Motorola Corporation

Terry K Mansfield

Paul H Gailus

William J Turney

William J Martin

Edward T Clark

Joshua E Dorevitch

Bradley Michael Hiben

David G Wiatrowski

Christopher N Kurby

Lawrence Marvin Ecklund

Thomas B Bohn

Steven F Gillig

Gregory J Buchwald

Peter Nanni

Thomas J Senese

Walter J Rozanski, Jr

Kenneth J Zdunek

Charles N Lynk

James K Gehrke

John P Belmonte

Alfred B Wieczorek

Robert L Epsom

Raul Olivera

Gary R Reynolds

Peter P Walter

Ross E Ruthenberg

Anthony M Pirih

Scott J Propp

Thomas R Gaynor

Jay G Smith

Thomas L Spicer

During operation of a secondary communication system, nodes having different channel monitoring capabilities or requirements will cooperatively monitor possible frequencies for transmissions, each node using only a subset of all possible modulation sensing schemes. All nodes will share channel occupancy information to other nodes within the communication system. For example, a first group of nodes may monitor possible frequencies for television transmissions, while a second group of nodes may monitor the possible frequencies for APCO 25 transmissions. A group of nodes may also cooperatively monitor possible frequencies for more than one type of modulation transmission. Channel information will be shared among the nodes.

Method and apparatus for determining appropriate channels for communication

In a TDMA system whereby the TDMA system comprises a plurality of subscriber units and a plurality of base radios, a method and system for providing access to a channel for voice transmissions where the first subscriber unit determines whether it is provisioned for polite access to the channel. In addition, the first subscriber unit is characterized by a first color code and a first talkgroup ID. The first subscriber unit also examines the voice transmissions on the channel for voice transmissions that are from a second subscriber unit with a second color code and a second talkgroup ID. If the first color code and the second color code match and if the first talkgroup ID and the second talkgroup match, then the first subscriber unit is allowed access to the channel for voice transmissions even though the channel is being used for voice transmissions by the second subscriber unit.

Method for allowing a subscriber unit to access a channel for voice transmissions

An integrated sigma-delta radio frequency (RF) receiver subsystem ( ) and method utilizes a multi-mode sigma-delta analog-to-digital converter ( ) for providing a single and multi-bit output. A programmable decimation network ( ) for reducing the frequency of the in-phase and quadrature bit stream and a programmable formatting network ( ) are also used for organizing the in-phase and quadrature components from the decimation network ( ) for subsequent signal processing. The invention offers a highly integrated digital/analog RF receiver back-end which incorporates integrated filtering and a smart gain control that is compatible for use with other receiver systems and offering superior performance characteristics.

Integrated multi-mode bandpass sigma-delta receiver subsystem with interference mitigation and method of using same

An integrated multi-mode bandpass sigma-delta radio frequency receiver subsystem with interference mitigation includes a first intermediate frequency amplifier. At least one mixer for mixing the output of the first amplifier and an oscillator signal. A second IF amplifier for amplifying and filtering the output of the at least one mixer. A multi mode multi bandwidth sigma delta analog digital converter for providing digital output signals with high dynamic range. A digital mixer providing I and Q signals a decimation network providing I and Q signals at reduced programmable data and clock frequencies and a formatting network for arranging the I and Q signals into a predetermined format for use with a digital signal processor.

Integrated multi-mode bandpass sigma-delta receiver subsystem with

A data transmission scheme for use in a low channel bandwidth-to-modulation symbol rate ratio (BW:R.sub.S) application employing a linear modulator for producing in-phase and quadrature (I and Q) components of a data stream inputted at a predetermined symbol rate. This transmission method allows for the recovery of signals having unfavorable delay spread characteristics. That is, a specialized function is used to process the I and Q components, whose time domain transfer characteristic remains within a predetermined range of a data constellation point for a duration that exceeds 25 percent of a symbol period corresponding to the predetermined symbol rate. The processed response is then band-limited to produce a modulation signal that is usable in the low BW:R.sub.S application.

Data transmission method and apparatus for use in low BW:R.sub.s

A radio communication system including a control station and at least one remote station (20) is provided. The control station has a receiver for receiving radio signals, a transmitter for transmitting radio signals and a demodulator for measuring the frequency of the received signals. Responsive to a request for frequency measurement received from the receiver, the control station also has an error signal encoder to provide an error feedback signal containing the polarity and magnitude of the frequency difference for transmission by the transmitter. At least one remote station (20) has a receiver (25), a transmitter (26), a frequency controller (46), an encoder for encoding the request for frequency measurement and for actuating the transmitter (26) to transmit the request, and a decoder (34), responsive to the received error feedback signal for adjusting the frequency control.

Radio frequency error detection and correction system

A variable characteristic impedance microstrip resonator for use in a tunable oscillator circuit, the resonator having relatively high characteristic impedance near its driven end to maximize tuning range and relatively low characteristic impedance near its opposite end to minimize losses and thus optimize sideband noise performance.

VCO having tapered or stepped microstrip resonator

A tunable resonant cavity filter structure is disclosed which includes an enhanced ground return internal to the cavity which effectively eliminates generation of deterioration wide band noise and optimizes unloaded Q as well as rending resonant frequency stable with vibration. In its preferred form, the enhanced ground return is in the form of a ground return clip with reliant radial projections that mate with the threads of the threadable tuning element used to determine final operating frequency. The radial projections are deflected in cantilever fashion so as to generate sufficient pressure to break thru any oxides in the tuning element threads and ensure metal-to-metal contact.

Tunable resonant cavity filter structure with enhanced ground return

The invention is a microphonics suppression means for a high frequency resonant cavity. The resonant cavity is used in a RF oscillator to generate UHF/VHF frequencies. The resonant cavity comprises an outer wall portion, a center conductor portion, a tuning slug and a plurality of coupling probes. The coupling probes, tuning slug and center conductor are held in a fixed relationship by a microphonics suppression means made of a low dielectric material which fits over and around the center conductor and encapsulates the coupling probes and collars the tuning slug. The microphonics suppression means reduces the effect of microphonics on the output signal of the RF oscillator, thus allowing a clean output signal suitable for high power applications.

Resonant cavity with integrated microphonic suppression means

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Palatine, IL, United States of America

Terry K Mansfield