CN101060379B - Carrier frequency estimating method - Google Patents

Abstract

The blind estimation method for DS/SS signal parameter comprises: using the delay time as the minimal sampling time (not equal to zero) for delaying the input BPSK-modulated wireless signal, multiplying the delayed signal with original signal, calculating power spectrum for the multiplied signal, and thereby realizes the blind estimation. This invention reduces signal noise efficiently, simplifies system structure, and improves calculation speed.

Description

Carrier frequency estimating method

(1) technical field

The invention belongs to electronic countermeasures and field of information processing, be specifically related to the carrier frequency blind estimating method in a kind of BPSK of estimation modulation communication signal and utilize this method to develop the blind estimation unit of a kind of realization carrier frequency.

(2) background technology

Wireless communication technology is widely used in the communication system, in order to realize radio control, needs to estimate the carrier frequency in the other side radio station.At present, the wireless communication signals carrier frequency blind estimating method and the device of many realization BPSK modulation arranged, realize carrier frequency as adopting quadratic method, but the signal to noise ratio that this method realizes can not be lower than-15dB; Also have simultaneously many scholars to adopt the method for High Order Moment to realize estimating carrier frequencies, but this method exist arithmetic speed to wait shortcoming slowly.

(3) summary of the invention

The object of the present invention is to provide a kind of new carrier frequency estimating method and the device that can realize the quick low signal-to-noise ratio estimation of the wireless communication signals carrier frequency of BPSK modulation.

The technical scheme of carrier frequency estimating method of the present invention is: the wireless communication signals of input is postponed to handle; Signal and original signal after handling are multiplied each other; Multiplying signal is carried out power spectrum computation, through the judgement peak value, calculate the outgoing carrier frequency at last.

Carrier frequency estimating method of the present invention also has some technical characterictics like this:

1, described delay time of delay of handling is for can realize non-vanishing and be far smaller than 2 π/ω _oShort delaing time;

2, described peak value is the peak-peak on the spectrogram, and carrier frequency 2 frequencys multiplication are the peak-peak on the corresponding spectrogram at the point on the spectrogram.

The scheme of product of the present invention is: it comprises input unit, delay cell, multiplier, power spectrum computation unit, decision unit and output unit; The input of input unit difference connection delay unit and the input of multiplier; The output of delay cell connects another input of multiplier; The output of multiplier connects the input of power spectrum computation unit, and the output of power spectrum computation unit connects the input of decision unit, and the output of decision unit connects output unit.

Product of the present invention also has some technical characterictics like this:

1, it also comprises pretreatment unit, and input unit connects pretreatment unit, the input of pretreatment unit difference connection delay unit and the input of multiplier;

2, described pretreatment unit is low-converter or amplifier;

3, described power spectrum computation unit is a frequency spectrograph.

The wireless communication signals that The present invention be directed to the BPSK modulation carries out the blind estimation of carrier frequency; Technical solution is: wireless communication signals multiplies each other with original signal after through the delay that is minimum sample unit a time of delay; Multiplying signal is carried out power spectrum computation, realize blind estimation carrier frequency.Input unit of the present invention is reception antenna, and delay multiplication can be realized through analogy method, also can realize through digital method; Can be minimum sample unit time of delay, also can be greater than sample unit, in the digital sample reprocessing; Should be a minimum sampling unit time of delay; And to the method for simulation when carrying out delay multiplication, should be the short delaing time that can realize time of delay, but can't be zero.Delay cell, multiplier, power spectrum computation unit and decision unit can directly adopt microprocessor to realize; Microprocessor can be programmable logic device FPGA, DSP, ARM, computer etc.; Should add the AD converting unit when adopting microprocessor processes, delay multiplication can also can be to realize in AD conversion back before the AD conversion simultaneously; Power spectrum computation can be to realize through frequency spectrograph; Also can be to obtain through Digital Signal Processing, as obtaining through computings such as FFT, implementation procedure be simple, fast.

In conjunction with Fig. 1, Fig. 1 is the principle schematic of carrier frequency blind estimating method of the present invention.The wireless communication signals formula of BPSK modulation is as follows:

$s\left(t\right)=\sqrt{2}\mathrm{Ac}\left(t\right)\cos ({\mathrm{\ω}}_{o}t+\mathrm{\φ})$

Wherein:

Receive signal amplitude, c (t): information code, in the BPSK modulation, its bit width is T _c, be worth digital quantity for+1 or-1; ω _o: carrier angular frequencies; φ: receive the signal initial phase.

Through being not equal to time of delay zero and being far smaller than 2 π/ω _oDelay cell 11 back and original signal through multiplier 12 mutually after, it is exported formula and is:

$s_{\mathrm{\τ}}\left(t\right)=A^2\{\underset{n}{\mathrm{\Σ}}g\left[\frac{T_c}{T_c-\mathrm{\τ}}(t-{\mathrm{nT}}_c-\mathrm{\τ})\right]+\underset{n}{\mathrm{\Σ}}{c}_n{c}_{n-1}g\left[\frac{T_c}{\mathrm{\τ}}(t-n{T}_c-\mathrm{\τ})\right]\}$

Wherein: g (t) is a square wave function; c _nBe the another kind of expression way of c (t), c _nc _N-1For the front and back information code multiplies each other.

Following formula is carried out power spectrum computation through power spectrum computation unit 13, ignore other component, it is output as:

Wherein: $K=\frac{T_c-\mathrm{\τ}}{T_c};$ δ (ω): impulse function.Judge peak value through decision unit 14, estimate carrier frequency.

Can find out that the wireless communication signals of BPSK modulation is non-vanishing and much smaller than 2 π/ω through time of delay _oDelay multiplication after, it is carried out power spectrum computation, can realize blind estimation, and carrier frequency is irrelevant in the position of power spectrum and time of delay to carrier frequency.

The present invention has following characteristics and good result:

The present invention introduces the delay multiplication device, behind delay multiplication, can reduce the influence of signal noise effectively, and this is one of innovative point of existing carrier frequency estimating method of difference and device.

The present invention through behind the delay multiplication, through power spectrum computation, realizes the estimation of carrier frequency with signal, and is simple in structure, fast operation, this be existing carrier frequency estimating method of difference and device innovative point two.

After adopting foregoing invention, carrier frequency blind estimating method and device have following advantage:

1) can realize the Fast estimation of carrier frequency under than the low signal-to-noise ratio condition;

2) carrier frequency of estimating and time of delay, it doesn't matter;

3) simple in structure.

(4) description of drawings

Fig. 1 is the principle schematic of carrier frequency blind estimating method of the present invention;

Fig. 2 is the implement device figure of the blind estimation of embodiment 1 carrier frequency;

Fig. 3 is the implement device figure of the blind estimation of embodiment 2 carrier frequencies;

Fig. 4 is the implement device figure of the blind estimation of embodiment 3 carrier frequencies.

(5) embodiment

Below in conjunction with accompanying drawing the present invention is specifically set forth:

Embodiment 1:

In conjunction with Fig. 2; The wireless communication signals of the BPSK modulation that antenna 21 receives is through behind the pretreatment unit 22 (down-conversion or amplifier), and signal is input to digital signal in the microprocessor 24 through A/D converting unit 23; Microprocessor can be FPGA, DSP, ARM, computer etc.; After microprocessor is the delay of a sample unit time through time of delay, after multiplying each other through multiplier with supplied with digital signal, through power spectrum computation; And adjudicate (as: point of corresponding carrier frequency 2 frequencys multiplication of the peak-peak on the spectrogram on spectrogram), realize blind estimation to carrier frequency.

Embodiment 2:

In conjunction with Fig. 3, the wireless communication signals of the BPSK modulation that antenna 21 receives is not equal to zero and very little (as: less than 2 π/ω through behind the pretreatment unit 22 (down-conversion or amplifier) through delay cell 11 time of delays _o1/8) delay after, after multiplying each other through multiplier 12 with original signal,, realize estimation to carrier frequency through frequency spectrum arithmetic element 25 (frequency spectrograph etc.).

Embodiment 3:

In conjunction with Fig. 4, the wireless communication signals of the BPSK modulation that antenna 21 receives is through behind the pretreatment unit 22 (down-conversion or amplifier), through being not equal to zero and very little (as: less than 2 π/ω time of delay _o1/8) delay cell 11 after, after multiplying each other through multiplier 12 with original signal,, digital signal is input in the microprocessor 24 through A/D converting unit 23, microprocessor carries out the frequency spectrum computing, realizes the estimation to carrier frequency.

Claims (1)

1. carrier frequency blind estimating method; It comprises following steps: the wireless communication signals of input is postponed to handle, the signal after handling and the wireless communication signals of input are multiplied each other, multiplying signal is carried out power spectrum computation; Through the judgement peak value, calculate the outgoing carrier frequency at last; It is characterized in that: be non-vanishing and be far smaller than 2 π/ω the time of delay that described delay is handled _oShort delaing time; Described peak value is the peak-peak on the spectrogram, and carrier frequency 2 frequencys multiplication are the peak-peak on the corresponding spectrogram at the point on the spectrogram.