Static on analog trunks 1

[telcodog]

I have a BCM50 rel 2 that was recently upgraded from rel 1 and customer says ever since, they have static on all 5 of their CO trunks. I was there today and it sounds more like a loud "hiss" more akin to white noise than static.

Have checked all trunks at the demarc with my butt set and all are clean.
Scenario is, all 5 lines ring and apear on all sets. Have a mix of 7208 and a couple of 7316's. Have installed the latest cumulative patch but still no joy.
Is it possible that the trunks are set too "hot" from the telco?
Anybody have any idea why this is happening? We have swapped out all the associated hardware except for the main unit itself.

BTW, 2 of the trunks are in the main unit an 3 are on a GATM4 in the expansion module.

Thanks

 

[MagnaRGP]

Have you tuned the trunk ports? I don't know the process by memory and I'm not near any access to docs, but when the trunks are first connected to the hardware, they need to be tuned (akin to setting the short/long CO settings).

Look through the guides and or handouts including those included with the GATM.

 

[telcodog]

Thanks for the suggestion. I tried that already though. I set them all to all 3 different settings and still the problem persists.

I can find only one mention in the patch updates that says anything about the loss plan for the trunks and that service update has been applied.

The customer insists that this problem only started after the system was upgrade from release 1 to release 2. I can't prove that it didn't so I will take them at their word that that is the case. I was wondering if anyone else out there has had the same issue.

 

[MagnaRGP]

I didn't mean only the loss settings. Here is the exact process you should try:

How to tune the GATI and GATM ports on a BCM50

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Problem Description
BCM50 and SRG50 GATI (integrated Global Analog Trunk Interface) and GATM (Global Analog Trunk Module installed in BCM50 expansion chassis) may both experience various audio quality symptoms if not "tuned" while analog circuits are connected to BCM50. Symptoms can include echo or low volume if ports are not tuned to existing facilities after installation of BCM50 and Analog trunk loss package is configured for short, medium, or long Central Office setting using Element Manager.


Problem Resolution
Follow these steps to tune the GATI ports on a BCM50. GATI ports must be tuned to ensure effective, proper operation and optimum audio quality:

1) Configure impedance for 600 or 900 ohms depending on the CO termination impedance.

2) Configure the Analog trunk loss package. It is recommended to start by setting the loop-length according to the actual physical loop length of the line. Short is <2km, Long is >4km as a guideline.

3) Connect all lines to be used off GATI analog interface to the CO lines at the facility point as in normal operation. This step is vital before tuning as each line tunes independently and must be connected for the tuning process to take place. No test test equipment should be connected in parallel with the lines.

4) Reboot the system using Element Manager. Select Administration, Utilities, Reset, "Reboot BCM50 System". All active calls will drop, so clear this with the customer. As the system recovers from the reboot, two "clicks" will eventually be audible from the main unit at some point in the recovery process.

5) At this point, GATI lines are tuned and available. Optimum performance is now expected. Do not try to use the lines until after the clicks are heard, as the lines can appear available in Element Manager before tuning is actually complete.

6) **Note: Each line tunes independently. If lines are added to ports that were open or unused when tuning was performed, the process will have to be repeated with the lines connected as described above in step 3 to insure optimum performance.

7) If lines are added at a later date, GATI ports must be re-tuned using steps 1 through 4 above.


When a GATM is installed, the GATM must be tuned to ensure effective, proper operation and optimum audio quality:

1) Configure impedance for 600 or 900 ohms depending on the CO termination impedance.

2) Configure the Analog trunk loss package. It is recommended to start by setting the loop-length according to the actual physical loop length of the line. Short is <2km, Long is >4km as a guideline.

3) Connect all lines to be used off GATM analog interface to the CO lines at the facility point as in normal operation. This step is vital before tuning as each line tunes independently and must be connected for the tuning process to take place. No test test equipment should be connected in parallel with the lines.

4) Using Element Manager or Set-based administration select the module supporting the connected lines, and "disable". This operation will need to be performed on BOTH 4-line sub modules of a GATM8. Active calls to the GATM will drop, so clear this with the customer.

5) "Enable" the modules using Element Manager or Set-based administration. This will tune the GATM to provide minimal side tone which may be heard as echo. Two audible "clicks" should be heard approximately 3 minutes after the module is enabled. At this point, GATM lines are tuned and available. Optimum performance is now expected. Do not try to use the lines until after the clicks are heard, as the lines can appear available in Element Manager before tuning is complete.

 

[telcodog]

Thanks MagnaRGP. I did reboot the beast but can't actually say for sure if I heard those clicks before the lines got used. Next time I'm there, I will certainly try it. It's the only thing that makes sense so far.