CN108111453B - An open-loop carrier extraction method for binary differential phase shift keying signal - Google Patents

Abstract

The invention discloses a binary differential phase shift keying signal open loop carrier extraction method, which is realized by a sampling module, a frequency multiplication module, an FFT conversion module and a carrier extraction module. The sampling module samples the binary differential phase shift keying signal to form a sampling sequence; the frequency doubling module carries out frequency doubling processing on the sampling sequence to form frequency doubling time domain data of 2; the FFT conversion module carries out FFT conversion on the 2 frequency multiplication time domain data to obtain frequency domain data; and the carrier extraction module extracts the carrier frequency according to the frequency domain data. The invention solves the problem that the traditional carrier extraction method can not carry out carrier extraction on the phase shift keying signal.

Description

An open-loop carrier extraction method for binary differential phase shift keying signal

technical field

The invention relates to a carrier extraction method, in particular to a binary differential phase shift keying signal open-loop carrier extraction method.

Background technique

When the missile-borne spread spectrum receiver is working, it is necessary to extract the carrier of the received binary differential phase shift keying (2DPSK) signal. The traditional carrier extraction method is often realized by a closed-loop structure phase-locked loop. The phase negative feedback control system consists of a phase detector, a loop filter and a voltage controlled oscillator. The phase detector is a phase comparison device used to detect the phase difference between the phase of the input signal and the phase of the feedback signal; the loop The filter is a linear circuit, which can not only play the role of a low-pass filter, but also can play the role of loop parameter adjustment; a voltage-controlled oscillator is a voltage-frequency conversion device, which acts as a controlled oscillator in the loop. Its oscillation frequency varies linearly with the input control voltage. The closed-loop structure of the phase-locked loop is not suitable for the carrier processing of the spectrum symmetrical signal, so the traditional carrier extraction method cannot be used to extract the carrier of the binary differential phase shift keying signal.

FFT is Fast Fourier Transform, which can convert time domain data to frequency domain data.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide an open-loop carrier extraction method for binary differential phase shift keying signals, which solves the problem that the traditional carrier extraction method cannot perform carrier extraction for phase shift keying signals.

The specific steps of a binary differential phase shift keying signal open-loop carrier extraction method are:

The first step is to build an open-loop carrier extraction platform

The open-loop carrier extraction platform includes: sampling module, frequency multiplication module, FFT transformation module and carrier extraction module. The function of the sampling module is: to sample the binary differential phase shift keying signal to form a sampling sequence; the function of the frequency multiplication module is: to perform 2 frequency multiplication processing on the collected data to form 2 frequency multiplication time domain data; FFT transformation module The function of the module is: perform FFT transformation on the double-frequency time domain data to obtain the frequency domain data; the function of the carrier extraction module is: extract the carrier frequency according to the frequency domain data. Run the above modules in an FPGA chip.

The second step sampling module samples the binary differential phase shift keying signal to form a sampling sequence

The sampling module samples the binary differential phase shift keying signal x(t) to form a sampling sequence x(n), the sampling frequency is f _s , the sampling time interval is T _s , T _s =1/f _s ; t is a time parameter, n is the time domain point index value, n=0,1,...,N-1, and N is the length of the sampling sequence x(n).

The third step frequency multiplication module performs 2 frequency multiplication processing on the sampling sequence

The frequency multiplication module performs 2 frequency multiplication processing on the sampling sequence x(n): x'(n)=[x(n)] ² to obtain 2 frequency multiplication time domain data x'(n).

The fourth step FFT transformation module performs FFT transformation on the double-frequency time domain data

The FFT transformation module performs FFT transformation on the double-frequency time domain data x'(n):

e^-j2πkn/N为复数表示形式，表示cos(-2πkn/N)+jsin(-2πkn/N)。Transform the double-frequency time domain data x'(n) into frequency domain data X(k), where k is the frequency domain sampling point index, k=0,1,...,N-1; j represents

e ^-j2πkn/N is a complex representation, which means cos(-2πkn/N)+jsin(-2πkn/N).

Step 5: The carrier extraction module extracts the carrier frequency according to the frequency domain data

The carrier extraction module extracts the carrier frequency according to the frequency domain data X(k):

The carrier frequency f is obtained, where |·| represents the complex modulo operation.

So far, the open-loop carrier extraction of the binary differential phase shift keying signal has been realized.

The method solves the problem that the traditional carrier extraction method cannot perform carrier extraction on the phase-shift keying signal. After various experiments and tests, it is considered that this method is effective and feasible. At present, this method has been successfully applied to the ground-to-air series missile spread spectrum receiver, and in the test, the carrier frequency extracted by the missile-borne spread spectrum receiver from the binary differential phase shift keying signal open-loop is accurate, which meets the requirements of the system.

Detailed ways

The specific steps of a binary differential phase shift keying signal open-loop carrier extraction method are:

The first step is to build an open-loop carrier extraction platform

The open-loop carrier extraction platform includes: sampling module, frequency multiplication module, FFT transformation module and carrier extraction module. The function of the sampling module is: to sample the binary differential phase shift keying signal to form a sampling sequence; the function of the frequency multiplication module is: perform 2 frequency multiplication processing on the collected data to form 2 frequency multiplication time domain data; FFT transformation module The function of the module is: perform FFT transformation on the double-frequency time domain data to obtain the frequency domain data; the function of the carrier extraction module is: extract the carrier frequency according to the frequency domain data. Run the above modules in an FPGA chip.

The second step sampling module samples the binary differential phase shift keying signal to form a sampling sequence

The sampling module samples the binary differential phase shift keying signal x(t) to form a sampling sequence x(n), the sampling frequency is f _s , the sampling time interval is T _s , T _s =1/f _s ; t is a time parameter, n is the time domain point index value, n=0,1,...,N-1, and N is the length of the sampling sequence x(n).

The third step frequency multiplication module performs 2 frequency multiplication processing on the sampling sequence

The frequency multiplication module performs 2 frequency multiplication processing on the sampling sequence x(n): x'(n)=[x(n)] ² to obtain 2 frequency multiplication time domain data x'(n).

The fourth step FFT transformation module performs FFT transformation on the double-frequency time domain data

The FFT transformation module performs FFT transformation on the double-frequency time domain data x'(n):

e^-j2πkn/N为复数表示形式，表示cos(-2πkn/N)+jsin(-2πkn/N)。Transform the double-frequency time domain data x'(n) into frequency domain data X(k), where k is the frequency domain sampling point index, k=0,1,...,N-1; j represents

e ^-j2πkn/N is a complex representation, which means cos(-2πkn/N)+jsin(-2πkn/N).

Step 5: The carrier extraction module extracts the carrier frequency according to the frequency domain data

The carrier extraction module extracts the carrier frequency according to the frequency domain data X(k):

The carrier frequency f is obtained, where |·| represents the complex modulo operation.

So far, the open-loop carrier extraction of the binary differential phase shift keying signal has been realized.

Claims (1)

1. a binary differential phase shift keying signal open-loop carrier extraction method, is characterized in that concrete steps are: The first step is to build an open-loop carrier extraction platform The open-loop carrier extraction platform includes: a sampling module, a frequency multiplication module, an FFT transformation module and a carrier extraction module; the functions of the sampling module are: sampling the binary differential phase shift keying signal to form a sampling sequence; the function of the frequency multiplication module In order to: perform 2-fold frequency processing on the collected data to form 2-fold frequency time-domain data; the function of the FFT transform module is: perform FFT transformation on the 2-fold frequency time-domain data to obtain frequency-domain data; the function of the carrier extraction module is: Extract the carrier frequency according to the frequency domain data; run the above modules in the FPGA chip; Step 2: The sampling module samples the binary differential phase shift keying signal to form a sampling sequence The sampling module samples the binary differential phase shift keying signal x(t) to form a sampling sequence x(n), the sampling frequency is f _s , the sampling time interval is T _s , T _s =1/f _s ; t is a time parameter, n is the time domain point index value, n=0,1,...,N-1, N is the length of the sampling sequence x(n); Step 3: The frequency multiplication module performs 2 frequency multiplication processing on the sampling sequence The frequency multiplication module performs 2 frequency multiplication processing on the sampling sequence x(n): x'(n)=[x(n)] ² to obtain 2 frequency multiplication time domain data x'(n); The fourth step FFT transformation module performs FFT transformation on the double-frequency time domain data The FFT transformation module performs FFT transformation on the double-frequency time domain data x'(n):

Transform the double-frequency time domain data x'(n) into frequency domain data X(k), where k is the frequency domain sampling point index, k=0,1,...,N-1; j represents

e ^-j2πkn/N is a complex number representation, which means cos(-2πkn/N)+jsin(-2πkn/N); Step 5: The carrier extraction module extracts the carrier frequency according to the frequency domain data The carrier extraction module extracts the carrier frequency according to the frequency domain data X(k):

Obtain the carrier frequency f, where |·| represents the complex modulo operation; So far, the open-loop carrier extraction of the binary differential phase shift keying signal has been realized.