Uniden America Corporation

Ben F McCormick

William B Ahlemeyer

Noel D Atkinson

Stephen T Crum

Joseph E Boone

Self-programming scanning receiver having superheterodyne circuitry, microprocessor controlled synthesized frequency tuning circuitry, frequency validation means, a learn mode to invoke the frequency validation means for all frequencies tunable by the tuning circuitry, listen mode for scanning of frequencies learned in the learn mode, and an ignore mode for erasing frequencies from permanent memory. The frequency validation means comprises a detector output connected to a high pass filter input, high pass filter output connected to a noise detector, noise detector output connected to a first A/D converter input, algorithms stored in microprocessor program memory for analyzing A/D samples obtained via first A/D for squelch condition, detector output also supplying the input of a low pass filter, output of low pass filter connected to a second A/D converter input, algorithms for analysis of A/D samples obtained from second A/D to determine sufficiency of modulation level and lack of digital waveforms, electrically alterable permanent memory for storing information identifying voice channels.

Self-programming scanning radio receiver

A high-speed, multi-band scanning radio receiver. A frequency synthesizer loaded with a digital code read from memory performs band switching and supplies tracking signals and a local oscillator signal to multi-band RF amplifier and mixer circuitry. An output of an FM detector in the receiver is connected to a squelch circuit which includes a high-pass filter network and a diode detector, with the diode detector output being connected to an internal A/D converter of a microprocessor which converts multiple samples of the incoming signal to digital values and generates a mute signal when the average value of the converted samples is below a predetermined squelch level. An output line from the FM detector to audio output circuitry in the receiver is grounded in response to the mute signal. The microprocessor is also programmed to control receiver tuning during SEARCH mode such that searching continues until the demodulator output signal for an active channel is substantially in the center of the demodulator S curve, as detected by a window detector.

Scanning radio receiver

A rapid scanning radio with multi-mode local oscillator control. In one embodiment a phase-locked loop is closed for tuning to all frequencies of interest, and each time the loop locks a DAC is loaded with successive digital values until a value corresponding to the steady-state VCO tuning voltage is found for the currently tuned channel. That digital value is stored for later recall as the tuning value for that channel. Once digital values are determined for all the tunable frequencies in the radio, the loop is opened for high-speed scanning under open-loop control of the DAC.

Rapid scanning radio with multi-mode local oscillator control

A multi-band scanning radio receiver operable without reprogramming in a plurality of geographical regions. Digital codes for public-service-band frequency allocations for each of a plurality of geographical regions are stored in a memory which is sequentially accessed to read the digital codes for the frequency allocations for a selected geographical region. A frequency synthesizer loaded with a digital code read from memory performs band switching and supplies tracking signals and a local oscillator signal to multi-band RF amplifier and mixer circuitry.

Growing community of inventors

Noblesville, IN, United States of America

Ben F McCormick