American Telecom AM64/128A manual System Overview

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AM64/128A User Manual	System Overview

The interface circuit performs a number of functions : it converts between the user data from the appropriate interface and the 64kbps or 128kbps, which is transmitted down the line; it links the control circuit to the control channel; it interfaces the control circuit to the control lines of the data ports. Again, these functions are performed by a custom IC supported by a number of standard components. Looking at each function in turn, user data at 64kbps and 128kbps is sent without processing; byte-timing is maintained by the transmission system and is available if required. Data at 56kbps is sent in a 7+1 format, i.e. data plus status information. At all lower rates the data is transmitted as octets comprising 6 data bits, 1 framing bit and 1 status bit. At rates below 48kbps the octets are iterated as appropriate to fill the transmission channel.

The control channel, uses 4 bits from each transmission frame to transmit control information to the unit at the other end of the line, e.g. user data rate selection, and to monitor the overall performance of the link.

With regard to the remaining function of the interface circuit, the control lines of the data ports mainly require buffering; however, in the case of X.21 the various control patterns have to be generated or detected. The control circuit is based on a microcontroller and determines the state of the unit according to the state of the transmission system, the state of the data interface and the configuration information received from the front panel and from the control channel. It also provides the front panel display with information on the current state of the unit which can be reviewed via a simple menu structure.

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Contents ATL Part No /203/002/610 Issue 4 September Base Band ModemInformation Contained This Document is Confidential to Contents Appendix B Introduction International ModelsInterface Modules Constructional DetailsBaseband Modems System Overview System Overview Installation TestingBBM to BBM Link Self Test PassLTU Ready No Alarm LTU Not Ready Link ModeNetwork Mode BBM to Line Card LinkFront Panel Features Menu OperationLoop back Off Loop back OnLoop Active Status MenuOver all Status Alarm Status No Alarm No Signal Receiving AIS No AlignmentLOS/CD Fail CD FailInterface Status User RateLine Rate Operating Mode Link Mode Network ModeTest Menu Local loopLocal loop from menu Top level display shows Loc Loop Off Loc Loop OnLoopback Local loop from DTELoopback is applied by selecting the display Loopback Off Loopback OnRemote Loop Remote Loop from menuRem Loop Off Rem Loop OnBin Keys Off Sending Bin Binary PatternsRemote loop from DTE Error Count Bit Error Rate BER = User Data Rate x Time Data TestOverview OperationErrors nnnnnn Errors s000001Errors Data TestInjection Mode Transparent ModeInjecting 0s Injecting 1sService Test Svc TestComms Evp Rx Evp Tx Time If the count is stopped the display is StopLamp Test Self TestCommunication Channel Loopback Comm Loop OffRate Menu Rate 4.8KMaster 64K BT Slave 4.8K Option Menu 2 X.21bis3 G.703 Asynchronous ModeSignalling Rate Character Length Char LenLine Rate Configuration MenuMaster Slave Synchronisation Type for software versions below 3 X.21 Loop ControlModem Synchronisation Type for software version V1.3 and above Ext Byte ClkExt Bit Clk Internal ClkMenu Lock 5 64k ModePower Level Glossary of Terms Band circuits General Specifications Appendix a Interface Pin Connections Way D type X.21 bis V.24 / V.28* Connector pin allocationWay D-type X.21 V.11 Connector pin allocation Mrac Connector Pin allocation Way D-type V.36 Connector pin allocationWay D-type RS-530 Connector pin allocation Line ConnectorAppendix B Internal Link Settings Page Interface Modules Interface ModuleRS530 Interface Module 21bis Interface ModuleService Test Facilities Frame StructureAppendix C In Service Test LVD Safety Statements TTE Network and Safety statementsAppendix E 21 bit timing cable 15 way to 15 way D type plugs35 bit timing cable 34 way to 34 way Mrac plugs 21 byte timing cable 15 way to 15 way D type plugs24 / V.28 bit timing cable 25 way to 25 way D type plugs 21 bis V.36 bit timing cable 37 way to 37 way D type plugs RS530 bit timing cable 25 way to 25 way D type plugsAppendix F Troubleshooting Slave Mode 64K Rate Power 10dBmMaster Mode C 64K Rate Rate 64K