摘要:
A communication system (200) employs a method and apparatus for performing diversity voting in the communication system. A comparator (206) receives a signal frame (207-209) of code words from each of multiple signal sources (202-204). A prioritized code word of each signal frame occupies a corresponding frame position and has a respective signal quality metric associated therewith. The comparator determines whether each signal quality metric accurately represents the signal quality of its respective prioritized code word. When the signal quality metrics do not accurately represent the signal qualities of their respective prioritized code words, the comparator determines a supplemental signal quality metric for each prioritized code word. The comparator then selects one prioritized code word from all the corresponding prioritized code words based on a comparison of the supplemental signal quality metrics for input into the corresponding frame position of a voted signal frame (330).
摘要:
A mobile repeater (300) is improved to include a database (303) that allows the mobile repeater to store registrations received from subscriber units. Additionally, the mobile repeater may include a voice on control switching element (309) for use with an extended control channel. Further still, the mobile repeater may include encryption elements (305-308) for the maintenance of encrypted control channels. In this manner, the mobile repeater may provide an improved quality of services to subscriber units.
摘要:
Power consumption in a portable communication unit (101) is reduced by first transmitting at a first time, a message (701) at a first transmit power level to a repeater (103) on a first communication channel. At a second time the message (701) is repeated (903) by the repeater on a second communication channel, thereby transmitting a delayed message (703). The portable communication unit (101) tunes (807) to the second communication channel after transmitting all of the message (701), so as to receive at least part of the delayed message (703). The repeater (103) establishes a receive quality metric (705) for the message (701) and transmits (909) the receive quality metric after all of the delayed message (703) is transmitted. The portable communication unit receives and stores (809) the receive quality metric (705), and determines a second transmit power level for transmitting another message using the receive quality metric.
摘要:
A signal selection system is disclosed wherein a plurality of received signals are analyzed to determine their statistical characteristics. These characteristics are compared to a predetermined statistical distribution. The signal that is statistically closest to the statistical characteristics of a known signal is selected for further processing and reception.
摘要:
Disclosed is a synchronous secure communication system wherein an information signal is encrypted in an encryption means. The encrypted signal is compressed to allow the insertion of a synchronization signal, and the combined signals are transmitted. At the receiver, the synchronization signal is extracted and used to synchronize the receiver to the incoming data stream thereby improving receiver sensitivity and range.
摘要:
The transmitter in a digital communication system sends a synchronization sequence that uniquely identifies the polarity of the received data. From the received data, the receiver produces non-inverted and inverted polarity data streams that couple to like synchronization detectors. Only the detector to which the correct polarity data stream is coupled responds. Logic circuitry determines which detector responds and, accordingly, selects the polarity of received data to be further processed by the receiver.After polarity is established, both detectors monitor the received data stream of the selected polarity to determine whether synchronization shifts after having been initially established. Monitoring continues until terminated by other receiver circuits.
摘要:
A detector for delta modulated digital signals is disclosed that provides a signal quality voltage having a magnitude that is indicative of the degree of quality of the detected delta modulated digital signal. The detector totalizes the number of bit transitions occurring in successive N bit intervals. If successive totalized numbers of bit transitions are outside of a predetermined range centered about one-half of N, the detector provides a detect indication signal indicating that the delta modulated digital signal is present. Otherwise, a random or pseudorandom signal such as noise or error bursts may be present. Digital circuitry provides the detect indication signal with a logical high state when successive totalized numbers of bit transitions are outside of the predetermined range, and a logical low state when succesive totalized numbers of bit transitions are within the predetermined range. The detect indication signal may be further integrated and amplified to provide a signal quality voltage which has a magnitude indicative of the quality or signal to noise ratio of the detected delta modulated digital signal. The signal quality voltage may be advantageously utilized in a receiver voting system having a plurality of receivers for selecting the receiver having the highest quality signal.
摘要:
A method includes: receiving a burst including payload and a synchronization field, wherein the synchronization field contains a synchronization pattern; selecting, from a plurality of expected synchronization patterns, a target synchronization pattern dependent on an operating mode; comparing the received synchronization pattern against the target synchronization pattern; and if the received synchronization pattern is of the target synchronization pattern, processing the payload; otherwise, discarding the burst.
摘要:
In a wireless communication system with an air interface comprising a plurality of bursts, a plurality of bursts is defined. Each burst comprises a field (300) embedded within the burst. The field is one of a synchronization field (300′) and a signaling field (300″). When the field is a synchronization field, a position of at least one subsequent burst comprising the signaling field is defined, and a position of at least one subsequent burst comprising the synchronization field is defined.
摘要:
A method voting multiple messages begins with a communication unit (111) transmitting (301) a message. At each of a plurality of sites, the message is received (303) and decoded (305) such that a minimized metric is computed and decoded message is extracted from the message. The minimized metric is adjusted (307), producing an adjusted metric. Each of the plurality of sites transports (309) its decoded message and its adjusted metric to a comparator. The comparator receives (311) selecting the decoded message and the adjusted metric from each of the plurality of sites, compares (313) selecting the adjusted metric from each of the plurality of sites and finds an optimal adjusted metric. The decoded message associated with the optimal adjusted metric is then selected (315).