American Telecom AM64/128A Slave Mode 64K Rate, Power 10dBm, Master Mode C 64K Rate, Rate 64K

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Appendix F - Troubleshooting	AM64/128A User Manual

In some environments, the external timing input (SEXT on X.21 or circuits 113 on the X.21 bis interfaces) of an AM64/128A set in Master Mode may become sensitive to external coupled noise. This may have the effect of pulling the modem’s VCO (internal oscillator) off to one side and causing a normal Master to Slave Baseband link to lose synchronism.

It is recommended that, if the external timing input of the modem is not to be used, these inputs are disconnected at the interface of the Master modem.

If disconnection of these inputs is not possible or in convenient they may be joined to signal ground at the Master modem interface.

11. A sample setup procedure follows for a pair of BBMs.

Using the front panel push buttons and LCD display, set one unit as follows.

In the Configuration Menu of the first unit (*Config Menu*) set:

C > Slave Mode

C > 64K Rate

C > X21 Loops On (only available on X.21 unit at unstructured rates - see 5.5 Rate Menu)

C > Power 10dBm

In the second unit, set the Configuration Menu (*Config Menu*) to:

C > Master Mode C > 64K Rate

C > 64K Mode Off C > X21 Loops On C > Power 10dBm

(only available with X.21 interface)

(only available on X.21 unit at unstructured rates - see 5.5 Rate Menu)

In the Rate Menu (only available in Master Mode) set 64K data rate:

R > Rate - 64K

Connecting the two units back to back should now cause the fault LED to go out, the two units should be in synchronisation and can be connected together.

If further problems are encountered, please contact your local distributor initially or ask for ATL Telecom Transmission division Technical Support on - + 44 2920 500 700.

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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 ModelsConstructional Details Baseband ModemsInterface Modules System Overview System Overview BBM to BBM Link InstallationTesting 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 OnStatus Menu Over all StatusLoop Active LOS/CD Fail Alarm StatusNo Alarm No Signal Receiving AIS No Alignment CD FailUser Rate Line RateInterface Status Operating Mode Link Mode Network ModeLocal loop from menu Top level display shows Loc Loop Off Test MenuLocal loop Loc Loop OnLoopback is applied by selecting the display Loopback Off LoopbackLocal loop from DTE Loopback OnRem Loop Off Remote LoopRemote Loop from menu Rem Loop OnBinary Patterns Remote loop from DTEBin Keys Off Sending Bin Overview Error Count Bit Error Rate BER = User Data Rate x TimeData Test OperationErrors Errors nnnnnnErrors s000001 Data TestInjecting 0s Injection ModeTransparent Mode Injecting 1sComms Evp Rx Evp Tx Service TestSvc Test 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.21bisAsynchronous Mode Signalling Rate3 G.703 Character Length Char LenConfiguration Menu Master SlaveLine Rate 3 X.21 Loop Control ModemSynchronisation Type for software versions below Ext Bit Clk Synchronisation Type for software version V1.3 and aboveExt Byte Clk Internal Clk5 64k Mode Power LevelMenu Lock Glossary of Terms Band circuits General Specifications Way D type X.21 bis V.24 / V.28* Connector pin allocation Way D-type X.21 V.11 Connector pin allocationAppendix a Interface Pin Connections 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 plugs21 byte timing cable 15 way to 15 way D type plugs 24 / V.28 bit timing cable 25 way to 25 way D type plugs35 bit timing cable 34 way to 34 way Mrac 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 Master Mode C 64K Rate Slave Mode 64K RatePower 10dBm Rate 64K