GB239856A - Improvements in or relating to wireless signalling - Google Patents

Abstract

239,856. Soc. Franþaise Radio-Electrique. Sept. 10, 1924, [Convention date]. Transmitting systems and apparatus; oscillation generators.-In order to maintain a constant radiation frequency from any generator in which the frequency transmitted depends on the electrical characteristics of a reaction circuit, the main oscillator is coupled to an auxiliary source of standardized frequency and the resulting beat wave is rectified and utilized to saturate an iron-cored inductance, or other variable impedance, contained in the main oscillatory circuit. As shown in Fig. 1, a source of standard frequency 5 is coupled to the main oscillatory circuit 1, 2, 3, and the resultant beat frequency is rectified by a valve 11. This intermediate frequency is then applied to the slightly detuned input 13 of a second detector 15, and the rectified plate output is caused to saturate the iron core of transformers 3, 4 the secondary windings of which are contained in the main circuit. Any alteration in the main frequency affects the beat frequency, and thereby changes the effective impedance of the windings 3, thus acting automatically to stabilize the circuit 1, 2, 3. Fig. 2 shows a modified arrangement in which the plate of the second detector 17<1> is connected to a shunt circuit 14<1>, 15<1> tuned to the actual beat frequency, and in which there is no separate source of high tension. The secondary windings 3<1> of the variable impedance devices are included in the main oscillatory circuit, as before. Signalling is effected by means of a key 8 which short circuits a part 6 of the total inductance 6, 7 in the output circuit of the standardized oscillation generator 5.