| 摘要 |
PURPOSE:To switch a locking frequency and a locking frequency range in two ways by allowing a switch element to switch the signal flow to the 1st frequency discriminator and the 2nd frequency discriminator. CONSTITUTION:In throwing a switch 4 to the position A, an AFC loop is an AFC circuit using a frequency discriminator 5 and when an fS is within (fA+ or - DELTAfA), a VCO13 changes an fLO to lock the fS to the fA. In throwing the switch 4 to the position B similarly, when the fS is within (fB+ or -DELTAfB), the fS is locked to the fB. If the AFC circuit cannot lock the fS to the fA at the transient response, a broad band frequency discriminating characteristic is formed at the B position, the DELTAfB is increased and the locking frequency fB is adjusted to the same value as the fA so as to prevent it. |
