SYNTHESIZER OF DIGITAL REPEATER

摘要

PURPOSE: A synthesizer of digital repeater is provided to generate plus off-set frequency and minus off-set frequency selectively by preparing a VCXO(voltage controlled crystal oscillator) in a synthesizer. CONSTITUTION: A channel VCXO(31) generates a channel signal for a channel. A first directional coupler(32) divides the output signal of the channel VCXO(31). A mixer(33) mixes an intermediate frequency output from the first directional coupler(32) with an off-set frequency supplied by a divider(39). An off-set frequency control unit(200) outputs a voltage signal variably according to the output signal of the channel VCXO(31) supplied by the first directional coupler(32). A multiplexer(34) multiplies a reference signal and the output signal of the mixer(33) according to an established selection signal and outputs them selectively. A phase detector(35) detects a phase from the output signal of the multiplexer(34). A PLL(phase locked loop)(36) determines the phase in comparison with a phase difference detected in the phase detector(35). An off-set VCXO(37) makes a plus or a minus off-set frequency of the output signal of the PLL(36) according level of a voltage signal output from the off-set frequency control unit(200). A second directional coupler(38) divides the output signal of the off-set VCXO(37) and outputs it each to the divider(39) and a mixer of digital TV repeater.