SU1096761A1 - Receiver of phase-shift keyed signals with single side band - Google Patents

Abstract

RECEIVER PHASOMANIPULATED. Single sideband signals containing a series-connected input bandpass filter and a phase detector, as well as a series-connected add-on filter and a synchronization unit, characterized in that, in order to improve noise immunity, between the output, the input band-pass filter and the input of the addition filter are included successively the first mixer, the other input of which is connected to the output of the synchronization block carrier and the differentiating circuit, and between the clock output of the synchronization block and the other input a phase detector connected in series second and third mixers, the other inputs of which are connected to the outputs polutaktovoy soot and carrier frequency synchronization block (L, respectively.

Description

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e: The invention relates to a communication technique and can be used in devices for receiving signals with phase shift 180 of a single sideband in radio communication, radar and radio measurements. A known receiver of phase-shifted signals with one sideband, containing a filter of one sideband, the output of which is connected to the first input of a synchronous detector and. through a narrowband filter to the second input of the synchronous detector Cl 3,. The specified receiver is characterized by insufficient noise immunity, since a part of the frequency band and the channel power are diverted for transmitting the clock information. The closest in technical essence to the present invention is a single-sideband phase-shifted signal detector containing a series-connected input bandpass filter and. a phase detector, as well as a series-connected complementary filter and a C2 J synchronization unit. The well-known receiver also does not provide high noise immunity, especially when transmitting information over a frequency-limited channel. The purpose of the invention is to increase the resistance of the reception of the phase manipulator -. signals from a single sideband. To achieve this goal, in the receiver of phase-shifted signals with a single sideband, containing a series-connected input bandpass filter and a phase detector, as well as successively connected auxiliary filter and synchronization unit, the first mixer is connected between the output of the input band-pass filter and the addition of the second filter, the other input of which is connected to the output of the carrier synchronization unit, and the differentiating circuit, and between the clock output of the synchronization unit and the other input of the phases detector in series of the second and third mixers, the other inputs of which are connected to the outputs of 14 W I 14h / - x "" L I1 .. V .. polutaktovoy and carrier frequency synchronization unit, respectively. Figure 1 shows the structural with the proposed receiver, figure 2 1 12 spectral diagrams showing the signal processing in the receiver. The receiver of phase-shifted signals with one sideband contains a bandpass filter 1, a first mixer 2, a differentiating circuit 3, an auxiliary filter 4, a synchronization unit 5, a second mixer 6, a third mixer 7, and a phase detector 8. The receiver works as follows. The input of the bandpass filter 1 is a signal (f | cosf fl, + - t-4 (with phase manipulation by 180 TeV {t (, j; J, and modulation of the amplitude over the length of the interval) 0.3 a sinusoidal law with a frequency equal to half the clock frequency, i.e. A (((2 |, whose spectrum is limited to one side band (SSB), where i, {is the carrier frequency and the beginning of the phase of the input phase-shifted signal, respectively; f , f, the frequency and the initial phase of the signal at the clock frequency, respectively; T cycle length or the duration of the information package of the manipulating sequence From the output of the bandpass filter 1, the signal (Fig. 2a) is fed to the first input of the first mixer 2, to the second input of which the signal cqs (7 (l / onl from the output of the carrier frequency of the synchronization unit 5 (Fig. 2b).) I f Ij of the phase-shifted SSB signal in the bosho of the first mixer 2 is taken to be numerically equal to half the clock frequency of the manipulating sequence |, 0.5,. (FIG. 2b). At the same time, all harmonics of the SSB signal spectrum receive an additional phase shift (Qf) determined by initial phase fofi reference oscillation per hour tote At the output of the differentiating circuit 3, a two-band phase-manipulated signal is formed with a rectangular manipulating message on the carrier frequency, those equal to the clock frequency, the initial phase of which is (/ (j-fV {2-font, i.e. A (t | co5 2I (f, tO,) t + f (i} fr | 2-fat, where A {tl is the envelope of the two-band phase-shift keyed signal with a right-hand coal manipulating signal J - h .-- ..; ..- j, l " lh) l. (fig.2g). Thus, in the receiver of phase-shifted SSB signals with a fully suppressed carrier, the spectrum is balanced by the frequency f Т T ft at - 2 transmission of the upper sideband. In this case, the transfer coefficient of the differentiating circuit 3 is determined by the ratio of the spectral density of the FM OPB signal from the rectangular bending manipulator at the carrier frequency () determined in the feff. Band and the spectral density of the FM OBP signal with the cone-shaped envelope of the manipulating sprinkling on the carrier {n in the same frequency band and equal to K (if). („. o, 5),„ „. chain j 2Ff and the Hilbert transformer with n koe 1d fOt y jtjoi l rtii / iiv./ 1 h l j ". the transfer factor j2F (fj (-0 | 5f), however when f c is its 2-t struc- ture — the structure corresponds to the differentiation of the circuit; and its subsequent differentiation allows it to be converted into a two-way phase-shift keyed signal with a rectangular shape of the manipulating band at the carrier frequency, the value of which is numerically equal to the clock frequency. This is necessary if the bandwidth of the communication channel is not equal. In this case, the spectrum of the two-band phase-shift keyed signal generated at the output of the differentiating circuit 3 is not symmetrical relative to the subcarrier and the complementary filter 4 equals the quadrature component of the signal. 3 through a complementary filter 4, the signal is fed to the input of synchronization unit 5. In synchronization unit 5, the methods 4 are known (for example, the Sifrov.Costas scheme, etc.) from a two-way phasicman of a paged signal the form of the manipulating parcel is the formation of a reference oscillation at the carrier frequency f j -1s with the initial phase (H + 0,), i.e. . (.5f) tf {VH O..n) and reference oscillation of the half-clock C05 (. + OL / t-) clock synchronization circuit (fig. 2e). The generated reference oscillations from the outputs of the half-clock frequency of the synchronization unit 5 go to the first and second inputs of the second mixer 6, respectively, at the output of which the differential frequency signal COS ((Fig.2e) comes out. The signal from the output of the second mixer 6 goes to the first input of the third mixer 7 The second input of which receives the reference oscillation of the carrier frequency f ° (2Ti ttnt of the output {of the carrier block of synchronization 5. At the output of the third mixer 7, a reference oscillation is formed that is coherent with the carrier frequency of the input phase After the multiply input of the phase shift keyed signal and the reference signal formed by the third mixer 7, an information sequence of cone-shaped pulses is formed at the output of the phase detector 8 (FIG. 2g). The structure of the synchronization unit 5, depending on the stability of the carrier frequency of the input signal of the FM OBP, can be implemented according to two functional schemes. In the first case, at high stability of the carrier frequency, the structure of the synchronization unit 5 includes a reference highly stable asynchronous local oscillator with a frequency op f the initial phase τ ofj and the formation of coherent subcarrier oscillations and clock frequency from the phase-shifted signal with two sidebands on the clock carrier. When the frequency instability of the carrier of the input signal of the FM SSB synchronization unit 5 can be implemented according to a scheme that includes a carrier synchronization scheme, for example, performed according to the Sifrov scheme and a clock frequency synchronization scheme, for example, performed according to the multiplication scheme of two clock information sequences shifted relatively friend- ha per poltakta. The increase in noise immunity in the proposed receiver as compared to limestone 4 is explained as follows. In the scheme of the known device, the bandwidth ui part is allocated for transmitting the sync information and only the remaining ifrt part is used for transmitting information.

In the proposed device, the synchronization channel is formed by directly processing the information signal. Therefore, in this case, the entire channel bandwidth is used to transmit information. Since the sending energy transmitted in the band 4f will be greater than the sending energy in the Aiy band (since), the noise immunity of the reception of single pulses, determined by the ratio of signal energy to the noise spectral power, will be higher in the proposed device than in the known

The inventive device also reduces the effect of intersymbol interference leading to an increase in the probability of error. it

This is explained by the fact that the duration of transients At, which is a function inversely proportional to the channel bandwidth (), is reduced in the proposed device by expanding the information channel bandwidth.

The third factor that determines the noise immunity is the formation of a signal coherent with the carrier frequency signal in the proposed scheme from a signal with 15 higher energy, which will reduce the effect of the synchronization channel on the error probability. After passing through to filter 4, a two-band signal is formed in the 4f, 20A band in the well-known device in the L band, where only a part of the spectral components of the input phase-shifted signal is located.

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Claims (1)

THEIR SIGNALS WITH ONE SIDE BAND, comprising a series-connected input band-pass filter and a phase detector, as well as a series-connected complementary filter and a synchronization unit, characterized in that, in order to increase noise immunity, between the output of the input band-pass filter and the input of the complementary filter are connected in series the first mixer, the other input of which is connected to the output of the carrier synchronization unit and a differentiating circuit, and between the clock output of the synchronization unit and the other phase input · a detector included sequentially the second and third mixers, the other inputs of which are connected to the outputs polutaktovoy and carrier frequency synchronization unit, respectively.