Patent GB-729255-A (GB)
Title: Improvements in or relating to pulsed radio communication systems
IPC: H04B7/17
Filed: 1953-02-02
Abstract: 729,255. Pulse signalling; pulse circuits. TELEFUNKEN GES. FUR DRAHTLOSE TELEGRAPHIE. Feb. 2, , 1953 (Feb. 16, 1952], No. 2954/53. Classes 40(5) and 40 (6). Relates to arrangements, for use at a relay station in a radio pulse. multiplex communication system, by which channel signals are removed from the incoming pulse train and further channel signals are inserted in their place. In the embodiment described the channel pulse recurrence frequency is 8 kc/s. and the number of time-modulated channels is twenty-four. The circuits for the west-east direction comprise the channel selector and demodulator Z1, DA, Fig. 2, where from the incoming pulse train a, Fig. 6, of recurrence frequency 192 kc/s. are derived two interlacing 96 kc/s. trains b, c occurring between the channel pulses. The channels to be removed are selected and demodulated in circuit DA and passed over lines T to the local telephone system. Channels to be inserted are fed over local lines M to the pulse modulator MB associated with the selecting and mixing circuits Z2, Mi. The circuits PhI and PhII in units Z1, Z2, derive from the synchronizing pulses sine waves of frequencies 96, 24 and 8 kc/s. to control the channel separators and modulation circuits, the two latter frequencies being available at adjustable phase. A circuit for the production of gating pulses, for the removal of channels from the incoming train, has five inputs 1 . . . 5, Fig. 4a. Inputs 1, 4 are the 96 kc/s. pulse trains b, c, Fig. 6, and 2, 3 and 5 are the 8 kc/s., 24 kc/s. and 96 kc/s. sine waves, respectively. The series-connected secondaries of transformers U1 ... U3 and U1<SP>1</SP> . . . U3<SP>1</SP> produce sum voltages which on application to diodes D1, D2 respectively are clipped to yield a single pulse of each group of twelve, the diodes being biased for peak-clipping by resistance-capacitance combinations R1, C1 and R2, C2 respectively. The particular pulses selected are determined by the phases of the 8 and 24 kc/s. sine waves from the circuit PhII selected by switches S3, S4 respectively. The polarity of the 96 kc/s. pulses is determined by the setting of switches S1, S2. As shown, a positive pulse d, Fig. 6, from input 1 is developed across the load R3 of diode D1 and a negative pulse e from input 4 across the load R4 of diode D2. The positive pulse charges capacitance C0 through diode D3 and the negative pulse discharges it through diode D4, so that at the output terminal 6 is developed a gating pulse f covering a single selected channel interval or a selected number of adjacent channel intervals. If it is desired to remove alternate pulses only from the incoming pulse train, the pulse f is applied to the control grid of a mixer valve Ro<SP>11</SP>6, to the cathode of which are applied 96 kc/s. rectangular pulses g from a squarer valve Ro<SP>11</SP>5 fed with the sine wave input 5. The resulting gating wave h appears at the anode 7 of the mixer valve. To remove the corresponding channel pulses from the pulse train a applied to input 8, Fig. 4b, this train is fed through valve Ro<SP>11</SP>7 to the cathode of valve Ro<SP>11</SP>8 while the gating wave h is fed to its control grid from terminal 9. The resulting output i of unsuppressed pulses is fed to the grid of valve Ro<SP>11</SP>9 whose cathode 10 is supplied with fresh modulated channel pulses k to fill the gaps, a completed pulse train being fed to the phase inverter valve Ro<SP>11</SP>10 for retransmission.