GB1071392A - Multiplex pulse transmission system - Google Patents

Abstract

1,071,392. Multiplex pulse signalling. PRECISION MECANIQUE LABINAL. May 21, 1964 [May 22, 1963; March 20, 1964], No. 21070/64. Addition to 1,053,492. Heading H4L. The multiplex pulse transmission system of the parent Specification wherein control signals are represented by the time interval between a reference pulse and a signal pulse is modified in that the pulses consist of, and are identified by, stepwise variations in the repetition frequency of short pulses of oscillations of constant frequency, the signal pulse of each channel having its own distinctive variation. At the transmitter periodic reference pulses (R), Fig. 1 (not shown), and control pulses (1 and 2) whose leading edges are coincident with (R) and trailing edges represent the analogue values to be transmitted are produced, the trailing edges being converted into pulses (6, 7) correspondingly time spaced from the reference pulses (R). Each of the pulses (R, 6 and 7) consists of a stepwise variation in the quenching frequency of pulses of high frequency oscillations, pulse (R) being characterized by quench frequencies appearing in the order (# B , # C , # A ), pulse (7) by quench frequencies (# C , # A , # B ) and pulse (6) by quench frequencies (# A , # c , # B ), Figs. 3 to 5 (not shown). A further sequence (# B , # A , # C ) is used for discrete signals. The analogue control signals are supplied to modulators 16, 17, Fig. 6 and the discrete signal is controlled by switch 18, the respective outputs being supplied to a logic unit 19 supplied with reference pulses from generator 20 and controlling gates 25a, 25b, 25c. The three quench frequencies are generated by crystal controlled oscillators 21 &c., converted into rectangular waves by the clippers 24 and supplied to the respective gates 25a, 25b, 25c. Under the control of the input signals the unit 19 opens the appropriate gates and operates a selector 13 so that pulses of R.F. from oscillator 10 at the quench frequencies representing the pulses R, 6 and 7 are transmitted via power amplifier 14. A similar selector 13a and power amplifier 14a provides diversity transmission. The receiver, Fig. 7 (not shown), is provided with three filters 36a, 36b, 36c, tuned to the respective quench frequencies, following the demodulator 35, which are connected to a logic unit 38 whose outputs are connected to load circuits 39, 40, 41. An anti-jamming device 42 controlled by the logic unit is connected to the outputs 39, 40. In a modified transmitter, Fig. 8 (not shown), a master switch (48) controls gates (45, 46, 47) in the input circuits so that only one gate may be opened at a time to prevent overlap of signals and is arranged so that the analogue control signal gates are opened alternately when the two input signals are coincident.