SU1218492A1 - Demodulator of phase-shift keyed signals - Google Patents

Abstract

The invention relates to telecommunications. Increased immunity is provided. The input phase-mapped signal Uc (t) is fed to the multiplier 8 and through the delay block 11. to the manipulator 3. The signal Ua (t) from the phase detector 1 comes to the other input of the manipulator 3 through the phase generator 2. Balance /%. , the modulated oscillation Uo (f :) from the output of the manipulator 3 is fed to the multipliers 9 and 10. To the other input of the multiplier 9, the reference voltage Mtj (t) from the phase shifter (PV) 6 arrives. The signal Uj (t) from the multiplier 9 through the filter 5 of the carrier carries an additional PV 7. From the additional PV 7, the reconstructed reference oscillation of the subcarrier t-si (t) is fed to another input of the multiplier 10, and the reference oscillation of the subcarrier Ue, ( t) - to the reference input of the multiplier 8. From the multiplier 10, the recovered reference carrier oscillation through the filter 4 of the carrier and the PV 6 enters the phase detector 1, which receives the signal from the multiplier 8. 1 sludge. (L Ucft) ITM ND 00 CO K tJi (t

Description

The invention relates to telecommunications and can be used in radio systems for demodulating signals.

The purpose of the invention is to increase the noise tolerance during demodulation of the phase shift keyed signals on the subcarrier.

The drawing shows a structural electrical circuit of the proposed demodulator.

A demodulator of phase-shifted signals contains a phase detector 1 driver 2, manipulator 3, carrier filter 4, subcarrier filter 5, phase shifter 6, additional phase shifter 7, multipliers 8, 9, 10, delay block 11.

The demodulator works as follows.

The input phase-shift keyed signal on the subcarrier, having the form, for example,.

Uc (t) L (t) Sin {SJt + Y) sin (u) J to),

whereD (1) is an information signal; tj y - circular frequency and phase

carrier; 0. circular frequency and phase

subcarrier

enters the input of the multiplier 8 and the block 11 of the delay. In this case, the voltage from the output of block 11

Claims (1)

U, (i) A (t-Li) -, Sin (51 + M) Sin (i4H%) Invention Formula and the voltage from the output of shaper 2 connected to the output of phase detector 1, UjCt) ia-) arrive at the inputs of the manipulator 3, the output of which creates a balanced and modulated oscillation ) (SJt-f f) Sin (tJD o), where, (t-, tb) -Aa-t). The amplitude Lee of the output oscillation UoCt) of the manipulator 3 reaches the maximum value when selecting the delay time of the block 11 equal to the time of the information signal L (t -t). Output voltage K) (t) of the manipulator 3 and the reference voltage of the carrier from the output of the phase shifter 6 Uo (t) o.Sin (4tt-M o,) arrive at the inputs of the multiplier 9, creating a signal Uj (t) AoSin (,) bt..coeT. , where lz This signal is further filtered by the subcarrier filter 5 and phase-locked by the phase shifter 7. From the output of the phase shifter 7, the restored reference oscillation of the subcarrier  or (t) b- SinCSit + 4-. ) supplied to the input of a multiplier 10 installed in a carrier recovery chain. The filter 4 filters the reference oscillation carrier, and the phase shifter 6 is used for its phasing. When feeding the restored reference oscillations  U.i, (t) vsin (sit +) and carrier; Us (t), AjSin (uV + 0) To the reference inputs of the multiplier 8 and phase detector 1, demodulated information signals are created at their outputs. 0 five 0 five A demodulator of phase-shifted signals containing a series-connected carrier filter, a phase shifter, a phase detector, a driver, and a manipulator, which, in order to improve noise immunity during demodulation of phase-shifted signals on a subcarrier, a delay block, the first multiplier and the second multiplier connected in series, the subcarrier filter, the additional phase shifter and the third multiplier, and the input of the block, the delay and the third multiplier are combined and are the demodulator input, the output of the delay unit is connected to another input of the manipulator, the output of which is connected to the first inputs of the first and second multipliers, the second inputs of which are connected to the other outputs of the corresponding 11218492 4 phase shifters, the third multiplier is connected to the first multiplier is connected with the other input of the phase detector the input of the carrier filter and the output p