| 摘要 |
1,262,447. Frequency discriminators. HONEYWELL Inc. 23 July, 1970, No. 35651/70. Heading H3A. [Also in Division G4] A frequency discriminator comprises: a signal source 11 having a frequency which is high compared with the maximum frequency of a frequency modulated signal to be detected; means 12 for counting the high frequency signals to provide a count signal representative of the time period of a cycle of the frequency modulated input; and means 14 for operating on the count to provide an output having a linear relation to the frequency of the modulated signal. At a predetermined point in a cycle of the modulated signal, a gate in control unit 13 is opened to feed pulses from clock source 11 to a counter in unit 13. At a count of 202, the gate closes and another gate opens to feed the clock pulses to a counter 12 which commences counting with a count of 202. At the corresponding predetermined point in the next cycle of the modulated signal unit 14 divides a constant by the count attained in unit 12 to produce a signal proportional to frequency, and subtracts from this signal a further constant dependent on the mean frequency of the modulated signal to produce a signal proportional to the frequency deviation. A serial digital output is directly obtainable from unit 14, a parallel digital output is obtainable via a hold register 16, and an analogue output is obtained from a D/A converter 17 fed with the hold register output. Details of the units 13, 14 are given, Figs. 2, 3 (not shown). |
