Abstract: In a communication environment (140) having multiple vehicular repeater systems (110, 120) operating according to a priority scheme designating primary responsibility for retransmitting signals, a vehicular repeater system (120) supports automatic transitioning from a non-priority mode to a priority mode (410, 420). The vehicular repeater system (120), when operating in a non-priority mode, detects that a communication signal was submitted for retransmission by a priority vehicular repeater system (440), and monitors for a particular time period to detect an acknowledgment signal (450). When no acknowledgment signal is detected within the particular period, the priority scheme is modified, preferably such that the non-priority vehicular repeater assumes priority repeater status (460).

Abstract: A signal receiving system has an antenna assembly divided into sectors. Each sector employs diversity by having at least two antennae for receiving signals from that sector. Signals from the antennae are passed to filters where the filters contain superconductors requiring cooling. The filters are housed in cryocoolers in a manner such that no cryocooler contains more than one filter receiving signals from a given sector. After filtering, the signals are sent to diversity receivers which combine or compare signals from antennae in the same sector.

Abstract: A power supply unit with a switch on/off facility for powering radio equipment is disclosed. The power supply unit includes an input portion having keys, a power generating circuit for generating power, and a switch connected to the power generating circuit for turning on and off the power to the radio equipment. The power supply unit further includes a disabling portion for disabling the on/off switch in response to operation of a predetermined one of the input portion keys.

Abstract: Base stations located at physically separate, remote locations are operated as a single site to permit trunked radio communications between portable radios located at those split sites. A first trunked RF communication site located at a first split site location includes plural first base stations, each first base station including a transceiver corresponding to an RF communications channel. The first site also includes a first site controller, connected to each of the first base stations, for assigning base station transceivers to radios requesting an RF communications channel. A second trunked RF communications site is located at a second split site location remote from the first split site location and includes plural second base stations along with a second site controller.

Abstract: A communication network comprises a transceiver arranged for passing on signals, coming in via an incoming signal path, to an outgoing signal path. The transceiver is coupled by the incoming signal path to a first neighboring transceiver and by the outgoing signal path to another neighboring transceiver. The transceiver comprises an amplifier for amplifying the signals to be passed on. The transceiver is also coupled to a local power supply. The communication network is arranged for supplying remote supply power via the incoming signal path to the transceiver. The transceiver further comprises a coupling device which under normal circumstances is arranged for supplying local supply power from the local power supply to the amplifier and, when the local power supply fails, is arranged for supplying the remote supply power to the amplifier. As a result, the communication between the two neighboring transceivers is not deteriorated by a failure of the local power supply of the transceiver.

Abstract: The present invention provides a method of maintaining calls subsequent to a site controller failure. A site controller broadcasts call information to a plurality of standby repeaters. The standby repeaters receive the call information, build a call table including the call information, and utilize the call information to maintain calls in the event of a site controller failure.

Abstract: A method for securing the operation of a base station having a radio coverage area divided into at least two sectors, and a base station having antennas, with combiners and branching units, and at least one channel unit for each sector, which allow the base station to establish a radio connection with active radio transceivers currently located in the base station sectors. In the method, the base station is provided with an additional channel unit the traffic capacity of which is selectably switchable to one of the base station sectors. To secure the operation of the base station when one of the channel units fails, the operation of the channel units of the base station is monitored. When one of the channel units fails, the additional channel unit is connected to the antenna of the sector of the failed channel unit by a switch, which connects the antenna attachments of the additional channel unit to the antenna of one sector at a time.

Abstract: In a multiple site radio frequency (RF) simuicasting transmission system, voice and digital data distributed via multi-phase modem over "land-line" inter-site communication links from a control point to the RF transmitter sites exhibit random time delay skew because the modems at each site recover clock signals from an arbitrary one of multiple phases. Reference "tones" for data alignment, consisting of a high frequency clocking signal and a low frequency "gating" signal, are generated at each site synchronized to a GPS broadcast reference signal. Similar tones are also provided to transmitter sites along with the distributed data via the land-line inter-site communication links as a backup. The pair of "backup" reference tones supplied via land-line are automatically aligned at each site to the GPS receiver generated reference tones by individual phase comparison and dynamically-adjusting delay circuits.

Abstract: A selective call receiver (126) automatically orients a pluridirectional wireless infrared communication interface (220) to allow directional wireless infrared communication between the pluridirectional wireless infrared communication interface (220) of the selective call receiver and a wireless infrared communication interface (134) of a device (132). The pluridirectional wireless infrared communication interface (220) preferably includes more than one directional wireless infrared communication port (310). The selective call receiver (126) automatically orients the pluridirectional wireless infrared communication interface (220) by selecting one directional wireless infrared communication port (310).

Abstract: The present invention encompasses a method of reconfiguring a distributed communication system (100). A typical distributed communication system (100) includes a plurality of repeaters (102-106) connected via a LAN (108, 110). When a repeater that is acting as an active master (104) receives a Trunking Status Pulse (118), the active master (104) will compare the status information in the received TSP (118) with the present status information to determine which active master is the favorable active master. The active master with the favorable present resource allocation loading level will continue to operate as the active master, while the active with the least favorable present resource allocation loading level will relinquish control as an active master.

Abstract: An apparatus for transmitting a signal which is capable of connecting an N-number of main lines and one auxiliary line using an N-number of transmission switches (N denotes 1, 2, 3, . . . , n), thus more effectively transmitting a signal, which includes first and second input terminals selectively connected to first and second output terminals in accordance with normal/error control signals, with transmission line signal being applied to the first input terminals of the SPDT transmission switches, and with an auxiliary line signal being applied to the second input terminal of the last SPDT transmission switch; first output terminals of the transmission switches connected to an input terminal of a combining terminal; first output terminals of the SPDT transmission switches connected to first input terminals of the SPDT transmission switches; and a load resistor connected to the second output terminal of the first SPDT transmission switch.

Abstract: Base stations located at physically separate, remote locations are operated as a single site to permit trunked radio communications between portable radios located at those split sites. A first trunked RF communication site located at a first split site location includes plural first base stations, each first base station including a transceiver corresponding to an RF communications channel. The first site also includes a first site controller, connected to each of the first base stations, for assigning base station transceivers to radios requesting an RF communications channel. A second trunked RF communications site is located at a second split site location remote from the first split site location and includes plural second base stations along with a second site controller.

Abstract: A method and circuit arrangement for transmitting message cells via redundant virtual path pairs of an ATM communication network is provided. Two alternative solutions are employed for the transmission of message cells via virtual path pairs respectively formed of an active path and of an alternate path. A first solution is that the message cells transmitted via the active path and via the alternate path of a path pair are conducted up to the output of the switching network lying at the end of the corresponding path pair. Dependent on the number of message cells arriving via the active path and via the alternate path, a forwarding of the message cells of the active path or of the alternate path occurs proceeding from this point. The second solution is that the message cells of the alternate path are first discarded at the input of the corresponding switching network.

Abstract: The present invention relates to an improved RF converting system. The RF converting system is comprised of a plurality of RF converter modules which are configured for redundant system operation using distributed protection switching in an active "daisy chain" configuration. The "daisy chain" configuration distributes the converter protection switching functions to each individual RF converter module through a switching module coupled to each of the RF converter modules. The "daisy chain" terminates in a backup RF converter which assumes the frequency and attenuation of a faulted RF converter module. A high speed bus provides communication interface between each of the online RF converter modules and the backup RF converter module so that the backup RF converter module can detect faults and reconfigure the system to replace a failed RF converter module.

Abstract: A hitless path switching method without a bit loss. The same digital line signals on a working path and a protection path are continuously monitored independently for bit errors. If a bit error occurs in the working path and no bit error occurs in the protection path, a switching trigger is produced and a switching operation from the working path to the protection path is performed on a data block basis. Only correct data are transferred to downstream apparatuses. Reliable hitless switching is achieved not only in response to a failure in a path, but also in response to a bit error. Using data blocks of one frame length with an indicator for bit error checking placed at its beginning or top makes effective switching possible.

Abstract: The invention relates to a mobile telecommunication system having an auxiliary routing arrangement comprising auxiliary radio channel units and monitoring circuit. The auxiliary radio channel units are arranged in the base station of the system and the monitoring circuit are arranged in the mobile telephone switch of the system. The monitoring circuit monitor the setting-up of each call in the mobile telephone switch and, when faults occur, the monitoring circuit are adapted switch off the transmitter function of an affected radio channel unit and to replace the affected radio channel unit with an auxiliary radio channel unit which is allocated a frequency essentially corresponding to the frequency of the affected radio channel unit. The automatic replacement of an affected radio channel unit with an auxiliary radio channel unit ensures that the traffic handling capacity of the system is essentially unchanged.

Abstract: A cellular communication network (10) and method operates at frequencies above 2 GHz and achieves widespread coverage within a cell (14) by adapting routing channels, symbol rates, and FEC coding processes (78) to current RF broadcast conditions. A portion of subscriber nodes (16) act as repeaters for a base node (12). If subscriber nodes (16) cannot directly communicate with the base node (12), their communications may be indirectly routed to the base node (12) through one or more repeating subscriber nodes (16'). If current conditions do not support a high data rate, then lower data rates are supported by selection of FEC coding processes (78). If increasingly inclusive FEC coding does not achieve a data rate supportable by current conditions, slower symbol rates may be used. Communications at slower symbol rates may utilize narrower frequency bands thus keeping wider frequency bands available for higher speed usage.

Abstract: A mobile telephone system with two home location register units mirroring each other is disclosed. In the event of a crash in one unit a backup copy is first loaded. Thereafter, records in the loaded backup copy that have changed after the latest position dump before the crash are updated with information from the other home location register unit, the mirror copy of which is updated after the position dump.

Abstract: Radio working lines are provided to correspond to optical lines and a single radio standby line is provided. An optical-line failure detecting unit monitors occurrence of failure in each of the optical line, and a radio-line failure detecting unit monitors the occurrence of failure in each of the radio working lines. When occurrence of failure in an optical line has been detected, a relief-rank management unit makes the rank for relief of the radio working line corresponding to this optical line lower than rank for relief of radio working lines corresponding to optical lines that have not failed. When a failure has occurred in two or more radio working lines, a line changeover controller transmits data, which is to be sent to a radio working line that failed, via the radio standby line.

Abstract: A data communication apparatus for conducting relaying multi-address transmission comprises a detector for detecting the occurrence of a non-delivery status in which data is not transmitted to a relay station or a relay destination station, and a control unit for sending the data directly to the relay destination station without routing the relay station when the non-delivery status is detected by the detector.

Abstract: In order to mitigate problems caused by total or partial failure of a number of sectorised radio channel unit transceivers (RCU) in a base station of a particular cell (16) of a radio communications system, base stations (26, 32) in adjacent cells (14, 20) increase the power transmitted from RCUs controlling sectors adjacent to that particular cell 16, thereby filling the gap in coverage left by the failure of that cell (16).

Abstract: This invention relates to apparatus and a method for provision of diversity in reception in a communications system such as the GSM cellular radio system. A received call of low quality is received through a first of two antennas (15, 16) and through first of a plurality of receivers (10-14). A spare receiver that is not required for receipt of a call is identified and the spare receiver is switched to receive the call through the second antenna. The spare receiver is tuned to the frequency of the call of low quality and the calls are diversity combined through the first receiver and the spare receiver.

Abstract: A method for securing the operation of a telecommunications network in a cellular radio system, in which telecommunications network base stations are connected in series in such a way that at least one base station serves as a repeater for telecommunication signals of preceding base stations. For securing the operation of the telecommunications network, the base station is provided with a control unit monitoring its operation and with a repeater connected in parallel with the base station, the repeater having a power source independent of the base station. When the control unit detects a failure at the base station, the signals to be transmitted in the telecommunications network are directed to the repeater which transmits them further in the telecommunications network.

Abstract: A member communication system which includes a radio base station connected to an exchange for establishing a communication interface with a mobile terminal such as a car telephone set where the number of output carriers of a modulation apparatus to be inputted to an amplification apparatus is controlled so as to be decreased in response to failure of an amplification circuit or circuits so that an increase in intermodulation distortion is eliminated and the necessity for each amplification circuit to have a superfluous saturation output is eliminated, thereby reducing power consumption.

Abstract: A wireless communication system uses transmitted data signals to monitor and control redundant modulator hardware. A modulator unit signature identifying the modulator unit currently transmitting data is embedded into each data frame carried by the transmission signal. Each modulator unit can then independently monitor the transmission signal to determine which modulator is currently transmitting data. Each modulator unit then monitors the transmission signal in case the modulator unit actively generating the transmission signal fails. In a failure situation, the active modulator unit disconnects itself from the transmission circuity while the backup modulator unit independently connects to the transmission circuitry to begin active transmission.

Abstract: A local control mechanism for automatically parking an active combiner filter and activating an alternate combiner filter in an auto-tune combiner in a radio telecommunications network is resident entirely at a remote base station. The mechanism samples the radio frequency (RF) energy level on the active combiner filter in an auto-tune combiner and determines whether the measured RF energy level exceeds a predetermined RF energy threshold. The mechanism then determines the number of RF energy samples taken, compares this number to a trigger number, and parks the active combiner filter and switches to an alternate combiner filter when the number of consecutive RF energy samples below the RF energy threshold exceeds the trigger number.

Abstract: A radio communication system controller (100) includes a first (103) and second (104) processor for processing input communication messages (101) used in a radio communication system. The controller (100) further includes shared memory (105), which memory is accessible to each of the first (103) and second (104) processors, for storing the input communication messages (101). The controller (100) is further equipped with fault detection capability (107) for determining (402) when a processing fault has occurred.

Abstract: In a trunked communication system with a number of repeaters (101, 103, 105, 107), allocation of communication resources within each coverage area is controlled by one of the repeaters, which acts as an active resource controller. Communication resource control information is distributed between the repeaters via a data network (109). When a break (113) is detected (403) in the data network (109), a secondary communication unit (117) sends a notice of the break (405) to the plurality of repeaters located on each side of the break. The active resource controller determines which side of the break provides desired usage of the communication resources, and communications are maintained by that side (505, 509).

Abstract: The invention relates to a method for controlling base station transmitters in a cellular system, such as a GSM system, the base station comprising at least two transmitters (TX1 . . . TX4) transmitting on at least one control carrier and at least one traffic carrier, wherein the power transmitted on the traffic carrier is on the average lower than the power transmitted on the control carrier. In order to improve the overall life expectancy of the transmitters, at least the transmitter transmitting on the control carrier is changed constantly. (FIG.

Abstract: A redundant system includes a redundant structure and a selector of the output signals of the redundant structure the selector further including a selection/operation signal converter and a path operation signal processor provided in each circuit package. The signal converter converts selection signals of the selector into a path operation signal indicative of operation or non-operation of each signal path in each of the parallel connected systems. The signal processor transfers the path operation signal from a downstream circuit package to an upstream circuit package and judges path operation condition of the signal paths passing through each circuit package based on the transferred oath operation signal. Using the judgement, each circuit package can perform on/off control of the indication lamp by itself.

Abstract: A dispatch radio communication system (100) employs a method (200) and apparatus (101) for assigning one of a console station's control modules (113-115) to a communication resource. The assignment is initiated by associating (203) each control module (113-115) with a group of supported resource features and associating (205) each communication resource with a group of employed resource features. The latter association is then used to establish (211 ) a minimum set and an extended set of resource feature requirements for a particular communication resource that is to be added to a console station (109). The former association is used to identify (217) a group of candidate control modules (113-115) at the console station (109) that can support at least the minimum set of resource feature requirements. Upon identification of the candidate group (113-115), the candidate control module (e.g.

Abstract: A GPS utilizing redundant GPS receivers having position and time mark outputs connected directly to a processing block so that the time marks from both GPS receivers are received by the processing block and, in the event a first of the GPS receivers output becomes unusable and the system uses a second of the redundant GPS receivers while periodically checking the first for reusability, no time will be lost in the validation of the new channel.

Abstract: In a point-to-multipoint communication network wherein communication channels are established between a transmitting station and a plurality of receiving stations for transmission of data as a multicast signal, a reception confirming arrangement confirms reception of the multicast signal by the receiving stations to locate failing stations that fail to receive at least portions of the multicast signal. A retransmitting arrangement establishes relevant ones of the communication channels between the transmitting station and the failing stations for transmission of the portions to the failing stations. For reception confirmation, the data may be identified by data identifiers, as by a serial number. Alternatively, each receiving station may send back for comparison at the transmitting station a predetermined portion of datum which may be each of the data or a datum received latest at the receiving station under consideration.

Abstract: A radio communication system (100) includes a terminal/controller (110, 112) for transmitting an enable signal, data associated with the enable signal, and a disable signal following the data. A normally operating transmitter (105, 107) coupled to the terminal/controller (110, 112) receives, when operating normally, the enable signal and transmits the data associated therewith as a radio frequency (RF) signal. The normally operating transmitter (105, 107) further generates status information for indicating that the normally operating transmitter (105, 107) is functioning, wherein the status information includes at least the enable signal and the disable signal. The radio communication system (100) further includes a redundant transmitter (115) coupled to the normally operating transmitter (105, 107) and the terminal/controller (110, 112) for receiving the status information and determining therefrom whether the normally operating transmitter (105, 107) is functioning.

Abstract: A radio calling system includes a central control station simultaneously broadcasting a calling signal of an arbitrary pager terminal, and a plurality of radio transmitting stations coupled to the central control station. The plurality of radio transmitting stations simultaneously transmit the calling signal received from the central control station at the same radio frequency. The calling signal transmitted from the radio transmitting stations reach the arbitrary pager terminal and at least a neighboring one of the radio transmitting stations.

Abstract: In a secure trunked communication system that includes a central controller, communication between a distribution panel and a limited number of console interface units may be achieved in the following manner. At power up or upon a reset condition, the distribution panel transmits a status check message to each console interface unit in the system. Console interface units that are active respond by transmitting an acknowledgement. Upon receiving the acknowledgement, the distribution panel transmits the addresses of the active console interface units to the central controller. When the distribution panel receives secure information from the central controller, it interprets the information to identify a target console interface unit and transmits the received secure information to the target console interface unit.

Abstract: A data communication system which operates by the use of a main channel, and also a protection channel to back up the main channel using a channel switching circuit connected between a receiver and a transmitter. A receiver side channel switch includes a delay function for delaying the main channel data. A transmitter side channel switch includes a delay function for delaying the protection channel data when switching channels when a transmission fault occurs. The thus delayed data is effective for preventing a stoppage of data flow even in the event of a sudden transmission fault.

Abstract: In a trunked communication system using intelligent repeaters (101), each intelligent repeater performs a series of tests (602, 606, 610, 614, and 618) on its own functionality. The results of these tests are transmitted (622) to a resource manager, which is one of the intelligent repeaters at a communications site. Using the results of these tests, the resource manager then selects one or more of the intelligent repeaters to perform the functions of authorization, resource allocation (708), and logging of communications (713).

Abstract: An RF repeater for interfacing with a base station for exchanging transmit and receive signals in a time division duplex cordless telephone system comprises a multicarrier amplifier having an input and an output and a transfer switch connected to the amplifier output and the amplifier input and having first and second switch states. The switch means connects receive signals from the handset to the amplifier input and the amplifier output to the base station in the first switch state, and connects the base station to the amplifier input and transmit signals from the amplifier output to be broadcast to the handset in the second switch state. The operation of the switch is controlled so that the transmit and receive signals are alternately amplified by the amplifier. Thus, only a single amplifier is required.

Abstract: A method is used to switch a channel which is used for a communication between a transmitting end and a receiving end from a main channel to a protection channel. The method of the present invention allows automatic compensation for the loss caused by the switching of the channel to the protection channel. Furthermore, the level difference of the baseband signal outputs from each of the main channels can be automatically controlled to zero regardless of the main channel from which the channel is switched to the protection channel.

Abstract: A multichannel communication system carries signals having a different frequency range in each channel. In order to achieve a particular output power level from each channel, an amplifier is associated with each channel to boost the signal level. For reliability, a switching arrangement switches amplifiers among the channels in accordance with a priority, or substitutes a redundant amplifier for a degraded or failed unit in a channel. The amplifier is subject to distortion at the desired output level, and is cascaded with a distortion equalizer or linearizer for reducing the total distortion. In accordance with the invention, each distortion equalizer is fixedly connected in one channel, and is optimized for the relatively narrow frequency range of that channel, rather than being switched together with the amplifier and being optimized over the total or cumulative bandwidth of all the channels.

Abstract: A communication system serving a plurality of radio units in a frequency blocked area includes a remotely controlled and remotely configurable network of radiating coaxial conductors. The radiating coaxial conductors, along with associated amplification devices, are arranged to provide radio communication to an area around the network using radio frequency radiation released by the plurality of radiating cables. Remote control to the system is provided by a control station which transmits control data to the amplification devices through the network of radiating coaxial conductors. The amplification devices are arranged to control the radiating coaxial conductors in such a way that, in response to receiving the control data, the radiating coaxial conductors may be reconfigured to overcome faults occurring in the system.

Abstract: A route switching system in a communications network constituted of a transmitter and a receiver connected by a plurality of routes for switching a first route along which communication is being held by transmission of cells to a second route causing no blocking. The route switching system comprises a first switch provided in the transmitter for switching input cells from one route to another and outputting the cells, a first storage portion provided in the transmitter for storing the input cells, a second switch provided in the receiver for switching input cells from one route to another and outputting the cells, and a second storage portion provided in the receiver for storing the input cells. At the time when the route is switched over, the first switch is changed over so that the cells are transmitted through the first storage portion and, on the receiver side, the second switch is changed over so that the cells transmitted over the second route are stored into the second storage portion.

Abstract: A change-back system is designed for an asynchronous transfer mode network in which a rerouting path is set to replace an original path when a fault is generated in the original path within the network, which network includes a plurality of communication nodes which are coupled via lines and communicate information in the form of cells, and the original path and the rerouting path couple first and second communication nodes within the network. The change-back system makes a change-back process to change the path used from the rerouting path to the original path when the fault is restored.

Abstract: A communication unit (114) operates in a communication system (100). The communication unit (114) communicates with a central communication controller via one of a plurality of a communication controllers (104, 108, or 112) that transmits information signals containing its identification along with other information. The communication unit (114) receives and determines the signal strength (RSS) of these information signals. A controller (412) monitors changes in the signal strength of the received information signals over time and determines whether the signal strength has fallen below a predetermined level at a rate of change higher than a predetermined rate. Such sharp fall in signal strength is communicated to a circuit which attempts to access a new channel after waiting for a random amount of time.

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: The invention relates to methods and apparatus for isolating faults in link-connected systems utilizing fault reports generated from within the system itself. The reports are transmitted to a central location, preferably during a predetermined time period, and are used to create a single error message identifying the probable nature and location of the fault. A preferred embodiment of the invention does not require either the construction or maintenance of systemwide configuration tables, commonly used performing fault location and analysis. Instead, each unit of a pair of link coupled units, initially or on reconnection, interrogates a link adapter at the other end of the link for an identifier that identifies both the remote unit and the remote link adapter. This "nearest neighbor" information is stored locally at each unit, and is transmitted to the central location when an error is detected.

Abstract: A synchronization scheme for use in digital communications systems selectively replaces data-representative symbols that would ordinarily be transmitted through a plurality of communications channels with associated replacement symbols that represent the data and provide a synchronization mechanism. In the receiver, the replacement symbols are detected and control circuitry which determines the difference in propagation delay between communications channels. Advantageously, this scheme can provide a determination of the propagation delay difference between communications channels while such channels are being used to transmit customer data and does not alter the timing or format of such data.

Abstract: A LAN or other data network includes at least first and second repeater units for receiving data signals and repeating them to other parts of the data network and a transceiver unit for transmitting and receiving data which is connected to the first repeater unit by a primary data link and to the second repeater unit by a secondary data link. The primary data link comprises a primary transmit line for transmitting data from the transceiver unit to the first repeater unit and a primary receive line for receiving data from the first repeater unit and transmitting it to the transceiver unit; and the secondary data link comprising a secondary transmit line for transmitting data to the second repeater unit and a secondary receive line for receiving data from the second repeater unit and transmitting it to the transceiver unit.

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.