Abstract: In frequency-hopping spread-spectrum systems, it is necessary to maintain frequency and bit synchronization (sync) between the transmitter and receiver in order to maintain quality data recovery at the receiver. A protocol is described which includes a synthesizer lock field (109) to allow frequency sync, a clock sync field (123) to achieve quick clock sync, and a data sync field (125) to provide data sync. Other fields are provided in the protocol to allow both voice (141) and data (127) transmissions, inband signalling (139), and error correction (143). A method and apparatus, driven by a microprocessor (303) and ASIC (301) combination, are described that generate and transmit this protocol.

Abstract: In a communication system network that comprises a plurality of communication systems and a processing multiplexer, each of the plurality of communication systems is equipped with fallback operation circuitry. The fallback operation circuitry enables a communication system to operate as a standalone system when the interface buses that connect it to the processing multiplexer fail. In addition, the fallback operation circuitry enables the communication system to be reconnected to the processing multiplexer when the interface buses resume proper operation.

Abstract: A plurality of consoles (111-113) share use of a single landline (101) with minimal requirements for internal maintenance data signalling. As two or more consoles both share use of the link, a telephone interface (103) assigns one of the consoles to be responsible for maintenance signalling. If and when the assigned console concludes its communication needs or otherwise becomes unable to continue the maintenance signalling, the telephone interface will assign a new interested console to provide the maintenance signalling. This continues until no consoles remain having an interest in maintaining the communication link. In one embodiment, when the link is used by only a single console, a hold function can be accommodated. When two or more consoles are serviced, however, the hold function is not applied. Also, when the link has been placed on hold, any console can remove the hold condition.

Abstract: A personal communications device (100) includes a wireless transceiver (206, 207, 208) to allow a two-way exchange of user information, and to allow down loading of remote control signalling information. The latter can be transmitted via an appropriate transmitter (210 or 211) to facilitate remote control of a remote controlled device.

Abstract: A communication control console center, able to receive at least one phone call, has a ring tone mute button (103). To prevent indefinite or permanent muting of ring tones automatic disabling of the ring tone mute circuit is provided by a programmable timer (107). An automatic mute button (111) is presented to automatically disable ring tone muting at call termination.

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 method of message authentication in an encrypted communication system with over-the-channel rekeying features the ability of a communication unit (107) to authenticate (1709) a rekeying message (701) from a key management controller (101) using a message number (1517A) comparison, thereby preventing outside interference from unauthorized rekeying message transmissions.

Abstract: A data transmission system receiver is disclosed which receives a formatted data stream (302) and operates in one of at least a first bandwidth mode and a second bandwidth mode. The formatted data stream (302) comprises a plurality of data edges (108, 110) and is sampled by a first clock signal (320). A plurality of clock edges (102, 104) defining transitions from one logic state to another is used to define "early" and "late" data edge occurrences. These occurrences are accumulated in accumulators (310, 312) and used as inputs to a clock counter (318) which produces a phase-adjusted clock signal (320). Additionally, the data transmission receiver comprises a detector (330) for detecting when a limited data stream (306) is synchronized with the phase-adjusted clock signal (320) and, in accordance with a predetermined algorithm, is able to switch the phase-lock circuit from the first bandwidth mode to the second bandwidth mode.

Abstract: A trunked radio system range extender extends the range of a trunked radio system by having a second repeater station monitor the control channel for the trunked radio system detect and decode control information and rebroadcast it on to a second control resource. Communications resources from the first trunked radio system are similarly mapped into a second set of communications resources for subsequent broadcast throughout an extended geographic range. The extending repeater station uses the control resource from the first repeater station.

Abstract: This key management system effectively solves the key distribution problems of distance, time, operator error, and security risk by transferring encryption keys with appropriate system information between a key management controller (101) and a remote keyloader (109). The keyloader (109) is then coupled to a communication device to transfer (327) the keys and receive (329) identification information from the communication device. The keyloader (109) then sends (323) the information to the key management controller (101) that controls the distribution of the encryption keys and collection of the communication device identifications.

Abstract: An enclosure system (100) is disclosed which has a conductive cover shield (102) which is retained in contact with a substrate (104) having a radio frequency (RF) circuit disposed thereon. The enclosure system (100) is made up of a conductive area (116), disposed on the substrate (104) peripherally about the electrical circuit which is then connected to the conductive cover shield (102). This connection allows for substantial horizontal displacement (305, 305') of the substrate material (104). The natural resilience of the substrate (104) material then allows for substantial vertical displacement of the conductive cover shield (102) with respect to the substrate (104) without substantial loss of contact pressure between the conductive cover shield (102) and the conductive area (116). Additionally, this form of connection provides for at least partial isolation of the RF energy from an environment outside of the enclosure system.

Abstract: Formation and sending of rekeying messages (305, 415, 515, and 605) in an encrypted communication system with over-the-channel rekeying of communication units is performed by a KMC, key management controller (101). The KMC (101) forms messages to provide new keys (1541), zeroization information (1549), and key indexing information (1543) to communication units (107), and to provide keyloader upload data (1563). Acknowledgments and rekey requests are also handled between the KMC (101) and communication units (107).

Abstract: A single sync field (501) and multiple messages or message segments (503, 507, 511, and 515) are chained (407) together and encrypted (407) as a whole. When this encrypted chained message is received, it is decrypted as a whole (605), or in part (613) by setting up (609) and filling (611) a holding register with the encryption state of the encrypting device.

Abstract: A communication system (100) that varies the channel usage requirements of its communication resource assignment grant signals to accommodate the varying needs of communication units themselves as well as accommodating current loading conditions on an assignment resource.

Abstract: Independent communication systems are provided with additional receivers that allow the systems to monitor one another's outbound control signalling channels. Secondary control signalling can be interleaved with the primary control signalling information on this communication resource, which secondary control signalling information is intended for reception and use by the monitoring system.

Abstract: A simulcast transmission system (150) is disclosed in which a primary (402), a first, and a second transmitter site (302) form a first communication loop (403). The first communication loop (403) has at least a first and a second audio path, each of which are associated with a path identification (ID). The first and the second path IDs are also associated with a set of transmission delay parameters which are stored (401) at both the first and the second transmitter sites. The primary transmitter site (402) detects a location of an inoperative communication link (409) within the first audio path, and switches from the first audio path to the second audio path, whereby the second audio path does not traverse the inoperative communication link. The primary transmitter site (402) then broadcasts (512) a path condition ID to the first and the second transmitter sites. The first and second transmitter sites then retrieve (514) the set of transmission delay parameters associated with the second audio path.

Abstract: A radio communication controller (106, 401) is disclosed which is capable of accessing a database having a subscriber unit identification code (302, 601) and a preselected calling code, or area code, accumulating a keyed Public Switched Telephone Network (PSTN) telephone number from the subscriber unit wishing to make an interconnect call (110, 407), and comparing (215, 518) this area code with that of the controller site. The controller, as employed by the invention, is further capable of deciding whether or not the area code is required for completing the interconnect call, and if so, prefacing (217, 520) the accumulated PSTN telephone number with the area code preselected by the user of that subscriber unit.

Abstract: This method of key distribution rekeys (605) a group of communication units (107) within an encrypted communication system with over-the-channel rekeying. The method uses a key management controller (101) to manage and distribute keys (1541) to a plurality of communication units and handle acknowledgments from the plurality of communication units that are delayed from receipt of the rekeying message. The rekeying message (615) is sent to any of the group of communication units (107) when an acknowledgment is not received (611) from one or more of the group of communication units (107).

Abstract: A communication system supporting dispatch-like communications in a geographic reuse system environment. An originating user provides a verbal alias corresponding to a target communication unit. The system utilizes the verbal alias to locate a corresponding system identification code for the target unit. The system then determines the general whereabouts of the target unit, and establishes a communication path between the two units. The original voice message may be stored and subsequently transmitted to the target unit upon properly identifying, locating, and establishing a communication path to the target unit.

Abstract: In frequency-hopping spread-spectrum systems, it is necessary to maintain frequency and bit synchronization (sync) between the transmitter and receiver in order to maintain quality data recovery at the receiver. Two transmissions in adjacent hop-time intervals may overlap because of various time delays within the system. Collision bits (203 and 207) are used to realign the transmitted messages in time. The base station (103) manufactures (401) the collision bits (203 and 207) and transmits them to the communication unit (101), which echoes back (503) the bits on its next transmission. If the bits received at the base station do not match the bits sent (407), the base station (103) initiates (409) collision maintenance such that the communication unit (101) can adjust its DPLL (331) to realign its transmissions in time.