SU439928A1 - Tracking noise-like signals with a multichannel search device - Google Patents

Description

one

The invention relates to devices for detecting, recognizing and receiving phase-shifted noise-like signals and can be used in communication systems and in radar systems for measuring motion parameters.

The following noise-like signal receivers with a multichannel search device are known, containing an automatic frequency control circuit consisting of a series-connected mixer with a wideband amplifier, a channel correlator, an error sensor, a low-pass filter and a controlled local oscillator, a delay tracking circuit connected to the output mixer and consisting of a series-connected two-channel correlator, an adder with a low-pass filter, a controlled clock generator, a chopper, and the bit register and the search device with the t-channel threshold detector included in it with the AND circuit and the control circuit connected to the outputs of the channel correlators.

However, the known devices have a complicated process of transition of the receiver from the search mode to the tracking mode when using a two-channel discriminator in them.

In order to simplify the receiver circuit during the transition from the search mode to the tracking mode in the proposed device, the output of the controlled clock generator is connected via a key to the control circuit and the counter input, the outputs of which are through the diode

the matrix is connected to the assembly circuit and the signal inputs of the valves, the control inputs of which are connected to the outputs of the threshold devices of the channel correlators, and the outputs of the valves with the assembly circuit, with the output

the assembly circuit is connected to the first trigger input and to the bit inputs of the channel correlators, the second trigger input and the meter installation input are connected to the output of the AND circuit, and the trigger output is connected

to the control inputs of the notch and the key .:

The drawing shows a functional diagram of the proposed following receiver of noise-like signals with a multichannel search device ....

The proposed tracking receiver consists of an auto-tuning system, a delay tracking circuit, and a searcher. The system of automatic frequency control contains serially connected

a mixer with a wideband amplifier 1, a channel correlator 2, a mismatch sensor 3 (for example, a frequency detector), a low-pass filter 4 and a controlled local oscillator 5. One of the inputs of the mixer is

input intake receiver and the other connected

with the release of the local oscillator 5. Channel correlator 2 consists of a multiplier and an integrator with a reset. The received signal is received at the signal input of the multiplier, and the reference signal at the control input. The control input of the channel correlator 2 is connected to the output of the (t-1) -bit generator 6 of a pseudo-random sequence, which is an n-bit shift register with feedback.

The tracking circuit for the delay of the received signal contains two channel correlators 7 and 8, an adder 9 with a low-pass filter, a controlled clock generator 10 and a generator 6 of a pseudo-random sequence. The signal inputs of the channel correlators 7 and 8 are connected to the output of the mixer 1, and the control inputs are connected respectively to the outputs (t - 2) and t-bits of the generator 6 of a pseudo-random sequence. The correlators 7 and 8 and the adder 9 form a discriminatory characteristic of the delay tracking circuit.

The search device contains a control circuit 11, a notch 12, three channel detectors including channel correlators 2, 7 and 8 AND threshold devices 13-15, an AND 16 circuit, (t - 3) channel detectors, each of which contains a channel a correlator 17, a threshold device 18 and a valve 19, an assembly circuit 20, a key 21, a pulse counter 22, a diode array 23 and a trigger 24. The clock input of the control circuit 11 is connected to the output of the controlled clock generator.

The following receiving noise-like signals with the multichannel search device works as follows.

The AND 16 circuit transmits pulses with a period T (T is the time for examining one point of the time-frequency search domain) arriving from the second output of the AND control circuit only if there is no control voltage on its other inputs. If by the time of arrival of the next pulse the signal is not detected, i.e. the voltage at the inputs of the threshold devices does not exceed the threshold, then, having passed through the AND 16 circuit, this pulse throws the trigger 24 and sets the counter 22 to the zero position, while voltage from the output of the trigger 24 locks the notch and opens the key, through which the counter 22 and the control circuit I begin to receive pulses with a period of To, equal to the duration of one element of the pseudo-random signal.

After the meter receives m pulses at the (t - 2) output of the diode array and, therefore, at the output of the assembly circuit 20, a control voltage appears that discharges the integrators of the channel correlators and returns the trigger 24 to the initial state, With this, the key 21 is locked and the notch 12 is opened. Since the notch 12 is in a locked state during

Then, the delay of the reference signal generated by the pseudo-random sequence generator 6 relative to the received signal is increased by mto.

If the signal is detected by one of the channel correlators 2, 7, or 8, then a control voltage appears on the output of the corresponding threshold device 14, 13, or 15, which blocks the pulses from the second output of the control circuit 11, moreover, the delay of the reference signal and the frequency of the controlled local oscillator 5 do not change and the receiver goes into tracking mode. If the signal is detected by the channel correlator 2, then tracking of the frequency and delay starts simultaneously. When a signal is detected by channel correlators 7 or 8, due to the large delay between the received and reference signals, the signal in the frequency-control loop may not be sufficient to operate this circuit. However, this delay interval falls within the zone of discriminatory characteristics of the delay tracking circuit, which tends to

reduce the delay to zero. Starting with some values of the delays, the magnitude of the minimized signal in the frequency control circuit reaches a value at which the frequency control circuit triggers, and the receiver goes into tracking mode.

If the signal is detected by one of the channel correlators 17, then the search circuit is operated as follows.

The impulse from the second output of the control circuit, having passed through the “AND 16” circuit, flips the trigger 24 and sets the counter 22 to the zero position. The control voltage from the output of the trigger 24 locks the rejector 12, in

as a result, the clocking of pulses to the pseudo-random sequence generator 6 is stopped, the key 21 is opened, through which counter 22 and the control circuit 11 begin to flow

clock pulses, while the reference signal begins to lag behind the received signal.

When a signal is detected, the voltage that appears at the output of the corresponding threshold device is fed to the control input of the valve 19 connected to this threshold device. After the receipt of a certain number of pulses at the output of the matrix connected to the signal

the input of the valve 19, a voltage also appears, the valve 19 opens and the control voltage passes through the valve 19 and the assembly circuit 20, discharges the channel correlators integrators and returns the trigger 24 returning to the key 21 and the opening notch 12. In this case, the reference signal is delayed by such an amount that the received signal corresponds to the reference signal at the output

(t-1) bit generator 6 pseudo-random sequence. Therefore, from the output channel channel correlator 2 signal triggered, the threshold device 14 triggers the AND 16 circuit, which does not transmit pulses from the second output of the control circuit. Therefore, the delay of the reference signal and the frequency of the controlled local oscillator do not change, and the receiver goes into tracking mode.

If a signal is detected simultaneously by several channel correlators, the receiver will go into the tracking mode of the signal detected in the channel correlator, to the control input of which it receives the reference signal from the t of the pseudo-random sequence generator (), where i is that the difference (t - 1) - i is minimal, i.e., the tracking of the signal coinciding with the reference signal, which has a minimum delay relative to the reference signal coming from (t-1). The size of the generator 6 is pseudorandom. ty.

Thus, if the signal response appears simultaneously from the outputs of, for example, one of (t - 3) channel correlators 17 and one of the channel correlators 7, 2 or 8, then the AND 16 circuit will turn out to be locked by the control voltage the threshold device 13, 14 or 15 and does not transmit pulses from the second output of the control circuit, the delay of the reference signal does not change, and the receiver switches to the tracking mode of the signal loaded in one of the channel correlators 7, 2 or 8.

6 | Subject of invention

A follower receiver of noise-like signals with a multichannel search device, containing an automatic frequency control circuit consisting of a series-connected mixer with a wideband amplifier, a channel correlator, an error sensor, a low-pass filter and a controlled local oscillator, a delay tracking circuit connected to the mixer output and consisting of a series-connected dual-channel correlator, an adder with a low-pass filter, a controlled clock generator, a chopper, and a n-bit register, as well as a search device with incoming channel-channel threshold detector with an AND circuit and a control circuit connected to the outputs of the channel correlators, characterized in that, in order to simplify the receiver circuit during the transition from the search mode to the tracking mode , the output of the controlled clock generator through the key is connected to the control circuit and the input

counter, the outputs of the bits of which are connected through the diode array to the assembly circuit and to the signal inputs of the valves, the control inputs of which are connected to the outputs of the threshold devices of channel correlators, and the outputs of the valves to the assembly circuit, with the output of the assembly circuit connected to the first trigger input and the bit inputs of the channel correlators, the second trigger input and the meter setup input are connected to the output of the AND circuit, and the trigger output is connected to the control inputs of the notch and the key.

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