Abstract: A battery powered, adaptive signal decoder is disclosed which is capable of processing detected encoded signals in accordance with a plurality of decoding schemes. The decoder has an equivalent microcomputer implementation. Energy conservation means operating independently of the detected signals acts to conserve the energy of the battery.

Abstract: In a resistance comparator circuit a current mirror provides a reference current to a first conduction path and a mirror current to a second conduction path. A first transistor is coupled in series with the first conduction path and a reference resistance is coupled in series with the first transistor. A second transistor is coupled in series with the second conduction path and an input resistor is placed in series with the second transistors. A bias circuit supplies a bias signal to the control nodes of the first and second transistor. A logic transition occurs when the input resistor is equal to the reference resistor or a predetermined multiple thereof.

Abstract: A selective calling, paging and priority signalling system for two way communications between at least one primary and a plurality of remote stations. An automatic selective calling mode is provided in which the primary station operator enters the address of the desired unit and activates his microphone. Unmuting data packet will then be transmitted to the addressed remote station, unmuting the remote station. When the transmission ends, a mute data packet is transmitted, remuting the remote station.

Abstract: A data communications system is described in which variable length messages are communicated between a general communications controller (GCC) and a plurality of portable and mobile radios. The variable length messages include a bit synchronization field, a message synchronization field and a plurality of channel data blocks for efficiently and reliably handling long strings of data or text. Each channel data block includes an information field, a parity field for error-connecting the information field and a channel state field indicating whether or not the radio channel is busy or free. The GCC is coupled to a cellular arrangement of channel communications modules (CCM's), which each include a radio transmitter and/or radio receiver. The mobile and portable radios communicate with the GCC by way of the CCM's.

Abstract: A phase-locked loop comprises a reference source that produces a signal at a fixed frequency that is applied to a phase detector. That signal is compared in the phase detector with a divided quotient signal that is proportional to the output of a voltage-controlled oscillator. Comparison of the phase difference between the two signals creates an output voltage that is taken to an adaptive filter. The adaptive filter is controlled by an external logic circuit that selects a narrow bandwidth when phase lock is detected and a wider bandwidth when the absence of phase lock is detected. The divisor of the divider in the loop is also changed in response to a signal based on the phase difference. The output of the adaptive filter is taken to a summer which adds a modulating signal to form a combined controlled voltage for the VCO.

Abstract: The invention is a high frequency hetrodyne receiver front end for receiving a communications signal comprising a desired information frequency and an undesired image frequency. The receiver comprises a bandpass filter, a preamplifier responsive to the bandpass filter, a mixer and a coupler means between the preamplifier and the bandpass filter. The coupler means defines a reactive short at the undesired image frequency due to impedance characteristics of the coupler means. The coupler means thereby eliminates the image frequency noise at the input of the preamplifier. Preferrably the coupler means is a transmission line of a length L where L equals .eta..pi./.beta. and .eta. is an integer and .beta. is proportional to the wavelength of the image frequency.

Abstract: A low profile antenna is provided which includes a counterpoise above which are situated three parallel oriented L-shaped elements. Each of the elements includes leg and foot portions. One common end of the leg portions of the elements are electrically coupled together and to an antenna trimming stub. The remaining end of the middle element constitutes the feedpoint of the antenna together with the remaining ends of the other two elements. The dimensions of the counterpoise top surface are selected to be substantially less than one wavelength at the desired operating frequency of the antenna. In this manner, the antenna generates or is responsive to radio frequency waves exhibiting two polarizations.

Abstract: The invention is a mechanism for holding a waveguide assembly and a down converter module in locked force multiplied engagement within a transceiver housing. The mechanism includes a lever arm which pivots about a first end which is secured to a bracket. The bracket in turn is secured to the transceiver housing. A knob which includes a locking structure is coupled to the second end of the lever arm. The locking structure is retained in a channel in the transceiver housing. The channel allows the locking structure to move within the channel between a first and second position. There is a camming surface on the lever arm that is more proximate to the first end of the lever arm than to the second end of the lever arm. An aligning pin is mounted on said first assembly in a location so as to engage the lever arm camming surface when the locking structure is physically moved along the transceiver housing channel from a first position to a second position.

Abstract: An automatic level control system is described for use with a voice processor which generates an AGC control signal to vary the gain applied to an audio input signal. The system includes a dynamically adjusting peak detector for detecting noise peaks and voice peaks while ignoring voice lulls which occur after a voice peak. Detected peaks are processed by an improved voice/noise sensor which develops a first output signal when voice is detected and a second output signal in the absence of detected voice. These output signals are received by a gain control circuit which is adapted to prevent the AGC control signal from increasing system gain for an indefinite interval in response to the second signal, and to permit normal variation in the AGC control signal in response to the first signal.

Abstract: A decoder circuit is provided which employs digital sampling and correlation apparatus to detect the presence of a received tone signal exhibiting a predetermined frequency. Samples of received tone signals are taken and, in effect, multiplied by a substantially rectangular observation window which includes a bite interval of selected duration and location therein. A correlator correlates the windowed samples to detect samples corresponding to the predetermined frequency (main lobe frequency). A significant decrease in undesired side lobe response is thus achieved.

Abstract: In accordance with the present invention there is provided an auxiliary battery charging terminal that may selectively engage battery charging circuitry inside a portable radio pager. There is provided a current conducting cap having a downwardly and outwardly flared rim that deforms to lock under the crimped edge an insulating seal ring of a standard rechargeable cell by application of a compressive axial force. The auxiliary battery charging terminal is further provided with a central tip axially projecting upwardly from the cap. The auxiliary terminal may be further provided with a cap of reduced diameter to circumferentially engage the raised battery cathode terminal on the battery cell. A mating recess in a remote battery charging receptacle may receive the tip to captivate the battery cell against lateral displacement. The tip may be further provided with a rounded apex to relieve localized frictional forces upon insertion and removal of the battery cell from the remote battery charging receptacle.

Abstract: A method of programming a ROM for a multiple conversion frequency synthesizer provides a mechanism for avoiding receiver self-quieting. The method includes the steps of searching for frequencies which cause potential receiver self-quieting responses and selecting a second local oscillator frequency suitable for avoiding receiver self-quieting. A single bit of a ROM is used to represent possible second local oscillator frequencies synthesized by the frequency synthesizer which provide either high-side or low-side injection to the second mixer. Finally, the method includes the step of encoding the single second local oscillator frequency determining bit of the ROM appropriately for selecting the local oscillator frequency which avoids receiver self-quieting.

Abstract: A microphone mounting arrangement for altering the microphone's audio frequency response characteristic comprises a microphone disposed within an enclosure bounded by a loudspeakers cone on one side and a flexible diaphragm on the other side. The microphone is preferably mounted to a web-like mounting structure which is sandwiched between the loudspeaker and the flexible diaphragm. The resonant characteristic of the enclosure selectively alters the intensity of soundwaves impinging upon the diaphragm so that enclosed microphone's frequency response is altered. Improved intelligibility in high noise level environment is thereby attained.

Abstract: In a compensated VCO circuit arrangement for providing constant modulation level over a wide frequency band a VCO is disclosed having a linear VCO gain factor vs. control voltage curve over the wide frequency band of interest. A compensation network is coupled to the VCO to provide an audio output having a linear output level vs. control voltage curve. By appropriately matching the two linear curves the variation in modulation level over the frequency band of interest is substantially reduced.

Abstract: A cosine signal corrector circuit as for use in a decoder for a system wherein an information signal is transmitted in the form of one trigonometric transform function of that signal. The second trigonometric transform function signal, required for decoding the information signal, required for decoding the information signal, is obtained by first deriving the Hilbert transform of the transmitted signal and phase inverting it, producing an approximate second transform function signal. The decoder produces the sum of the squares of the two transform function signals, and the difference between that decoder output and 1.0 is an "error" signal. Under the control of the signum signal of the approximate second transform function signal, the error signal is added to the approximate second transform function signal to produce an accurate second transform function signal.