Abstract: A correlation demodulator unit (20) having gain normalization includes a correlation demodulator (12) for receiving a signal from a receiver (8). The correlation demodulator has a plurality of correlators (C1-CN) corresponding to a plurality of N correlator outputs. A gain normalizer (15) is coupled to the correlation demodulator for accumulating symbol energy on a symbol by symbol basis for each of the plurality of correlator outputs based upon a current symbol decision providing at least an accumulated value within an accumulator (43) for the plurality of correlators and for normalizing the plurality of N correlator outputs using the accumulated value(s).

Abstract: An automatic simulcast correction method (300) for a selective call receiver (100) includes the steps of measuring a received signal (304) for a received signal strength indication measurement and then determining if a protocol indicates a simulcast signal (310). If the received signal strength indication measurement is above a predefined threshold and the protocol indicates the simulcast signal, then the selective call receiver is optimized for simulcast delay spread distortion (312). If the received signal strength indication measurement is below a predefined threshold or the protocol does not indicate the simulcast signal, then the selective call receiver is optimized for static sensitivity (314).

Abstract: A method (200) of decoding a multi-level synchronous protocol having a first portion encoded as M/2-level signals and a subsequent portion encoded as M/2-level signal or M-level signals, wherein the M/2-level signals have expected larger than normal variation of deviations includes steps of decoding (202) the first portion using a biased mode which uses M correlators shifted (204) to adequately cover the frequency range of the expected larger than normal variation of deviations and determining (206) from decoding of the first portion whether the subsequent portion is the M/2-level or M-level signal. If a M/2-level signal is found, continue decoding (210) in the biased mode. If it's the M-level signal, then decoding continues in standard mode (214), which uses M correlators that are spaced in frequency to match M spectral deviations within a predetermined frequency range.

Abstract: A method (500) of baud detection in a communication device (700) includes the steps of sorting phase pulses among overlapping sets of time slots (502) and counting phase pulses within each of the overlapping sets of time slots creating corresponding counter values (504). Then, counter values are compared with predetermined thresholds (506-512), wherein a baud pass condition (570) is met when at least one counter has a counter value exceeding an upper threshold and wherein a counter N/2 positions away has a counter value below a lower threshold. The baud pass condition may he further conditioned on meeting the requirement that at least another counter value falls below a middle threshold.

Abstract: A selective call receiver (800), including a receiver circuit (101) and a processor (810), is used for synchronizing an internal reference to symbol edges of a plurality of symbols in a multi-level radio signal transmitted by a radio communication system. To perform this function the processor (810) is adapted to cause the receiver circuit (101) to demodulate the multilevel radio signal to in-phase and quadrature signals (108, 106), convert the in-phase and quadrature signals (108, 106) to a sequence of state transitions representative of the plurality of symbols, detect at least one same state transition from the sequence of state transitions, and synchronize the internal reference to the at least one symbol edge of the plurality of symbols based on the at least one same state transition.

Abstract: A selective call unit (800) comprising a receiver (100) and a processor (810) is used for decoding a 2-level radio signal. The processor (810) is adapted to convert in-phase and quadrature signals generated by the receiver (100) to a sequence of state transitions representative of the plurality of symbols. For each symbol in the plurality of symbols, the processor (810) counts the sequence of state transitions during a symbol period, and compares the recorded count to a predetermined threshold, thereby generating a comparison result. The processor (810) then calculates a bit decision threshold level based on an average of the comparison result for each symbol in the plurality of symbols. For each symbol in a plurality of subsequent symbols, the processor (810) then compares the bit decision threshold level to the sequence of state transitions counted during a symbol period to decode a digital logic level therefrom.

Abstract: A receiver (100) is utilized for demodulating a multi-level frequency shift keyed (FSK) signal. The receiver (100) includes a mixer (102) for mixing the multi-level FSK signal to generate an in-phase signal and a quadrature signal, and a demodulator circuit (110) coupled to the mixer (102). The demodulator circuit (110) is adapted to count a sequence of state transitions of the in-phase signal and the quadrature signal and to determine a frequency deviation of the multi-level FSK signal based on the sequence of state transitions counted.

Abstract: A communication device (400) with a polarization diversity antenna configuration, having a first antenna (410) with a first plane of polarization and a second antenna (412) with a second plane of polarization. Signal strength of a demodulated signal when the antenna switch (420) is coupled to one of the antennas (410, 412) is measured by a signal strength measuring circuit (440) to generate a short-term average signal power (SA) representing signal strength over a first predetermined number of symbol periods, a medium-term average signal power (MA) representing signal strength over a second predetermined number of symbol periods, and a long-term average signal power (LA) representing signal strength over a third predetermined number of symbol periods, greater than the second predetermined number of symbol periods and first predetermined number of symbol periods. Switching between antennas (410, 412) is made in response to differences between SA, MA and LA.