Abstract: An optical imaging system which includes a light valve array target for producing the output image, and a photoemissive target which is responsive to input radiation to produce the desired informational pattern which is reproduced in the output stage. The input radiation generates photoelectrons in the photoemissive target and these photoelectrons are used to produce an electrostatic field on the deformable light valve elements.

Abstract: Television signal amplifier apparatus is described which protects undesirable impairment of the television signal. The apparatus includes a video signal amplifier. High speed switching devices are operative to control the gain of the amplifier as well as the amplifier output. These high speed switching devices are operated by fast acting signal level detectors and a fast acting sync signal detector, such that any signals above certain levels in the white and black regions of the television signal are suppressed even if of very short duration. The synchronizing signal detector operates to reduce the gain of the amplifier to less than unity, thus suppressing oscillation modes established in the video signal transmission path caused by looping the output to the input, as may occur in the course of television signal handling operations.

Abstract: In a television receiver, a tuning voltage for a varactor tuner is generated by the actuated stage of a plural step neon lamp memory in which each memory stage corresponds to a different television channel. The memory stages are connected as a ring counter which is stepped sequentially by a two-speed oscillator having a fast scan for undesired channel representing stages, and a slow scan to maintain actuation for a short time period of selected memory stages which correspond to desired channels which are to be viewed. Each memory stage includes a potentiometer with a wiper adjusted to generate the tuning voltage. To preprogram the undesired channel representing stages, the potentiometers in the stages are adjusted to produce maximum voltage, which is detected by a threshold switch to cause the oscillator to rapidly step to the next memory stage.

Abstract: A ghost canceller for the cancellation of a ghost signal from a complex electrical signal including a desired signal component as well as the ghost is provided wherein an electronically variable delay line of the charge transfer type is incorporated in a negative feedback loop. Bucket-brigade and charge-coupled devices may be employed with associated variable frequency clock oscillators to provide remotely variable delay times in an easily implemented structure.

Abstract: This relates to an apparatus for obtaining a specific antenna current or voltage waveshape at an antenna. A reference network, which includes a low level lumped element model of the antenna and the transmitter output network, produces drive signals when impulsed. The first of these signals corresponds to a voltage having the desired antenna current waveshape. The second is a voltage having a waveshape which must be produced across the input terminals of the transmitter output network in order that the specified antenna current be produced. The third signal is a voltage which has a waveshape equivalent to the waveshape of a current which must be injected into the input terminals of the transmitter output network in order that the specified waveshape be produced. At least one of these signals is used to drive the transmitter.

Abstract: A system for creating independent communication channels using a single optical fibre, is provided. To this end, at the transmitting end, several "laser" diodes such as that E.sub.11 (FIG. 1) supply infrared rays of a wavelength defined to within at least 50 angstrom units (in the case of suitably doped gallium arsenide diodes), to selective mirrors such as that M.sub.11 which are quasi-transparent vis-a-vis other wave lengths. These rays focussed along with those coming from other diodes, upon the entry face 11 of the fibre. At the receiving end, there is an arrangement similar to that at the transmitting end, but comprising, instead of the diodes, photodetectors. A diode and a photodetector may be exchanged in order to provide a channel operating in the reverse direction.

Abstract: A radio receiver is provided having a selectively tunable tuner section and a second tuner section which may be preset to receive the signal transmitted from a single transmitting station. A single output amplifier (including intermediate frequency and audio frequency) is included which is connected to a loud speaker. The first selectively tunable tuner may be connected to the amplifier either by a manually actuated switch or by a clock controlled timer actuated switch through a two position snooze switch. The preset tuner is connected to a timer controlled switch and through the snooze switch to the amplifier. When the snooze switch is turned on, it is not possible to connect the first tuner to the amplifier, but the second tuner is connected provided the timer has not opened the second tuner circuit.

Abstract: A circuit for providing TV channel selection and tuning voltages utilizes a plurality of fixed resistors and a plurality of Q variable inductances. A channel selection switch connects particular resistors and Q variable inductances for channel selection and fine tuning. The Q variable inductances are used for fine tuning and are connected in circuit with an oscillator and a detector. The Q variable inductances each have an adjustable steel core with the position of the core determining the amplitude of the detected oscillator voltage and thus the fine tuning control voltage.

Abstract: In a circuit arrangement for digitally indicating the tuned frequency of a radio receiver operating in the AM and FM ranges in which the oscillations of the AM tuning oscillator and of the FM tuning oscillator are amplified, converted to rectangular oscillations, counted by means of electronic counters and then digitally displayed, the oscillations of the AM tuning oscillator and the oscillations of the FM tuning oscillator are amplified by a common broadband amplifier which is sufficiently broadbanded so that the oscillator frequencies for the AM range as well as those for the FM range are both passed and amplified and the coupling of the input of the broadband amplifier to the outputs of the tuning oscillators is so loose that the tuning oscillators are not noticeably detuned by changes in capacity in the broadband amplifier.

Abstract: A wide-band automatic fine tuning (AFT) circuit capable of a .+-.2 MHz pull-in range without false lockups responds to the output of a picture carrier discriminator, a sound carrier discriminator and a vertical synchronizing signal sensing means to operate a reversible digital counter in either its count up or count down direction depending upon the relationship of the outputs of the two discriminators and the synchronizing signal sensing circuit. The output of the counter is supplied to a digital-to-analog converter which produces a tuning control voltage used for controlling the frequency of operation of the local oscillator of the receiver. The output of the digital-to-analog converter is added to a conventional AFT voltage which maintains the desired tuning once it has been established by the wide-band AFT system.

Abstract: A voltage controlled tuner in a television receiver is tuned to a desired television channel by sequentially selecting first and second digits representative of a desired channel number. The digits are stored in first and second memory registers from which corresponding analog tuning voltages are developed. Noise immunity circuitry coupled to the memory registers assures accurate registration of the channel digits in the memory registers by minimizing effects of contact bounce and other extraneous noise signals.

Abstract: In a data transmission system which uses frequency-differential phase modulation including a composite signal comprising a plurality of carriers apparatus is described for receiving and demodulating the aforementioned signal. In the receiver the signal, so modulated, is coupled to a plurality of correlators which produce d.c. voltages having values indicative of the phase states of the carriers. Binary words, similarly indicative of the phase states, are derived from the d.c. voltages, and these are stored in consecutive form in binary stores. The differences between the binary words yield the transmitted data. The outputs of the aforementioned correlators are connected to inputs of a time multiplexer which acts to connect outputs of two correlators to two multiplexer outputs. The outputs of the time multiplexer are connected to a phase modulator which produces a phase modulated signal responsive to the time multiplexer output signals.

Abstract: An automatic gain control system in which a DC voltage proportional to an on-channel signal is used to control the gain of the RF stage but is keyed from the wide band output of the mixer stage to reduce the possibility of mixer overload.

Abstract: A circuit for terminating the scanning operation of a signal seeking receiver includes a double-ended limit detector which responds to the AFC voltage developed in the receiver to produce a stop signal when the frequency deviations of the IF signal are within a narrow band centered about 10.7 Mhz.

Abstract: The present system generates a local PN (Pseudo Noise) sequence demodulation bit stream in synchronism with the modulation sequence of a received baseband signal. The system is comprised of a PN sequence generator for generating a local PN sequence signal in response to the pulse rate of a clock signal. A digital delay line generates early and late phases of the local PN sequence, which phases are correlated with the modulation sequence of the received signal. Early correlation causes pulses to be inserted into the train of clock pulses while late correlation causes pulses to be deleted from the train of clock pulses. A phase error less than a predetermined range (dead band) results in no adjustments to the train of clock pulses.

Abstract: Elapsed time from turn-on of a fluid light valve to the time when the initial, turbulent fluid has settled to a quiescent condition on which a noise free image may be inscribed by an electron beam is reduced by expanding vertical sweep size of the raster, expanding horizontal sweep size of the raster, or reducing electron beam current. These operations, which may be controlled individually or in combination during the turn-on period, sweep out excess fluid from the raster area to ensure that fluid depth is adjusted to less than critical depth over the entire desired raster area so as to establish a smooth and uniform fluid surface by the time the turn-on sequence has been completed.

Abstract: In an image sensor having a large scale array of semiconductor photodetectors, only the noise component is delivered from a first photodetector subsequent to the readout of a stored signal, in synchronism with the readout of a signal of a second photodetector, so that the noise component may be utilized for the cancellation of the noise component in the output from the second photodetector.

Abstract: The amplitude of a local oscillator signal for use with a frequency mixer is maintained at a given constant level by a control signal derived from the direct current flow through the mixer diodes.

Abstract: A combined encoder-decoder for use in two-way radio systems. The apparatus is operable in an encoder mode to provide tone oscillations during operation of the radio apparatus in the transmit mode and also in a decoder mode to provide a control signal in response to a received tone signal of a particular frequency during operation of the radio apparatus in the receive mode. The encoder-decoder includes a single active filter and a feedback circuit selectively coupled to the filter to form an oscillator for producing the tone oscillations in the encoder mode of operation. An input amplifier/limiter is enabled to apply received tone signals to the active filter during decoder operation. A control circuit responsive to operation of the radio apparatus is coupled to the feedback circuit and to the input circuit so as to selectively enable the feedback circuit during encoder operation and the input circuit during decoder operation.

Abstract: A communication system between mobile and wayside stations wherein the mobile stations are traveling on a track which is divided into sections by means of an open-type transmission line paralleling the track. A frequency selection and conversion device for each section of transmission line or track is connected to the transmission line to define the length of each section. A series of lower frequency carriers transmitted on the line are allotted respectively to each specific section of transmission line. These low-frequency carriers travel with a low loss along the transmission line and they are selected and converted by their respective frequency selection and converter device to a common high-frequency carrier signal for leaky transmission to a mobile station on the corresponding track section.