RU2290758C1 - Method for transferring discontinuous information in radio line with hopping working frequency - Google Patents

Abstract

FIELD: radio engineering, possible use in information transfer systems with hopping working frequency.

SUBSTANCE: in accordance to method, in known method during transfer of information transformations of information series into decimal numbers are performed, which numbers determine code of pseudo-random series and bearing frequency of transmitter; signal generated on basis of pseudo-random series code is modulated by frequency, synchronized on basis of bearing frequency of transmitter; during receipt by means of frequency filtration channel is selected, by means of which transmission occurred, maximal value of peak of autocorrelation function is determined, which value is used to determine pseudo-random series code, from which by means of serial reverse transformations decimal number is received, which is transformed to binary form appropriate for transferred information.

EFFECT: increased resistance to interference, provision of information and structural concealment of message being transferred.

1 dwg

Description

The proposed method relates to the field of radio engineering and may find application in information transmission systems with hopping of the operating frequency.

A known method of transmitting information with frequency hopping described in the patent of the Russian Federation No. 2099886, H 04 L 5/02. Bulychev O.A., Kalinin V.M., Popov V.I. "A method of transmitting information in radio lines with pseudo-random tuning of operating frequencies and a device that implements it", 1997, in which packets are generated from an information signal that are modulated at the corresponding frequencies and emitted into space. The disadvantage of this method is that the transmitted information is not protected from unauthorized access.

A known method of transmitting information with frequency hopping described in the application of the Russian Federation for invention No. 2001102653, H 04 B 1/713, H 04 L 5/06, H 04 J 3/06. Postnikov V.A., Shubenkin V.V. "A method and apparatus for pseudo-random tuning of the operating frequency", 2003, in which the value of the operating frequency generated according to the pseudo-random law is changed at pseudo-random times that are guaranteed synchronous for both sides of the radio line (by using additional synchronous pseudorandom sequences). The disadvantage of this method is the need for accurate synchronization of the radio line, which will significantly complicate the equipment, as well as the fact that the transmitted information is not protected from unauthorized access.

The closest in technical essence to the proposed method is the method described in the application of the Russian Federation for invention No. 99123808, N 04 In 1/713. Derkach E.N., Popov V.I., Lazorenko B.C., Sivokonev V.N. "A method of transmitting discrete information in a radio line with pseudo-random tuning of the operating frequency and a device that implements it", 2001, adopted as a prototype.

The prototype method is as follows.

At the transmitting end of the radio frequency hopping radio frequency division, the input signal is divided into information blocks, the carrier frequency of the transmitter is tuned in accordance with the code of one of two or more pseudo-random sequences (PSP), and the transmitter carrier is modulated by the corresponding information block with its subsequent radiation into space. At the receiving end, the signal is received at the same time only at those frequencies that correspond to the current codes of one or more memory bandwidth generators, the choice of the frequency channel through which the transmission was made, with the control of the noise level, the conversion of the signal to an intermediate frequency, amplification, demodulation, packet decoding and supply of an information signal to the terminal device.

In the prototype method, when the information is transmitted over the communication channel to the authorized users, the message itself is transmitted, which allows unauthorized users to intercept even a very small number of packets (making up a small percentage of the entire message) with a high probability of restoring the entire message. In addition, with this method of transmission, the message is little protected from the effects of deliberate interference, and the use of noise-resistant coding reduces the speed of information transfer. Thus, the disadvantage of the prototype method is the lack of protection of the transmitted message from unauthorized access and low noise immunity.

To eliminate these shortcomings in the method of transmitting discrete information in a radio line with hopping of the operating frequency, including at the transmitting end dividing the input signal into blocks of information presented in binary form; at the receiving end of a radio line — receiving a signal at all possible frequencies and for all possible codes of pseudorandom sequences, converting the received signal to a binary information sequence and supplying an information signal to a terminal device, according to the invention, a binary number constituting each information block is converted at the transmitting end of the radio line, in decimal, which, according to the algorithms known at the reception and transmission, is converted into two other decimal numbers, followed by conversion which in accordance with other, different from the above known on reception and transmission algorithms determines the pseudorandom code sequence and the carrier frequency of the transmitter; on the basis of a certain pseudo-random sequence code, a signal is generated, modulated and radiated into space, the modulation frequency being synthesized based on a certain transmitter carrier frequency; at the receiving end of the radio line using frequency filtering, a channel is selected on which the transmission was made; form peaks of the autocorrelation functions of the received signals, by comparing with the threshold value, determine the maximum value of the peak of the autocorrelation function, which selects the type of pseudo-random sequence by which the code number of the pseudo-random sequence is determined; consecutively carry out the inverse transformations: the code numbers of the pseudo-random sequence into a decimal number and the resulting decimal number into another decimal number according to the above algorithms; the resulting decimal number is converted into binary form corresponding to the transmitted information.

The proposed method for transmitting discrete information is as follows.

At the transmitting end of the radio line, the input signal is converted into a binary sequence, dividing it into binary blocks with an equal number of elements (Z bits). The Z bit of a binary block is a binary number X, which is converted to a decimal number

Y∈ [0.2 ^X -1].

In turn, the resulting decimal number Y is converted to two other decimal numbers:

N ₁ = f ₁ (Y) ∈ [0,2 ^X <1]

N ₂ = f ₂ (Y) ∈ [0,2 ^X <1],

where f ₁ and f ₂ are known at the reception and transmission algorithms.

The resulting decimal numbers N ₁ and N _{2 are} converted to other decimal numbers:

N _SRP = g (N ₁ ) ∈ [0.2 ^M -1], M≥X

F _MHF = h (N ₂ ) ∈ [0.2 ^K -1], K≥X,

where g and A are known at the reception and transmission algorithms other than f ₁ and f ₂ .

Further, N is determined by _CAP CAP code with the base (L bits), and for F is determined by the carrier frequency _hopping transmitter. Based on a specific SRP code, a signal is generated that is modulated by a frequency synthesized based on a specific transmitter carrier frequency. The modulated signal is emitted into space.

The signal is received at all frequencies and for all possible SRP codes. Using the frequency filtering of the received signal, the channel through which the transmission was made is determined. Then, the autocorrelation function (ACF) of the received signal with reference SRP and the maximum peak value of the ACF are determined to select the type of SRP. The PSP code (N _PSP ), represented in decimal form, is determined by a certain type of memory bandwidth.

Based on the decimal number N of the _PSP , the decimal number is first determined by inverse conversion

N = g ^-1 (N _SRP )

and then another decimal number

Y = f ^-1 (N).

Next, the decimal number Y is converted to binary X, and then converted to Z bit of a binary block. The binary blocks obtained in this way are combined into a binary information sequence, which is converted into the output signal form and fed to the information receiver.

Thus, in the described method of transmitting information, the operating frequency is tuned in accordance with the change in the transmitted information, that is, in a jump manner.

Therefore, the proposed method for transmitting discrete information provides the highest noise immunity (due to the element-wise accumulation of an equal base bandwidth) while maintaining confidentiality (due to the multiple conversion of the information signal and the abrupt adjustment of the operating frequency).

Functional diagram of a device for implementing the proposed method is presented in the drawing, where the following notation is introduced:

1 - source of information (NI);

2 - packetizer-depaketator (PD);

3 - modulator;

4 - the first antenna-feeder unit (AFB1);

5 - sync generator;

6 - information receiver (PI);

7 - frequency synthesizer (MF);

8 - the first memory block (BP1);

9 - code generator (GK);

10 - microprocessor;

11 - threshold block;

12 - the second memory block (BP2);

13 ₁ -13 _k - correlators;

14 ₁ -14 _k - frequency filters (BF);

15 - the second antenna-feeder unit (AFB2).

The device with which the proposed method is implemented, contains a serially connected information source (AI) 1, the information input of which is the first input of the device (transmitting end), packetizer-depacketator (PD) 2, microprocessor 10, the first memory unit (BP1) 8, code generator (GK) 9, modulator 3 and the first antenna-feeder unit (AFB1) 4, the output of which is the first output of the device; a second memory block (BP2) 12 and a frequency synthesizer (MF) 7 connected in series, the output of which is connected to the control input of the modulator 3. the second input of the device (receiving end) is the input of the second antenna-feeder block (AFB2) 15, the output of which is connected to the combined information inputs k frequency filters (BF) 14 ₁ -14 _k , the combined clock inputs of which are connected to the second output of the clock 5, the first output of which is connected to the clock inputs of AI 1, PD 2, GK 9 and modulator 3. Outputs BF 14 ₁ -14 _k are connected to on unity corresponding parallel inputs k correlators January ₁₃ -13 _k, the combined clock inputs of which are connected to the second output of the clock generator 5 and the input of the receiver timing information (PI) 6, whose output is the second output device, wherein k parallel outputs TU1 8 are connected to respective inputs of successive correlators January ₁₃ -13 _k, the combined outputs of which are connected to the input of the threshold unit 11, whose output is connected to the second input 8 TU1, a second serial output which Cpd ene to the second input of the microprocessor 10, a second output coupled to an input 12 BP2, k parallel outputs of which are connected to the control inputs of the corresponding BSF January ₁₄ -14 _k. The third output of the microprocessor 10 is connected to the third input of the PD 2, the second output of which is connected to the information input of the PI 6.

The device with which the proposed method is implemented works as follows.

At the transmitting end, the input signal enters AI 1, from the output of which the binary information sequence is sent to PD 2, where it is divided into binary blocks of Z bits constituting binary number X. From the first output of PD 2, information blocks are fed to the first input of microprocessor 10 , in which the following conversions are made: binary X is converted to the decimal number Y, which, in turn, is converted to other decimal numbers N ₁ and N ₂ , which respectively determine the decimal numbers N of the _SRP and F of the _{frequency hopper} .

By N _CAP CAP TU1 8 defined code and _{frequency hopping} by F in 12 BP2 carrier frequency is determined. The PSP code (L bit) defined in BP1 8 is generated in GK 9 and fed to the information input of modulator 3, where it is modulated by the frequency synthesized by the MF 7 based on the transmitter carrier frequency determined in BP2 12. Modulated SRP is emitted into space using AFB1 4.

At the receiving end of the radio line, the input signal received by AFB2 15 is fed to the information inputs of the BF 14 ₁ -14 _k , where the frequency channel through which the transmission was selected is selected. Each of BSF January ₁₄ -14 _k tuned to the frequency (F _FH), the value which is stored in the BP2 12. In this case codes 12 BP2 k parallel outputs are fed to respective control inputs of BSF January ₁₄ -14 _k, to clock inputs of which are fed clock signal from the second output of the clock 5.

From the outputs of the BF 14 ₁ -14 _{k, the} received signal is fed to the corresponding parallel inputs of the correlators 13 ₁ -13 _k , where the correlation peaks are determined. Each correlator 13 ₁ -13 _{k is} tuned to a specific reference memory bandwidth, the value of which is stored in BP1 8. With k parallel outputs of BP1 8, control signals are fed to the serial inputs of the corresponding correlators 13 ₁ -13 _k .

The peak value of the ACF at the outputs of the correlators 13 ₁ -13 _{k is} compared with the threshold in block 11. The number of the correlator having the maximum value of the ACF determines the type of memory bandwidth by which N _PSP is determined in BP1 8, which is fed to the second input from the second serial output of BP1 8 block 10. In the microprocessor 10, based on the decimal number N of the _{SRP, the} decimal number N is first determined, and then the decimal number Y is determined, which is converted from the decimal form to binary X, which is fed to the third input of PD 2, where it is converted to Z bit of the binary block. The binary blocks obtained in this way are combined in the PD 2 into a binary information sequence, which from the second output of the PD 2 is fed to the information input of the PI 6, where it is converted into the output signal form and fed to the second output of the device.

In this case, the work of PI 6 is synchronized by the signal from the second output of the clock 5, and the signal from the first output of the clock 5 synchronizes the operation of AI 1, PD 2, GK 9 and modulator 3.

The use of correlators in the proposed device makes it possible to accumulate the received signal element by element, which provides protection against the effects of deliberate interference. The use of memory blocks allows identification of the memory bandwidth code and operating frequency, and the use of a microprocessor allows multiple conversions of the transmitted and received signals, which provides protection against unauthorized access.

Thus, a device for implementing the proposed method for transmitting discrete information allows for high noise immunity while respecting confidentiality.

Claims (1)

A method for transmitting discrete information in a radio line with a frequency-hopping operating frequency, including at the transmitting end dividing the input signal into blocks of information presented in binary form; at the receiving end of a radio line — receiving a signal at all possible frequencies and for all possible codes of pseudorandom sequences, converting the received signal into a binary information sequence and supplying an information signal to a terminal device, characterized in that at the transmitting end of the radio line, a binary number is made up of each information number block, in decimal, which, according to the algorithms known at the reception and transmission, is converted into two other decimal numbers, subsequently conversion which in accordance with other, different from the above known on reception and transmission algorithms determine pseudorandom code sequence and the carrier frequency of the transmitter; on the basis of a certain pseudo-random sequence code, a signal is generated, modulated and radiated into space, the modulation frequency being synthesized based on a certain transmitter carrier frequency; at the receiving end of the radio line using frequency filtering, a channel is selected on which the transmission was made; form peaks of the autocorrelation functions of the received signals, by comparing with the threshold value, determine the maximum value of the peak of the autocorrelation function, which selects the type of pseudo-random sequence by which the code number of the pseudo-random sequence is determined; consecutively carry out the inverse transformations; pseudo-random sequence code numbers in decimal number and the resulting decimal number in another decimal number according to the above algorithms; the resulting decimal number is converted into binary form corresponding to the transmitted information.