Abstract: A transportation vehicle alert monitor incorporating a speech synthesizer for voice announcement of vehicle location by stop number. The monitor includes a radio receiver responsive to coded RF signals containing either current vehicle location data or data for programming the monitor. Current location data includes school system number, bus number, route number, and stop number. Programming data includes school system number, monitor serial number, student number, two route numbers for one bus number, and initial and final alert stops for each route. Programability of initial alert stops allows each alert monitor to be remotely adjusted to allow varying conditions including the discharge between adjacent stops, traffic conditions, and distance from a passenger's house to the stop.

Abstract: A digital transmission system using standard FM broadcast stations employs an SCA subcarrier which is amplitude modulated with a second subcarrier modulated to have different phase orientations representative of digital data. Bits are separated from a digital data stream in groups and are differentially encoded into one of at least four phase orientations of the second subcarrier. The amplitude modulated SCA subcarrier is combined with the stereo signal output of a stereo multiplexer to form the modulating signal for the station FM modulator. The receiver includes a differential phase detector for reconstruction of the differentially encoded digital data.A system which additionally includes means for modulating the SCA subcarrier with a composite signal having an audio signal in addition to the differentially encoded second subcarrier is disclosed.

Abstract: A circuit arrangement for a wide band superheterodyne radio receiver for receiving wide band FM, narrow band FM, and AM modulated radio signals between 25 and 550 MHz. The first LO is a phase locked loop controlled VCO, with central processing unit control of the phase locked loop circuitry. The first IF frequency is higher than the highest received frequency and the output frequency of the first LO is higher than the first IF. A second LO and second mixer convert the signal to a second IF lower than the first IF. Separate third and fourth IF band pass filters are provided at the second IF for WFM and for NFM/AM, respectively. The output of the third IF filter (WFM) is converted by a third LO and third mixer to a third IF lower than the second IF. A WFM demodulator is provided at the third IF. The output of the fourth IF filter (NFM/AM) is converted by a fourth LO and fourth mixer to a fourth IF lower than the second IF frequency. A fifth IF band pass filter is provided at the fourth IF.

Abstract: An in-band television signal sync suppression scrambling system has two sync suppression modes which are aperiodically alternated. Horizontal and vertical synchronizing pulses are equally suppressed in one mode, and are suppressed to different levels in a dual modulus mode. In single modulus mode, horizontal and vertical sync pulses are both suppressed at 6 dB. In the dual modulus mode, sync suppression is dynamically shifted between 10 db suppression for horizontal sync pulses and 6 db for the vertical interval. Mode control data is conveyed on the audio carrier and is detected by decoding circuitry which enables the restoration of synchronization pulses in the scrambled television signal according to the mode indicated. Mode changes are aperiodically changed depending upon the scene content in the TV picture or a random generator.

Abstract: A load management system which includes a central message generator and a plurality of addressable remote load controllers which selectively connect and disconnect high power deferrable loads to and from a power source in response to transmitted messages. The load controllers include means for translating coded tone pair inputs into digital data. Tones selected from three such tone pairs are used in one scheme, where a tone selected from the first tone pair is used for the initial bit of a message, and subsequent tones are alternately selected from the remaining two tone pairs or the remaining bits. One of the tones of the first tone pair is utilized as a test tone which initiates a test routine sequence. The test tone can be transmitted by a portable, low power transmitter to test the functioning of the remote units. A message format includes two code sets, a zone code set and a command/address code set.

Abstract: A load management system which includes a central message generator and a plurality of addressable remote load controllers which selectively connect and disconnect high power deferrable loads to and from a power source in response to transmitted messages. The load controllers include means for translating coded tone pair inputs into digital data. Tones selected from three such tone pairs are used in one scheme, where a tone selected from the first tone pair is used for the initial bit of a message, and subsequent tones are alternately selected from the remaining two tone pairs or the remaining bits. One of the tones of the first tone pair is utilized as a test tone which initiates a test routine sequence. The test tone can be transmitted by a portable, low power transmitter to test the functioning of the remote units. A message format includes two code sets, a zone code set and a command/address code set.

Abstract: A load management system which includes a central message generator and a plurality of addressable remote load controllers which selectively connect and disconnect high power deferrable loads to and from a power source in response to transmitted messages. The load controllers include means for translating coded tone pair inputs into digital data. Tones selected from three such tone pairs are used in one scheme, where a tone selected from the first tone pair is used for the initial bit of a message, and subsequent tones are alternately selected from the remaining two tone pairs or the remaining bits. One of the tones of the first tone pair is utilized as a test tone which initiates a test routine sequence. The test tone can be transmitted by a portable, low power transmitter to test the functioning of the remote units. A message format includes two code sets, a zone code set and a command/address code set.

Abstract: An automatic direction finding (ADF) system including a direction finding antenna array which connects to a radio receiver to process an audio output signal selectively illuminating a segment of a segmented circular visual directional display indicating the direction from which the received signal arrived. In an FM version, the ADF system electronically switches between antennas in the direction finding antenna array alternately incorporating vector information onto the received carrier in a manner that can be phase detected to produce an audio frequency signal within the normal pre-audio bandpass of the receiver. The audio frequency is then demultiplexed to produce separate vector signals. These separate vector signals are then processed for selectively illuminating a segment of the segmented circular visual directional display.

Abstract: A signal-seeking radio receiver is disclosed which can be manually programmed to receive a number of different channels in any combination with three bands with a minimum of switching circuitry. The receiver has pre-IF circuitry which includes at least one PNP transistor associated with each band, the base terminal of each transistor being connectable to one output of a solid state counter for controlling the band of operation of the receiver.

Abstract: A multi-band radio receiver is disclosed for automatically and sequentially tuning to a plurality of discreet, separate preselected frequencies. The receiver incorporates a phase locked loop frequency synthesizer which includes two separate voltage tuned oscillators alternately operative according to the band of operation of the receiver. Channels are selected by inserting metal combs having teeth removed to form a binary coded memory into corresponding sockets in the receiver. One comb is used for each of the channels to which the receiver can tune. By replacing a specific comb with an alternate comb, the channel to which the receiver tunes can be correspondingly changed. The combs are made of relatively brittle aluminum in order that they may be readily programmed to the appropriate binary coded decimal arrangement of pins.

Abstract: A signal-seeking radio receiver is disclosed which can be programmed to receive 20 different channels in any combination of three bands with a minimum of switching circuitry. Additionally disclosed is tuning circuitry for tuning the receiver in response to the programming to either the upper or lower portion of any given band.

Abstract: A signal-seeking radio receiver is disclosed which has two different types of local oscillator circuits. One type of local oscillator includes two transistors, the emitter of the first connecting to the base of the second and having a capacitor connecting between the emitter of the second and the base of the first. A large number of diode switched crystals can be connected to the base of the first transistor of the local oscillator without introducing an instability in the oscillator circuit. The second type of local oscillator is of the same general design as the first type except that it additionally includes a third transistor connected to the second transistor in a fashion similar to the first transistor. In this second oscillator configuration, the circuitry used to step among the channels also is used to alternately make either the first or third transistor operative in the local oscillator circuit.

Abstract: A receiver is disclosed for signal-seeking operation on a plurality of channels. The receiver uses power cycling of the RF amplifier stage, mixers, local oscillators and intermediate frequency amplifiers which is in synchrony with the electronic stepping switch used to sequence among the channels. The power which is cycled to these portions of the receiver passes in series through light emitting diode channel indicators.

Abstract: The invention pertains to means for selecting transmit and receive frequencies in a multi-channel transceiver. The superheterodyne-type receiver includes a mixer and a crystal controlled oscillator to provide a variable frequency signal to the mixer, while the transmitter employs a separate crystal control oscillator to provide an appropriate signal to the modulator. Elements of a first bank of crystals are individually connected to the mixer oscillator by the action of two stepping switches which are alternately operable, through the action of a load switch, to forwardly bias a diode connected in series between one of the crystals and the oscillator. A mode switch grounds one side of either of the stepping switches to render it capable of biasing the diode into conduction. A second bank of crystals is selectively connected to the modulator oscillator by means of a third stepping switch which is mechanically ganged to one of the receive stepping switches.