Key modulated pulse-train generator for telecommunication system

Claim 1

A system for the simultaneous generation of several frequency-modulated pulse trains for multichannel telecommunication, comprising: a source of clock pulses recurring at a fixed cadence fk; a first binary frequency divider with n cascaded stages connected to receive the train of clock pulses from said source for deriving therefrom a set of square waves of different fundamental frequencies subharmonically related to said fixed cadence, said square waves being available at respective outputs of said n stages; a plurality of coincidence gates connected to receive different combinations of square waves from said outputs with said train of clock pulses from said source for deriving therefrom respective pulse sequences each with a pulse width substantially equal to that of said clock pulses and with a recurrence rate equal to the fundamental frequency of the longest square wave received by the corresponding coincidence gate, said pulse sequences being mutually staggered; logical circuitry including a set of OR gates for selectively combining certain of said pulse sequences to derive therefrom up to N different pulse groupings all recurring identically with a repetition frequency of fk/2n, N having a maximum value of 2n-1, the number K of pulses in said groupings being different for each grouping and ranging between 1 and N, said logical circuitry further including gating means in the input of each OR gate connected to be traversed by at least one relatively low-rate pulse sequence while being bypassed by at least one relatively high-rate pulse sequence in noncoincident relationship with said low-rate pulse sequence; high-speed telegraphic keying means connected to said gating means for selectively suppressing said relatively low-rate pulse sequence in the input of any OR gate to produce an alternation between two different pulse trains; and a second binary frequency divider with m cascaded stages for each of said groupings connected to convert same into an alternation of two final square waves of different but substantially constant keying frequencies centered on a mean fundamental frequency equal to Kfk/2n m.

Claim 2

A system for the simultaneous generation of several frequency-modulated pulse trains for multichannel telecommunication, comprising: a source of clock pulses recurring at a fixed cadence fk; a first binary frequency divider with n cascaded stages connected to receive the train of clock pulses from said source for deriving therefrom a set of square waves of different fundamental frequencies subharmonically related to said fixed cadence, said square waves being available at respective outputs of said n stages; a plurality of coincidence gates connected to receive different combinations of square waves from said outputs with said train of clock pulses from said source for deriving therefrom respective pulse sequences each with a pulse width substantially equal to that of said clock pulses and with a recurrence rate equal to the fundamental frequency of the longest square wave received by the corresponding coincidence gate, said pulse sequences being mutually staggered; logical circuitry including a set of OR gates for selectively combining certain of said pulse sequences to derive therefrom up to N different pulse groupings all recurring identically with a repetition frequency of fk/2n, N having a maximum value of 2n-1, the number K of pulses in said groupings being different for each grouping and ranging between 1 and N, said logical circuitry further including gating means in the input of each OR gate connected to be traversed by at least one relatively low-rate pulse sequence while being bypassed by at least one relatively high-rate pulse sequence in noncoincident relationship with said low-rate pulse sequence; high-speed telegraphic keying means connected to said gating means for selectively suppressing said relatively low-rate pulse sequence in the input of any OR gate to produce an alternation between two different pulse trains; and a second binary frequency divider with m cascaded stages for each of said groupings connected to convert same into an alternation of two final square waves of different but substantially constant keying frequencies centered on a mean fundamental frequency equal to Kfk/2n m.