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 clock recovery circuit for recovering a symbol clock (226) includes a level decoder (210) for determining one of a plurality of received states of a demodulated signal (105) during each symbol period of the symbol clock (226). Each of the plurality of received states corresponds to one of at least two modulation levels. The level decoder (210) generates for each of the plurality of received states a sign signal (212) having transitions at central threshold transition times and a magnitude signal (211). An edge selector (220) determines selected central threshold transition times. A synchronizable clock (225) is synchronized by the selected central threshold transition times, resulting in a significant reduction of symbol clock (226) jitter.

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.

Abstract: A data receiver (110) for processing multiple signals includes a receiving circuit (120) for demodulating at least first and second signals and a selector (125) coupled to the receiving circuit (120) for comparing the at least first and second signals to estimated peak and valley values. The selector (125) generates error values associated with the at least first and second signals and selects a data symbol associated with one of the estimated peak and valley values based on the error values. A timing circuit (140, 150) activates the selector (125) at predetermined times, and a controller (140) coupled to the selector (125) and the timing circuit (140, 150) recovers information in accordance with the data symbol and other data symbols.

Abstract: An apparatus and method for updating upper and lower thresholds in peak and valley systems. The apparatus includes comparators which determine which peaks or valleys are eligible for use in the calculation of upper or lower threshold levels. The comparators output the eligible peaks and valleys into statistical blocks that calculate the mean of the peaks and valleys as well as the deviation over a predetermined number of samples. Additional comparators compare either the mean deviation, standard deviation, or variance of the eligible peaks and valleys to predetermined deviation thresholds to determine whether the mean peak or mean valley should be used to calculate update thresholds. The apparatus further includes memory elements that store the mean peak or mean valley values used in the calculation of upper or lower thresholds.

Abstract: A communication system providing selective encoding of digital messages (408) comprising a plurality of transmitting devices (116) and a plurality of receiving devices (122). The transmitting devices (116) transmit an encoded address (404), encoded message vector (406) in a first portion of the message, and digital message (408) in a second portion of the message. The digital message (408) is encoded in the second portion of the message with an error correction code if the digital message is a data message (414), and without the overhead of an error correction code if the digital message (408) is a voice message (410). The receiving device (122) decodes the encoded address (404), encoded message vector (406), and digital message (408) transmitted by the transmitting devices (116) in the first and second portion of the message.