SU1453414A1 - Digital correlator for detecting an echo signal - Google Patents

Abstract

The invention relates to computing and is intended for real-time intercorrelation processing of a sounding signal and an echo signal having a Doppler frequency shift. The aim of the invention is to expand the band of the analyzed frequent Doppler shift towards negative increments of the frequency of the signal. The correlator contains recirculation memories of the probing device.

Description

The invention relates to computing and is intended for real-time intercorrelation processing of a sounding signal and an echo signal having a Doppler frequency shift.

The purpose of the invention is to expand the frequency of the analyzed frequency of the Doppler shift towards negative increments of the echo frequency.

FIG. 1 presents a digital correlator circuit diagram for echo detection | Fig. 2 shows a structure} -5 on the recirculation memory of a probe device;

The correlator (FIG. 1) contains the recirculation memory devices 1 of the probe screen (n number of analysis channels), the elements of OR-NO 3, analog-digital conversion ™, call number 4, register 5, key 6, loop li 7, counter 8, gene €; rator 9 pulses,, generator 10 clock pulses, element 11, input 12 zones d1-1 of the correlator signal, input 13 of the correlator echo signal, installation input 14 of the correlator , channel outputs 15 of the correlator, the recirculation memory of the probing signal (FIG. 2) contains an analog-11 1-converter converter 16, The first 17 and second 18 registers, the switch 19, the key 20, the element And 21, the first counter 22, the generator 23 pulses and the second counter 24.

The principle of operation of the correlator is based on the fact that in the presence of a Doppler shift of the echo signal frequency

the measurement of the mutual correlation function between the sounding signal and the echo signal is possible only if the condition K, f + uf) is fulfilled, where K and

to

five

0 5

3

0

Kj, respectively, the compression coefficients of the probing signal and echo ™. By selecting the K value, the Doppler frequency of the echo signal is compensated for in the recording channel of the probing signal. The change in the coefficient 1g is carried out by changing the pulse duration at the output of the pulse generator introduced into the pulse shaping circuit to take samples of the input signal. This pulse blocks the information shift. The delayed sampling circuit and the sampling circuit of the input signal are for a time equal to its duration, resulting in an increase in the sampling period of the input signal, which corresponds to an increase in the compression ratio when recording zones that trigger the signal.

The compression ratio of the echo signal in the recirculation memory of the echo signal is selected average relative to the compression ratio of the probing signal through the channels of the diffuser.

The correlator works as follows.

The setup pulse at input 14 is fed to the inputs of counters 22 and 24 of all recirculation storage devices 1 of the probing signal and sets them to the zero state. At the output of the counter 24, a potential arrives at the switch 19, the pulse generator 23 and at one of the inputs of the element. AND-NOT 11, and the switch 19 connects the output of the second register 18 to the input of the key 20, closing the ring recording probing signal. From the generator of 23 pulses operating in the standby mode, remove the t-block from the block and the output of the element

314

AND-NE 11 appears a potential blocking counter 8 and element AND 7, preventing the echo signal from being recorded at the time of the emission of the probe pulse in

After the setting pulse ends, counter 22 starts counting the clock pulses from the generator 10 clock pulse outputs, and with the arrival of the Nth pulse generates a pulse of duration T .. which is used to sample the input signal and lock the key 20 for the recording time of the input sample into the register 17. A sampling of the probing signal from the output of the analog-digital converter 16 is recorded in the register 17. The trailing edge of the output pulse of the counter 22 starts the generator of 23 pulses, the output of which is pulse pause blocked through OR-NO element 21 and element 3 and the counter 22, whereby the clock pulses are no longer supplied to the registers 17 and 18 is stopped and the shift information.

This state is held until the end of the pause pulse, after which the blocking is released and the next control pulse is generated at the output of the counter 22 after N cycles and the second sample of the probe signal is written to the register 17, then the pulse generator 23 is triggered, and the recording process repeat until the recirculation memory 1 of the probing signal is filled. The number of memory samples is determined by a second counter 24, to the input of which pause pulses are received. When a specified number of 1-CLOCK recordings is reached, the signal at the output of the second counter 24 changes to inverse, as a result of which the recirculation storage device 1 switches to the information storage mode (the second register 18 is excluded from the signal sample circulation ring) steps of the next setting pulse. The signals from the output of the second counter 24 of all channels are fed to the inputs of element I-NE 11, and after the recording of the probing sigma is over, all channels on the output of element I-NE 11 appear to be able to remove the lock from the recirculation memory. echosig14

therefore starts echo recording. Compressed copies of the probing signal and the echo-signal, are sent to the computation inputs of the correlation futzcia of the corresponding channels, where the computation of the correlation function e

. The goat echo compression trigger is set by a pulse generator 9. To ensure synchronous circulation of samples of the echo and sounding signal, the period of circulation of the samples of the sounding signal is extended by applying an impulse. The echo channel from the output of the generator 9 pulses through the corresponding element lilM-HE 3.1 - .. 3-n blocks the shift of information samples in all recirculation memories of the correlator.

The scheme for constructing a correlator with a Doppler filtering ensures the coincidence of the clock pulses in all channels after the recording of the probed signal is completed. This condition is fulfilled. Due to the fact that the recording time of the probing signal in any kanzle is proportional to NT - - t, N, (NT ,, + пТ, д,) NT, 6 (N + n), where .jj о u.t. In addition, in each channel after the end of the recording of the recording of the ETS signal before the transition to the echo analysis mode, the circulation period is also equal to NT (gg, which leads to synchronous operation of the correlator channels.

Claims (1)

Invention Formula A 1.1-digital correlator for detecting echoes, containing a recirculation memory, a coding signal device, a computing unit for the inter-correlation function clock generator i-TMnj bcoB, a register, a key to an analog-to-digital converter, whose information input is a correlator echo input, the first And element, counter and pulse generator, the output of which is connected to the reset input of the counter and the first input of element And, the counter overflow output is connected to the input of the pulse generator stop, clock input nalogo-digital converter and a control input of the key, the output of which through the mounting OR connected to the output of the analog-digital converter and the information input of the register, the output of which is connected to the first input of the computation block of the intercorrelation function, the register clock input is connected to the output of the element and the second input of which is connected to the counter of the clock pulse generator to the counter input of the counter, the first switch The national memory of the sounding signal contains the analogue analogue of the converter, the key, the switch i, and two registers, moreover, in the first recirculation storage device -, stve probe signa1a ny information input analog yt1frozogo transform ers is input probing signal correlator, taktovsh input; The analog-to-flat converter is connected to the control input of the key ,, informational output of which, via: mounting OR connected to the output: analog-digital converter,; connected to the information input; the first register, which output is connected to the first information the input and the information input of the second register 5 which is connected to the second information input of the switch and the second input of the calculation block of the reciprocal of the geothermal function, the code of which is the output of the correlator, a switch in the first recirculation of the memory storage device of the probe: the signal is connected to the information input of the key, characterized in that, with a remote extension of the frequency band, the scrambled offset: neither towards the negative increments of the frequency of the echo signal, the recirculation is entered into it memory probes of the usb probe (n is the number of analysis channels) n-1 computing units mutually correlate the pdon function of the n elements OR ni and the ni element, and in each transfer there is a probing memory Two counters were introduced into the signal, element I, and the generator of I1 pulses, with, in each section, the skins 1- (ion memory ten 20 25 4534 ; P thirty 35 40 45 146 The probing signal output device of the first counter is connected to the control input of the key and the trigger input of the pulse generator, the output of which is connected to the counting input of the second counter, the output of which is connected to the input of the blocking of the pulse generator and the control input of the switch element output And with every P1r- the gokul-snub storage device of the probing signal of the under-1 l is damped to the clock inputs of the first and second registers, the output of the register is connected to the information input of the key and the combined first inputs units of calculation of the mutual correction function, the second inputs of which are connected respectively to the outputs of the second registers of the corresponding recirculating memory of the probing signal, Informational inputs of analog-digital converters of handheld probes are interconnected, the combined reset inputs The first and second counters of the recirculation memories of the downmixed signal are the installation inputs of the correlator, the generator output The first pulses are connected to the counting inputs of the first counters and the first inputs of the elements and the recirculation suppressing devices of the probing signal, the code of the generators of pulses of the rectifier recording locks of the KSFflix devices of the probe signal are connected to the first inputs of the corresponding elements of ILs and 11 LEDs. connected to the stop inputs, the first counters and the ETopbUvm inputs of the elements AND the corresponding recirculation memories of the probing signal devices, the combined inputs of the elements OR — NOT connect Nena yield gfshulsov generator, vyho0 d: s second & p counters of recirculating memory devices of the zoidrgate are connected directly to the inputs of the NAND element, the output of which is connected to the input of the counting counter and the third input of the element I. FIG. 2