JPS5826710B2 - Carrier wave regeneration method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a carrier wave regeneration method for regenerating a reference carrier wave from an amplitude phase modulation signal.

Conventional carrier wave regeneration methods generally involve multiplying the received signal by the output signal of a voltage controlled oscillator and comparing the phases.

For this reason, it could not be used for carrier wave synchronization pull-in for phase modulated signals in which the carrier wave phase changes.

In order to eliminate the drawbacks of the conventional example, the present invention utilizes the high frequency component of the carrier wave obtained from the zero crossing point of the amplitude phase modulation signal as a line spectrum, and makes it possible to pull in synchronization also for the amplitude phase modulation signal. This provides a carrier wave regeneration method.

Hereinafter, embodiments will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, where 1 is an input terminal, 2 is a Schmitt circuit for zero crossing detection, 3 is a monomulti, 4 is a phase comparator, 5 is a low-pass filter, and 6 is a voltage A controlled oscillator, 7 a branching unit, and 8 an output terminal.

The operation of this embodiment will be explained with reference to FIG.

First, the signal input from the input terminal 1 is converted into a square wave as shown in FIG. 2B by the zero-crossing detection Schmitt circuit 2, and then converted into a square wave as shown in FIG. 2C by the monomulti 3. It is converted into a pulse having a constant length from the rising point.

The length of this pulse is desirably selected to be 1/2N (N is the number of modulation phases) of one period of the carrier wave.

This pulse is input to the phase comparator 4 and multiplied by the output of the voltage controlled oscillator 6.

As a result, the phase comparison output shown in FIG. 2E is obtained.

The output of this phase comparator 4 passes through a low pass filter 5 and controls a voltage controlled oscillator 6.

The output of this voltage controlled oscillator 6 is shown in the second diagram.

The output waveform of this second diagram is a depolar signal with a frequency N times that of the carrier wave, but this is because if the output of the second diagram is unipolar, the amplitude phase modulation has a zero oscillation state. This is because the output of the phase comparator changes depending on the amplitude modulation.

The output of the voltage controlled oscillator 6 is input to the phase comparator 4, and the frequency is divided by 1/N by the frequency divider 7 to produce the signal shown in FIG. 2F, which is output from the output terminal 8. .

In this embodiment, the oscillation frequency of the voltage controlled oscillator is controlled by the average value of the output of the phase comparator 4, and a stable state is achieved when the phases are synchronized.

FIG. 3 is a diagram showing this phase synchronization condition, in which the horizontal axis represents the phase of the amplitude phase signal over a range of 0 to 2π, and the vertical axis represents the average value of the output of the phase comparator.

That is, the phase has a stable state at intervals of 2π/N, and synchronous pull-in is established for the amplitude-phase modulated signal.

FIG. 4 shows the phase comparator 4 and low-pass filter 5 of the present invention.
A specific example is shown in which 41 is an AND circuit, 42 is an operational amplifier, 43 is an addition resistor, and 52 is an operational amplifier.

As explained above, according to the present invention, the carrier wave of an amplitude phase modulated signal can be recovered, so there is an advantage that it can be effectively used in a carrier wave recovery circuit for synchronous detection, etc.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is an explanatory diagram of signal conversion in FIG. 1, and FIG. 3 is a diagram showing the phase pull-in characteristic of the method of the present invention. , FIG. 4 is a diagram showing a specific circuit of a part of the present invention. 1... Input terminal, 2... Schmitt circuit, 3... Mono multi, 4... Phase comparator circuit, 5... Low range Filter, 6...
Voltage controlled oscillator, 7... Frequency divider, 8...
・Output terminal, 41...AND circuit, 42, 52
......Operation amplifier, 43...Resistor.

Claims (1)

[Claims] 1 In a method of regenerating a reference carrier wave for detection from an amplitude phase modulation signal, when a pulse having a constant pulse width is generated from the zero crossing point of the amplitude modulation signal and the number of modulation phases is N, the frequency is N times the carrier wave frequency. The square wave output of the voltage controlled oscillator, which oscillates at a frequency of A carrier wave regeneration method characterized by synchronization pull-in at the frequency of .