| 摘要 |
PURPOSE:To enable round of N notation, by changing the 9-notation counter into N-notation counter, through the display of frequencies of a broadcasting station through the round of received frequency every 9-notation. CONSTITUTION:With the pulse T1 from the control signal generator 7, the preset circuit 3 presets the value of the counters 1,2 to-459 when the intermediate frequency is at 455kHz. The succeeding pulse T2 opens the gates 8-10, and the counters 1,2 count the local oscillation frequency f0. When this count value reaches a given number, e.g. all ''0'', the numeral detection circuit 5 operates the 9-notation counter 4 via the control signal generator 7. This counter 4 counts f0 in synchronizing with the counter 2. When the pulse T2 is disappeared, the counters 1,2,4 stop operation. The numeral detection circuit 6 detects the value of the counter 4 and pulse T3 is generated from the control signal 7 so that the clock CL can be counted on the counters 2,4 until this value reaches ''0''. The value on the counter 2 shows accurate broadcasting frequency every 9kHz. |
