RU2237359C2 - Signal generation and compression method - Google Patents

Abstract

FIELD: electrical engineering; radio and acoustic measurements.

SUBSTANCE: proposed method depends on generation of pulses transmitted in the form of train and on amplification of pulse signal received followed by its processing; in the course of signal generation coming pulse, starting from third one, is generated at interval that differs from preceding ones by value comparable with pulse length; compression of received signal is effected by adding pulses, interval between adjacent pulses being defined as ΔT_i+1 = ΔT₁+si, where ΔT₁ is value of first interval; i is ordinal number of pulse; s is increment of interval equal in particular to pulse length.

EFFECT: simplified signal generation and processing algorithm with amplitude of central maximum being maintained higher than side components.

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Description

The invention relates to the field of electrical engineering and can be used in radio engineering and acoustic measurements.

A widely known method of generating and compressing a signal with pulse modulation involves processing a signal represented as a sequence of radio pulses equally spaced from each other [1]. When this signal is compressed in this way, side components are formed, the presence of which causes ambiguity in the measurement.

A known method of processing a pulse signal, which suppresses the side components [2]. The disadvantage of this method is the reduction in amplitude and the expansion of the pulse corresponding to the central maximum.

The prototype of the invention selected the closest to the claimed method of generating and compressing a signal with pulse modulation, presented in the form of a sequence (packet) of pulses, which is formed by shifting each of the pulses relative to the beginning of the sequence by an amount that varies depending on the position of the pulse in the packet, in the process of processing the received signal, the oscillations are converted, the pulses are delayed, and the signal is compressed by adding pulses [3].

The problem to which the invention is directed is to simplify the algorithm for generating and compressing a pulse signal while maintaining the processing quality of the received signal.

This problem is solved by the fact that, using the method of generating and compressing the signal, based on the generation of pulses transmitted in the form of a sequence, as well as on the amplification of the pulse signal after it is received and subsequent processing of the pulses, when generating a sequence of pulses, the generation of the next pulse, starting from the third , carried out with an interval different from the previous ones, for example, the named interval is changed by a value commensurate with the pulse duration (approximately equal to the pulse duration). To transmit a signal at a carrier frequency, amplitude modulation of the carrier oscillations is carried out using the above-mentioned pulses generated during the formation of the sequence. Compression of the received signal is carried out by optimal processing of the pulse sequence, for example, the summation of the pulses is carried out after a delay of time

where t _n is the duration of the pulse sequence; Δ T _j is the interval between adjacent pulses; t _u is the pulse duration; i is the sequence number of the pulse in the sequence; N is the number of pulses in the sequence, and the value of Δ t _{1 is} set depending on the increment of the specified interval between pulses in the process of their generation, for example, take Δ t ₁ ≥ 0 when changing the interval by an amount approximately equal to the pulse duration.

The technical result of the invention is the implementation of the possibility of generating and processing a signal according to a simplified algorithm while maintaining the same as in the known method, excess of the amplitude of the central maximum over the side components, which simplifies the implementation scheme, improves the reliability and efficiency of the method.

The invention is illustrated by drawings, where figure 1 presents a block diagram of the formation of a sequence of pulses; figure 2 shows a diagram of signal processing by compressing a burst of pulses.

To form a burst of pulses, a circuit can be used containing, according to FIG. 1, a pulse generator (GI) 1 connected to a control unit 2 and connected to a delay line (L3) 3 connected to an adder 4, the output of which is connected to a modulator 5, to the second whose input is a high-frequency signal (carrier voltage) ~ u. The output of modulator 5 is connected to a transmitter (not shown).

The circuit that provides compression of the signal by summing the pulses, in accordance with figure 2 contains connected to the receiver (not shown) mixer 6, which is connected to the local oscillator 7; an intermediate frequency amplifier (IFA) 8, connected to the output of the mixer 6 and connected to the rectifier 9, the output of which is connected via a block 10 delay lines (LH) to the linear adder 11 connected to the recording device 12.

The formation of a packet transmitted at the carrier frequency of the pulses is as follows.

At the output of the GI 1, upon the command of the control unit 2, a rectangular pulse is generated, which is fed to the inputs of the LZ 3, where the pulse is delayed for a given time. The time shift (delay) of the pulse relative to the beginning of the sequence for each LH is different and is determined in accordance with the equality

where i is the serial number LZ 3 corresponding to the pulse number in the packet; Δ T _j - the interval between this and the previous pulse, which is determined by the formula

where s is the increment of the interval. In the particular case s≈ t _u , in this case, Δ T ₁ ≥ 0. The offset pulses from the outputs of LZ 3 are supplied to the inputs of the adder 4, where a sequence of pulses is formed, which are then fed to a modulator 5, to which, in addition, a high-frequency voltage is applied ~ u. The result is a pulse modulated signal, which is then transmitted. It is also possible the formation of a sequence of pulses with reduced to the end of the sequence duration of the intervals. Moreover, to determine the interval between pulses, the above expression is used, assuming s≈ - t _u . In this case, set

Signal processing is as follows.

The pulse signal received at the carrier frequency is fed to a mixer 6, which also receives a signal from the local oscillator 7. As a result, the frequency is converted. In the process of amplification and filtering of oscillations in the amplifier 8, an intermediate frequency signal is isolated. After rectification in the rectifier 9, a signal in the form of a packet of video pulses is fed to block 10 LZ. If the signal is amplified at the carrier frequency, then there is no need for frequency conversion. The delay of each pulse is carried out in accordance with its time offset by a time determined in accordance with expression (1). The pulse delay corresponding to the offset is achieved by pre-setting (selecting) the LZ of block 10. After the delay, the pulses are fed to a linear adder 11, where the signal is accumulated by summing the pulses. The maximum value of the signal obtained as a result of the summation is measured using a recording device 12. With a rational choice of the duty cycle and the number of pulses in the packet, the lateral components of the total signal have a minimum value. The central maximum, representing the sum of all pulses, has an amplitude tens of times higher than the noise level formed by the side components, which eliminates the ambiguity in the measurements.

As shown by experimental verification on digital models, the formation of a signal in accordance with expression (2) and its processing by delaying pulses in accordance with expression (1) and summing provide a solution to the problem. The high efficiency of the compression process of the considered sequences was also confirmed, regardless of the method of optimal processing of the pulse signal.

Sources of information

1. Radar devices / VVVasin, OVVlasov, VVGrigorin - Ryabov and others. Ed. V.V. Grigorina-Ryabova. - M .: Owls. Radio, 1970, pp. 195-200.

2. Shirman Y.D., Manzhos V.N. The theory and technique of processing radar information against the background of interference. - M .: Radio and communications, 1981, p.122-123.

3. Patent RU 2154899, 7 Н 04 В 1/64, 08.20.2000 (prototype).

Claims (3)

1. A method of generating and compressing a signal based on the generation of pulses transmitted in the form of a sequence, as well as on the amplification of the received pulse signal and its subsequent processing, characterized in that when transmitting the signal, the generation of the next pulse, starting from the third, is carried out with an interval different from the previous ones by a value commensurate with the pulse duration, the compression of the received signal is carried out by summing the pulses, while the interval between adjacent pulses is determined as Δ T _{i + 1} = Δ T ₁ + si, where Δ T ₁ is the value of the first in order interval; i is the pulse sequence number; s is the increment of the interval, in the particular case equal to the pulse duration. 2. The method according to claim 1, characterized in that the generation of pulses is carried out at a carrier frequency. 3. The method according to claim 1 or 2, characterized in that when generating the signal, set the value to the first-order interval Δ T ₁ ≥ 0, if the value s, which determines the increment of the interval between pulses, is positive, and if the value s is negative, set to parameter

where N is the number of pulses in the sequence.

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