Abstract: A reproducer for reproducing a binary digital data signal from a signal received at a receiver side. A pulse train is detected from the received signal at a pulse detector. Each pulse in the pulse train sets a first D-type flip-flop, which is, in turn, cleared by a clear pulse produced by a second D-type flip-flop in response to a clock pulse just after the first D-type flip-flop is set. The output of the first D-type flip-flop is applied to a data input terminal of a third D-type flip-flop and is taken into the third D-type flip-flop by the same clock pulse. The clock pulse repetition frequency is synchronous with the binary digital data signal. Thus, the reproduced binary digital data signal is obtained on an output of the third D-type flip-flop.

Abstract: A multi-drop local area network utilizes alternating current power lines as a transmission channel. Identical transceivers are used as a master and as up to 255 slaves. Each transceiver comprises modulator and demodulator units and a microprocessor control unit which may be connected to a host. The modulator and demodulator are connected to the alternating current power line through a high pass filter comprising a split bobbin, iron core transformer having an air gap which also provides impedance matching. The demodulator includes a clipper and analog circuitry providing a band pass filter and generating a square wave corresponding to the received carrier. A state machine acting as a digital filter produces a received carrier signal only when each half cycle of the carrier square wave is of the proper duration and the carrier signal has existed for slightly more than one half of the transmitted bit duration, which is a predetermined number of carrier cycles.

Abstract: A synchronization device for digital data frame transmission system comprising an n bit series register transferring its contents at the line frequency to a parallel register also of n bits. The m first bits of the series register are also directed to a logic circuit which tests their conformity with the beginning of the synchronization word. When there is conformity, the logic circuit controls a divider dividing by n which controls, in its turn, at the line frequency divided by n, the transfer of the contents of the parallel register to a PROM memory. The purpose of the PROM is to recognize the entire synchronization word. When there is no recognition, the operation of the divide by n divider is inhibited and the procedure begins again.

Abstract: An apparatus and method, for connecting a node to and disconnecting a node from a high speed data communications network, has a dead man switching element and high speed solid state switching circuitry interconnected therewith to avoid the effects of mechanical contact bounce normally associated with operation of the mechanical switching element. Thereby, massive data losses on high speed communications paths, and token loss in a token-passing ring network, are substantially avoided. The switch has the solid state switching circuitry connected both in parallel and in series with its mechanical contacts for providing node isolation and communications path bypass channels during the time that the mechanical switch bounce occurs. The alternate paths are maintained during a change of state of the mechanical device, that is, when the node is being connected or disconnected from the communications network.

Abstract: A PSK demodulator has two phase detectors for detecting the phase of a PSK signal and a carrier generator for supplying carriers of different phases to the two phase detectors, respectively. The PSK demodulator also includes squaring means for squaring output signals from the two phase detectors, difference computing means for computing the difference between output signals from the squaring means, product computing means for computing the product of the output signals from the two phase detectors, and product detecting means for detecting the product of an output signal from the product computing means and an output signal from the difference computing means, the arrangement being such that the frequencies and phases of the carriers generated by the carrier generator are controlled by an output signal from the product detecting means.

Abstract: Apparatus for decoding a self-clocking, encoded signal wherein a series of data bits is encoded such that for each data bit, the encoded signal contains a first transition, and, for each data bit for which the succeeding data bit has the same binary value, the encoded signal contains a second transition occurring within a predetermined time interval after the first transition.

Abstract: A signal control circuit for a burst signal transmission system has a comparator for receiving a burst control signal from a burst control signal generator and an output signal from an envelope detector and for generating a difference signal therebetween. The difference signal is supplied to an attenuator, a preamplifier or a nonlinear power amplifier for receiving a modulated carrier wave so as to control attenuation of the attenuator or gain of the preamplifier or nonlinear power amplifier whereby a waveform of the output signal from the nonlinear amplifier is made analogous to that of the burst control signal from the burst control signal generator.

Abstract: An tuner unit is provided for communications receivers with automatic self-balancing of the individual high frequency filter circuits. An assigned frequency applied to the desired receiver channel is fed to the antenna input during the automatic balancing process. The voltage of this assigned frequency picked up at the output of the filter circuits changes according to a stepwise increase of a tuning voltage controlled by a microprocessor. The tuning voltage is applied to the filter circuit to be balanced via a digital-analog converter and via a switching means controlled by the microprocessor. The automatic balancing is provided by switching the switching means successively to connect to the individual filter sections.

Abstract: A multipath distortion reducing circuit particularly adapted for use with stereophonic receiving circuits in which the amount of mixing between right and left channels is reduced. In accordance with the invention, the envelope of the received FM signal is AM detected, and the envelope detected circuit is multiplied by the FM detected signal differentiated to provide a distortion cancelling signal. The distortion cancelling signal is summed with the detected FM signal to provide an output having a reduced multipath distortion component.

Abstract: This invention is a circuit for detecting a framing pattern consisting of a pseudo random shift register sequence. This circuit utilizes an extremely long framing pattern without either a large amount of memory or the need to receive a large number of bits in order to recognize the framing pattern. The use of lengthy framing patterns minimizes the chance of false framing caused by patterns in bit positions other than the framing bit position. In addition, the incoming data stream may be connected directly to the shift register mechanism.

Abstract: To utilize indirect-path signals in a receiver for fixed and mobile transmitter-receiver stations of a TDMA spread-spectrum digital radio system, coherent detection is employed. At the same time, the signal imaging the multipath profile is continuously regenerated by a regeneration circuit. The regeneration circuit provides a phase-coherent signal employed for demodulating the received signal.

Abstract: The baud rate of a digital signal is estimated using a method based on a mean squared error determination. The disclosed method fits a sine wave curve to the digital signal and varies its frequency until the mean squared error is a minimum, wherein the error is defined as the distance of the sine wave curve from its center line at each transition of the digital signal. The disclosure includes an apparatus for carrying out the method of the invention. In addition, the method is suitable for execution as a stored program within a high-speed signal processor.

Abstract: An adaptable homotropic antenna system for use with a portable communication transceiver is described. The antenna system can be used for reception or transmission and can be completely enclosed within the portable transceiver housing. The homotropic antenna system evaluates the quality of a received signal and if the signal is below a predetermined threshold level, an alternate antenna will be selected. The antenna system will continue to sample the available antennas until an antenna produces a signal of acceptable quality.

Abstract: A circuit and technique for directing an adaptable antenna system is described. The invention is coupled to the output of an RF receiver configured to provide a data signal output, and evaluates the quality of the receiver data signal. The invention switches antennas when the signal quality deteriorates below a predetermined level.

Abstract: A waterproof enclosure for a portable radio, tape recorder/player, or the like includes a flexible membrane with a finger control pocket adjacent the control knobs of the radio, an opening for inserting and removing the radio from the enclosure with a waterproof sealed cover to close the opening, and a waterproof seal around the earphone plug connector that extends through the flexible membrane. A waterproof earphone speaker is also provided, which has a conical waterproof boot fitted snugly over the speaker. Annular collars on the conical boot anchor the speaker in a person's ear and seal water out of the ear and conical boot.

Abstract: A circuit arranged to measure and correct for transmission line induced disturbances at discrete intervals after receipt of a header pulse by recording the presence of any voltage deviating from a set level. These levels are registered and during receipt of the data pulses are utilized at times corresponding to the relative position of the preceding data pulses to modify subsequent data bits.

Abstract: The present invention relates to a closure of relatively rigid material adapted to fit over the visible portion of an auto radio assembly on a dashboard, or at least over the portion thereof enclosing the tape deck, and to lock in place in such tight relationship with the dashboard or area where the radio is mounted so as to conceal the radio, and particularly the tape deck, so that on relatively close inspection a thief would observe no more than a blank panel resembling that used when there is no radio in the vehicle.

Abstract: FM transmission system in which, besides program content, an auxiliary carrier of, for example 57 kHz, is radiated, which auxiliary carrier is modulated by an announcement recognition (AR) signal and by a region or radio-station recognition (RR) signal, the AR and RR signals being low-frequency, AM modulations on the auxiliary carrier. To enhance recognition of an AR signal, e.g. between 142 and 170 Hz, is enhanced, in spite of reception difficulties, for example due to multi-path reception and the like, by decreasing the modulation of the 57 kHz subcarrier by the RR signal to 30% or less, while the AR signal is modulating the subcarrier, so that the AR modulation may extend to 60 and even 90% modulation. Multiple AR frequencies can be used, for example to characterize different announcements, e.g. in different languages, or of different characteristics, such as traffic, news, sports, or others, recognition of the AR signal in the receiver permitting switch-over from other reproduced programs, e.g.

Abstract: A cordless communications system wherein transmission is made and received via magnetic lines of induction comprises a base station and at least one mobile station wherein the base station receives and transmits voice or data signals at different frequencies. The base station employs at least two magnetic loop antennas for transmission and reception, respectively, oriented so as to provide a toroidal magnetic field which allows 360 degree transmission and reception in the planes of the antennas. The components of the at least one mobile station are mounted in an article of clothing. The mobile station is arranged in the article of clothing in such a manner as to insure a substantially constant effective coupling area with the base station antenna.

Abstract: An ASK carrier current digital data transceiver for transparent transfer of data between a broadband communication port and a baseband port consists mainly of an integrated circuit with transmit/receive logic for providing the required transparency and the ability to sense a contending signal. The transmit/receive logic places the transceiver in the transmit mode only when the baseband port is pulled low externally and not internally. This provides "listen-while-talk" contention sensing when the baseband port is high.