| 摘要 |
<p>PURPOSE:To obtain a pilot signal for tracking control, by selecting a prescribed division ratio from a common reference signal and therefore attenuating the 3rd higher harmonic wave down to a level sufficient for practical application. CONSTITUTION:An output signal (a) of a programmable counter 13 produces pulses after counting (l1+l2) units of reference signals 378fH. Then the signal (a) produces pulses with a cycle of (l1+l2) to reset the counter 13. A signal (b) counts l1 units of signals 378fH and produces pulses, and the cycle between signals (a) and (b) is set at l1. AND circuits 16 and 17 deliver AND outputs (e) and (f) of an RS-FF14 and FF15, respectively. Electronic switches 18 and 19 are turned on and off when signals (e) and (f) are set at high and low levels, respectively. A ternary staircase wave signal (g) is obtained by switchs 18 and 19 and resistances R1, R2 and R3. The signal (g) satisfies h=h' and therefore contains no even-order higher harmonic wave. Four pilot signals are obtained by giving 1/58, 1/50, 1/40 and 1/36 divisions to the reference signal 378fH through the counter 13. As a result, it is possible to attenuate the level of the 3rd higher harmonic wave down to a level sufficient for practical application even through l1:l2=2:1 is not satisfied.</p> |
