HEAD-END DEVICE FOR TERRESTRIAL DIGITAL BROADCAST RECEPTION, LEVEL ADJUSTING DEVICE, AND TERRESTRIAL DIGITAL BROADCAST COMMUNITY RECEPTION SYSTEM

摘要

PROBLEM TO BE SOLVED: To improve broadcasting performance and to expedite cost reduction by making an inexpensive SAW filter usable by reducing influence of a disturbing wave caused by a frequency shift. SOLUTION: A 1st mixer (46) and a 2nd mixer (49) use in common one local oscillation frequency (1st local oscillation frequency fa) generated by a 1st local oscillator (51). A disturbing wave is suppressed by eliminating the frequency shift between the 1st mixer (46) and 2nd mixer (49) and the influence of only "fluctuations" of one local oscillation frequency (2nd local oscillation frequency fb) is exerted to reduce the fluctuations nearly to a half as compared with a conventional technique which sums up "fluctuations" of two local oscillation frequencies (f1, f2). COPYRIGHT: (C)2006,JPO&NCIPI