| 摘要 |
A frequency selector and tuning means for a radio or TV includes a keyboard input to receive a code from a user and a processor for calculating an address from the code and also for incrementing a signal applied to a phased locked loop. Once the station has been found, the incremented signal, which is a division ratio fed to a programmable divider which applies an output signal to a phase comparator of the phased locked loop, is stored in a random access memory at a location designated by the address calculated by the processor. A search mode allows a user to locate all stations and store, in the above described manner, division ratios in the memory which may be used to tune to that station later. To tune a particular station, the user keys in the code he has selected. The processor calculates the address and retrieves the division ratio from the memory. This division ratio is fed to the programmable divider to cause the frequency synthesiser to tune to the station represented by the code. |
