RU2165677C1 - Digital-data-to-broadband signal link - Google Patents

Abstract

FIELD: digital data transmission by broad-band phase-keyed signals over high-noise radio channels. SUBSTANCE: proposed link has on sending end data source, pulse- width modulator, phase modulator, balance modulator, power amplifier, transmitter synchronizer, carrier-frequency generator, phase-keyed noise-like signal generator, and transmitting antenna; on receiving end it has receiving antenna, mixer, local oscillator, intermediate-frequency amplifier, phase-keyed reference-signal generator, correlator unit, receiver synchronizer, demodulator, and data addressee, squarer, Fourier transformer, and Fourier inverter are also provided on sending and receiving ends. EFFECT: improved noise immunity of link due to reduced probability of synchronization beyond side lobe. 4 dwg

Description

 The proposed device relates to the transmission of discrete information by broadband FM signals and can be used in radio channels for transmitting information in a complex jamming environment.

Known communication systems with noise-like signals (for example, N.T. Petrovich, M.K. as a modulated parameter, the delay τ.
The noise generator gives a voltage r (t), the spectrum of which is formed by the filter. The signals r (t) and r (t-τ) are added in the adder and transmitted on the air.

 At the receiver, a correlation function is calculated.

 However, the noise immunity in this device is not high, since for receiving information it is necessary to establish the presence of a partial maximum of the correlation function, the amplitude of which is two times less than the amplitude of the main maximum.

 Also known is a digital communication system with phase-shift ShPS (L.E. Varakin "Communication systems with noise-like signals." - M .: Radio and communication, 1985, p. 16, Fig. 1.7), designed to transmit discrete messages. In the transmitter, information is fed to the input of the phase modulator, to the second input of which an FM signal from the FM signal generator — GFM — is fed. The operation of the GFM is controlled by a synchronizer, which generates the necessary control signals and frequencies. The sequence of SHPS in the form of FM signals, carrying information symbols, enters the modulator, in which the balanced modulation of the oscillation is carried out with the carrier frequency of the FM signals. A power amplifier amplifies these oscillations and radiates through the antenna into the ether.

 At the receiver, the signal is transferred to an intermediate frequency, amplified, and processed by a matched filter. From the output of the matched filter, the signal is supplied to the synchronizer and the resolver. The synchronizer searches for the FM signal by frequency and time, controls the operating mode of the deciding device.

 To search for a signal by frequency, the synchronizer rebuilds the local oscillator. Since a matched filter is included in this device, only incoherent reception of orthogonal signals is practically possible in this device, which leads to insufficient noise immunity of receiving information, since higher noise immunity is ensured by coherent reception and use of opposite signals. In addition, the practical implementation of a matched filter at large signal bases is a difficult technical task.

 Closest to the technical nature of the claimed object is the "Communication system with phase-shift ShPS" (L.E. Varakin, "Communication systems with noise-like signals." - M .: Radio and communication, 1985, p. 18, Fig. 1.9), taken for the prototype.

The functional diagram of the prototype device is shown in FIG. 1, where the notation is introduced:
1 - source of information;
2 - pulse width modulator;
3 - phase modulator;
4 - balanced modulator;
5 - power amplifier;
6 - generator FM ShPS;
7 - carrier frequency generator;
8 - synchronizer;
9 - transmitting antenna;
10 - receiving antenna;
11 - mixer;
12 - intermediate frequency amplifier - UPCH;
13 - block correlators;
14 - demodulator;
15 - recipient of information;
16 - local oscillator;
17 - generator FM reference signal;
18 - synchronizer.

 The prototype device has the following functional relationships. Serially connected information source 1, pulse-width modulator 2, phase modulator 3, balanced modulator 4 ,, power amplifier 5, the output of which is connected to the transmitting antenna 9. Serially connected synchronizer 8 and the FM generator ШПС 6, the output of which is connected to another phase input modulator 3. Another output of the synchronizer 8 is connected to another input of the pulse-width modulator 2. The output of the carrier frequency generator is connected to another input of the balanced modulator 4.

 On the receiving side, it contains a series-connected mixer 11, an intermediate frequency amplifier (IFA) 12, a correlator block 13, a demodulator 14, and an information receiver 15. In this case, one of the outputs of the synchronizer 18 is connected through the local oscillator 16 to the input of the mixer 11, the other input of which is connected to the receiver antenna. Another output of the synchronizer 18 through the FM generator of the reference signal 17 is connected to one of the inputs of the correlator block 13, the other input of which is simultaneously connected to one of the inputs of the demodulator 14 and the corresponding output of the synchronizer 18, the input of which is connected to the output of the correlator block 13.

 The prototype device operates as follows.

 In the transmitter, a telephone message (Fig. 2a) from the information source 1 is fed to the input of a pulse-width modulator 2, from the output of which a PWM signal (Fig. 2b) is fed to the input of a phase modulator 3, to the second input of which an FM NPS is fed (Fig. 2c) ) generated by the FM 6 generator. The phase-manipulated signal from the output of the phase modulator 3 (Fig. 2d), containing information, is fed to the input of the balanced modulator 4, in which the balanced oscillation modulation with the carrier frequency from the carrier frequency generator 7 is carried out. Then, amplified by power power amplifier 5 FM signal via an antenna 9 is radiated into space.

 The work of the pulse-width modulator 2 and the FM signal generator 6 is controlled by a synchronizer 8, which generates the necessary frequencies and control signals.

 At the receiver, the signal received at antenna 10 is fed to a mixer 11, where, using a local oscillator 16, it is transferred to an intermediate frequency and, after amplification in an intermediate frequency amplifier 12, is fed to a block of correlators 13. A reference signal in the form of an FMB is supplied to the second input of the block of correlators of the generator 17 ( see Fig. 2c). The block of correlators 13 consists of a multiplier and an integrator. The correlator block performs optimal processing of the received signal. The voltage at the output of the correlator contains a telephone message in the form of a PWM signal, which is fed to the input of the demodulator 14, from the output of which the received telephone message is transmitted to the recipient of information 15.

 The operation of the receiver as a whole and its individual units (local oscillator 16, FM generator 17, correlator block 13, demodulator 14) are controlled by a synchronizer 18, which first searches for FM NPS by time and frequency, and then maintains synchronism.

 But this prototype device has the disadvantage that the FM signal of the SHPS in its frequency spectrum has side lobes reaching 20% or more of the main lobe. The presence of side lobes in the frequency spectrum of the transmitted signal when searching by frequency often allows the receiving device to synchronize behind the side lobes, which leads to a significant deterioration in the noise immunity of the received information.

 To eliminate this drawback, a device containing an information source on the transmitting side, the output of which is connected to an input of a pulse-width modulator, the second input of which is connected to one of the synchronizer outputs, the output of a pulse-width modulator is connected to one of the phase modulator inputs, and the second output synchronizer is connected to the input of the generator FM ShPS. The output of the carrier frequency generator is connected to one of the inputs of the balanced modulator, the second input of which is connected to the output of the phase modulator, and the output of the balanced modulator through the power amplifier is connected to the transmitting antenna, on the receiving side, the receiving antenna is connected to the input of the mixer, the second input of which is connected to the output local oscillator, and the mixer output through an intermediate frequency amplifier is connected to one of the inputs of the correlator block, the output of which is connected to the synchronizer input and one of the demodulator inputs, the path of which is connected to the input of the recipient of information, the FM generator of the reference signal, the input of which is connected to one of the outputs of the synchronizer, the second output of which is connected to the input of the local oscillator, and the third output of this synchronizer is connected to the second inputs of the block of correlators and the demodulator, a direct converter is introduced on the transmitting side Fourier, the input of which is connected to the output of the FM ShPS FM generator, and the output is connected to the input of a quadrator, the output of which is connected to the input of the inverse Fourier converter, the output of which is connected to the second input of the phase modulator; on the receiving side, there is a direct Fourier converter, the input of which is connected to the output of the FM signal generator of the reference signal, and the output through a quadrator with the input of the inverse Fourier converter, the output of which is connected to the third input of the correlator block.

In FIG. 3 shows a functional diagram of the proposed device, where the notation is introduced:
1 - source of information;
2 - pulse-width modulator (PWM);
3 - phase modulator;
4 - generator FM ShPS;
5 - transmitter synchronizer;
6 - balanced modulator;
7 - carrier frequency generator;
8 - power amplifier;
9 - transmitting antenna;
10 - receiving antenna;
11 - mixer;
12 - local oscillator;
13 - intermediate frequency amplifier (UPCH);
14 - generator FM reference signal;
15 - block correlators;
16 - receiver synchronizer;
17 - demodulator;
18 - information recipient;
19, 24 - direct Fourier converters;
20, 23 - quadrators;
21, 22 - inverse Fourier transforms.

 The proposed device has the following functional relationships.

 On the transmitting side, it contains a serially connected information source 1, a pulse-width modulator 2, a phase modulator 3, a balanced modulator 6, a power amplifier 8, the output of which is connected to a transmitting antenna 9. Serially connected synchronizer 5, a generator of FM ШПС 4, a direct Fourier converter 19 , quadrator 20, inverse Fourier converter 21, the output of which is connected to another input of the phase modulator 3. Another output of the synchronizer 5 is connected to another input of the pulse-width modulator 2. The output of the carrier generator their frequencies 7 is connected to another input of the balanced modulator 6.

 On the receiving side, it contains a series-connected mixer 11, an intermediate frequency amplifier (IFA) 13, a correlator block 15, a demodulator 17, and an information receiver 18. One of the outputs of the synchronizer 16 is connected through the local oscillator 12 to the input of the mixer 11, the other input of which is connected to the receiving antenna 10 The other output of the synchronizer 16 through a series-connected generator FM 14, a direct Fourier transform 24, a quadrator 23 and an inverse Fourier transform 22 is connected to the corresponding input of the block of correlators 15, the other input of which o is simultaneously connected to another input of the demodulator 17 and the corresponding output of the synchronizer 16, the input of which is connected to the output of the correlation block 15.

 The proposed device operates as follows.

 In the transmitter, a telephone message (see Fig. 2a) from the information source 1 is fed to the input of a pulse-width modulator 2, the output of which the PWM signal (see Fig. 2b) is fed to the input of the phase modulator 3. From the generator, the FMB 4 is fed to the input of the direct Fourier transform 19, at the output of which we obtain the frequency spectrum of the signal, unfolded in time (see Fig. 4A). From the output of the direct Fourier transform 19, a signal representing the frequency spectrum of the video signal, deployed in time, is fed to a quadrator 20, where the signal spectrum is squared.

 In the inverse Fourier transform 21, into which the signal is supplied from the quadrator 20, the inverse Fourier transform is performed, and the signal is obtained at its output as a function of time with squaring the spectrum of the original signal.

 The second input of the phase modulator 3 receives a signal from the output of the inverse Fourier converter 21. The phase-manipulated signal with a squared spectrum containing information from the output of the phase modulator 3 is fed to the input of a balanced modulator 6, in which balanced modulation with a carrier frequency from the carrier frequency generator is carried out 7. Then, amplified by power in the power amplifier 8, the signal through the antenna 9 is radiated into space.

 The work of the pulse-width modulator 2 and the FM signal generator 4 is controlled by a synchronizer 5, which generates the necessary frequencies and control signals.

 At the receiver, the signal received at the antenna 10 enters the mixer 11, where, using the local oscillator 12, it is transferred to the intermediate frequency and, after amplification in the intermediate frequency amplifier 13, is transmitted to the correlator block 15.

 The FM generator of the reference signal 14 generates the FM SHPS, which is fed to the input of the direct Fourier transformer 24, at the output of which we obtain the frequency spectrum of this signal, unfolded in time. From the output of the direct Fourier transform 24, the signal in the form of a frequency spectrum is fed to a quadrator 23, where the square of the frequency spectrum of the original signal is produced. In the inverse Fourier transducer 22, into which the signal is supplied from the quadrator 23, the inverse Fourier transform is performed, as a result of which the output is a signal as a function of time with the squared spectrum of the original signal. From the output of the inverse Fourier transform 22, the signal is supplied to the second input of the block of correlators 15.

 The block of correlators 15 consists of a multiplier and an integrator and in it the optimal processing of the received signal is performed. The voltage at the output of the correlator block 15 contains a telephone message in the form of a PWM signal, which is fed to the input of the demodulator 17. From the output of the demodulator 17, the received telephone message is transmitted to the recipient of information 18.

 The operation of the receiving device as a whole and its individual units (local oscillator 12, the FM generator of the reference signal 14, the correlator block 15, the demodulator 17) is controlled by the synchronizer 16, which first searches for FM BSS by frequency and time, and then maintains synchronism.

In FIG. 4a shows the frequency spectra of FM SHPS, unfolded in time:
1 - frequency spectrum of the original signal;
2 - frequency spectrum of the original signal squared.

 In FIG. 4b shows the harmonics of the frequency spectrum of the original signal and the squared spectrum.

 It can be seen from graph 4a and table 4b that when squaring the frequency spectrum of an FM NPS, its side lobes sharply decrease and this, in turn, can significantly reduce the likelihood of false captures in the receiving device when searching by frequency.

 The implementation of Fourier converters 19, 21, 22, 24 can be carried out on Fourier processors RD Р16515. The implementation of the remaining blocks and nodes does not cause any difficulties, since they are well known and widely covered in the technical literature.

Claims (1)

 A communication line for discrete information with broadband signals, containing on the transmitting side a series-connected information source, pulse-width modulator, phase modulator, balanced modulator and power amplifier, the output of which is connected to the transmitting antenna, a transmitter synchronizer, one output of which is connected to the second input of the latitudinal pulse modulator, and the second output of the transmitter synchronizer is connected to the input of the phase-manipulated noise-like signal generator, and the carrier frequency generator Whose output is connected to a second input of the balanced modulator; on the receiving side there is a series-connected mixer, an intermediate frequency amplifier, a correlator block, a demodulator and an information receiver, one of the outputs of the receiver synchronizer is connected through the local oscillator to the input of the mixer, the other input of which is connected to the receiving antenna, the other output of the receiver synchronizer is connected to the input of the phase-manipulated reference generator signal, the input of the receiver synchronizer is connected to the output of the correlator block, the second input of which is simultaneously connected to the second input of the demodulator RA and the third output of the receiver synchronizer, characterized in that the forward-side Fourier converter, the input of which is connected to the output of the phase-manipulated noise-like signal generator, the quadrator and the inverse Fourier converter, the output of the inverse Fourier converter is connected to the other input of the phase modulator; on the receiving side, a direct Fourier converter, a quadrator, and an inverse Fourier converter are connected in series, the output of which is connected to the third input of the correlator block, and the input of the direct Fourier converter is connected to the output of the phase-manipulated reference signal generator.

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