Motorola Corporation

Casimir Karczewski

Paul R Christian

Soeren Henrik Thomsen

Charles A Sherwood, Ii

A communication device (140) for receiving and decoding a codeword of predetermined length, wherein the codeword includes information and parity bits, comprises a memory (315) for storing the codeword in the form of segments, wherein each segment comprises multiple bits forming bit combinations. A first look-up table (326, 327, 328, 329) included in the communication device (140) stores parity vectors corresponding to the bit combinations, and a second look-up table (325) stores values corresponding to syndrome vectors. A processing unit (310) coupled to the memory (315) and the first and second look-up tables (325-329) uses the bit combinations of the segments as indices into the first look-up table (326-329) to locate corresponding parity vectors, adds the corresponding parity vectors using modulo 2 arithmetic to form a resulting syndrome, and uses the resulting syndrome as an index into the second look-up table (325) to locate an erroneous bit included in the codeword. In similar manner, the communication device (140) can encode parity bits into the codeword using the reduced-processing method.

Method and apparatus for encoding and decoding error correction codes in

In a transmitter (100), circuitry is employed to automatically calibrate errors in a modulated carrier signal. A generator (320) is activated to generate (510) a low frequency square wave for use as data, which is used to generate a modulating signal from which the modulated carrier signal is generated. The modulated carrier signal is down-converted to an intermediate frequency (IF) signal having a steady state IF signal level. The instantaneous IF signal level is compared (545) to the steady state IF signal level to determine (550) whether the instantaneous IF signal level differs from the steady state IF signal level by greater than a predetermined amount, and, when the instantaneous IF signal level differs from the steady state IF signal level by greater than the predetermined amount, the modulating signal is adjusted (560).

Method and apparatus for automatic modulation calibration in a radio

A simulcast transmission system (100) utilizes adaptive demodulation to provide a method and apparatus for automatic delay equalization measurements. The simulcast transmission system (100) comprises a control station (101), and a plurality of remote transmission stations (201, 301) capable of re-transmitting a received delay equalization measurement signal which includes at least a correction bit pattern signal followed by a synchronization pattern signal. The control station (101) comprises a transmitter (131, 181) which transmits the delay equalization measurement signal, a receiver (151, 191) which receives the re-transmitted delay equalization measurement signal, a correlator (115, 762) which correlates the received synchronization pattern signal to obtain a coarse time of reception, a correction bit pattern analyzer (115, 776-802) which analyzes the received correction bit pattern signal to derive a fine reception time correction factor, and a time corrector (115, 804) which corrects the coarse time of reception with the fine reception time correction factor to obtain a corrected time of reception of the delay equalization measurement signal at the control station (101).

Method and apparatus for transmission path delay measurements using

This invention provides an improved method for synchronizing a slave oscillator with a master oscillator. The slave includes two counters designated Reference and System, driven by its oscillator; the master includes a System Counter driven by its oscillator. The master sends a reset signal to the slave, simultaneously resetting its System Counter. Periodically, the master sends to the slave a synchronization signal, which signal is generated at predetermined intervals based upon the master's System Counter. Upon receipt of the reset signal, the slave resets its counters. Later, upon receipt of the synchronization pulse, the slave modifies the value of its System counter based upon the closest multiple of the expected count value for the synchronization signal interval. The Reference Counter is not synchronized and runs free. At each synchronization signal, the slave compares its System Counter and Reference Counter to compute an oscillator error thus: ##EQU1## The slave stores this value and, depending on its mode of operation, uses it warp its own oscillator.

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Lake Villa, IL, United States of America

Casimir Karczewski