Carrier wave reproducing circuit

Abstract

Abstract PURPOSE:To prevent degradation of the error rate for carrier wave reproducing, by using the phase control signal with a demodulation eye pattern as the maximum to control the center frequency of a narrow band filter and by compensating phase error generated by input fluctuation, temperature change, and so on. CONSTITUTION:4-Phase PSK wave (a) is multiplied by 4 in multiplying circuit MLT to become carrier wave (e) of the quadruple frequency with modulation components eliminated, and this wave (e) is applied to tracking filter TF consisting of mixing circuits MIX1 and MIX2, band pass filter BPF, and voltage control oscillator VCO and is output as carrier wave (f) with needless components and noise components eliminated. The output of filter TF is 1/4-divided by frequency dividing circuit DVD to reproduce carrier wave (q) of the 4-phase PSK wave, and this wave (q) is applied to demodulating circuit DEM where the 4-phase PSK wave is input, and demodulation outputs (b) and (c) are applied to phase error detecting circuits PED. Outputs (b) and (c) are subjected to arithmetic operations in circuit PED to detect phase error, and this detection output (d) is applied to oscillator VCO of filter TF to control the center frequency, thereby compensating phase error.

Inventors

• 👤 Sadao Takenaka
• 👤 Tadayoshi Kato

Bibliographic Details