SU1072252A1 - Tracking filter of phase-modulated pseudo-random signal - Google Patents

Abstract

1. CONTINUOUS FILTER FAZOMA .NIPULIROVANNOGO dither signal comprising a block automatic frequency control (AFC) consisting of sequentially soedinen-, nyh.smesitel broadband Intermediate Frequency amplifier and poremnozhitel sequentially soedivennyh narrowband amplifier npoi- l interstitial frequency, a frequency discriminator, a low-pass filter / and a controlled oscillator, the output of which is connected to the input of the mixer, the delay tracking unit, status -. st. of the following in series:: delay discriminator, multiplier, the other input of which is connected -. chen to another, discriminatory output; , - ra frequency of the low-pass filter block, dryer, other input; which through linear transformation-. The coil is connected to the output of the low-pass filter of the AFC unit controlled by .-. generator and driver support. pseudo-random sequence. (PSP), the first output of which is connected to the second input of the multipliers: the bodies of the AFC block, which is different, so that, in order to improve the noise immunity, a control block is inserted into it, the first whose information input is connected to the multiplier output, the second and third information inputs with the corresponding outputs of the discriminator of the delay, the first control input with the first input of the control unit, the second and third control inputs are combined and connected dinene with a second output, control unit, and input with an input of a narrow-band intermediate frequency amplifier; an adjustable delay unit is introduced into the delay tracking unit, 8 inputs of which are connected to the second and third outputs, a control input to the second output, control inputs to the second output control unit, and go to the corresponding inputs of the delay discriminator. 2, The filter according to claim 1, 1, of which the control unit contains in series connected. R5 trigger, -element Neither a pulse counter, the direct output of which is connected via the OR element to the R input of the RS trigger, and in- I is the second output of the control unit, the first output of which is the inverse output of the meter of pulses, the input of the zero setting of the pulse counter is combined by i: with the second input of the OR element, and the input of the zero setting of the control unit, the second input of the element AND input signal of the reference frequency, and RS trigger, the input of the tracking mode enable signal.

Description

The invention relates to radio engineering and can be applied in radio systems for location, navigation and communication using phase-shifted pseudo-random radio signals, the phase of which is manipulated on a binary memory bandwidth. The following signal filter with a hollow carrier is known, the phase of which is manipulated according to the SRP law, containing an automatic frequency control unit and a delay tracking unit with a non-coherent delay discriminator, which are: a synchronization system with cross-links, However, the use of this filter is advisable if the synchronization error over the envelope (modulation signal) does not exceed the period of the signal carrier frequency, otherwise anomalous tracking errors are observed in the filter. The probability of the occurrence of anomalous errors in tracking the delay depends on the signal-to-noise ratio and on the ratio of the spectrum width of the phase-shifting pseudo-random radio signal to its central frequency and becomes unacceptable to large when the carrier frequency of the signal increases. Closest to that proposed by technical dryness is the following filter of a phase-manipulated pseudo-random signal containing a frequency control unit consisting of a series-connected mixer, wideband amplifier, intermediate frequency (IF), multiplier, narrowband IF, frequency discriminator, low pass filter (LPF) ) and a controlled generator, the output of which is connected to the mixer input, a delay tracking unit consisting of a delay discriminator connected in series, a multiplier, another the input of which is connected to another output of the frequency discriminator of the AFC block, LPF, adder, and another, the input of the kSertor is connected via the linear converter to the output of the LPF block of the AFC block, controlled oscillator and driver of the reference PSR, the first output of which is connected to the secondary input of the multiplier of the AFC block and the second the third outputs - to the corresponding. the relevant inputs of the discriminator delay C23. However, the known device has a low noise immunity. The Gaussian approximation in the problem of nonlinear synthesis leads only to asymptotically optimal structures for high a posteriori exactness. In practice, the assumption of high a posteriori accuracy is unacceptable in a transient mode, i.e. | 1process capture signal, or; when the signal / noise ratio is not high enough. Indeed, a priori errors in estimating the delay G,. received, for example, from a search and detection device, are substantially more a posteriori. Otherwise, the use of the following filter does not make sense. Due to the substantial difference a priori. (t 0} and a posteriori (t) error estimates of the delay, the equivalent signal-to-noise ratio in the bluetooth of the AFC is significantly worse in the transient mode (capture mode) than in the steady state. These energy losses, due to significant initial synchronization errors in support, sharply decrease . The accuracy of the capture, characterizing the noise immunity of the following filter in the transient mode (capture mode) ;, In addition, the need arising from the synthesis of the device to form a time-arbitrary signal from the signal to implement the optimal delay discriminator is simulated by a fixed finite difference of time shifts of the reference signals implemented in the dual-channel delay correlation discriminator. The time delay, ± ± d between the shifted copies of the reference signal determines the delay discriminator aperture and selects the outcome from a compromise between the conditions signal capture and noise immunity of established tracking processes. Therefore, the value of .tj does not satisfy the criterion of the minimum probability of capture in the transient after a signal is detected. The non-optimalness of the delay discriminator is the greater, the greater the ratio of the a priori error in estimating the delay, which determines the size, of the aperture of the delay discriminator to its steady-state a posteriori value. The purpose of the invention is to increase the noise immunity of the next filter. The goal is achieved by the fact that a phased-manipulated pseudo-random pseudo-random signal containing an automatic frequency control unit (AFC) consisting of a series-connected mixer, a broadband intermediate frequency amplifier and a multiplier, serially connected narrow-band intermediate frequency amplifier, a frequency discriminator, a low-pass filter frequency and generator control.

the output of which is connected to the input, the mixer, the delay tracking unit, consisting of the Delay discriminator connected in series, the multiplier, the other input of which is connected to another output of the frequency converter of the AFC block, the lower filter often ;, the adder, another input through the linear the converter is connected to; the output of the low-pass filter of the AFC unit, the controlled generator and the reference pseudo-random sequence (PSP) generator, the first output of which is connected to the second frequency converter of the AFC unit, a control unit is inserted, the first information block is entered into the AFC unit. the input of which is connected to the output of the multiplier, the second and third information inputs - with. correspondence; The first outputs of the discriminator delay, the first control input with the first output of the control unit, the second and third control inputs are combined and connected to the second output of the control unit, and the output with the input of the narrow-band intermediate frequency amplifier has an adjustable delay block entered in the delay output unit, whose inputs connected to the second and third outputs of the shaper of the reference SRP, the control inputs to the second output of the control unit, and the outputs to the COOTvetads of the inputs of the delay discriminator.

In addition, the control unit contains a series-connected RS flip-flop, an And element and a counter

: IMPUL.SOV, WHICH DIRECTLY EXIT

connected through the element. OR to the R-BXO of the RS flip-flop and is the second in (control unit input, the first output of which is the inverse output of the pulse counter, while the zero input input of the pulse counter is combined with the second input of the OR element and , the second input of the And element is the input of the reference frequency signal, and the s-input of the RS flip-flop is the input of the tracking mode enable signal,:

Fig. 1 shows the structural electrical circuit of the following filter of the phase-manipulated pseudo random signal / Fig. 2 - V is a structural electrical circuit of the control unit (FIG. 3); a structural electrical circuit of the adjustable delay unit.

The following filter of the phase-manipulated pseudo-random signal (FIG. 1) contains an AFC block 1 and. unit 2 for tracking. Block 1 of the AFC consists of a ring-mounted mixer 3, a wideband UPCH 4, a multiplier 5, a block of weighted summation, a narrow-polar UPCH 7, a discriminator 8 chtbt, a low-pass filter 9, and a controlled oscillator io. The weight summation block B consists of elements 11–13 with controlled transmission coefficients, the outputs of which are combined by adder 14, Block 2 for tracking:, the delay consists of ring-connected discriminator 15 delay, multiplier 16, low-pass filter 17, adder 18, control generator 19, the driver 20 of the reference bandwidth and the block 21 of the adjustable delay. The discriminator 15 delay consists, for example, of two multipliers 22 and 23, the outputs of which through subtractor 24 under: are connected to the input of the narrowband amplifier. 25. The filter also contains a control unit 26 .., the first output of which is connected to the control input of the element 11, the second output to the control inputs of the elements 12 and 13 and to the control inputs of the adjustable delay unit 21. The output of the frequency converter 8 is connected to another input of the multiplier 16, the output of the low-pass filter 9 through the linear converter 27 with the second input of the sum-0 of the mat 18, the output of the driver 20 of the reference memory bandwidth with the second input of the multiplier 5, the output of the multiple broadband amplifier 4 with the inputs of the multiplier 22 and 23, the other inputs of which psd- switches to the outputs of the variable delay unit 21, and the outputs to the information inputs of elements 12 and 13,

The control block 26 (phi g, 2) holds a series-connected RS flip-flop 28, an AND element 29, and a pulse counter 30, as well as an OR element 31, and the S-input RS flip-flop 28 is the input 32 of the signal

enable tracking mode, R-input through the element OR 31. connected to. the direct output of the pulse counter 30 is the second output 33 of the control unit, the inverse output 34 of the pulse counter 30 is the first output of the control unit 26, the zero input input of the pulse counter 30 is combined with the second input of the element OR 31 and is the input

control unit zero is the control unit 26, and the second input element AND 29 is a reference frequency signal input L0 35.

Block 21 adjustable delay (Fig, 3) consists of two blocks 36

and 37 delays and each of which

consists of a register 38 (39) shift, the outputs of which are connected to the inputs of the elements And 40-i (41-i),;

where i 1/2,

,,, n, and n - the resolution of the peiracTpa 38 (39) shift, the outputs of which are combined by the element OR 42 (43).

The trail of the phase-shift keyed pseudo-random signal works as follows.

The control unit 1 and the cross-link delay tracking unit 2 ensure synchronization of the controlled generator 10 and the driver 20 of the reference bandwidth, respectively, with the center frequency of the spectrum, which is a manipulated pseudo-random radio signal and its temporal position. In order to ensure the operation of block 1 of the AFC, the phase-shifting pseudo-random radio signal is convolved, the result of which from the output of the narrowband IFC 7 enters the 8-frequency discriminator (or phase). The error signal in frequency (or phase), taken from the output of the discriminator 8 frequency, through the low-pass filter 9 acts on the control input of the controlled generator 10 in such a way that the change in the frequency of its oscillations is different. Cutting head 3 eliminates a mismatch. In block 2 of delay tracking, a temporal mismatch between the received phase-shift pseudo-random radio signal causes an error signal at the output of the delay discriminator 15. The sign of the error signal is determined by the phase of the oscillations at the output of the delay discriminator 15 with respect to the phase of the result of convolution of the phase-shift pseudo-random radio signal in block 1 of the AFC. The error signal from the output of the delay discriminator 15 is fed to the multiplier 16, which functions as an error signal detector. To ensure detection, the second signal is fed to the other input of the multiplier 16. From the output of the discriminator 8, the frequency in the case of non-coherent implementation of the delay tracking unit 2 or from the reference input of the phase detector in the implementation of the quasi-coherent tracking unit 2: delay. The detected error signal through the low-pass filter 17 and the adder 18 acts on the controlled oscillator 19 in such a way that a change in the clock frequency eliminates a temporal error from the neck. Linked from the output of the low-pass filter 9 of block 1 of the AFC through the linear converter 27, and the adder lec controlled by the input of the controlled generator 19 provides software control over the rate of change of the delay of the reference signal, thereby reducing the dynamic errors of the block 2 of tracking the delay, to which the initial processing function is assigned. delay mismatch.

convolution of a phase-shift pseudo-random radio signal to the reference SRP in three multipliers 5, 22 and 23 by weight summing up the results of the works in block 6 of the weight summation and filtering the amount obtained in narrowband AMF 7. The control unit 26 together with the adjustable delay unit 21 and the & weight summation implements the function of controlling the aperture of the discriminator and the form of the result of the convolution of the phase-shifting pseudo-random radio signal from its detuning relative to the reference bandwidth during the transition process. The moment of the beginning of the transient process (t вы) is given by a command from the outside (from the device controlling the operating modes of the equipment, for example, at the moment of detecting the: signal). This command is fed to the input 32 of the control block 26. Changing the discriminator aperture is done by changing the detuning value of shifted copies of the reference bandwidth, and changing the shape of the convolution result from the phase detuning of the manipulated pseudo-random radio signal relative to the reference memory bandwidth as changing the detuning value of / / TEK and changing the weighting factors of the radio signal output signal output signal. The values of At (j and weights are set by control block 26. At the initial moment of operation of the following filter (t b), control block 26 sets the delay between shifted copies dtp equal to the length of the elementary signal bandwidth, tr, t. e. to (0) -t-, and the values of the weight coefficients for the product of the received signal by the reference signal Kijj (0) O and shifted copies of the reference signal). Over time, the delay decreases to a stationary value, the values of the coefficients K (t) decrease to stationary values) 1, and the value of the coefficient K (, (t) increases to a stationary value K, (t) 0.

in the process of reducing the delay between shifted copies .St, from the initial value equal to the duration of the elementary signal LSP G, the slope of the discriminatory characteristic in the vicinity of its zero (f 0) does not change, as determined by the slope of the original autocorrelation function of the reference chipboard, Indeed, in the neighborhood of “O, the discriminatory characters A. (..-“.) Where Hell is the signal amplitude for VE r O, R (C) is the value of the normalized autocorrelation; SRP functions as the normalized correlation function nCnR (f) 1-1. -. . -. .-, ..- er,: with fTJ 4tj. However, with a decrease in .at JJ, the length of the lignal region of the cryptomagne dionine decreases; specifications. If the change of the Ato (t) hold between the shifted copies of the reference signature is not fast / i.e. in such a way that the error, the estimated delay of the block 2 signal tracking delay does not exceed the linear portion of the discriminatory characteristic, the parameters of the block, the second block of the delay associated with its dynamics (dynamic subtraction (current, duration of the return process, if there are no It does not change the nonlinearities. The noise component of the norffesiah unit of the tracking unit 2 is smaller; the prototype, and the smaller, the smaller the delay between the shifted copies of the reference signal. This increases the tracking accuracy of the reference signal was achieved by reducing the noise level; at: the output of the discriminator 15 is delayed while reducing the time difference between shifted copies of the reference signal. Indeed, at the values of this detuning less than the duration of the elementary symbol, the noise components at the output of the multipliers 22 and 23 of the discriminator; 15 delays are corrected with a positive correlation coefficient of g. By definition, the correlation coefficient is .-.,., ....,; , (t) Xg (t |). V .-; - -v / v where X {t | t {h (tJ4S {t) is the noise realization on the BbixoAGi variable of bodies 22 / / At V bodies, r ((t) fS (tnc (- Realization / noise qi at the output of the multipliers of bodies 23; n (t) is the realization of noise on ..: 8., ... signal inputs multiply -,., lei 22 - and.;.; -: S (t) - realization of the Rmanipuli phases of the pseudo-random pseudo-random radiosign. ;; ::,.;... nal., input of the driver 15 for holdings / U (t) - supporting binary ncii .g /, 6jt) ± r) i mGp%) - dispersion / (noise powerj the corresponding process /) 1, since Uj, (t) 1 1; M | J -: the symbol of the operation of the mathematical, who is the expectation (averaged over the realizations} .. MHtOR (tJ 2 -. "(4). RCf) - the normalized autocorrelation function of the reference bandwidth. Sensitivity of output noise subtracted. 24: - , (2.f ((utJJ. Ak as in the range of (G / i C, R T) b .. 6 consequently, the level of the discriminator 15 Delay is achieved by subtracting these gels in subtraction 24. Thus, the contradiction a wide round of wider 15 for the provision of normal signal capture and high awnings in the steady state, with respect to the same for example, the noise components of the validity in the proposed file are higher than in the prototype, which indicates an increase in noise immunity in the mode that has developed. The minimum time value, At {, (t), is determined by the maximally acceptable a posteriori error distribution error Wp5) namely: the values of the error with a high probability should not go beyond the lines of the linear section of the discriminatory characteristic. Otherwise, in block 2, the threshold effects begin to appear and the noise error components immediately begin to increase. In addition, the minimum value of Ato should not exceed the duration of phase transitions (the duration of the fronts of the phase-controlled pseudo-random radio signal, which have a finite duration of real signals. The formation of a harmonic signal for the operation of the 1 ASCh block is carried out by summing the results of the phase-shifting multiplier Psecd in block 6 - tea radio signal in three multipliers 5, 22 and 23 with a reference pep and its shifted CAPS51MY and subsequent filtering of the result of production in a narrow band UPCH 7., Shat th signal on the output of narrowband UPCH 7 is defined by the expression. LPh№ N (o-%).. Where .-... ..:. / V) 4f, {tH (tM {r) + K (iIAT4 - fi |; A (T) ApRt-e); , AO - signal amplitude,, (t :) - normalized. aBTOKOJpectional function / K (t) is the weighting factor for multiplying the received signal by shifted copies of the reference signal Ai. (ti.t K: (t) is the weighting factor to reproduce the received signal on the reference signal, t) J is the time delay between the shifted copies of the reference /; signal. . :; Thus, the dependence of the amplitude of the signal obtained at the output of the narrow band OAC 7 harmonic signal from the error estimate for the delay T in block 2 in the proposed technical solution may be less than in the prototype. Block. 26 managing delays of shifted copies of signal ilto (t) and weighting coefficients) and Ko (t) (implemented in elements 11, 12 and 13 with controlled transmission coefficients, respectively), can provide the optimal value of the signal-to-noise ratio for the operation of block 1 of the AFC when the posterior variation of the likelihood probability error of the delay estimate WpglC, t varies in time in block 2 of the initial (a priori, prior to the established (stationary) probability distribution VfJ.f). At the initial operation time of the system (), 26 controls, setting the values of the weighting factors K (0) 1 and Kp (0) 0, provides the widest possible mutual correlation function of the input and reference signals, which determines the amplitude of the signal at the output of the narrow-band ULF 7. most likely, the probability of capturing the signal of the 1 frequency control unit increases. with significant a priori errors of estimating the delay and decreasing the losses by detecting the error signal in block 2. Over time, control block 26 programmatically reduces the coefficient K, H) and increases Кjj (t), maintaining the optimal form of the function of mutual Correlation of the input and reference signals when evolving. a posteriori probability distribution law for the error in estimating the delay. The criterion of optimality over time varies from the criterion of the maximum probability of capture at the initial moment of operation of the following filter under the worst synchronization conditions for the delay to the criterion of maximum average signal-to-noise ratio at the output of the narrowband IFCH 7 when averaged by the stationary a posteriori law of the distribution of delay errors .. Thus, in the steady state, the values of K (t); -and Co 11) are determined from the condition:, ut, / C)) rftV l -oo ((), 6 |) at. where.A (K-, Kd,.) is the amplitude of the signal at the output of narrow-band UPCH 7, (K.KO. -dispersion of noise at the output of narrow-band UPCH 7f WN (0.6-5.) - normal - approximation of the stadionary apicalor The uncertainties of the errors in estimating the delay f. This increases the noMie resistance of the following filter, both in transient mode 1 when capturing the signal and in the steady state: ... block 26 of control is made in the counter of 30 transient time pulses process with start-stop control of counting pulses (RS-flip-flop 28, ale and 29). The state of a certain radar - and the pulse counter 30 controls the delay between the shifted PSRs of the reference SRP dt and the values of the weighting factors K and KJ. Thus, the generated control code is one-bit and takes only two values and 1. At the same time, K and Kd also yes take the values O and f, i.e. the signal is allowed to pass to the input of the adder 14 or the input is activated. Therefore, the element. 11, .12 and 13 with controllable transmission coefficients can be: -gout; they are designed as controllable gates that let the input signal pass through or not to the output. Adjustable delay unit 21 is made in the form of two delay units 36 and 37, each of which consists of a register 38 (shift 39G, with taps whose switching is performed by AND 40-i 1 - f elements) (a function with vb; n CJ a, b signals with a shift of the shift register 38 C39lj t - control signal) by a signal, from the counter 30 transient pulses. The approximation of the functions A, f (f, t) ig.Gy, t) is carried out in the following way: ALA 4tg tj; lc K K.fj.f (YES; CRM. Thus, a wide delay aperture 15 of the discriminator 15 takes place before t) and a wide area of strong correlation of the input phase-manipulated pseudo-random signal with a reference for the operation of block 1 of the frequency control unit and after the moment c, the discriminatory characteristics and areas of strong correlation are narrowed, which provides: increased noise immunity of the proposed filter compared to the prototype. the invention In radio systems for the transmission of discrete information, the quality of the synchronization of the transmitted information increases and, as a result, the probability of errors in the received information symbols decreases, since the quality of synchronization is in some cases important.In addition, the use of the proposed filter in the combined measurement-informational systems of systems of radiolocation and radio navigation using phase-shift keyed pseudo-syllabus. In order to increase the noise immunity of the apparatus both in the capture mode and in the tracking (tracking) mode. The reduction of the noise components of signal measurement measurements of signals is especially important in radionavigation systems. Teriaxj, since the accuracy of measuring coordinates and motion parameters in these systems is associated with measurement errors of the primary radionavigation parameters (latency, duplex frequency shift, etc. {through the geometric factor, which significantly increases the effect of these errors.

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Claims (2)

1. NEXT PHASE FILTER - .NPULATED PSA A SIGNAL containing an automatic frequency control unit (AFC), consisting of a series-connected mixer, a broadband amplifier of an intermediate frequency and a multiplier, connected in series to /. nennogo narrow-band 'intermediate frequency amplifier, frequency discriminator, low-pass filter and · controlled generator, the output of which is connected to the input of the mixer, the unit for tracking the delay, consisting. from series-connected delay discriminator, multiplier, another input of which is connected to another output of the frequency discriminator of the AFC unit / low-pass filter, adder, other input _:. 'which through a linear converter is connected to the output of the low-pass filter of the AFC unit controlled by the · generator and driver of the reference pseudorandom sequence, (PSP), the first output of which is connected to the second input of the control multiplier, the second input of the element is the I-input of the reference frequency signal , the unit of the AFC, and the S-input of the RS-flip-flop is the signal input so that, in order to increase the amount of switching on the tracking mode. noise immunity, a control unit is introduced into it, a weight summing unit is introduced into the AFC unit, the first information input of which is connected to the output of the multiplier, the second and third information inputs with the corresponding outputs of the delay discriminator, the first control input with the first output of the control unit, the second and third control the inputs are combined and connected to the second output of the control unit, and the output to the input of a narrow-band amplifier of intermediate frequency, an adjustable delay unit is introduced into the delay tracking unit, passages which are connected to second and third outputs of the driver support cap, the control inputs to the second control unit Yield, as you move bi - to respective inputs of a delay discriminator. 2. Filter by π. 1, the difference is that the control unit contains an RS-trigger in series, an AND element, and a pulse counter, the direct output of which is connected via an OR element to the R-input of the RS-trigger and is the second output of the unit control, the first output of which is the inverse output of the pulse counter, at. The pulse counter zero input is combined. with the second input of the OR element and is the input of setting the block zero>