Abstract: An apparatus for controlling a transmitter-receiver which can transmit and receive an aural signal and a data signal. In the transmission mode, the control apparatus detects a data transmission instruction of the transmitter-receiver and changes to the mode in that the data signal is supplied to the transmission unit of the transmitter, thereby executing the data transmission. On the other hand, in the reception mode, the control apparatus discriminates that the signal received is the transmission data to the transmitter-receiver and reduces the output volume of the receiving unit, thereby allowing the transmitter-receiver to receive the reception signal as the data signal.

Abstract: A terminator for a transceiver device for transmitting data signals to and receiving data signals from a second transceiver device over a transmission line therebetween. The terminator has a transmitter connected to the transmission line for transmitting data signals to the second transceiver device, a receiver connected to the transmission line for receiving data signals from the second transceiver device, a termination resistor connected to the transmission line for improving the transmission characteristics of the transmission line, and a switch device between the termination resistor and the transmission line. The switch device is closed for a portion of the time when the receiver is receiving data signals from the second transceiver device such that when it is closed the termination resistor is connected to the transmission line, and is open for the remainder to the time such that when it is open the termination resistor is not connected to the transmission line.

Abstract: Interference from frequency modulated transmitter signals, such as radar jamming signals, is cancelled in a nearby receiver by orthogonally related cancellation signals derived from the transmitter signal. The cancellation signals are controlled or modulated by corresponding cancellation modulation signals derived from the transmitter frequency modulation signal superposed on weighting signals. The employment of the transmitter frequency modulation signal as part of the cancellation modulation signals reduces cancellation error resulting from differences in frequency dependent delay shift in different transmission paths for the interfering signal and the cancellation signal.

Abstract: A local computer network transceiver is provided for a distributed control local computer network which applies a signal to a medium which has a DC component wherein isolation is implemented at the medium interface without need for direct current coupling of any active circuit to the communication medium. The medium is typically a coaxial cable. Transmit isolation transformers are coupled across a coaxial coupler, the medium side thereof being coupled in series with a diode. A plurality of transmit isolation transformers may be coupled in parallel to the medium to permit operation at substantially higher frequencies than would otherwise be permitted due to self-resonant frequencies of the isolation transformers. A receive interface through a receive isolation transformer is provided with capacitive balancing to prevent common mode voltages from being converted into recognizable signals.

Abstract: A system is disclosed which includes a radio transceiver and a radio broadcast-band receiver housed in a package that is supported by a helmet of the type worn by mobile users such as motorcycle, bicycle, moped and skateboard riders and the like; or by non-mobile users such as policeman, fireman, construction workers and the like. In the absence of signals to or from the transceiver the user listens to radio broadcasts. Voice actuated circuitry disables the radio receiver and enables the transceiver transmitter for message transmission by the user to a remote station against a background of silence, or against a background of the user's voice. Other circuitry is responsive to a message from a remote station received by the transceiver receiver for disabling the radio receiver so that message is heard by the user against a background of silence.

Abstract: An electronic process and device are provided for decoupling a receiving antenna situated in the immediate vicinity of a transmitting antenna transmitting a frequency modulated interfering signal.The process consists in superimposing on each of the signals for the static control of variable attenuators, disposed in a regulation loop for cancelling out the interfering signal received by the antenna, a signal whose amplitude is proportional, at all times, to the difference between the carrier frequency of the interfering signal and the instantaneous value of its modulation signal .phi.'.sub.B (t).

Abstract: A vehicle radio telephone system is constructed to talk between a vehicle and a fixed station through any one of a plurality of radio channels. Upon degradation of a talking condition during talking, the radio channel is switched and a tone is sent to talkers to inform them that the radio channel is now being changed.

Abstract: A voice-controlled, operator-interacting radio transceiver has a transceiver for transmitting and receiving radio frequency signals under plural potential operating conditions including on/off, transmit/receive, frequency of operation, squelch, volume control, etc. A speech recognition circuit receives audible verbal phrases spoken by a human operator and produces control signals in response to certain predetermined recognized phrases. The operation of the transceiver is controlled in response to the control signals and further coded data signals representative of the respective predetermined operating condition of the transceiver are also produced. Output devices are responsive to the further coded data signal for producing an output signal perceptible to the human operator and confirmatory of the control action then being effected.

Abstract: An adaptive canceller construction for cancelling signals received by a radio receiver operating in close proximity to a transmitter having means for extending the usefulness of the device over a wide band of frequencies. The canceller is provided with a memory which will remember the adopted parameter from one time in a given band to the next, so that as a jammer frequency jumps back and forth among several narrow frequency bands, the canceller will jump among a corresponding set of remembered parameters.

Abstract: Frequency division communication system wherein conventional transmitter-transceiver can be used as or repeater or local base station. No additional transmitter and receiver are required to adapt transceiver to function as interchannel repeater.

Abstract: A system for automatically controlling the changeover of transmission and transmission stop, and being employed in the transmitting device provided with a vibration pick-up type microphone for picking up bone-conducted voice sounds. The automatic changeover of transmission and transmission stop is attained by control signals corresponding to impact vibrations except voice signals uttered by a microphone wearer himself, transmitted through his bones and picked up by the microphone or another controlling microphone.

Abstract: In acoustical sound processing equipment, a combination microphone and blow actuated keying and unkeying means. The speaking person blows a first time into a tube to key the processing equipment and blows a second time to unkey the equipment. The person also vocalizes into the tube. The tube is in fluid communication with a chamber which houses the microphone. A blow detector senses the blowing action and triggers a bistable flip-flop which in turn drives a keying relay.

Abstract: Hands-free control circuitry for a mobile radiotelephone is described that allows hands-free voice communications in a vehicular environment having a high level of ambient background noise. The hands-free control circuitry includes switches in the audio path from a microphone to the radio transmitter and the audio path from the radio receiver to a speaker, where, at all times, one audio path is closed to pass audio signal and the other audio path is open to block audio signals. The presence or absence of audio signals from the mobile party via the microphone and land party via the radio receiver is determined by separate detecting circuitry including a logarithmic amplifier, envelope detector, valley detector and summing circuitry, and comparator. Whenever the envelope of the audio signals exceeds its minima by an amount greater than a reference voltage, the detecting circuitry generates an output signal indicating that audio signals have been detected.

Abstract: Prior to each voice activity period, the transmitter supplies a digital preamble for coding the speech signal levels and during these periods high frequency signals modulated in substantially constant amplitude, but transmits nothing other than said preamble and said periods. On reception, a signal detector and logic elements control a switch to obtain only speech signals at the input of an attenuator. The preamble decoding circuit controls the attenuation value of the attenuator in order to resupply to the receiver output signals of the same relative level as those applied to the transmitter input.

Abstract: A two-way business-band transceiver for operation on an assigned FCC frequency includes a chassis housing a plurality of printed circuit boards which are surrounded by a three-part enclosure. This enclosure includes a main body portion having a top half and a bottom half and a control head portion which is separable from the main body portion. The transceiver circuitry which is arranged both within the main body portion as well as within the control head portion includes frequency synthesizing means which are selectable yet nonaccessible from the front of the control head portion. Frequency selection is accomplished by gaining access to a programming circuit portion which is located within the control head portion. This programming circuit portion includes a plurality of 10-position, rotary BCD switches which are arranged for channel 1 and channel 2 operation.

Abstract: The transceiver according to the invention is controlled by an automatic alternation device in order to permit transmission solely when voice signals are to be transmitted and when the receiver does not receive such signals. On transmission, the transmitter supplies constant amplitude-modulated, high frequency signals during voice activity periods and supplies nothing outside these periods. On reception, a detector for detecting the rapid amplitude transitions of the received signals and a logic circuit control the switching off of an electronic switch during the voice activity periods, so that the output of the receiver only supplies voice signals. The gain of the receiver amplifier is controlled by an automatic control loop. The value of the time constant of this loop is controlled so as to be low during the voice activity periods and high outside these periods.

Abstract: An improved marine radio telephone is disclosed having a microphone, display, speaker, and controls. The controls include switches and a keyboard located together with a display in a panel, a microphone conveniently located as to the front panel, and a push-to-talk switch incorporated in the microphone. A panel printed wiring board is provided for the control circuits. Digital logic circuits, including a special purpose microcomputer and a power supply mounted on a second printed wiring board, interface with the control circuits and display. The control circuits include circuit blocking means which can be readily removed to permit, when authorized, transmission on Coast Guard auxiliary channels 21, 23, 81, 82, and 83. A frequency synthesizer interfaces between the logic circuits and a transmitter and receiver. The synthesizer and receiver are mounted on a third PWB, and the transmitter is mounted on a fourth printed wiring board.

Abstract: Data signals are transmitted from a transmission unit (12) through a hybrid coil (16) and transmission line (18) to a remote transceiver. Data signals of a different frequency are received from the remote transceiver through the transmission line (18) and hybrid coil (16) in a full duplex mode and passed to a reception unit (26). A ratio of the signal levels of the received data signals passed through the hybrid coil (16) in a desired manner to transmitted data signals which leak through the hybrid coil (16) in an undesired manner is sensed at a reception signal output of the hybrid coil (16). The resistance of a variable resistance pad (17) provided in the transmission line (18) is varied in accordance with the sensed ratio so as to adjust the ratio to a predetermined optimum value. The sensed ratio is a predetermined function of the impedance of the transmission line (18) as viewed from the hybrid coil (16).

Abstract: In a radio of the type having a selectively operable transmitter portion and an associated receiver portion for two-way communication, such as a CB radio, plus an auxilliary receiver for reproducing auxilliary audio signals, such as an AM/FM radio, a system is provided for automatically interrupting the audio signal output of the auxilliary receiver whenever the transmitter portion is operated. When the transmit/receive switch is in the transmit position, an auxilliary electronic switch interrupts the audio output of the auxilliary receiver by by-passing to ground the audio signal input to the audio amplifier section of the auxilliary receiver.

Abstract: To alert users of Citizen-Band (CB) radios of an emergency situation, a CB transceiver has a tone generator associated therewith generating an emergency signal, for example a high pitched tone. Upon operation of an emergency switch, the transceiver is placed in the "transmit" mode, and the channels thereof are selectively stepped through for transmission, each one of the channels being modulated by the emergency high pitched tone signal generated in the emergency tone generator; the transceiver, finally, reaches a predetermined channel, for example channel 9, reserved for emergency communication and is thereupon switched to receiving mode. The emergency switch can be incorporated as part of an impact switch in a motor vehicle, thereby sending out the emergency signal, automatically, upon collision, and alerting other users of CB equipment that an emergency exists, regardless of the channels on which the other users may be operating.

Abstract: A portable telephone assembly has a portable assembly and a base assembly each provided with a radio transmitter and receiver. The portable unit is operative to generate first and second frequency signals one of which is interruptable upon dialing. The base unit includes frequency responsive means operable to connect the base unit to a telephone line when both signals have been received and for interrupting and reestablishing the connection during dialing.