Common television is high frequency the body of the head this machine oscillator is by LC oscillating circuit place is comprised, LC oscillator has the following drawback: 1, produce frequency drift easily, its oscillation frequency follows the change of temperature and change. 2, harmonic radiate is bigger, cause interference easily. 3, dog performance is bad, make in same frequency paragraph inside give the program that shows some channel to close inspect the effect to very much some of channel closes inspect the phenomenon with bad result. Very much now user is signal of use cable television, and cable television is to use adjacent frequency to transmit a technology, frequency drift can produce the phenomenon that the graph sound between adjacent channel disturbs. Additional, harmonic radiate can build the interference of didymous oneself to still can cause the interference of pair of other TV sets not only.
New-style now this machine of high frequency head oscillating circuit is to use Suo Xianghuan frequency to synthesize a technology, its component has: 1, fiducial crystal oscillating circuit (if the structure pursues) . 2, phase comparator. 3, scale down of pilot of IC bus line implement. 4, VCO oscillator. 5, pilot of IC bus line frequency paragraph switch implement. Generator of 6 harmonious voltage. Among them 1- - 4 comprised frequency of a Suo Xianghuan to synthesize an oscillator, its characteristic is oscillation frequency stability quite tall, harmonic radiate is little, because its can arise,comparative frequency has the oscillation of high accuracy to dog goodly so function, control scale down through IC bus line implement scale down number can achieve the goal that produces different oscillation frequency. The error tension that comparator place produces produces a harmonious tension through harmonious voltage generator, send VCO on one hand, send Gao Fang the return choosing frequency of class on the other hand, the structure that the weakness that this kind of high frequency head overcame common and high frequency head not only still changes as a result of one of body (will this brace up, frequency paragraph control, harmonious voltage produces part at an organic whole) make his stability is mixed but * sex has bigger rise.