GB678773A - Improved method for the quantization and coding of signals and apparatus therefor - Google Patents

Abstract

678,773. Pulse code modulation systems. TESLA, NARODNI PODNIK, and CARNIOL, B. Aug. 30, 1950 [Sept. 8, 1949], No. 21453/50. Class 40 (v). Amplitude-modulated pulse signals are converted into binary code pulse groups by applying them to a resonant circuit to produce free damped wave trains, of duration shorter than the repetition period of the input pulses, the oscillations of which down to a predetermined level being counted and the sum transmitted as a code. In the system described the sinusoidal output of a 10 kc/s. oscillator 8, is clipped and peaked in circuits 10, 12 to produce pulses 13 which together with the signal wave 36 from circuit 16 are applied to the pulse amplitude modulator 14. The amplitude modulated pulses 15 are fed into a 1 Mc/s. resonant circuit 17 to produce damped wave-trains 18, which are amplified and limited in circuit 19 to produce oscillations 20. The latter are fed through a filter 21, which removes those below a predetermined level, to a 5-unit binary counter 22. The 10 kc/s. wave from oscillator 8 is also fed to phasing circuits 23 ... 27, the outputs of which are spaced apart by 36 degrees and provide similarly-spaced trains of code pulses from circuits 28 ... 32, respectively. The code pulse trains are applied respectively to gate circuits 40 ... 44, which are opened or closed depending on the condition of the five counter stages in circuit 22. The gate circuit outputs which form 5-unit code groups are combined in a common output circuit 37, 38. After each coding operation, the counter stages are re-set by pulses from circuit 35 fed from the oscillator 8 through phase-shifter 33 and a limiting and peaking circuit 34. The amplitude-modulator 14 may comprise a valve to the grid of which are applied pulses and to the anode of which is applied the modulating signal, Fig. 1 (not shown).