RU2595494C2 - Method for formation of pulse code sequences and processing thereof for discrete information transmission systems - Google Patents

Abstract

FIELD: radio engineering and communications.

SUBSTANCE: invention relates to radio systems for digital information transmission, operating on a common frequency, in which transmission is carried out by short radio pulses with modulation by changing time position of radio pulses on clock interval, designated for information unit transmission. Method comprises steps of each code sequence produced from same type of pulses with equal intervals between them, wherein duration of interval between adjacent pulses in code sequence is a multiple of two times duration of a single pulse at output of amplitude of receiver of detector, and number of pulses in each code sequence is chosen on a greater than maximum number of transmitters whose signals are simultaneously present at input of a separate receiver system, but should not take place at output of code pulse sequence processing apparatus, only one signal is provided to a receiver pulse signals with tap-delay line for subsequent receiver circuits - signal minimum level.

EFFECT: technical result is elimination of occurrence at output of receiver of signals from external transmitter.

1 cl, 1 dwg

Description

The invention relates to a combination of several discrete information transmission radio systems operating at a common frequency, and in particular, to a variant in which the transmission is carried out by short radio pulses with modulation by changing the time position of the radio pulses in the clock interval allocated to the transmission of a unit of information.

To ensure high-quality operation of radio systems, it is necessary that the receiver of each of the systems included in the aggregate react only to the signals of its transmitter and do not receive signals from other transmitters.

Two methods are known for fulfilling this requirement. The first way is that the pulses of each transmitter have additional modulation that is different for each transmitter. The modulation parameters for each pulse are selected so that the totality of all signals satisfies the condition of mutual orthogonality. At the same time, signals from extraneous transmitters are suppressed by a filter configured to receive pulses from its transmitter (MB Sverdlik, Optimal impulse signals, chap. 2-4, - M .: Sovetskoe Radio, 1975).

The second method is that instead of a single pulse, a code sequence of several pulses is emitted with different intervals between them. Reception is made by a receiver including a series-connected high-frequency unit, an amplitude detector, and a delay line with taps arranged so that at some point in time all pulses of the code sequence appear simultaneously at the input of the line, at its output, and at all intermediate taps. Next, the summation of the signals from the input, output and all taps of the delay line. The selection of the values of the intervals between pulses in each code sequence is based on the requirement that on the taps of the delay line configured to receive its code sequence, pulses do not coincide from all other code sequences. This requirement is called "no more than one coincidence" (MB Sverdlik, Optimal impulse signals, - M .: "Soviet Radio", Chapters 5-6, 1975). In the second method, simple-shaped pulses are applied without additional modulation.

The disadvantage of the first method is the increased complexity of constructing transmitting devices and receiver filters. In addition, it may turn out that the transmitters and receivers of individual systems included in the aggregate differ significantly in the circuit-technical aspect. This increases the complexity of their manufacture.

The main disadvantage of the second method is that one of the pulses of any transmitter necessarily arrives at the outputs of all receivers, which reduces the noise immunity of the reception. To minimize this negative effect, the number of pulses in the code sequence should be significant. At the same time, the intervals between pulses in the same code sequence must be different, and the durations of the intervals turn out to be extremely large (to preserve the property of "no more than one match").

The aim of the invention is a method of forming an ensemble of pulsed code sequences with pulsed signals without additional modulation on the transmitting side and processing them on the receiving side, which completely eliminates the appearance at the output of the receiver of signals from each extraneous transmitter separately. This eliminates the disadvantage of the first analogue, which consists in the complexity of constructing the equipment, and the disadvantage of the second method, which consists in getting one of the pulses from each extraneous transmitter to the output of the receiver.

This goal is achieved in that each code sequence is formed from pulses with the same intervals between them. For different transmitters, the intervals should be different. The difference in the intervals between pulses belonging to different code sequences should be a multiple of two durations of one pulse at the output of the receiver amplitude detector.

In particular, the interval between adjacent pulses in the code sequence related to the system with number k can be chosen equal to 2 (k-1) τ, where τ is the duration of a single pulse at the output of the receiver amplitude detector.

In the simplest case, it is enough to compose each code sequence with just two pulses.

The generated code sequences are received at a receiver consisting of a high-frequency block, an amplitude detector, and a delay line with taps arranged so that all pulses of the code sequence appear simultaneously at the input, output, and all intermediate taps of the line at some point in time. An algorithm for further processing the sequence is proposed different from the known one. It consists in the fact that instead of the sum of the signals from the delay line, only one signal is supplied to the subsequent receiver circuits - a signal with a minimum level. The signal selection block with a minimum level implements a new method for processing a code sequence of pulses.

The structural diagram of the device for processing the code sequence of pulses according to the claimed method is shown in figure 1. Here, the number 1 indicates the delay line with taps, and the number 2 indicates the pulse selection block with the minimum amplitude. Directly, based on the purpose of the blocks and the type of their connection, it can be seen that at the output of block 2 from the code sequence that the processing device is configured to receive, only one pulse is generated, which is fed to the standard decision-making circuit for the transmitted symbol of discrete information.

Because the time intervals between pulses of different code sequences are different, then pulses of an arbitrary code sequence cannot simultaneously appear at the input, output, and at all taps of the delay line designed to receive a different sequence. In this situation, on some taps only a weak signal may appear due to noise at the input of the receiver, which will pass to the output of the pulse selection unit with a minimum amplitude, thereby recognizing the absence of an informational message. Thus, a separate extraneous transmitter will not be able to affect the operation of any other system.

In the particular case, when the code sequences consist of only two pulses, the signals to the selection unit must come from the input and output of the delay line. Due to the difference in the intervals of sequences of different transmitters, the signal from a separate extraneous transmitter cannot appear simultaneously at the input and output of the line.

However, the situation changes if signals from several extraneous transmitters are simultaneously received at the input of the receiver. In particular, if the code sequences consist of two pulses, then signals from two extraneous simultaneously operating transmitters can generate one false pulse at the output.

An increase in the number of pulses in the code sequences (for example, to the number n) allows one to increase the number of pulses from extraneous transmitters that do not pass to the output of the pulse selection circuit with a minimum amplitude.

A false pulse will appear if only on the outputs of the delay line simultaneously there are extraneous pulses with a number equal to the number of pulses in the code sequence, i.e. n pulses appear. Therefore, the number of pulses in each code sequence is selected one more than the maximum number of transmitters, the signals of which can be simultaneously present at the input of the receiver of a separate system, but should not pass to the output of the code sequence pulse processing device.

Moreover, depending on the specific values of the intervals between pulses in the code sequences, the number of simultaneously working (and not interfering with each other) transmitters can be different, from two to the number n.

Thus, an increase in the number of pulses in the code sequence contributes to an increase in the number of simultaneously operating extraneous transmitters of the system, the combination of signals of which does not affect the quality of information reception.

Using this method of generating and processing pulsed signals allows you to create a set of discrete information transmission systems operating at a common frequency without mutual influence on the reception of information in each of the systems. Moreover, for the separation of signals from different transmitters do not need additional pulse modulation, different for each transmitter.

Claims (1)

A method of generating pulse code sequences and processing them for discrete information transmission systems operating at a common frequency without interfering with the reception of information in each of them, characterized in that each code sequence is formed from the same type of pulses with the same intervals between them, while the duration of the interval between adjacent pulses in a code sequence is a multiple of two durations of one pulse at the output of the receiver amplitude detector, and the number of pulses in each code the new sequence is selected one more than the maximum number of transmitters, the signals of which can be simultaneously present at the input of the receiver of a separate system, but must not pass to the output of the code sequence processing device, and in the receiver of pulse signals from the taps of the delay line, only one signal - a signal with a minimum level.

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