CN106597382A - Analyzing method for influence of simulated filter characteristics on microwave landing phase signal solution - Google Patents

Abstract

The invention provides an analyzing method for the influence of simulated filter characteristics on microwave landing phase signal solution comprising: establishing a microwave landing medium frequency modulation signal source; obtaining the transmission system transmission parameters of the simulated intermediate frequency filter hardware measurement or simulated design parameter S to obtain an output signal; and then conducting inverse Fourier transform to the output signal to obtain a time domain signal; then performing DPSK demodulation to the time domain signal; and comparing the demodulated data with original data to calculate the transmission error rate. According to the invention, a relationship between the microwave landing simulation filter characteristics and the system phase information solution is established directly through the digital processing mode in the frequency domain so as to provide a good model for the system design and evaluation as well as the design and evaluation of the filter, enabling it to possess a strong engineering application.

Description

Analog filtering characteristic resolves the analysis method for affecting to microwave landing phase signal

Technical field

The invention belongs to navigation field, is related to the resolving of microwave landing system airboarne receiver phase signal, particularly relates to And a kind of analog filter characteristic resolves the analysis method for affecting to microwave landing airboarne receiver phase place.

Background technology

Time reference scanning beam (TRSB) (TRSB) microwave landing system (MLS) is a kind of relatively advanced ground base navigation landing system, By the way of air-derived data, orientation, the elevation angle and range information are provided for landing aircraft.Wherein orientation, elevation information Include phase information and amplitude information in form, for completing the calculating to orientation and elevation angles.Contain in phase information The information such as important time reference information, function code, excessive loss or mistake can directly contribute the invalid of data calculation data, The correct transmission for guaranteeing phase information is the basis of resolve angles.Generation, data antenna of the phase information through ground transmitter Transmission, the propagation in space, the process of receiver and further resolve, numerous links can all cause phase information a certain degree of Distortion.For receiver, the distortion effects of the phase signal that should make great efforts to receive from self-view are preferably minimized, and then Good condition is provided for indexs such as the sensitivity index of receiver, calculation accuracies.It was verified that MLS airboarne receiver intermediate frequencies The characteristic of wave filter is larger to the impact that receiver resolves phase information.

Previous methods are all the detached resolvings for treating analog filter and system phase information, independent to carrying out both which Analysis, no contact for being given from system perspective therebetween, pertinent literature also analyze many digital filters to phase place solution The impact of calculation information, the impact that seldom explanation analog filter is resolved to phase information.

The content of the invention

In order to overcome the deficiencies in the prior art, the present invention to provide one kind assessment simulation in MLS airborne equipment system designs The method of the impact of wave filter, it is considered to impact of the difference of signal to noise ratio to error code, it is established that analog intermediate frequency filtering characteristic and phase place The model of Control of Bit Error Rate is resolved, analog filter resolves phase information resolving with system in solving microwave landing airboarne receiver Error code can not directly set up the problem of contact, and then instruct the design of analog filter and the design of system.

The technical solution adopted for the present invention to solve the technical problems is comprised the following steps：

(1) microwave landing modulated intermediate frequency signal source, modulated signal x (t)=cos (2 π f are set up_cT+ π a (t)), its In, t is the time, and a (t) is phase modulation baseband signal, f_cFor frequency of carrier signal；The digital sampled signal of x (t) is x (i)=cos (2πf_ct_i+π·a(t_i)), i=0,1,2 ..., t_iFor sampling time point, Fourier transform is carried out to x (i), then modulated signalN counts for Fourier transform, ω_N=e^(-2πi)/N, k=0,1,2 ...；

(2) obtain Transmission system configured transmission S21 of the actual measurement of analog intermediate frequency filter hardware or design of Simulation S parameter；

(3) X (k) is multiplied with S21, product Y (k)=X (k) * S21；

(4) ask Y (k) complex conjugate be Y (k) ', output signal Z (k)=Y (k)+Y (k) '；

(5) inverse fourier transform, time-domain signal are carried out to Z (k)

(6) DPSK demodulation is carried out to x (j)；

(7) data after demodulating are contrasted with initial data a (t), calculate transmission error rates.

The invention has the beneficial effects as follows：By way of unified digital processing in a frequency domain, microwave landing is directly established Relation between analog filtering characteristic and the resolving of system phase information, is that system design and assessment, wave filter design are carried with evaluation A good model is supplied, with stronger engineer applied.

Description of the drawings

Fig. 1 is two groups of filter characteristic schematic diagrams；

Fig. 2 is DPSK demodulation bit error rate schematic diagrams under three kinds of different situations.

Specific embodiment

The present invention is further described with reference to the accompanying drawings and examples, and the present invention includes but are not limited to following enforcements Example.

The present invention is comprised the following steps：

(1) microwave landing modulated intermediate frequency signal source is set up, is input into for the excitation to system algorithm model, using standard Phase-modulated signal describes method, and method is as follows：

Set up brewed letter x (t)=cos (2 π f_cT+ π a (t)), wherein, t is the time, and unit is the second, and a (t) is phase modulation Baseband signal, f_cFor frequency of carrier signal, the digital sampled signal of x (t) is x (i), i=0,1,2 ..., according to certain sampling speed Rate, the modulated signal after sampling are x (i)=cos (2 π f_ct_i+π·a(t_i)), t_iFor sampling time point, Fourier is carried out to x (i) Leaf transformation, then modulated signal be transformed to：N counts for Fourier transform, ω_N=e^(-2πi)/N, k=0, 1,2,…；

(2) obtain by vector network analyzer measure analog intermediate-frequency filter parameter or by ADS design of Simulation softwares Delivery intends intermediate-frequency filter design parameter characteristic, show that wave filter magnitude-phase characteristics S21, S21 are Transmission system configured transmission；

(3) what above-mentioned steps were obtained is the data of one group of frequency domain, and X (k) is multiplied with S21, and product Y (k) is：Y (k)=X (k)*S21；

(4) complex conjugate for seeking Y (k) is Y (k) ', and the system of signal is output as combination Z (k) of Y (k) and Y (k) ', Z (k)= Y(k)+Y(k)‘；

(5) inverse fourier transform, time-domain signal are carried out to Z (k)

(6) DPSK demodulation is carried out to x (j)；

(7) data after demodulating are contrasted with initial data a (t), calculate transmission error rates.

Have selected one group of analog simulation design filter parameter and one group of hardware simulation intermediate frequency for having designed herein respectively Filter parameter carries out comparative illustration.As shown in figure 1, left column is hardware filter, the right side is classified as emulation for the characteristic of two kinds of wave filter Design simulation wave filter.The basic design parameters of two groups of wave filter are：

Filter centre frequency：31.2MHz；

Wave filter three dB bandwidth：≥±70kHz；

Wave filter 60dB bandwidth：≤±150kHz.

Show that by figure the Character Comparison of two filter is as shown in table 1.

1 two filter Character Comparison of table

Parameter	Wave filter in kind	Emulated filter
			Mid frequency MHz	31.2	31.2
Bandwidth kHz	150	140
			60dB suppressing bandwidth kHz	350	320
Passband fluctuation dB	15	2
			With interior Group Delay Ripple us	40.0	8.0

Two groups of filtering are applied in brewed intermediate-freuqncy signal according to above-mentioned steps, in order to analysis filter is in different noises Situation than under, modulated signal have been superimposed the white noise of certain signal to noise ratio, it is assumed that demodulation does not introduce any error, by meter Calculate, output bit error performance of the different wave filter under different signal to noise ratios is as shown in Figure 2.

Thus, the present invention establishes analog filter and resolves the relation of error code with system.

Claims (1)

1. a kind of analog filtering characteristic resolves the analysis method for affecting to microwave landing phase signal, it is characterised in that including following Step：

(1) microwave landing modulated intermediate frequency signal source, modulated signal x (t)=cos (2 π f are set up_cT+ π a (t)), wherein, t is Time, a (t) are phase modulation baseband signal, f_cFor frequency of carrier signal；The digital sampled signal of x (t) is x (i)=cos (2 π f_ct_i+ π·a(t_i)), i=0,1,2 ..., t_iFor sampling time point, Fourier transform is carried out to x (i), then modulated signalN counts for Fourier transform, ω_N=e^(-2πi)/N, k=0,1,2 ...；

(2) obtain Transmission system configured transmission S21 of the actual measurement of analog intermediate frequency filter hardware or design of Simulation S parameter；

(3) X (k) is multiplied with S21, product Y (k)=X (k) * S21；

(4) ask Y (k) complex conjugate be Y (k) ', output signal Z (k)=Y (k)+Y (k) '；

(5) inverse fourier transform, time-domain signal are carried out to Z (k)

(6) DPSK demodulation is carried out to x (j)；

(7) data after demodulating are contrasted with initial data a (t), calculate transmission error rates.