American Telecom AM64/128A manual Appendix F Troubleshooting

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AM64/128A User Manual

Appendix F - Troubleshooting

 

 

Appendix F - Troubleshooting

Please check the following points if problems are encountered when setting up a BBM link.

1.Ensure the modem is being used on unconditioned copper twisted pair wire.

2.Check one modem is set to Master and the other modem is set to Slave.

3.Check line rate is set correctly at each modem (64K Rate or 128K Rate). This setting has to be made at each end of a link - it cannot be downloaded from Master to Slave unit.

4.Check pin connections on telephone line connector - (RJ11 pins 3 and 4), (BT connector pins 1 and 6).

5.If link will not function error free at the 128kbps line rate, try using the 64kbps line rate to check whether the line loss / attenuation is within the capability of the BBM (the BBM has a greater range capability at the 64kbps line rate as shown in the table below).

Wire Gauge mm

Transmission Distance in km (conservative estimate)

64K Line Rate

128K Line Rate

 

 

 

 

0.32

3.9

3.1

 

 

 

0.4

5.0

4.0

 

 

 

0.51

6.9

5.5

 

 

 

0.64

9.9

7.9

 

 

 

0.9

15.9

12.7

 

 

 

6.Check that no test loops are active in the modem or being set by the DTE.

7.If using an X.21 bis - V.24/V.28 interface at a structured rate (see section5.5 - Rate Menu) ensure that the circuit 105 Request to Send is turn on by:

I)Setting it at the DTE or by setting the 105 interface line to the ON state (pin 4 set > +3V option) or

II) Go to the Option Menu and scroll down and select 105 set on

If using any of the interfaces X.21 bis V.24/V28, V.35, V36, or RS530 (which have single ended unbalanced interface loop selection lines) the use of screened cables are recommended. In particular, if these interfaces are to be used without screened cables, or without connecting them at the DTE, or on excessively long noise prone cable runs, then precautions will need to be taken to stop noise glitches from applying erroneous data loops - which can cause a link to error. Since most data loops can be applied from the BBM Test Menu, it is recommended that the DTE loop selection lines are tied to the off state usually V off where -10V > V off < 0.8V.

8.Check the interface cable pin out requirements as described in the DTE manuals and Appendix A for the BBM. A special cable may need to be made for external timing applications, as per Appendix E.

9.Check both modems are operating in Link Mode (last item in the Status Menu) for a BBM to BBM link. 10.Check that the External Element Timing Inputs of AM64/128A set in Master Mode:

A-15

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Contents Base Band Modem ATL Part No /203/002/610 Issue 4 SeptemberInformation Contained This Document is Confidential to Contents Appendix B International Models IntroductionInterface Modules Constructional DetailsBaseband Modems System Overview System Overview Testing InstallationBBM to BBM Link Self Test PassLink Mode LTU Ready No Alarm LTU Not ReadyBBM to Line Card Link Network ModeMenu Operation Front Panel FeaturesLoop back On Loop back OffLoop Active Status MenuOver all Status No Alarm No Signal Receiving AIS No Alignment Alarm StatusLOS/CD Fail CD FailInterface Status User RateLine Rate Link Mode Network Mode Operating ModeLocal loop Test MenuLocal loop from menu Top level display shows Loc Loop Off Loc Loop OnLocal loop from DTE LoopbackLoopback is applied by selecting the display Loopback Off Loopback OnRemote Loop from menu Remote LoopRem Loop Off Rem Loop OnBin Keys Off Sending Bin Binary PatternsRemote loop from DTE Data Test Error Count Bit Error Rate BER = User Data Rate x TimeOverview OperationErrors s000001 Errors nnnnnnErrors Data TestTransparent Mode Injection ModeInjecting 0s Injecting 1sSvc Test Service TestComms Evp Rx Evp Tx Time If the count is stopped the display is StopSelf Test Lamp TestComm Loop Off Communication Channel LoopbackRate 4.8K Rate MenuMaster 64K BT Slave 4.8K 2 X.21bis Option Menu3 G.703 Asynchronous ModeSignalling Rate Char Len Character LengthLine Rate Configuration MenuMaster Slave Synchronisation Type for software versions below 3 X.21 Loop ControlModem Ext Byte Clk Synchronisation Type for software version V1.3 and aboveExt 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 Way D-type V.36 Connector pin allocation Mrac Connector Pin allocationLine Connector Way D-type RS-530 Connector pin allocationAppendix B Internal Link Settings Page Interface Module Interface Modules21bis Interface Module RS530 Interface ModuleFrame Structure Service Test FacilitiesAppendix C In Service Test TTE Network and Safety statements LVD Safety Statements21 bit timing cable 15 way to 15 way D type plugs Appendix E35 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 RS530 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 plugsAppendix F Troubleshooting Power 10dBm Slave Mode 64K RateMaster Mode C 64K Rate Rate 64K
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