Raytheon Company

Harris Corporation

John P Wendler

Brian J McNamara

Kamal Tabatabaje-Alavi

Kamal Tabatabaie-Alavi

Alan Palevsky

Robert Jastram

Embodiments of the present invention provide a system, apparatus and method for an audible indicator of a quality of a received digital radio transmission. After receiving a digital radio transmission in a digital radio receiver, the quality of the received digital radio transmission is detected. Then an audible communication from the received digital radio transmission is decoded. Then an audible indicator is superimposed onto the audible communication, to form a composite audible signal. Finally, an amplitude of the audible indicator is dynamically adjusted relative to an amplitude of the audible communication, responsive to a quality of the received digital radio transmission.

Simulated degradation of SNR in decoded digital audio correlated to wireless link bit-error rate

Mixer circuitry having a semiconductor body formed therein mixer circuitry having an oscillator having a heterojunction bipolar transistor and a mixer having a Schottky diode. The heterojunction transistor has a collector region formed in one portion of doped layer of the semiconductor body and the diode has a metal electrode is Schottky contact with another portion of such doped layer. The mixer is includes a diode and a DC biasing circuit, comprising a constant current, for biasing such diode to predetermined operating point substantially invariant with power of an input signal fed to such mixer.

Heterojunction biopolar mixer circuitry

Heterojunction bipoplar mixer circuitry

Method for making heterojunction bipolar mixer circuitry

An RF circuit which may be for example a high pass filter, low pass filter, phase shifter, bandpass filter, termination network, bias network, or series or parallel resonance circuit includes at least one strip conductor coiled about a region and an outer or ring strip conductor disposed about a periphery of the at least one coiled strip conductor and coupled to said at least one coiled strip conductor through a dielectric. Parasitic capacitance between the coiled conductor and outer or ring conductor provide capacitor elements for the circuit.

Monolithic lumped element networks

An analog phase shifter is provided by cascading T high pass filter and .pi. low pass filter sections. The low pass filter network is selected to have a cut-off frequency above the highest frequency in a predetermined frequency range of the phase shifter and includes a fixed inductor element as a series element of the network and a pair of variable capacitor elements disposed in shunt between said inductor element and ground. The high pass filter network has a cut-off frequency below the lowest frequency of the predetermined frequency band. The network includes a fixed inductor element disposed as a shunt element of said network and a pair of variable capacitor elements disposed in series. The inductor element is coupled between a common connection of said pair of variable capacitor elements and the reference potential. The .pi. network and the T network are cascaded connected between the pair of terminals of the network. The voltage level is fed to each one of the variable capacitor elements and provides a variable capacitance in response thereto and thus imparts to said network a variable phase shift over the operating frequency range of the phase shifter.

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Stowe, MA, United States of America

John P Wendler