Abstract: In the field of powerline carrier transmission and reception for remote control, a slave receiver counts cycles of carrier in a time window near to a zero-crossing of the power main. The receiver is implemented using discrete components (1,2,3) and a microprocessor. The discrete components form an input filter (1), a limiting preamplifier (2), a demodulator and noise filter (3) and, along with the microprocessor, a system (4) to detect the zero-crossing points. A capacitor is charged and discharged, depending upon the rate of occurrence of carrier cycles to produce a binary signal dependent on the digital value present on the carrier. By measuring the length of time the binary signal is in one of its states in said time window, the microprocessor determines whether the signal resulted from noise or not.

Abstract: An electrical appliance remote control system comprises a transmitter supplying digital control messages onto a power main and a receiver for receiving those messages to activate an appliances accordingly. Each message comprises words each of which is transmitted twice. A repeater is coupled to the main to receive the first occurrence of the word and to retransmit that word onto the main, or onto another main, in the period containing the second occurrence of the word.

Abstract: A transmitter, for electrical appliance control by transmitting digital control signals on a power main, comprises two releasably connected parts, a first part comprising m actuators to initiate the generation of m control signals, and the second part containing a generator for the control signals, and a selector for selecting m out of n control signals. The selector is hidden by the first part when the parts are joined together and may be adjusted to select different groups of m control signals from the n possible signals. All n control signals can be produced, in groups of up to m signals for each condition of the selector. A monitor is also provided to monitor the main in order to achieve transmitter queueing dependent upon the selector settings at the transmitters.

Abstract: The switching circuit couples an appliance (1) to a power main (LN) via remotely controllable switching means (2) and is operable to change the state of the switching means (2) in response to a manual double switching of the appliance power switch so that the appliance can be manually switched ON after it has been remotely switched OFF.A capacitor (CAP1) generates from the mains voltage an alternating current signal of a phase differing from that of the mains voltage by an amount dependent on the external impedance across the output. The switching circuit monitors this phase difference and changes the state of the switching means (2) if it detects two phase difference changes exceeding a predetermined value in opposite senses within a predetermined time period, this being indicative of a manual double switching of the appliance power switch.The switching circuit does not operate spuriously for thermostatically controlled appliances nor in response to noise spikes.

Abstract: An applicance control system comprises a data transmitter and plurality of slave units plugged into outlet sockets of a power main of a building, appliances being coupled to the slave units. The transmitter housing includes a data input arrangement by which slave unit addresses and operation signal can be input and means for producing therefrom digital address and operation signals injected onto the main for receipt by the slave units. Each slave unit is enabled by a digital signal complying its address to effect an appliance operation as defined by a received digital operation signal.

Abstract: An acoustic remote control link transmits different value bits as pulses containing different numbers of carrier cycles and identifies those bits on reception on the basis of the received pulses containing numbers of carrier cycles in one or other of two ranges. Each word transmitted is accompanied by a word of inverse digital value, the two words being compared on reception. A received pulse is deemed to have finished when a gap of given duration exists in the carrier.

Abstract: Gramophone equipment has a record changing mechanism including a screw arrangement which can be operated to lift and lower a record support platform.

Abstract: A record player has a record track selection system using sensing means to scan a record to identify selected record tracks, the sensing means feeding signal processing circuitry having a gain or threshold adapted to individual record characteristics as determined by a record scan prior to track identification.

Abstract: Gramophone equipment incorporating photoelectric scanning to detect bands between record tracks; an electronic counter to count the detected bands; a selector for making track selections; an electronic memory for storing selections; control circuitry for comparing the contents of the counter and memory to control a tone arm of the equipment to play selected tracks and lift from a record at the end of a selection; and a tone arm drive comprising means for lifting and lowering the arm and means for driving the arm laterally under control of the control circuitry.

Abstract: A calculator utilizing floating point logic by means of registers in the form of random access memories the bit positions of which are sequentially addressable, reversible timing means for addressing each register sequentially in either direction and programming means for causing numbers to be handled in said registers in the form of the exponent and mantissa of said numbers. The preferred embodiment of calculator also has control logic for said registers enabling bits to be displaced in said registers in a direction selected by said timing means for effecting the operations of multiplication and division by ten.