CN202551028U - Anti-jam receiver in differential frequency hopping communication system - Google Patents

Abstract

The utility model relates to an anti-jam receiver in a differential frequency hopping communication system, and a relevance feedback pre-adding window is additionally arranged. According to the utility model, one path of output of a full frequency pectination adding window module of the relevance feedback pre-adding window connected with an FFT (fast fourier transformation) module is connected with a pre-adding window module and a first scanning maximum value module; one path of the first scanning maximum value module is directly connected with a selector module, and the other path of the first scanning maximum value module is connected with the selector module through a threshold comparison module band a trigger module; the other path of output of the full frequency pectination adding window module is connected with a second scanning maximum value module and the selector module; and the output of the selector module is connected to a carrier frequency recognition module and a Viterbi decoding module, and the feedback of the carrier frequency recognition module is connected to the frequency channel pre-adding window module. The receiver can carry out frequency domain pre-adding window filtering on f frequency points which can appear in the next hopping action in differential frequency hopping communication, and the detrimental effect of interference is lightened; and a threshold is adopted for comparing, an error is less than the threshold, the all band scanning of the frequency channel pre-adding window module is adopted for obtaining the maximum energy value, and the error spread is corrected.

Description

Antijam receiver in the Differential Frequency Hopping Systems

(1) technical field

The utility model relates to the Anti-Jamming Technique of digital communicating field, is specially a kind of antijam receiver of Differential Frequency Hopping Systems.

(2) background technology

Be different from the traditional conventional frequency hopping; Differential jumping frequency (DFH; Differential Frequency Hopping) technology has been represented modern frequency hopping communications latest development; Even on the shortwave frequency range, also can realize high-speed frequency-hopping (frequency hopping rate can reach 5000Hop/s) and high speed data transfer (transmission rate can reach 19.2kbit/s), and greatly having improved the ability that anti-tracking is disturbed and investigated, the validity of transfer of data greatly improves.

In the DFH communication system, coding, modulation and frequency hopping adopt the integrated implementation of Trellis-coded modulation (TCM, Trellis Coded Modulation).Transmitting terminal, information data are that frequency hop sequences, control digital controlled oscillator (DDS, Direct Digital Synthesizer) produce corresponding frequency-hopping carrier through the G Function Mapping through after the chnnel coding again; At receiving terminal; The A/D sampled signal is carried out producing after the digital quadrature down-conversion signal of two-way quadrature; Subsequently it is carried out FFT (FFT; Fast Fourier Transformation), transformation results obtains effective Frequency Hopping Signal through the judgement of frequency hopping detecting unit, demodulates the data message of transmission again according to the good rule of predefined through the frequency sequence decoding module.

Because DFH communication system adopts broadband reception; Has bigger frequency hopping bandwidth; Traditional receiver is difficult to avoid the influence of disturbing factors such as alien frequencies interference and multipath interference to the judgement of reception machine testing device, thereby produces the communication error code for receiving by symbol detection in radio communication.Especially in military radio communication,, the error rate that makes system is significantly increased if third party's jammer adopts identical frequency translation matrix emission interference signal, even paralysis fully.

(3) utility model content

The purpose of the utility model is the antijam receiver that proposes in a kind of Differential Frequency Hopping Systems; In former difference frequency-hopping receiver, increase the preparatory windowing module of relevant feedback; The frequency that possibly occur next jumping according to the correlation of G function carries out preposition frequency domain and adds window filtering in advance; Only can carry out the selectivity reception by employable frequency, alleviate multifrequency and disturb adverse effect Differential Frequency Hopping Systems to differential jumping frequency.

Antijam receiver in the Differential Frequency Hopping Systems of the utility model design has increased the preparatory windowing of relevant feedback existing by on the Differential Frequency Hopping Systems receiver basis of symbol detection; The utility model receiver comprises that the reception antenna, the radiofrequency signal that connect successively receive (RF) module, analog-to-digital conversion (ADC) module, down conversion module and FFT (FFT Fast Fourier Transformation) module, also have the Viterbi decoding module.The output of down conversion module also inserts early window synchronization module late, and early the output of window synchronization module inserts the FFT module late.

The receiver of the utility model has increased the preparatory windowing of relevant feedback, and the preparatory windowing of relevant feedback is connected between FFT module and the Viterbi decoding module.The preparatory windowing of relevant feedback mainly comprises full range pectination windowing module, the preparatory windowing module of frequency range, the first scanning maximum module, second scanning maximum module, thresholding comparison module, igniter module, selector module and the carrier frequency identification module.The output of FFT module inserts full range pectination windowing module; Full range pectination windowing module has 2 tunnel outputs; Wherein one the road insert the preparatory windowing module of frequency range; The output of the preparatory windowing module of frequency range inserts the first scanning maximum module, and the output one tunnel of the first scanning maximum module directly inserts selector module, another road is inserted igniter module through the thresholding comparison module and got into selector module again; Another road output of full range pectination windowing module inserts the second scanning maximum module, and the second scanning maximum module directly inserts selector module; The output access carrier identification module of selector module, the output of carrier frequency identification module inserts the Viterbi decoding module, obtains the reception signal that reduces after the decoding, and carrier frequency identification module feedback inserts the preparatory windowing module of frequency range.

Under AWGN (additive white Gaussian noise) channel, adopt existing general Differential Frequency Hopping Systems by the symbol detection receiver, suppose that the work at present channel frequency is ω ₀, then corresponding receiver receives signal r ₀Be this distributed random variable of Lay, probability density function is:

$p\left(r_0\right)=\frac{1}{4E_s{N}_0}\exp (-\frac{r_0+E_s^2}{4E_s{N}_0})I_0\left(\frac{\sqrt{r_0}}{N_0}\right)$

r ₁, L r _N-1Be corresponding ω ₁, L ω _N-1The reception signal of frequency is separate and stochastic variable identical rayleigh distributed, and probability density function is:

$p\left(r_n\right)=\frac{1}{4E_s{N}_0}\exp (-\frac{r_n}{4E_s{N}_0})$

Then error sign ratio is:

$p_e=\underset{n=1}{\overset{N-1}{\mathrm{\Σ}}}{(-1)}^{n+1}{C}_{N-1}^n\frac{1}{n+1}{e}^{-\mathrm{\γn}/(n+1)}$

When the antijam receiver of the Differential Frequency Hopping Systems that adopts the utility model, error sign ratio:

$p_{s1}=\frac{2(f-1)}{f}{p}_e=\frac{2(f-1)}{f}\underset{n=1}{\overset{N-1}{\mathrm{\Σ}}}{(-1)}^{n+1}{C}_{N-1}^n\frac{1}{n+1}{e}^{-\mathrm{\γn}/(n+1)}$

$p_{s2}=\frac{2(f-1)}{f}{p}_e=\frac{2(f-1)}{f}\underset{n=1}{\overset{f-1}{\mathrm{\Σ}}}{(-1)}^{n+1}{C}_{f-1}^n\frac{1}{n+1}{e}^{-\mathrm{\γn}/(n+1)}$

p _u＝(1-p _s2)p _s2+p _s2p _s1

p _d＝(1-p _s1)p _s2+p _s1p _s1

P wherein _uBe the error sign ratio upper limit; p _dBe the error sign ratio lower limit.

During the operation of the antijam receiver in the utility model Differential Frequency Hopping Systems; Reception antenna and Receiver Module receive time-domain difference frequency hopping radiofrequency signal; Be digital signal through analog-to-digital conversion earlier; Become intermediate-freuqncy signal through down conversion module again, gained time-domain difference Frequency Hopping Signal is a frequency-region signal through FFT module (FFT) module converts, sends into full range pectination windowing module to frequency domain information then;

Full range pectination windowing module is carried out pectination to known all possible frequency and is added window filtering, is divided into two paths of signals then, sends into second scanning maximum module and the preparatory windowing module of frequency range respectively;

Carry out comb filtering to received signal, the frequency domain pectination windowing of carrying out after just handling through FFT to received signal significantly reduces resource consumption.

Second scans the maximum module to filtered signal scanning energy maximum, and exports the corresponding frequency label of maximum energy value and send into selector module;

The preparatory windowing module of frequency range is through the frequency information of carrier frequency identification module feedback; The individual frequency of f (fan-out coefficient) that possibly occur to next jumping carries out frequency range and adds window filtering; Send into the first scanning maximum module then; The energy maximum of signal after the preparatory windowing module filtered of scanning band, and export the corresponding frequency label of maximum energy value and send into selector module, maximum energy value is sent into the thresholding comparison module; Correlation and fan-out coefficient f by the G function structure; The preparatory windowing module of frequency range promptly can be foreseen next according to the frequency information of carrier frequency identification module feedback and jump f possible frequency; The preparatory windowing module of this step Mid Frequency is only carried out frequency domain to this f frequency and is added window filtering; Be that this device only can carry out the selectivity reception by employable frequency to next jumping of differential jumping frequency, alleviated the influence that the adverse effect of disturbing, especially alien frequencies disturb to a great extent;

The thresholding comparison module carries out threshold judgement to the maximum energy value of the preparatory windowing module output of frequency range, and selector module is sent in decision value output;

If decision value is greater than zero, selector is exported the corresponding frequency label of full range pectination windowing module maximum energy value; If decision value is less than zero, selector is exported the corresponding frequency label of the preparatory windowing module of frequency range maximum energy value; When error code appears in the preparatory windowing of frequency range, possibly cause follow-up whole error code.Therefore this law adopts thresholding relatively, and when error code occurring, thresholding then adopts the maximum energy value of the full frequency band scanning gained of the preparatory windowing module of frequency range less than zero, can guarantee that error code is repaired immediately, the error code diffusion can not occur.

The frequency label of selector output is directly sent into the carrier frequency identification module, and the carrier frequency identification module converts the frequency label to the frequency sequence coding, sends into the Viterbi decoding module then, simultaneously control signal is fed back to the preparatory windowing module of frequency range; In this step; The carrier frequency identification module converts the frequency label to the frequency sequence coding, because the coding of G function has correlation, encoding according to the frequency sequence of current conversion is measurable next frequency sequence coding; Therefore feedback control signal is to the preparatory windowing module of frequency range; Through the adjustment window, only f the frequency that possibly occur carried out selective filter, disturb the adverse effect that produces thereby effectively reduce.

The Viterbi decoding module is deciphered according to the frequency sequence coding, restores corresponding receiving data information.

The advantage of the antijam receiver of the utility model Differential Frequency Hopping Systems is:

1, the correlation of utilization G function; F the frequency that only possibly occur next jumping in the differential jumping frequency communication carries out frequency domain and adds window filtering in advance; Promptly only can carry out the selectivity reception by employable frequency to differential jumping frequency; Alleviated the adverse effect that the adverse effect of disturbing, especially alien frequencies disturb to a great extent;

2, adopt frequency domain windowing filtering mode, directly utilize original fast Fourier transform module in differential jumping frequency (DFH) communication system, carry out signal processing, effectively reduced system complexity, reduced the consumption of hardware resource at frequency domain;

3, this receiver is equally applicable to the Differential Frequency Hopping Systems networking, when the networking user adopts the different frequency group to carry out internetwork communication, uses other users of this receiver between can suppressing effectively to net interference;

4, when the error code diffusion occurring, can correct error code immediately, guarantee to separate the correctness of jumping figure certificate, avoid the error code diffusion.

(4) description of drawings:

Fig. 1 is the example structure block diagram of the antijam receiver of this Differential Frequency Hopping Systems.

Fig. 2 is the correlation curve of receiver error sign ratio of sequential decoding under awgn channel of embodiment and traditional differential frequency-hopping communication system of the antijam receiver of this Differential Frequency Hopping Systems.

(5) embodiment

Antijam receiver embodiment in the Differential Frequency Hopping Systems is as shown in Figure 1, comprises the reception antenna, radiofrequency signal receiver module, analog-to-digital conversion module, down conversion module, FFT module, the preparatory windowing of relevant feedback and the Viterbi decoding module that connect successively.The output of down conversion module also inserts early window synchronization module late, and early the output of window synchronization module inserts the FFT module late.The preparatory windowing of relevant feedback mainly comprises full range pectination windowing module, the preparatory windowing module of frequency range, first, second scanning maximum module, thresholding comparison module, igniter module, selector module and carrier frequency identification module.The output of FFT module inserts full range pectination windowing module; Full range pectination windowing module has 2 tunnel outputs; Wherein one the road insert the preparatory windowing module of frequency range; The output of the preparatory windowing module of frequency range inserts the first scanning maximum module, and the output one tunnel of the first scanning maximum module directly inserts selector module, another road is inserted igniter module through the thresholding comparison module and got into selector module again; Another road output of full range pectination windowing module inserts the second scanning maximum module, and the second scanning maximum module directly inserts selector module; The output access carrier identification module of selector module, the output of carrier frequency identification module inserts the Viterbi decoding module, obtains the reception signal that reduces after the decoding, and carrier frequency identification module feedback inserts the preparatory windowing module of frequency range.

The embodiment of the antijam receiver of this Differential Frequency Hopping Systems utilizes the characteristics of difference correlation, on frequency domain, the differential jumping frequency frequency is carried out selectivity and adds the window filtering reception, effectively strengthens the alien frequencies antijamming capability.This example is as shown in Figure 2 with the correlation curve of receiver mismark probability of sequential decoding under awgn channel of the traditional differential frequency-hopping communication system that pursues symbol detection.Abscissa is signal to noise ratio Es/No among Fig. 2, and unit is dB; Ordinate is the mismark probability P of sequential decoding under awgn channel; The line is represented the mismark probability curve of the receiver of traditional differential frequency-hopping communication system;

line is represented the mismark probability upper limit curve that this is routine, and the ◇ line is represented the mismark probability lower limit curve that this is routine.The mismark probability that can be seen this method by Fig. 2 obviously descends, i.e. the influence of multifrequency interference alleviates greatly.

The foregoing description is merely concrete example of purpose, technical scheme and beneficial effect further explain to the utility model, and the utility model is not to be defined in this.All any modifications of within the scope of disclosure of the utility model, being made, be equal to replacement, improvement etc., all be included within the protection range of the utility model.

Claims (1)

1. the antijam receiver in the Differential Frequency Hopping Systems comprises the reception antenna, radiofrequency signal receiver module, analog-to-digital conversion module, down conversion module, the FFT module that connect successively, also has the Viterbi decoding module; The output of down conversion module also inserts early window synchronization module late, and early the output of window synchronization module inserts the FFT module late, it is characterized in that:

This receiver has increased the preparatory windowing of relevant feedback, and the preparatory windowing of relevant feedback is connected between FFT module and the Viterbi decoding module; The preparatory windowing of relevant feedback mainly comprises full range pectination windowing module, the preparatory windowing module of frequency range, scanning maximum module, thresholding comparison module, igniter module, selector module and carrier frequency identification module; The output of FFT module inserts full range pectination windowing module; Full range pectination windowing module has 2 tunnel outputs; Wherein one the road insert the preparatory windowing module of frequency range; The output of the preparatory windowing module of frequency range inserts the first scanning maximum module, and the output one tunnel of the first scanning maximum module directly inserts selector module, another road is inserted igniter module through the thresholding comparison module and got into selector module again; Another road output of full range pectination windowing module inserts the second scanning maximum module, and the second scanning maximum module directly inserts selector module; The output access carrier identification module of selector module, the output of carrier frequency identification module inserts the Viterbi decoding module, obtains the reception signal that reduces after the decoding, and carrier frequency identification module feedback inserts the preparatory windowing module of frequency range.

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