Harris Corporation

Ericsson Gmbh

Eagle Technology, LLC

Mac Lamar Hartless

Daniel Wayne Ericson

Dennis Layne

Nathan T Prosser

Catherine D Royster

William Oscar Janky

Stephen Robert Wynn

Richard Taylor

David William Brown

Steve R Wynn

George W Kellam, Iii

Darryl W Royster

John V Hughes

David P Cullen

Dennis R Layne

Ericson Daniel W

Daniel W Ericson

Richard D Taylor

Systems and methods for operating a communication device so as to mitigate intermodulation interference to a signal. The methods comprise: continuously monitoring several communication channels by the communication device; using a noise floor level estimate of the communication device to detect when the communication device is under an influence of hig interference; determining an optimal level of attenuation to be applied by a variable attenuator of the communication device's receiver so as to mitigate the influence of intermodulation interference to the signal; and selectively adjusting an amount of attenuation being applied by the variable attenuator to achieve the optimal level of attenuation for mitigating intermodulation interference.

System and method for mitigating broadband interference

Systems and methods for mitigating broadband and/or Intermodulation ('IM') interference. The methods comprise: monitoring performance of at least one demodulator performance metric of a communication device; detecting when the communication device is under or will be under an influence of IM interference based on a performance of the at least one demodulator performance metric; determining an improved level of gain to be applied to (i) a variable attenuator of the communication device or (ii) a variable gain low noise amplifier of the communication device; and selectively adjusting an amount of gain being applied by the variable attenuator or variable gain low noise amplifier based on the improved performance achieved with new level of attenuation.

System and method for optimizing intermodulation performance of receivers

A wireless communications device may include a wireless receiver, and an adaptive demodulator coupled to the wireless receiver. The adaptive demodulator is configured to apply first and second bandpass filters to amplitude information of a received signal at first and second frequency bands, respectively, and classify the received signal as one of a PSK modulation type, a second PSK modulation type, and a third FSK modulation type based upon whether a tone exists in the amplitude information of the received signal in one or more of the first and second frequency bands. The adaptive demodulator is configured to adjust a demodulating parameter based upon a classified modulation type of the received signal.

Communications device with adaptive demodulator for PSK and FSK modulations and related methods

Symbol sampling in a high time delay spread interference environment includes acquiring () a time varying baseband waveform. The waveform has a signal amplitude that varies between one of a plurality of symbol states. The waveform is sampled () at a rate of m times the symbol rate. During an evaluation time, an error value is calculated () for each of m data sample positions. Each of the error values comprises an average distance between the measured value of the waveform as indicated by the data sample and a closest known symbol value. The error values are used to create an error surface. Thereafter, the error surface is modeled as a quadratic and an optimal sample time is determined () based on finding the time location where the quadratic surface is minimum. A sinc interpolator is then used to resample the data.

Method for symbol sampling in a high time delay spread interference environment

Method for optimizing the delay spread performance of a radio receiver () includes evaluating () a delay spread environment to determine if a desired RF signal is being received under conditions of low delay spread or high delay spread. If a low delay spread condition, the baseband digital data signal is filtered using a narrow filter (). Otherwise, the signal is filtered using a wide bandwidth filter () having a bandwidth wider than the narrow filter. The center frequency of the wide bandwidth filter is selectively shifted () in accordance with a predetermined frequency offset if a second received power level of an interfering signal in an adjacent channel exceeds the first received power level by a predetermined threshold amount. This frequency shift of the filter allows for improved delay spread performance while minimizing any performance degradation when an interfering signal is present on an adjacent channel.

Method for improving radio performance in a simulcast environment using phase tilted filters

A wireless communications system includes a base station, and a communications device configured to communicate with the base station via different wireless communications channels using a modulation standard wherein a received modulation differs from a transmitted modulation (e.g., due to environmental conditions) as measured by a modulation fidelity value. The base station and the communications device are configured to cooperate to determine respective modulation fidelity values associated with a current channel and an alternate channel based upon an estimated modulation fidelity calculated from the received modulation, and to selectively switch between the current channel and the alternate channel based upon the determined modulation fidelity values.

Communications system providing enhanced channel switching features based upon modulation fidelity and related methods

Peak fade depth is measured () over a period of time, and a bandwidth of a channel filter () is then determined () according to the measured peak fade depth (). In preferred embodiments the average peak fade depth over two or more time slots is used. In a specific embodiment, an &#x3b1; filter () is used to determine the bandwidth of the matched filter (), in which &#x3b1; is determined based upon the measured peak fade depth (). In various embodiments, peak fade depth is correlated to the Doppler shifting of the channel, which in turn is used to determine the bandwidth of the matched filter by way of the &#x3b1; parameter. Hence, a non-linear equation can be used to determine the value of &#x3b1; which yields a minimum bit error rate for the matched filter (). More specifically, a matched filter () is matched to a received signal r(t) having k states according to a plurality of matched filters Mand outputs a signal given by |r(t)&#x2212;C(t)*M(t)|, in which C(t) is a channel estimate provide by a channel tracker () for a state k at time period t that is given by C(t)=&#x3b1;*c(t)+(1&#x2212;&#x3b1;)*C(t&#x2212;1), c(t)=M*r(t)/(M*conj(M)), and conj(M) is the complex conjugate of M. For each time slot, &#x3b1; is computed from the running average of the peak fade depth () according to a predetermined equation ().

Adaptive channel tracking using peak fade depth estimation over a slot

Methods and systems for controlling site scanning of a wireless device by adjusting the rate at which the wireless device site scans based on whether the wireless device is in motion. Furthermore, this determination may be made by determining a fade rate and then basing the rate of site scanning on this determined fade rate. Preferably, the rate at which the wireless device site scans proportionally to the fade rate. Multiple thresholds of fade rate may be used to adjust the site scanning rate to provided multiple site scanning rates.

Adaptive site scanning based on fade base estimation

These and other objects of the present invention are achieved using an Adaptive Multi-Path Filter (AMPF) which eliminates audibly objectionable click noise generated at the output of an FM discriminator to prevent audible distortion or other corruption of the desired signal which may include voice and low speed digital data. Clicks are detected at the discriminator output using a colored-noise, matched filter designed and adapted to the click signature/shape as well as to the desired signal characteristics. The colored-noise matched, filter output is then compared to an adaptive threshold. When the threshold is exceeded, a click is registered as detected. Click duration is then estimated. An estimate of the desired signal is generated and that replaces the originally received data signal estimate within the click duration region. Using characteristics of the desired signal just before and after the detected click noise, the adaptive filter accurately estimates the parameters of the desired signal so that the replacement signal fairly models what the desired signal would have looked like had the click not occurred. In this way, a substantial portion of the desired signal is preserved.

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Forest, VA, United States of America

Mac Lamar Hartless