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"Transmission of documents via telephone wires is possible in principle, but the apparatus required is so expensive that it will never become a practical proposition."
Dennis Gabor, British physicist
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| Number | Title | Issue Date |
| 5241537 | Conventional base station interface architecture for RF trunking multisite switch An interface for a conventional base station into a digitally trunked network of RF communications systems acts a pseudo-down link from a multisite switch to a trunked site controller. The interface monitors the conventional channels from the base station... | 08/31/1993 |
| 5239677 | Method and apparatus for initiating communication on an assigned frequency A portable transceiver system (100) has at least one base site (200) capable of communicating with at least one of a plurality of portable transceivers (108). The at least one base site (200) comprises communicators communicating on first and second frequ... | 08/24/1993 |
| 5235631 | Trunked talk-group assignment method A trunked communication system having reassignable talk-groups. By having the talk-groups reassignable, the trunked communication system can accommodate a large number of user groups without adding to the control resource traffic congestion.... | 08/10/1993 |
| 5222248 | Call hand-off with user selectable site switching In a trunked communication system with at least two communication sites, a call hand-off mid-call may occur when a mobile radio (109) moves from the coverage area of one site to the coverage area of another site. This second site may not have any communic... | 06/22/1993 |
| 5187810 | Route guidance system for provding a mobile station with optimum route data in response to a guidance request together with base station data indicative of an identification of a base station A mobile telecommunications system includes a plurality of base stations each being communicatable with a mobile station by radio. A telecommunications network accommodates the plurality of base stations for switching communications to the plurality of ba... | 02/16/1993 |
| 5179720 | Method and apparatus for extended coverage of a trunked radio communications system 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 ... | 01/12/1993 |
| 5148148 | Radio alarm system A radio alarm system for detecting abnormalities such as a fire having a central unit which is adapted to receive and decode the radio signal transmitted from each terminal device and to give an alarm and a plurality of terminal devices which is connected... | 09/15/1992 |
| 5133080 | Repeater for a controlled radio system A repeater (30) is provided for relaying communication between a subscriber unit (24) and a central station (10) when the repeater recognizes transmission from the subscriber unit to the central station but detects a lack of response by the central statio... | 07/21/1992 |
| 5123110 | Channel assignment method for multi-site trunked radio system A method for allocating communication resources within a communication system wherein communication resources are assigned only within critical sites and within non-critical sites containing critical users. A central controller checks the critical site li... | 06/16/1992 |
| 5103445 | Method of adapting a mobile radio communication system to traffic and performance requirements A method in a mobile radio communication system for adapting the system and communication to prevailing traffic and performance requirement. According to the invention a mobile station inserts information on particular codes in its messages transmitted to... | 04/07/1992 |
| 5101407 | Multiple-access communications system A multiple access communications system for use between a base and a plurality of substations and having a first channel for transmission of data from the base to the substations and a second channel for transmission of data from the substation to the bas... | 03/31/1992 |
| 5101502 | Wide area trunked channel busy override A typical multi-site trunked communication system comprises communication units that are arranged into talk groups, communication resources distributed among communication sites, and a communication resource allocator. In such a system, a methodology is i... | 03/31/1992 |
| 5095529 | Intersystem group call communication system and method Communication systems having dedicated communication resources are provided with receivers that monitor the communication resources of other communication systems, and roamers are preregistered in non-home systems. Using this infrastructure, a group call ... | 03/10/1992 |
| 5086507 | Drop channel pre-alert for trunked radio communication system To help prevent call bridging and increase the reliability of channel de-assignment in a trunked radio repeater system, the working channel sends a drop channel "pre-alert" message to on-channel mobile units just before sending the drop channel signal. Th... | 02/04/1992 |
| 5060296 | Communication system with squelch control A trunked communication system (100) wherein an EOT (308) as transmitted by a communication unit (103) is used by the system to initiate a squelch methodology, but is not used by the resource controller (101) to determine reallocation of the communication... | 10/22/1991 |
| 5058199 | Inter-truncked radio systems bridge protocol A radio signal relay system for use with dispatch communication systems is disclosed. The radio signal relay system includes a linking device constructed with a first and a second full duplex transceivers such that it has the capability of communicating w... | 10/15/1991 |
| 5054111 | HF data communications system with network management A method of network management for a radio communications network comprising a plurality of stations each of which includes a transceiver and control means therefor, the transceiver and control means of the respective stations being substantially similar,... | 10/01/1991 |
| 5050234 | Method for connecting a channel between a base station and a mobile station A radio communication system comprises a plurality of subsystems each including a base station and a mobile station. A connection is to be allowed between the base and mobile stations in a subsystem by a first decision, when they have a first distance sho... | 09/17/1991 |
| 5038398 | Method of assigning communication links in a dynamic communication network A method of assigning communicaton links in a dynamic communication network, such as a network of earth orbiting satellites arranged, for example in three constellations. The assignments are made in phases, with the first phases assigning high priority li... | 08/06/1991 |
| 5034993 | Method for allocating communication resources among RF communications systems A method for allocating RF communication resources among RF communication systems. This allocation may be base strictly upon demand or it may be based upon the loading of an RF communication system or the relative loading among a group of RF communication... | 07/23/1991 |
| 5025254 | Communication system with improved resource assignment A trunked communication system wherein some of the communication resources are preassigned for exclusive use only by a predetermined group, such as a public safety agency. In addition, to assure optimal assignment of communication resources, communication... | 06/18/1991 |
| 4998290 | Frequency-hopping radio communication network A system for effecting radio communication over a given range of frequency channels among a plurality of participating local stations, includes: a variably settable channel transmission unit at each such participating local station; and a controller or ce... | 03/05/1991 |
| 4995097 | Radio system to allow for exchanging messages between a set of stations A radio system allows for exchanging messages between a set of relay stations (R1, R2, R3 . . . ) and mobile access stations (M . . . ) for communications. At least one common semaphore channel is used through which the relay stations simultaneously trans... | 02/19/1991 |
| 4939746 | Trunked radio repeater system A digital trunked radio repeater system provides substantial improvements in timeliness of channel acquisition and channel drop, and in reliability of critical control signalling. The system uses a much higher digital signalling rate than is typically fou... | 07/03/1990 |
| 4837858 | Subscriber unit for a trunked voice/data communication system A trunked voice/data subscriber is provided that operates in either a voice mode, or one of three data modes. In a first data mode, the voice/data subscriber monitors the voice control channel to enable rapid participation in a voice call. In a second dat... | 06/06/1989 |
| 4833701 | Trunked communication system with nationwide roaming capability Selected regional trunking systems are equipped with telephone interconnect capability and provided with local computers (106), which communicate with a national hub computer (110). At each selected trunking system, several IDs are reserved as "roaming ID... | 05/23/1989 |
| 4680583 | Terminal address assignment in a broadcast transmission system In a broadcast transmission system, in which in normal operation messages and terminal addresses are transmitted between a master station and a plurality of terminals each having an assigned address, the master station initially assigns the addresses to t... | 07/14/1987 |
| 4672601 | Duplex interconnect/dispatch trunked radio system A dispatch trunked radio system which provides duplex or simplex telephone interconnect communications to subscriber units is described. The system allows duplex capable trunked system subscriber units to establish a full duplex communication link with co... | 06/09/1987 |
| 4658435 | Radio trunking system with transceivers and repeaters using special channel acquisition protocol An arrangement for establishing communication between a first mobile radio transceiver and a second mobile radio transceiver through a repeater over a radio frequency channel selected from a plurality of such channels. A repeater distinguishes between two... | 04/14/1987 |
| 4654879 | Cellular mobile radio subscriber location detection The locating function of a cellular mobile radio telephone system is implemented so that, when the locating radio detects a sustained change from a very low signal quality or amplitude (indicating background noise rather than an active call in an adjacent... | 03/31/1987 |
| 4646345 | Automatic unit ID for quasi-transmission trunked systems The system requires the use of the permanent ID of the requesting unit in every channel request made on a control channel before every transmission. The channel grant will include the ID along with the channel number and these may be recorded for possible... | 02/24/1987 |
| 4618998 | Radio communications control system which automatically returns the system to the speech channel A radio communications system having a call channel and a plurality of speech channel one of which is to be selected, is provided with means for returning to a last used speech channel in the event that a call is required within a predetermined time perio... | 10/21/1986 |
| 4573207 | Queued community repeater communications system A communication system which controls access to a single communications channel by a plurality of remote units arranged in predetermined groups is disclosed. Assignment of the channel is controlled by a central control station which provides time periods ... | 02/25/1986 |
| 4553262 | Communications system enabling radio link access for non-trunked radio units to a multifrequency trunked two-way communications systems An improved multifrequency trunked, two-way communications system is provided in which a plurality of conventional single channel radio units are provided access. The system includes a predetermined number of information channels that are shared by a plur... | 11/12/1985 |
| 4553263 | Queued community repeater mobile A remote unit which transmits and receives messages within a fleet of remote units on a single communications channel shared by a plurality of remote unit fleets is disclosed. Access to the channel is regulated by a central control station which transmits... | 11/12/1985 |
| 4519069 | Communication system interconnecting radios and operators located at different positions A communication system using a control bus and an audio bus to interconnect operator positions and radio positions. Each position is allocated, by a timing circuit, time slots on the control bus during which it applies digital words to the control bus ind... | 05/21/1985 |
| 4477809 | Method for random-access radio-frequency data communications A method for random-access data communications to and from a central controller, from and to at least one of a plurality of remote stations, by providing at least one radio-frequency channel having the bandwidth thereof allocated into at least a message c... | 10/16/1984 |
| 4345334 | Reduced-cross talk telemetry system and method of manufacture thereof Method and apparatus for providing a multi-channel telemetry system in which the fundamental frequencies of the transmit-receive channels of the system are selected from a series of tentative fundamental frequencies. The successive fundamental frequencies... | 08/17/1982 |
| 4090036 | Satellite communications system A satellite communications system provides automatic channel assignment without employing a dedicated signalling channel. A major station detects carrier-free forward channels and transmits on each a forward signal. A minor station hunts all available for... | 05/16/1978 |
| 4009347 | Modular branch exchange and nodal access units for multiple access systems Modular digital exchanges linked by earth satellite provide coordinated time division switching and time compressed communication services relative to externally attached telephone and data (user) trunks. Branch exchange modules (NCU's) perform call switc... | 02/22/1977 |
