of any frame format.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a carrier wave recovery circuit according to the present invention, FIG. 2 is an explanatory diagram of the operation of FIG. 1, FIG. 3 is an explanatory diagram of the PSK modulation method, and FIGS. It is an explanatory diagram. 11... Inverse modulator, 12... Bandpass filter, 13...
- Demodulator, 16... synchronization pattern detection section.

Claims (1)

[Claims] Receiving a PSK modulated wave in which each digital signal is modulated in correspondence with a sine wave whose phase is shifted, and assuming a reference phase based on a synchronization pattern located at the head of the received PSK modulated wave, the PSK modulation is performed as described above. In a carrier wave regeneration circuit in which a reference carrier wave for demodulating a wave is regenerated by an inverse modulator, a synchronization pattern detection section is provided on the input side of the inverse modulator, and the synchronization pattern detection section is not provided. A filter that allows only the above-mentioned synchronization pattern of modulation to pass; an envelope detector that inputs the synchronization pattern and reproduces and outputs its envelope; and an envelope detector that inputs the output of the detector and detects when the voltage exceeds the reference voltage. and a voltage comparator that outputs an inverse modulation stop signal to the inverse modulator, stops the inverse modulation operation by the inverse modulation stop signal, assumes the reference phase based on the synchronization pattern, and reproduces the reference carrier wave. A carrier wave regeneration circuit characterized by: