Motorola Corporation

Other

James D Solomon

Steven C Jasper

Mark J Johnson

Mark A Birchler

A quad 16 QAM transmission and reception methodology wherein a time domain pilot reference is advantageously associated therewith. There may be one or more such pilot references for each packet of multiple 16 QAM pulses. Depending upon the embodiment, each 16 QAM pulse can include a time domain pilot reference, or an estimated pilot reference for that pulse can be determined either by reference to pilot references in other pulses sharing the same packet, or by reference to pilot references for other previously received 16 QAM pulses corresponding to that same pulse.

Communication signal having a time domain pilot component

In order to synchronize wideband signals in time while reducing the necessary amount of processing, a number of narrowband signals (203, 205, 207, and 209) are modulated (503) on their own frequency sub-carriers, such that the summation of these modulated signals remains within the bandwidth of the wideband signal (201). This composite signal is transmitted (507) to a receiver, which uses a matched filter bank (405) to recover timing data from each transmitted frequency sub-carrier.

Wideband signal synchronization

A method of recovering a frequency modulated signal wherein the frequency modulated information signal is sampled at a rate less than the Nyquist sampling rate, following which the under sampled signal can be demodulated to extract the original information signal.

Digital FM demodulator with a reduced sampling rate

An improved method of statistically determining the presence of noise on an FM communications channel permits digital signal processing techniques to more reliably squelch unnecesssary segments of an FM receiver reducing noise and power consumption. Digital samples of an FM signal having real (in-phase) and imaginary (phase quadrature) components representing the real and imaginary components of a phasor rotating about the origin of a Cartesian coordinate system at a rate indicative of a signal on the channel are mathematically operated on. Successive digital samples are multiplied by the complex conjugate of temporally adjacent samples producing a new stream of phasors representative of the phase change between samples. The phase changes between samples are processed to produce a number that indicates the probability of the channel having noise present. This number indicative of the probability of noise content is compared to a threshold value and used to decide whether or not successive receiver stages should be squalched or unsquelched.

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Hoffman Estates, IL, United States of America

James D Solomon