Abstract: A liquid crystal display module with self contained display decoder circuitry is attached to a radio frame with a minimum of electrical interconnections. Module assembly and attachment are both accomplished without the use of tools. Attaching the module to the frame interlocks the module to prevent accidental disassembly and places a preload force on the electrical interconnections to insure good electrical continuity. Ambient light reflection provides primary display illumination while lamps, controlled by an integral switch, provide secondary illumination.

Abstract: A mismatch detector is provided for determining whether or not a particular load impedance is matched or mismatched to the characteristic impedance of a transmission line. The detector is capable of determining if a particular load impedance has a value outside of an impedance threshold circle having a center at a location other than at the center of the Smith Chart. This flexibility enables the detector to be more selective in determining improper load conditions.

Abstract: An R.F. switch includes a directional coupler with a main line and a quarter wavelength coupled arm. One end of the main line is connected to a first input port and the other end is connected to a first output port. The coupled arm is selectibly terminated at one end in either its characteristic impedance or a short. A PIN diode controls the termination. The second end of the coupled arm is connected to a second input port. A PIN diode switch is connected between the second end of the coupled arm and a second output port. In a first position, signals present at the input ports are combined and appear at the first output port. The directional coupler provides isolation such that the signal at the second input port is not coupled to the first input port. In the second position, the signal at the second input port is disconnected from the first output port and only connected to the second output port.

Abstract: An improved method of doppler searching in a digital GPS receiver is described. According to the principles of the present invention, an N-point fourier transform is performed on samples of a down converted GPS signal representing the entire range of Doppler-shifted GPS carrier frequencies. The magnitude of the square of each of the output samples is calculated to produce N power quantities, corresponding to N search frequencies. The power quantities for each of the N search frequencies are then summed to produce N quantities proportional to average power. The maximum of the N-power quantities indicates the presence of the corresponding GPS signal.

Abstract: An alerting device, such as a radio pager, which produces an audible alerting signal, in response to a unique identifier received and decoded by said device, incorporates circuitry for periodically reminding the user that a lagging signal has been received. In this context, a short alerting signal or call reminder alert occurs periodically upon cessation of the originating alert and/or message. This method of operation continues until the user manually discontinues it.

Abstract: A paging simulcast station remote control system encoder is described. The paging system encoder generates signals in accordance with a predetermined signalling scheme comprising a series of tones and timed pauses and generated in response to control signals supplied either manually and or by a paging terminal. The paging system encoder provides control signals which instruct a paging transmitter to transmit a subsequent paging signal or to inhibit transmission until instructed to do otherwise. The paging encoder can generate signals to individually control as many as 30 individual simulcast transmission remote stations through an existing paging RF link.

Abstract: A paging system providing an LPC encoded speech output having an adaptive bit rate. The LPC bit rate is adaptively modified based on paging system airtime loading. Synthesizer circuitry in the paging receivers, together with a system signalling scheme is used to update the paging receivers as to the LPC bit rate, allows the paging receiver to decode the adaptive bit rate signal.

Abstract: An I.sup.2 L programmable read only memory (PROM) row driver circuit sinks current from a row of memory elements when selectively activated. The circuit operates in the read mode at very low power levels and down to 1.0 volt. The circuit has two current sinking capabilities, a low current capability for the read mode and a high current capability for the program mode. Switching between modes is accomplished merely by changing the voltage on a power supply terminal; 1-3 volts for the read mode and 9-12 volts for program.

Abstract: An RF interconnect between a printed circuit board and a coaxial connector mounted in a housing is self-aligning along all three major axes. The coaxial connector has a pin connected to its inner conductor that extends beyond the edge of the outer conductor. The outer conductor has an external circumferential groove. The interconnect includes two terminals wherein the first terminal includes a substantially "M" shaped wire formed conductor having five functional segments: two flexible attaching segments near the ends of the wire, two substantially parallel pin contact segments, and a joining segment connecting the pin contact segments. The coaxial connector pin is inserted between the parallel pin contact segments of the wire formed conductor and a clamping force is generated on the pin by the joining segment. The second terminal includes a flat flexible conductor that has a "U" shaped lug at one end and a snap ring at the other end which is inserted into the groove of the coaxial connector.

Abstract: In a multiple state data signal, a first and second state are equated to logic states while a third state is designated as a read state. The read state and one of the two logic states are alternately generated so that each logic state is immediately preceeded by a read signal which may be utilized to tell the peripheral that a valid bit of data follows.

Abstract: A logic circuit is provided in a multifunction selective call receiver operating in a time sequential zone batched message communication system to prevent repeated alerts of the same message. A single lockout timer is reset by the first detection of a message function signal, and further alerts for that function are disabled for a time interval which may be extended by additional message function detects corresponding to other functions.

Abstract: A portable radio housing has a shield that provides electromagnetic isolation between logic and radio boards operating on close frequencies. The radio board is positioned in a conductive frame having fours sides surrounding a central opening. A tab on the frame is connected to a power module on the radio board to sink heat from the power module. A middle shield having sides with integral spring fingers at calculated intervals is attached to the frame over the rear surface of the radio board. A logic board and rear shield are attached to the frame over the middle shield. A connector protrudes through an opening in the middle shield and interconnects the logic and radio boards. A front shield, also having sides with integral spring fingers, is attached to the frame over the front surface of the radio board. The front shield has an integral speaker baffle and tabs for holding a connector. An outer housing and keypad/display module enclose the frame.

Abstract: An electrical battery is provided which includes a current sensing resistor situated in series with a plurality of battery cells located within a housing. The respective ends of the plurality of cells are coupled to positive and negative contacts on an external surface of the battery. The respective ends of the current sensing resistor are coupled to first and second sensing contacts on the external surface of the battery. A battery structure is thus provided which is capable of supplying electrical energy while permitting sensing of the magnitude of electrical current drawn from the battery.

Abstract: This microphone includes a microphone element, speaker and antenna all internal to the microphone housing. These components are carried by a chassis that is fastened to the microphone body at its lower end which also provides the effective attachment point for the microphone cable. The speaker is mounted in the chassis at an angle having its face slight upwardly incline to project sound towards the top of the microphone. An antenna element includes walls on either side of the speaker for reflecting sound upwardly. The antenna element has apertures in its top portion to allow for the passage of sound therethrough. The microphone element is also in a position for picking up sound through the top of the microphone.

Abstract: A flexible printed circuit board assembly having an integrated circuit die bonded directly thereto. A first layer of the flexible printed circuit board assembly includes a plurality of conductive paths and geometrical patterns on each of its surfaces. The conductive patterns include pads for mounting the integrated circuit die and connecting the wires from the integrated circuit. Additional intermediate layers of the flexible printed circuit board assembly, having an aggregate thickness greater than the height of the integrated circuit die and associated leads bonded thereto, surround the integrated circuit die. The top layer of the flexible printed circuit board provides for total encapsulation of the integrated circuit die for protection thereof. In the preferred embodiment that portion of the top layer which covers the integrated circuit die is opaque to prevent the passage of ultraviolet light which might otherwise cause damage to the integrated circuit.

Abstract: An electrically variable three terminal monomorphic piezoelectric capacitor is manufactured with thick or thin film hybrid microelectronic circuit technology. A first capacitor plate and a ridge, which substantially surrounds and extends above the first capacitor plate, are formed on the surface of a substrate. A monomorphic piezoelectric wafer having a control plate and a second capacitor plate on opposing surfaces is bonded to the upper surface of the ridge. During bonding, a force is applied at the center of the wafer which fixes a permanent bow in the wafer in the direction of the first capacitor plate. A four terminal monomorphic embodiment and three and four terminal bimorphic embodiments are also described.

Abstract: A digital FM demodulator is described. According to the principles of the present invention, a digital FM signal is demodulated by processing sampled input vectors of a quadrature FM digital signal centered approximately zero frequency. The sampled quadrature input vectors are quantized to lie within a predetermined magnitude range. The quantized vectors are coupled to a phase accumulator which generates a current coarse phase value related to input vectors of the quadrature FM signal. The output of the phase accumulator is also coupled to a vector rotation means which rotates the input vector to a predetermined quadrant to determine a fine phase value based on said rotated input signal vector. The fine and coarse values are then summed and output as a composite phase value, and digitally filtered by subtracting the value of the previous composite phase angle sample from the value of the current composite phase angle sample to produce a demodulated message sample.