GB1073071A - Improvements in and relating to receivers - Google Patents

Abstract

1,073,071. Tunnel-diode detectors; remote control of receivers; radio signalling; amplitude modulation. STANDARD KOLLSMAN INDUSTRIES Inc. Headings H3Q, H3R, H3T and H4L. A tunnel diode is arranged to operate as a self-oscillating super-regenerative detector (Fig. 12) for modulated carrier waves applied at 63, the squegging frequency being determined by circuit 65, 72 being a filter to reject the carrier frequency. The modulating frequency is taken off through a filter 79 which rejects the squegging frequency, and is applied to an amplifier 76. The tunnel diode is biased to its negative resistance region by a D.C. source 77. The detector is described in connection with a remote control system for a television receiver comprising a tunnel-diode squegging oscillator as transmitter in the remote location. This oscillator (Fig. 3, not shown) is basically the same circuit as is used for the detector, having a tunnel diode (31) and resonant circuits tuned to the carrier frequency of 1000 Mc/s. (45) and the modulating frequency (32) respectively. The modulating frequency may be 100-500 kc/s., e.g. 455 kc/s., or may be up to 1 Mc/s. The modulating frequency sweeps the tunnel diode in and out of its negative resistance region so that the carrier frequency is generated during alternate half-cycles of the modulating frequency. More than one modulating frequency circuit may be provided so that several modulating frequencies may be generated alternatively for selective operation of different controts of the television receiver according to a pre-arranged code. To do this (Fig. 13, not shown) a push-bar (84) connects the bias battery (82) and one or the other of two inductors (87, 88) in the circuit tuned to the modulating frequency so that R.F. pulses are emitted for the time that the bar is depressed to one side or the other. A tapped inductor may be used instead of two separate inductors (Fig. 18, not shown). It is stated that the capacitance of the tuned circuit may be altered instead of the inductance. Instead of the D.C. bias source the induction generator of Specification 1,073,072 may be used to provide A.C. bias, the on-off switch being in this case combined with the generator. The aerial unit (Fig. 6, not shown) comprises a copper strip (53) serving both as radiator and as oscillator tuned circuit, tuned by a capacitor (52) and enclosed in a metal housing (51) to confer directional properties. The receiver of the remote control system comprises an aerial unit identical with that of the transmitter, followed by the detector circuit described above. The tuned copper strip (Fig. 14, not shown) forms the carrier frequency tuned circuit of the detector. An alternative disposition of the components is given (Fig. 17, not shown). The detector output is applied to an amplifier (Fig. 15, not shown) powered from the television receiver supply via transformer (105). The modulating frequency is amplified by transistors (115<SP>1</SP> and 115) and applied to two circuits (116 and 116<SP>1</SP>) tuned to respond selectively to two different frequencies, e.g. 181 kc/s. and 197 kc/s., for performing different operations, e.g. tuning, on-off and volume control. Each signal is amplified by a separate transistor (110, 121) and passed to the appropriate relay (118, 122) for energizing a motor for the desired operation.