TUNING SYSTEM FOR DIGITAL SATELLITE RECEIVER PROVIDED WITH DEVICE FOR PRECISE TUNING

摘要

PROBLEM TO BE SOLVED: To provide an economical tuning system for digital satellite television with which possibility for the operation of a carrier wave reproducing loop for demodulating a digitally encoded intermediate frequency(IF) signal to be interrupted by a tuner during a precise tuning mode is lowered. SOLUTION: A tuner 9 is composed of a single converting step utilizing a conventional ground tuning control PLL integrated circuit 921 for controlling a local oscillator frequency. An integrator filter 925 related with the PLL integrated circuit 921 is changed for decreasing the rate of change in the local oscillator frequency during the precise tuning mode. Since speed for controlling the frequency of local oscillator signal is decelerated during the precise tuning mode concerning PLL arrangement 919, a digital data demodulator 11 can extremely easily follow up the frequency change of IF signal during the precise tuning mode and possibility to interrupt video and audio responses is decreased.