Motorola Corporation

Other

Allen L Davidson

Jona Cohn

Marc Kenneth Chason

Leigh M Chinitz

Mark A Gannon

Anthony P Van Den Heuvel

Garry C Hess

Richard S Bickham

Morton Stern

Ronald J Wanat

Roger J Jellicoe

Douglas M Hamilton

James M Durante

Pitt W Arnold

Richard L Carlson

Steve Dunkerton

A desirable operating condition is maintained in a communication device (100) that is operating in an undesirable environment by reducing the number of radio frequency signals being amplified and subsequently transmitted by the communication device (100). The remaining radio frequency signals transmitted will be transmitted at full power, so that coverage area is maintained in a tradeoff for reduced capacity.

Apparatus and method for protecting a communication device operating in

An antenna structure (108) operates in the presence of narrow or wide band interference and yet is able to enjoy high receiver sensitivity. This is done by steering the antenna structure (108) radiation pattern null in its near field at the noise source.

Adaptive antenna structure for a computational device

A receiver (100) that includes an antenna (101) employs a method and apparatus for producing diversity gain of a signal (106) received by the antenna (101), wherein the signal (106) is subject to a time-variant fading condition. Upon receiving the signal (106), the receiver (100) determines a signal quality metric of the signal (106) and compares the signal quality metric to a quality threshold. When the signal quality metric is below the quality threshold, the receiver (100) orients a predetermined antenna pattern (304) of the antenna (101) to improve the signal quality metric, thereby producing the diversity gain.

Method and apparatus for producing diversity gain of a received signal

In a radio communications system, a selectively enabled time- and/or frequency-diverse signaling scheme is employed to improve signal quality. In particular, a method of exchanging a message between communication devices using a communications resource might include the step of transmitting a first portion of the message on a first frequency within the communications resource. After determining the quality of the communications resource to be unfavorable, a second portion of the message might be transmitted on the first frequency, and also re-transmitted on a second frequency and/or at a separate time.

Method and apparatus for selectively-enabled diversity signaling in a

A transmission line using superconductors instead of conventional conductors substantially reduces ohmic losses compared to conventional conductors. The superconductors are cooled by refrigerant flowing through a hollow superconducting inner conductor. The refrigerant is transported to the inner conductor using a novel connector.

Superconducting transmission line cable connector providing capacative

Disclosed is a communication system of the type adapted to communicate a message substantially simultaneously between a plurality of fixed location sites having respective radio coverage areas. The system has an arrangement comprising first and second radio frequency transceiver means located at respective first and second sites. The first radio frequency transceiver means is designed for operating on a first set of frequencies. The second radio frequency transceiver means is designed for operating on a respective different set of frequencies than the first set of frequencies. The second radio frequency transceiver means has means for receiving and converting the first set of frequencies to the respective different set of frequencies.

Improved multiple site communication system

A method for obtaining a linear cellular array employing cosine-squared antenna patterns is disclosed. The array herein described provides an essentially infinite linear band of coverage utilizing only six frequencies. The embodiment of this invention provides early frequency reuse and superior co-channel interference to existing cellular systems used today. An alternate embodiment provides total area coverage along selected portions or the entire linear band of cellular coverage.

Method for obtaining a linear cellular array employing cosine-squared

A method is disclosed whereby adjacent transmitting antenna arrays may be more closely spaced to each other and to receiving antenna arrays while still maintaining a high level of isolation between arrays. In each antenna array, first and second parts thereof are identified. The two parts of each transmitting array are driven in phase quadrature with each other and at substantially equal power levels, and the antenna arrays are spaced sufficiently close to each other so that radiation emitted by one array and received by another array undergoes a cancelling effect before reaching the RF generator associated with the other array. The two parts of each receiver array are coupled to their associated receiver by a signal path such that substantially quadrature phasing is established between the first and second parts thereof to cause received radiation to cancel in the signal path before reaching the receiver.

Method for achieving high isolation between antenna arrays

A same-frequency repeater used in a system that has at least one other same-frequency repeater is protected against oscillation resulting from feedback of signals broadcast by the same-frequency repeater, either directly or after reception and rebroadcast by another same-frequency repeater. A tag is added to the signal to be broadcast from the first SFR, and one tag detection and canceling system is added to the first SFR for each SFR, in the system. Each tag detector senses the presence of tagged signal received by the first SFR and adjusts amplitude and phase of an appropriately delayed signal that is fed back to cancel the signal containing tag.

Method and means of preventing oscillations in a same-frequency repeater

Simulcast distortion in a receiver when using a same-frequency repeater is minimized by applying double modulation to a signal that is broadcast to the same-frequency repeater. A voice signal is applied without delay as AM on a carrier to a modulation index of up to 30%, and the same signal is also applied as FM on the same carrier with a time delay equal to the time delay in the same-frequency repeater. The same-frequency repeater detects the AM and applies the detected signal as FM on a carrier that is rebroadcast. Received FM signals are thus delayed by substantially the same amount whether they are received from the original broadcast or the same-frequency repeater.

Method and means of minimizing simulcast distortion in a receiver when

Spillover of RF signal from the output of a same-frequency repeater to the input is reduced by attaching a tag to the output signal. The tag is double-sideband, suppressed carrier to place two spectral spikes, one above and one below the carrier. The tag is applied to the signal in the IF. A tagged signal of variable amplitude and phase is added to the received signal so as to cancel the tag and hence the spillover signal, leaving only the desired signal. A feedback system controls the amplitude and phase of the cancelling signal.

Tag generator for a same-frequency repeater

A complex RF weighter provides an RF output signal controlled in amplitude and phase with respect to an input signal. The input signal is applied to a quadrature hybrid that is terminated with two PIN diodes, one of which is one-eighth wavelength farther from the hybrid than the other. Independent control of the bias on the PIN diodes provides control of the relative amplitude and phase of the output signal.

Complex RF weighter

The inventive antenna coupling system is capable of simultaneously radiating an omnidirectional signal pattern for a plurality of transmitters as well as providing a directive pattern to a receiver. An antenna array is coupled to the transmitters and receiver via a plurality of antenna couplers. Each coupler includes an antenna terminal, coupled to a corresponding antenna, a transmitter input terminal and a receiver output terminal. Multiple transmitters are coupled to the transmitter input terminals through a hybrid network array. The receiver is coupled to the receiver output terminal via a logic controlled antenna switch. The antenna couplers, which may be comprised of either high pass-low pass filters or circulators provide isolation between the transmit and receiver signals.

Multi-transceiver antenna

A radiated signal, received by each one of a plurality of spatially separated antennas, forming a directive array, is coherently recovered by the lens. The lens is comprised of a plurality of vertically standing and circularly arranged printed circuit panels, each of which includes a conductive strip connected at one end to each antenna. A plurality of semi-elliptical circuit panels are affixed to the vertical panels at a predetermined angle with respect thereto. Plated on the semi-elliptical panels are metal strips of predetermined length to provide the desired time delay to the antenna signals. A combining strip couples to the time delay strips and provides a combined output signal at one end of the semi-elliptical panel. The angle at which the semi-elliptical boards are affixed to the vertical boards corrects for time delay distortion caused by the placement of the combining strip.

Antenna array with printed circuit lens in coupling network

An antenna for a hand-held radio transceiver includes first and second elements extending from the radio's case. The first element is comprised of a pair of series coupled members having electrical lengths of one-half and one-quarter wavelength, respectively, with the free end of the second member being coupled to the transmitter output. The second element couples to the radio's electrical ground and is configured to form a transmission line with the second member. The effective electrical length of the second element, including the influence of the elements parasitic coupling to the radio, is adjusted to be one-quarter wavelength. The resulting antenna structure minimizes surface currents across the radio's body, thereby substantially eliminating power loss caused by absorption in the user's body.

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Crystal Lake, IL, United States of America

Allen L Davidson