Abstract: An intersystem communication path (20, 67) can be established on an as needed basis. Already established paths are fully utilized before new paths are established. Already established paths can be automatically disconnected when no longer needed, or when existing calls can be merged on to fewer lines. Dial up lines can be mixed with dedicated lines. If desired, excess capacity can be guaranteed to accommodate high traffic conditions and/or other conditions that precipitate a likely need for communication services between systems.

Abstract: A spread spectrum system provides bidirectional digital communication on a vacant television (TV) channel for simultaneous use by more than 75,000 subscribers using time and frequency division multiplex signals locked to horizontal and vertical sync pulses of an adjacent channel Host TV station. The system, whose operation is analogous to a radar system, comprises: (1) the Host TV station to send down-link sync and data pulses to subscribers during the horizontal blanking interval (HBI), (2) subscriber "transponders" which detect those signals and transmits up-link "echo" data pulses only during the HBI to eliminate interference to TV viewers, and (3) a central receiver which also uses the host TV sync pulses to trigger range gates to detect the up-link data pulses.

Abstract: A method of collapsing a communication path among at least two communication units (104-107) reduces the number of sites normally required to provide a communication. Each of a plurality of site controllers (103) in a radio communications system has a corresponding coverage area (100, 101), and at least some of the coverage areas (710-712) overlap one another. The method includes the step of determining (402) whether the communication units are currently being serviced by different sites, and then determining (405) whether they can be serviced by a common site. When the communication units are serviceable by a common site, the call might be established (406) through the common site, resulting in a reduced number of sites required to complete a call.

Abstract: A communication unit within a trunked communication system can reduce control channel traffic by maintaining a data base of the communication system services that it can perform. The data base is maintained by the communication unit selecting a service that it desires to perform. Having selected the service, the communication unit verifies that it is one of the services that it can perform and transmits a request to perform that service to a communication resource allocator. The communication resource allocator responds to the request and the communication unit updates its data base based upon the response from the communication resource allocator. The response transmitted by the communication resource allocator may comprise either a grant to the communication unit that allows it to perform the selected service or a denial that the selected service is one that the communication unit is not allowed to perform.

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: Communication systems (101, 102) having dedicated communication resources are provided with receivers (111, 116) that monitor the communication resources (104, 108) of other communication systems. Communications between communication units in various systems are interchanged through appropriate interaction of the repeaters and the dedicated receivers so provided.

Abstract: A radio communication system includes a central station such as a repeater for transmitting FM signals to a plurality of radios. The repeater 11 is capable of receiving both analog speech FM signals and compressed voice signals. This permits the use of energy efficient transmission schemes by some of the radios operating in the system while permitting use of both types of transmission by the various remote radios.

Abstract: A site architecture for a trunked radio frequency communications system provides better fault tolerance capabilities than are available from architectures including redundant hardware. During normal system operations, a primary site controller performs most or all system control functions while signal processing functions are performed in a distributed manner by trunking cards associated with individual repeater channel receivers and transmitters. In the event the site controller fails, the trunking cards also begin performing trunking and other control functions. The trunking cards cease attempting to communicate with the failed site controller, and begin communicating directly with one another via a high speed backup serial link.

Abstract: A wireless PBX system provides ease of installation without site engineering or trial-and-error placement of components within the system. In its basic form, the wireless PBX system consists of only two types of components: a control unit including an radio frequency transceiver; and fixed location terminals, such as telephones and voice/data stations, which also include radio frequency transceivers. Portable handsets are optionally included in the system to allow for customer mobility. Installation of the PBX system is achieved simply by placing the system components in the desired locations at a premises, plugging them into line power, and performing some simple programming steps including a final step of initiating an automatic configuring process. Through this process, the system automatically configures itself for optimum operation in view of the radio environment and placement of components within the system at the customer premises.

Abstract: A system and method for providing single channel remote site trunking is described. The present invention allows for radios (116) operating in single channel non-dedicated control channel sites (104) to communicate with radios (112, 114) in dedicated control channel sites (102) which are part of the system (100). Further, the present invention will allow for non-trunked radios to utilize the benefits of trunking when operating in the single channel remote site. By mapping the ID's of the radios in the system (100) the system can keep track of all radios in the system whether in a remote single site (104) or in one of the dedicated control channel sites (102) and thereby link allow radios in one site to automatically communicate with the radios in the other site.

Abstract: An RF repeater for receiving and retransmitting video composite signals, especially wherein the signals of different channels are spectrally adjacent includes discrete aural and visual stages for separating the composite video signal into its components. The aural stage includes a phased locked loop filter while the visual stage may use a SAW filter. After separation and amplification, the two signals are up-converted and combined for retransmission. The visual stage also includes a phase locked loop for synthesizing a local oscillatoar signal and for phase lock detection.

Abstract: The relay base of the invention comprises a receive antenna connected to a receiver coupling member associated with receiver members connected to respective digital processing units. The digital processing units are connected to transmitter members via link lines each of which is associated with one of the digital processing units and all of the transmitted members via parallel connections, each transmitter member including a switching member causing one of the link lines to be put into communication with the associated transmitter member.

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: A method of predicting cell-to-cell hand-offs of mobile subscribers for a satellite cellular communications system. Each satellite of a constellation projects a number of beams or cells upon the earth for communication with mobile subscribers. The satellite transfers (hand-offs) communications links from cell to cell as the satellite moves over the mobile subscriber. Since the movement of the satellite is stabilized in three directions, the projection of the beams or cells follows a predictable path across the face of the earth. Each satellite moves across the earth in one direction. Once a subscriber is located within one cell, the next cell to which the mobile subscriber is handed-off may be determined from the geographic position. For mobile users which are close to boundaries between cells, additional position location may be determined by the calculation of bit error rates.

Abstract: A system and a method for extending coverage of a cell site in a cellular radio telephone system include a plurality of repeaters or boosters which are spaced through the region where increased coverage is desired. A first booster is in radio communication with the transceiver for the cell site. The remaining boosters are linked together, by radio transmissions, in a series configuration with only one of those linked to the first booster. A movable transceiver operating in the extended area of coverage is in radio communication with the closest booster unit and, via the serial chain of boosters in communication with the controlling cell site. As the movable unit moves along the extended area of coverage from one booster area to another, it is automatically picked up by the approaching booster and dropped by the receding booster while continuing to be in communication ultimately with the cell site via the series coupled booster chain.

Abstract: A radiotelelphone system in the form of a private branch exchange (12) within and/or outside one or more buildings is equipped with a plurality of mobile subscriber units (28), a plurality of transmitter/receiver units (27) capable of communicating with the subscriber units (28) by radio, and a central unit (26) cooperating with the transmitter/receiver units (27). In order that such a radiotelephone system not only permits mobile telephoning within and/or outside buildings but also can be installed later and adapted to changing requirements in a simple manner, the transmitter/receiver units (27) are arranged and designed to form not only a radio link to at least one of the subscriber units (28) but also, via respective adjacent transmitter/receiver units (27), a radio-link chain (radio bus) to the central unit (26), which has a separate transmitter/receiver unit.

Abstract: In a trunked radio frequency communications system, a dynamic regrouping scheme includes an effective user interface, automatic support of multi-site systems, the capability to program individual radio transceivers with multiple new groups dynamically, a fast rate of reconfiguration, instantaneous switch over to prevent radios from residing in immature groups, and a satisfactory mode of operation should the site controller (or site controllers in non-fault tolerant systems) fail. Some of the dynamic regrouping features includes unlimited prestored plans and source and destination groups per plan, regrouping at the plan or destination group level, an advanced user interface, automatic support of multiple sites, fast regrouping at the rate of over 30 radios per second while reducing loading on the system control channel, and fast activation/deactivation. Each plan can be immediately activated or deactivated and users are effectively regrouped together.

Abstract: A cellular communication system booster has plural narrowband and wideband channels each having down mixers, local oscillators, IF filters, and amplifiers for amplifying communication signals. On a narrowband channel preferably not in use, and preferably in a time-multiplexed manner, a reference signal of known signal strength is substituted at the output amplifier in lieu of a normal communications signal. When this amplified reference signal is broadcast at the output antenna a portion of the signal is feed back to the input antenna due to imperfect isolation between the antennas. This feedback signal is measured by a Radio Signal Strength Indicator (RSSI) circuit at the point of its receipt into the IF filter of the narrowband channel. The measured signal strength serves as a measurement of signal isolation/feedback between the antennas.

Abstract: 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 can be sourced in one system and relayed to roamers located in other systems.

Abstract: A trunked radio frequency (RF) repeater system for public service trunking (PST) or the like includes a fault detection system having an RF output power monitoring, over-the-air RF monitoring and other repeater transceiver testing capabilities. An over-the-air monitor continually tests the digital signalling transmitted by different transceivers within the repeater system. The site controller automatically removes transceivers that test faulty, and does not permit tested faulty transceivers to go back on line until they have passed poll response, power output and RF digital signalling tests.

Abstract: Disclosed is an apparatus for receiving a selected channel of a signal having a plurality of channels, each channel having a plurality of subchannels. A parabolic reflector, low noise amplifier and block converter receive the signal. A tuner detects the selected channel in the received signal and provides a detected signal corresponding to the selected channel. A demodulator demodulates the detected signal into a baseband signal corresponding to the selected channel, the baseband signal being modulated with the subchannels of the selected channel. An analog bus is connected to the demodulating means for providing the baseband signal. A first demodulator connected to the analog bus demodulates a first subchannel of the subchannels of the baseband signal and provides a signal representative of the first subchannel. A second demodulator connected to the analog bus demodulates a second subchannel of the subchannels of the baseband signal and provides a signal representative of the second subchannel.

Abstract: A trunked radio communications system is disclosed which includes a repeater base station and plural fleets of mobile and/or portable radio transceivers. When all communication channels are busy, not only is the initiating unit informed that it has been placed in a queue of channel assignment requests, but also the called units in the respective called fleet are given an indication that in effect they have been placed in the queue. This indication may, for example be an audible indication and/or a visual indication from a display lamp, light emitting diode or liquid crystal display. In this fashion, each mobile or portable radio in a fleet is provided with advance notice that it is about to receive a call momentarily. Such a mobile or portable radio is thereby informed that as soon as the system can provide a channel assignment for the calling unit, that a call will be received.

Abstract: 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 link classes. Subsequent phases assign lower priority link classes. A set of constraints is established, and a high priority subset of these constraints can be assured by requiring that any assignment set to be accepted results in a network topology satisfying that subset of constraints even if existing links must be intentionally broken. Other constraints are met only if existing links need not be broken.

Abstract: A signal repeater assembly (1) for a spacecraft, includes a channel selectivity network (CSN) (2) having a plurality of first input ports (4-13) connected by selectively operable filter circuits (14-23) to a plurality of first output ports (24-31) to enable a signal at any selected first input port (4-13) to be passed to any selected first output port (24-31). The CSN (2) is connected to a shared power amplification module (SPAM) (3) having a plurality of second input ports (44-51) for receiving signals from the first output ports (24-31), a plurality of second output ports (52-59) and a network (60) of balanced amplifier devices (61) operable to couple the second input ports (44-51) to the second output ports (52-59) so that any amplification of a signal received at any one of the second input ports (44-51) is shared by all the amplifier devices (61) to allow the total available amplification power to be used by any one or a combination of second output ports (52-59).

Abstract: A downlink between a communications dispatch console and a digitally trunked radio repeater system site controller efficiently transfers message data between the site controller and the console over a standard 9.2 kilobit per second landline. A downlink trunking card identical in structure to trunking cards used in the preferred embodiment system for RF channel signal processing interfaces the site controller with the landline link. A similar trunking card on the other side of the landline link interfaces the dispatch console processor with the landline link. Message protocol and format is translated between the site controller and the landline link and between the landline link and the dispatch console. Data buffering at each end of the landline link maximizes data transfer rate over the landline, and in addition, a priority scheme insures that more important messages are transmitted over the downlink before less important messages.

Abstract: A trunked communication system utilizes talkgroup synchronization for roaming communication units. By automatically matching the communication unit's talkgroup in a first area-wide system with an talkgroup in a second area-wide system, the communication system facilitates rapid association with a desired talkgroup.

Abstract: An apparatus and method for selecting a number of cellular radio channels to be boosted in a given geographical area provides either F1-F1 or F1-F2 operation. The signals are be boosted at the same frequency with input to output isolation being achieved by the use of directive transmit and receive antennas physically positioned to achieve sufficient isolation. Each signal is individually filtered, amplified, and recombined for transmission. Any number of signals may be accommodated depending upon the number of retransmission channels available. Apparatus is also provided to retransmit a signal at a different frequency from that at which it is received.

Abstract: In a data communication system, such as an earth station for a satellite communication system, a level control unit enables control of an amplitude of a data signal which is reduced in a cable, regardless of the form of the data signal. The data communication system includes a first system including a unit for sending a continuous signal having a first frequency and a data signal having second frequency, a cable, and a second system for receiving both sent signals through the cable. The second system includes a unit for correcting an amplitude of the data signal on the basis of an amplitude of the continuous signal to a predetermined level. The second system may also include a unit for further correcting the amplitude of the data signal on the basis of the frequency difference between the data signal and continuous signal, so that the amplitude is adjusted at the second frequency.

Abstract: A digital mobile radio transceiver allows even the most unsophisticated user to simply and easily obtain emergency communications. The transceiver is programmed with "personality" data specifying one or more "systems", each "system" specifying one or more "groups" of or individual radio transceivers. Systems are selected by operating a first selector switch, and groups are selected by operating a second selector switch. The transceiver simultaneously displays the "group" and "system" which have been selected. One or more group identification codes uniquely designate an emergency communications handler (e.g., an emergency dispatch operator). The group designated by the transceiver group selector switch position "9" of each system programmed into the radio transceiver corresponds to this emergency group identification code. Moreover, the "system" designated by system selector switch "11" has only one "group"--the emergency group identification code corresponding to the group selector position "9".

Abstract: A method and apparatus for allowing a radio control console to failsoft to a predetermined channel assignment plan, without disrupting emergency calls then in progress, upon the failure of a CAD host computer link that would ordinarily provide control signals to the console. Channels are deassigned unless they are supporting an emergency call, and then reassigned to a default assignment. If the reassignment would cause a duplicate assignment, the duplicate assignment is first deassigned prior to making the new default assignment.

Abstract: In antenna arrays having normally unexcited or little-excited elements, a technique for configuring the array to provide both global and spot beam coverage, wherein the normally unexcited or little-excited elements are excited at a higher level, together with other normally excited elements to provide spot beam coverage, the normally unexcited elements being left unexcited to provide global beam coverage. Ring redundancy configurations for amplifiers in a transponder provided in the configuration are optimized to minimize additional hardware requirements. The specific example of the INMARSAT II satellite system is discussed.

Abstract: A roadside antenna system permitting the transmission of data to a vehicular navigation system and providing for the recalibration of positional data carried by the navigation system includes an antenna structure and transmitter system which permits the data transmission signal to be broadcast in a wide pattern. Meanwhile, the signal that provides for positional recalibration is broadcast in a high directivity signal or split beam. The positional accuracy of the navigator system is improved by performing the positional calibration only when intercepting the narrow beam pattern. Data transmission and reception can be carried out within a larger effective reception area without affecting the positional accuracy.

Abstract: Disclosed is a method to dynamically allocate a number of data channels on a trunked radio system (100). The data activity is monitored during a predetermined time interval. If activity is above predetermined maximum, an additional channel may be reserved for data use. Conversely, if data traffic is low, a data channel may be reallocated for voice message use. Moreover, should the amount of data traffic among the available data channels be unbalanced, the present method contemplates reassigning subscriber units (114 or 116) to the available data channels to balance the data traffic load, thereby providing superior access time and system performance.

Abstract: An improved communication system is disclosed wherein at least one reprogramming station is added to a communication system. The reprogramming station is constructed and arranged to communicate with the subscriber units thereby either reprogramming or regrouping them. The subscribing units receive the reprogramming command and acknowledge individually, altering a memory means until either reprogrammed back to the original state, or to another state. In another mode, the reprogramming station transmits a regrouping command wherein two or more groups are combined to form a super group.

Abstract: In a frequency division multiple access (FDMA) communication system, a plurality of carrier frequencies relating to a predetermined frequency band for transmitting a PSK (phase shift keying) signal are provided on a frequency scale. When a service is a low bit rate signal, it is transmitted by using a single carrier frequency and its related frequency band. When a service is a high bit rate signal which can not be transmitted in a single carrier signal, the service signal is divided in to a plurality of low bit rate PSK signals, each of which is transmitted by using a single carrier frequency and the related frequency band.

Abstract: Direct relay equipment includes a first antenna, a second antenna, an up direction circuit connected from the first antenna via a first circulator to the second antenna via a second circulator, and a down direction circuit connected from the second antenna via the second circulator to the first antenna via the first circulator. In the up direction circuit and the down direction circuit, the received signal having a frequency f.sub.1 from the first (or second) antenna is amplified by a microwave amplifier, the output of the microwave amplifier is converted to a signal having a frequency f.sub.2 (sending frequency), the signal having the frequency f.sub.2 is amplified by the same amplifier, and the amplified signal having a frequency f.sub.2 is sent from the second (or first) antenna.

Abstract: A cell enhancer for use by one cellular provider in a cellular radio-telephone system includes a wideband amplifier for amplifying both down-link and up-link signals and a filter system for ensuring that signals outside of the cellular bands are not amplified. The filter system includes a wideband filter that passes at least the voice channels assigned to the cellular provider in the cell and a narrow band filter that passes the paging/access control channel in the cell. By using the filter system, signals outside the band assigned to the cellular provider, and particularly signals in the band assigned to the other cellular provider which may be present in the area, will not be amplified by the cell enhancer.

Abstract: A mobile radio communication system has base stations 1a, 1b, 1c at the centers of major service areas A, B, C defined by a contiguous array of hexagons or partially overlapping circles, and repeater or one way relay stations 3a-3m at each vertex or intersection point. The repeater stations have directional receiving antennas subtending successive 120.degree. arcs of surrounding minor service areas similarly defined by a ring array of hexagons or circles, amplifiers for imparting a high gain to signals received from mobile units in the minor service areas, and narrow width transmitting antennas for relaying the amplified signals to the base station closest each mobile unit. Such an arrangement enables a substantial reduction in the transmitter output capacity of the mobile units.

Abstract: Disclosed is a communication system of the type adapted to communicate a message substantially simultaneously between a plurality of fixed location sites having respective radio coverage areas. The system has an arrangement comprising first and second radio frequency transceiver means located at respective first and second sites. The first radio frequency transceiver means is designed for operating on a first set of frequencies. The second radio frequency transceiver means is designed for operating on a respective different set of frequencies than the first set of frequencies. The second radio frequency transceiver means has means for receiving and converting the first set of frequencies to the respective different set of frequencies.

Abstract: A cell enhancer for use by one cellular provider in a cellular radio-telephone system particularly in a cell including a diversity function includes a first amplifier system for amplifying both up-link and down-link signals between a first set of upstream and downstream antennas and a second amplifier system for amplifying at least the up-link signals between a second set of upstream and downstream antennas. The upstream antennas have a selected minimum correlation between them to ensure that the diversity at the cell site is maintained.

Abstract: A console interface for a trunked communication system is disclosed wherein unique interface modules are coupled to the central controller and console network to establish communication therebetween. A console interface constructed and arranged to transceive trunking channel call information couples the dispatcher console to the console network thereby allowing the dispatcher to interact with the trunked system.

Abstract: A dynamically reconfigurable multiplexer (7) has applicability in a space diversity communications system or a polarization reuse communications system. Multiplexer (7) may be situated on board a communications satellite or at the control nexus of a terrestrial microwave communications system. Multiplexer (7) comprises a set of N series-connected field reversible circulators (51). Coupled to one of the three ports of each circulator (51) is a channelizing filter (53), followed by an output isolator (54) and a high power amplifier (55). The electromagnetic energy rotating within each circulator (51) is commanded to move in either a clockwise or counter-clockwise direction, depending upon whether it is desired to access the channel (52) corresponding to said circulator (51) via a first energy source (1) or second energy source (2). An input isolator (43, 44) associated with each antenna (1, 2) absorbs unwanted energy emanating from the opposing antenna (2, 1).

Abstract: Cooperation between two repeater transceivers of a radio trunking system causes a mobile radio transceiver to join or rejoin ongoing communications. To join ongoing communications, a radio transceiver attempts to acquire a free repeater communications channel by transmitting call signalling identifying a group of transceivers to be contacted. If the group to be contacted is already communicating on another repeater communications channel, the calling radio transceiver is forced to leave the communications channel it is trying to acquire and to begin scanning communications channels in search of call signalling identifying it. Meanwhile, the repeater permitting the ongoing communication interrupts the ongoing communications briefly and transmits the call signalling identifying the group of transceivers to be joined (including the radio transceiver which is to join the ongoing communications).

Abstract: A method and apparatus for providing interference free rf communications between remote handsets and host subscriber units in a Cellular Radio Telephone System includes the use of data transmission and voice channels assigned by microprocessors to track the currently assigned base station/subscriber unit channel assignment--but offset therefrom by one channel thereby to reliably and automatically arrive at an interference free channel.

Abstract: 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-tone signalling sequences and four-tone signalling sequences by determining the arrival rate over some predefined interval of a received signalling sequence. The repeater transmits a busy signal to alert mobile stations seeking to acquire a channel that the repeater is busy. The repeater interrupts the transmitted busy signal during a portion of the four-tone signalling sequence but not the two-tone signalling sequence to help prevent two-tone mobile stations from falsing on four-tone signalling sequences. The arrangement is thus made compatible with both two-tone signalling and four-tone signalling formats.

Abstract: "Dispatch overdialing" permits radio transceivers already communicating via a repeater with other transceivers in a trunked radio communications system to call additional radio transceivers onto the communications channel in use. A radio transceiver in a first group may "dispatch overdial" another radio transceiver in a different group by transmitting a dispatch overdial begin signal to the repeater. The repeater mutes all audio communications on the channel, and the radio transceiver then transmits a sequence of identifying signals which are identical to those used to establish communications initially. The radio transceiver then transmits a further sequence of identifying signals which identify a further radio transceiver (or group of transceivers) to be called onto the channel. If the first sequence of identifying signals matches the signals which were used to establish communications initially, the repeater initiates handshake signalling to call the further transceiver(s) onto the channel.

Abstract: In a radio transmission method for a mobile radio system, a link between a mobile station and a central station is established via one of several base stations. The selection of the base station is done by the mobile station in accordance with radio-engineering criteria, and only the transmitter of the selected base station is keyed. This makes the method economical with respect to frequencies, on the one hand, and on the other hand, requires little operational effort for the chain of base stations.

Abstract: A wide area coverage radio communication system of the type adapted to relay a message substantially simultaneously from a plurality of fixed location sites to a plurality of portable or mobile units includes a plurality of repeaters at each of the sites. Each of the repeaters is arranged to transmit and receive on a respective different frequency duplex pair or channel. Control means at one of the sites senses channel availability at all of the sites and causes one repeater at each of the sites to transmit the message on its respective different frequency. Access to the system by the portable units is provided on a trunked basis through the control means.

Abstract: 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 on the channel for remote units to request permission to transmit on the channel. As the channel becomes clear, the central control station transmits a grant of service to a requesting remote unit group permitting real time transmission of voice or data on the channel. At the conclusion of the transmission, the central control station detects an end-of-transmission condition and revokes the grant of service to the served remote unit group.

Abstract: A communications system central controller which regulates the access of a plurality of remote units to a single communications channel is disclosed. The central controller establishes a period of time wherein a remote unit may request service following the transmission of another remote unit. The central controller interprets the remote unit request for service, stores the request, and grants permission for the remote unit to transmit its message in accordance with the priority in the storage means. The grant of service is revoked by the central controller after a predetermined period of time following the conclusion of the remote unit transmission.