Abstract: 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.

Abstract: A system and method for effectively and reliably terminating a voice call in any burst within a multi-burst superframe. A transmitting unit generates a termination burst upon detecting a dekey event. The termination burst includes a data synchronization pattern, a slot type field indicating an end of a call, and an information field surrounding the data synchronization pattern and the slot type field. The information field is encoded from a predetermined voice encoder frame unique to the termination burst. Once all buffered voice information is transmitted, the termination burst is transmitted prior to the end of the multi-burst superframe. A base station or other receiving unit monitors the incoming signal. Upon detecting the data synchronization pattern, the receiving unit decodes the slot type field and the information field.

Abstract: 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.

Abstract: A system and method for effectively and reliably terminating a voice call in any burst within a multi-burst superframe. A transmitting unit generates a termination burst upon detecting a dekey event. The termination burst includes a data synchronization pattern, a slot type field indicating an end of a call, and an information field surrounding the data synchronization pattern and the slot type field. The information field is encoded from a predetermined voice encoder frame unique to the termination burst. Once all buffered voice information is transmitted, the termination burst is transmitted prior to the end of the multi-burst superframe. A base station or other receiving unit monitors the incoming signal. Upon detecting the data synchronization pattern, the receiving unit decodes the slot type field and the information field.

Abstract: A received synchronization pattern is compared against first and second known synchronization patterns. If the received pattern is of the first known pattern, the payload is processed as voice; and if the received pattern is of the second known pattern, the payload is processed as non-voice. In an alternative, the received pattern is compared against first and second known synchronization patterns. If the received pattern is of the first known pattern, a first operating mode is selected, and if the received pattern is of the second known pattern, a second operating mode is selected.

Abstract: A received synchronization pattern (300″) is compared against first and second known synchronization patterns. If the received pattern is substantially similar to the first known pattern, the payload is processed as voice; and if the received pattern is substantially similar to the second known pattern, the payload is processed as non-voice. Alternatively, a target synchronization pattern dependent on an operating mode is selected. The received pattern is compared against the target pattern. If the received pattern is substantially similar to the target pattern, the payload is processed; otherwise, the burst is discarded. In yet another alternative, the received pattern is compared against first and second known synchronization patterns having a common length. If the received pattern is substantially similar to the first known pattern, a first operating mode is selected, and if the received pattern is substantially similar to the second known pattern, a second operating mode is selected.

Abstract: 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.

Abstract: 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.

Abstract: 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).

Abstract: 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).

Abstract: In a system for transmitting digital information, transmitter operating parameters (503) are transmitted with other communication message information (501, 505, 507, 509, 511, 513, 515, and 517) to aid communications.

Abstract: A multiple-modulation communication system includes a transmitter that modulates and transmits communication signals modulated by a first modulation technique and communication signals modulated by a second modulation technique. The first modulation technique and the second modulation technique are different. The communication system also includes a receiver capable of receiving the communication signals modulated by the first modulation technique and the communication signals modulated by the second modulation technique and demodulating the communication signals.

Abstract: A method of decoding (311 and 417) by Viterbi algorithm is applied with a metric that limits effects on the metric's value. A received signal (109) comprised of symbols is filtered, thereby providing (303 and 403) a phase angle of the received signal (109) and providing (305 and 409) a magnitude of the received signal (109). The phase angle of the received signal (109) and the magnitude of the received signal (109) are sampled (309 and 413) once per symbol and then decoded according to the Viterbi algorithm with a metric that limits effects on the metric's value as the difference between the sampled phase angle and the decoded symbol increases.

Abstract: Synchronization of secure information on a control channel (104) of a secure radio trunking communication system (100), is maintained by periodically transmitting control encryption parameters (CEP) (111) by the controller (101) on the control channel (104). A secure communication unit (102 and 103) may receive and store the CEP (111) in memory (108 and 109), and subsequently, use the stored CEP (111) to communicate securely with the controller (101) on the control channel (104). When the secure communication unit is assigned to a working channel (105-107), the controller periodically sends the CEP (117) to the secure communication unit (102 and 103) on the working channel (105-107). When the secure communication unit (102 and 103) returns to the control channel (104), the secure communication unit may use the CEP (117) stored in the memory (108 and 109) to communicate securely on the control channel (104).

Abstract: A transceiver compatible with both wide channel constant envelope 4 level FSK FM modulation and narrow channel .pi./4 differential QPSK linear modulation allows compatible interaction between modified constant envelope and non-constant envelope transmitters. All Nyquist filtering occurs in the transmitters, and none in the receiver.

Abstract: 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.

Abstract: Discrete packets (306) containing encoded voice information are transmitted within frames (301 and 302) in a repetitive manner until all voice information has been sent. Following transmission of all packets containing such voice information, at least a predetermined number of additional packets (401) are then transmitted, which additional packets represent silence. Following this, a disconnect signal (304) is transmitted. So configured, loss of the disconnect signal due to fading or other communication pathway disturbances will not necessarily lead to audibilization of undesired sounds, as the decoding protocol at the receiver (200) provides for reprocessing of recently received packet information in the absence of newly available reliable information. Hence, the silence information is continually reprocessed until either reliable information is again available or a time out sequence concludes.

Abstract: In an encrypted radio system, transmsitters and receivers can each be provided with a plurality of encryption algorithms (407 and 425) and/or encryption key variables (408 and 426). A unique logical ID (409 and 427) corresponds to each of the above. During transmission of an encrypted message, both encryption synchronization information (319) and information concerning the logical ID (318) is repetitively interleaved with the encrypted message itself. So configured, a receiver that temporarily loses viable reception can again obtain encryption synchronization and algorithm/key information, and therefore rapidly recover from the reception disturbance.

Abstract: A layered session data unit frame (300) is provided wherein a first frame (200), designated a session data unit("SDU"), containing user information (209), a link control field (205) and an encryption field (207), is divided into a plurality of smaller frames (321, 323), each having an information field and designated a link data unit("LDU"). According to the invention, the SDU user information (209) is allocated into the information fields (211, 213) of the plurality of LDU's. The SDU link control field (205) is divided into a plurality of sub-fields and imbedded into the information fields of a first group of LDU's. The SDU encryption field (207) is divided into a plurality of sub-fields and imbedded into the information fields of a second group of LDU's. The sub-fields may be distributed throughout the LDU's in a generally uniform fashion.

Abstract: The present invention discloses a method of simulating the state of a TYPE I Linear Feedback Shift Register (LFSR) with information available as a result of a TYPE II LFSR implementation. This is accomplished by clocking a TYPE II LFSR to produce an output sequence. This sequence, or at least a portion thereof, is then stored in a storage medium, such as, for example, a shift register. Cascading a TYPE II LFSR output sequence into a shift register of length N, where N is the number of stages employed by the TYPE II LFSR, is the exact equivalent of a TYPE I LFSR. Accordingly, the shift register's contents will contain data corresponding to the state of a TYPE I LFSR.