RU2649418C2 - Method of information transmission by noise-like signals in mobile tactical communication system - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: mutually orthogonal or quasi-orthogonal information pseudo-random sequences are used to form the challenging and response signals of different objects. In a method of information transmission with noise-like signals in a mobile communication system on a transmitting side, the noise-like signals are formed by pseudo-random sequences including successively alternating information and masking pseudo-random sequences. The duration of the masking sequences varies depending on the digital data coming from the information source. A complex correlation function is formed on the receiving side, by means of a digital matched filter tuned to an information pseudo-random sequence. The digital data of the received information is determined from the time intervals between the maximums of the modules of the complex correlation function. Two information pseudo-random sequences are assigned to each object by its identification number, one for the challenging signal, the other for the response signal, which are selected from a plurality of orthogonal or quasi-orthogonal pseudo-random sequences. In this case, different information pseudo-random sequences for the response and challenging signal are used for different identification numbers, and the number of information pseudo-random sequences of both the challenging and response signals coincides with the number of objects in the tactical link.

EFFECT: elimination of intra-system disturbances.

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Description

The invention relates to the field of radio engineering and may find application in a mobile communication system between mobile tactical units.

The signals used in the system for transmitting information must have high noise immunity, ensure the secrecy of the structure and transmitted information, and also provide a sufficiently high speed of information transfer.

The listed requirements are best satisfied by noise-like signals obtained as a result of phase manipulation of a carrier frequency signal by pseudorandom sequences (PSP).

The prior art method for transmitting information in a communication system with broadband signals, which consists in generating carrier and clock signals, generating two quasi-orthogonal or orthogonal pseudorandom sequences from a clock signal, phasing pseudorandom sequences, one of which is phase-manipulated from the information source, form a second carrier signal, shifted relative to the first by 90 °; the signals generated at the carrier frequency are added up, the received signal is amplified and emitted through a communication channel; they generate a clock frequency signal from which two quasi-orthogonal or orthogonal pseudorandom sequences are formed, pseudorandom sequences are phased and synchronized, and information is extracted, digital data coming from the information source for a time equal to the period of the pseudorandom sequence is transformed one-to-one into one single pseudorandom shift sequence relative to another, and when receiving a signal determine the magnitude of this shift and pre it to form a digital data received information (see. eg. RU 2279183 "A data transmission method in a communication system with broadband signals", publ. 20.02.2006).

Also known from the prior art is a method for transmitting information in a communication system with noise-like signals, according to which digital data received from an information source is converted into a pseudo-random sequence generated over a time period during transmission (see, for example, RU 2286017 “Transmission method information in a communication system with noise-like signals ", publ. 04/27/2006).

The disadvantage of the methods in the above sources is the complexity of the implementation of the information transmission system using noise-like signals of short duration, which provide the highest stealth information transmission.

Closest to the claimed method of transmitting information is a method of transmitting information by noise-like signals, in which on the transmitting side the noise-like signals are formed by pseudorandom sequences, including sequentially alternating information and masking pseudorandom sequences, the duration of the masking sequences varies depending on the digital data received from the information source, and on the receiving side by means of a digital matched filter, on built on an informational pseudorandom sequence, a complex correlation function is formed, and the digital data of the received information is determined by the time intervals between the maxima of the modules of the complex correlation function (see, for example, RU2532085, published on 08.27.2014). In this method, the protection of the transmitted information from the means of intercepting an adversary in the Svoi-Alien identification system is carried out by using information and masking sequences in the signal, which are selected from a variety of orthogonal or quasi-orthogonal pseudorandom sequences. The information sequence is assigned the same for all means of identification and is changed simultaneously on all these means at set intervals. The masking sequence for each element of the interrogation or response signal is randomly selected from the set of sequences that do not coincide with the information sequence. The generated pseudo-random sequence for the interrogation or response signal is manipulated by the phase of the carrier frequency signal. At the receiving side, the signal is amplified and transferred to the zero frequency. After analog-to-digital conversion, a consistent signal filtering is performed. The digital matched filter is tuned to a pseudo-random information sequence. When a signal passes through a matched filter, a complex correlation function is formed at the output of the matched filter. The envelope of the complex correlation function is calculated and compared with the set threshold. Short pulses will be formed at the output of the threshold device only after passing through the information sequence to which the matched filter is configured. Masking sequences are orthogonal (quasi-orthogonal) to the information sequence; therefore, when passing signal sections containing masking sequences, the threshold will not be exceeded. The time intervals between pulses at the output of the threshold device determine the digital data of the received information.

The disadvantage of the described method of transmitting information is low immunity from intra-system interference, since all objects use the same information sequences for the request signal and the same information sequences for the response signal.

The purpose of the proposed method for transmitting information by noise-like signals in a mobile communication system is to reduce the effect of intra-system interference.

This goal is achieved due to the fact that in the method of transmitting information by noise-like signals between moving objects of a tactical link, in which, on the transmitting side, noise-like signals are formed by pseudorandom sequences, including sequentially alternating information and masking pseudorandom sequences, the duration of the masking sequences varies depending on digital data, coming from a source of information, and on the receiving side through digital about the matched filter tuned to the information pseudo-random sequence, form a complex correlation function, and the digital data of the received information is determined by the time intervals between the maxima of the modules of the complex correlation function, according to the invention, two information pseudorandom sequences are assigned to each object, one for the request signal, another for the response signal, which are selected from the set of orthogonal or quasi-orthogonal n sevd random sequences, while for different identification numbers use different information pseudorandom sequences for the response and interrogation signal, and the number of information pseudorandom sequences of both interrogation and response signals coincides with the number of objects in the tactical link.

The technical result provided by the given set of features is to reduce the influence of intra-system interference and increase the transmission capacity of information transmission. The relationship of the features with the technical result is disclosed below.

In the inventive method for transmitting information between objects of a tactical link, request and response signals are used. In standby mode at each object, the matched receiver filter is tuned to the information sequence of the request signal, which corresponds to its individual identification number. Both the interrogation and response signals consist of sequentially alternating informational (in other words synchronizing) and masking pseudorandom sequences. The duration of the masking sequences varies depending on the digital data coming from the information source. The first and last sequences are always informational. At the same time, each object by its identification number is assigned two pseudo-random information sequences, one for the interrogation signal and the other for the response signal. They are selected from a variety of orthogonal or quasi-orthogonal pseudo-random sequences. For different identification numbers, different information pseudorandom sequences are used for the response and request signal. The number of information pseudorandom sequences of both the request and response signals coincides with the number of objects in the tactical link.

To communicate with an object of a tactical link, it is necessary to determine the structure of the information pseudo-random sequence that will be used to form the request signal and the structure of the information pseudo-random sequence that will be used to form the response signal from its individual identification number. Digital data that must be transmitted over the communication channel from the information source is converted into the number of elements or the length of the masking sequences. The masking sequence for each element of the interrogation or response signal is randomly selected from the set of orthogonal (quasi-orthogonal) sequences that do not coincide with the information sequence. The generated composite pseudo-random sequence for the interrogation or response signal is manipulated by the phase of the carrier frequency signal. At the receiving side, the signal is amplified and transferred to the zero frequency. After analog-to-digital conversion, a consistent signal filtering is performed. The digital matched filter is tuned to a pseudo-random information sequence. When a signal passes through a matched filter, a complex correlation function is formed at the output of the matched filter. The envelope of the complex correlation function is calculated and compared with the set threshold. Short pulses will be formed at the output of the threshold device only after passing through the information sequence to which the matched filter is configured. Masking sequences are orthogonal (quasi-orthogonal) to the information sequence; therefore, when passing signal sections containing masking sequences, the threshold will not be exceeded. The time intervals between pulses at the output of the threshold device determine the digital data of the received information.

The inventive method allows to eliminate intra-system interference due to the fact that mutually orthogonal or quasi-orthogonal information pseudorandom sequences are used to form interrogation and response signals of different objects. A request or response signal can only be received by an object for which a matched receiver filter is configured for its information sequence. To protect against adversary’s technical intelligence, the law (one-to-one mapping), according to which the identification numbers of objects determine the structure of information pseudorandom sequences, can be changed at set intervals.

Claims (1)

A method of transmitting information by noise-like signals between moving objects of a tactical link, in which on the transmitting side noise-like signals are formed by pseudorandom sequences, including sequentially alternating information and masking pseudorandom sequences, the duration of the masking sequences varies depending on the digital data coming from the information source, and on the receiving side via digital matched filter tuned to information ion pseudo-random sequence, form a complex correlation function, and the digital data of the received information is determined by the time intervals between the maxima of the modules of the complex correlation function, characterized in that each object is assigned two pseudo-random information sequences by its identification number, one for the request signal and the other for the response signal which are selected from the set of orthogonal or quasi-orthogonal pseudorandom sequences, while for ase identification numbers using different pseudo-random sequence information for interrogation and response signals, and the amount of information as the pseudorandom sequences interrogation and response signals matches the number of objects in a tactical level.