Abstract: In a digital communication system, communication units may reduce power consumption while attempting to detect reception of valid data by sampling and filtering a data stream at a first sampling rate producing a first filtered data stream. When the first filtered data stream indicates potential valid data, the communication unit samples and filters the data stream at a second sampling rate, wherein the second sampling rate is greater than the first sampling rate and consumes more power, producing a second filtered data stream. The communication unit determines whether the data stream contains valid data based on the second filtered data stream.

Abstract: An uncorrectable set of input vectors (303), comprising a primary input vector (P) and a secondary set of input vectors (S), is provided at a sender (301). The secondary set of input vectors is error correction encoded and modulated with a predetermined input vector (PIV) to produce a secondary set of modulated vectors (S'). A predetermined codeword (PC) is sent along with the secondary set of modulated vectors to a target (302). At the target, the predetermined codeword is decoded and the resulting decoded predetermined codeword 306 is used to demodulate the secondary set of modulated vectors. As the predetermined codeword is chosen such that, when decoded, it is not identical to the predetermined input vector, the secondary set of demodulated vectors (S") will contain a sufficient number of errors to indicate to the target that the set of input vectors is uncorrectable.

Abstract: Communication units are provided access to a communication system (100) in the following manner. A base station (202) receives, from a requesting communication unit, a request, via a shared inbound communication resource (209), for an available message path (207). When a dual-mode outbound communication resource is operating in a control mode (205), the message path (207), having a first inbound communication resource (204) and the dual-mode outbound communication resource operating in a partial control mode (206), is assigned to the requesting communication unit. Thus, the shared inbound communication resource is consistently available, providing access to the communication system.

Abstract: An FM receiver (100) that includes a plurality of filtering elements (120-124) that have various center frequencies and bandwidths that adjust to maximize the signal quality of a desired signal (104) recovers the desired signal (104) by inputting the desired signal (104) to each of the plurality of filtering elements (120-124). Signal recovery is performed on an output of each of the filtering elements (120-124) to obtain a plurality of recovered signals. The recovered signals are then measured to obtain a plurality of signal quality metrics for the desired signal.

Abstract: In a simulcast communication system (100), a communication unit (110-115) may request enhanced coverage area services by transmitting a request for enhanced signal quality to a central simulcast controller (101). Upon receipt, the central simulcast controller (101) identifies, based on information pertaining to the location of the communication unit, a set of transmitters (102-109) to enhance coverage in the area of the communication unit. The central simulcast controller determines enhanced coverage area delays for each of the transmitters and adjusts the respective delays of each transmitter such that transmitted signal quality is enhanced at the location of the communication unit.

Abstract: An improved synchronization method and apparatus, according to the invention, is provided. According to the invention, in a simulcast system having a remote site receiving frames from a base site, each frame containing a predetermined number (k) of transmit sample periods, and the transmit sample clock and remote synchronization clock frequencies known (f.sub.tx and f.sub.pps respectively), the remote site synchronizes a frame as follows. First, it receives a frame from the base site. Second, it determines the sequence number n for the frame. Third, it determines the launch time the first frame was to be broadcast from the remote site. Fourth, it computes a realignment time based on [(n-1)*(k)+launch time for first frame] MOD (f.sub.tx f.sub.pps). Fifth, it transmits the first bit of the frame at the realignment time.