1298123 Frequency generators; multiplex systems INTERNATIONAL STANDARD ELECTRIC CORP 29 April 1970 [5 May 1969] 20597/70 Headings H3F H3P and H4R In a generator for one or more carrier frequency signals harmonics are generated in a first multiplier 2 from a standard frequency source 1, the harmonic 2n or (2p-1) where n is any integer and p any integer greater than unity is selected by means of a first band-pass filter 3 and is subsequently formed into a train of sharp pulses having the repetition frequency 2n# or (2n-1)#, where # is the frequency of the source 1, in a second multiplier 4. A frequency m 2n# or m (2p-1)# where m is any integer as the case may be is selected by a second band-pass filter 5 from the train of sharp pulses and is divided by the factor 2n or (2n-1) as the case may be, in a digital divider. In the case where division is by 2n the square wave pulse train thus obtained and having a repetition frequency m# is used directly as a carrier signal; alternatively it may be converted to a sine wave by means of a bandpass filter. In the case where division is by (2p-1) the waveform is either converted to a mark-to-space ratio of 1:1 by means of a pulse shaper 9, or a sinewave selected by means of a band-pass filter 8. The embodiment comprises an arrangement for generating carriers for secondary groups having the frequencies 1116 1364, 1612 ... 4092 and 430 KH2, all odd harmonies of 124 KHZ supplied by generator 1, the factor 2n being 10 and m being 35.
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