Re: [asterisk-users] Help 60Hz Hum?
On Sat, Oct 13, 2007 at 12:01:30PM -0700, Philip Prindeville wrote: [ quoting me: ] Actually, hum involving analog POTS lines is usually the result of the line becoming unbalanced to ground. Or else running your phone wiring in parallel with and too close to electrical (line voltage) wiring, resulting in induction (crosstalk, as it were). Well, if your line is properly balanced to ground, then it actually is very difficult to induce a hum in it this way. Cheers, -- jra -- Jay R. Ashworth Baylink [EMAIL PROTECTED] Designer The Things I Think RFC 2100 Ashworth Associates http://baylink.pitas.com '87 e24 St Petersburg FL USA http://photo.imageinc.us +1 727 647 1274 ___ --Bandwidth and Colocation Provided by http://www.api-digital.com-- asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
Re: [asterisk-users] Help 60Hz Hum?
On Fri, Oct 12, 2007 at 11:09:59PM +0200, F6HQZ wrote: Check if you have a ground loop. If yes, this is probably the cause of this hum. Open the loop. Actually, hum involving analog POTS lines is usually the result of the line becoming unbalanced to ground. Cheers, -- jra -- Jay R. Ashworth Baylink [EMAIL PROTECTED] Designer The Things I Think RFC 2100 Ashworth Associates http://baylink.pitas.com '87 e24 St Petersburg FL USA http://photo.imageinc.us +1 727 647 1274 ___ --Bandwidth and Colocation Provided by http://www.api-digital.com-- asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
Re: [asterisk-users] Help 60Hz Hum?
Jay R. Ashworth wrote: On Fri, Oct 12, 2007 at 11:09:59PM +0200, F6HQZ wrote: Check if you have a ground loop. If yes, this is probably the cause of this hum. Open the loop. Actually, hum involving analog POTS lines is usually the result of the line becoming unbalanced to ground. Or else running your phone wiring in parallel with and too close to electrical (line voltage) wiring, resulting in induction (crosstalk, as it were). ___ --Bandwidth and Colocation Provided by http://www.api-digital.com-- asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
Re: [asterisk-users] Help 60Hz Hum?
Yes, Jay and Philip, you are right, but you can also have hums if ground cables for chassis protection against electrical hazards are making loops, if certain of them are in parallel and if they have different length between the equipments to protect. Many audio stages (unbalanced side, not balanced line side) are sensitive to that case. You can also encounter this case with PCB ground design. You can also have hums (often harmonics) due to a poor filtering from the power supplies (too old or poor quality chimical capacitors). And also, in rare specific cases, due to a strong radio field, near high power transmitters. It's not so easy to found what is the exact cause. Use an oscilloscope to check the different signals (audio, power lines, earth cable, etc...). Best Regards, Francois BERGERET France ___ --Bandwidth and Colocation Provided by http://www.api-digital.com-- asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
Re: [asterisk-users] Help 60Hz Hum?
Hi, Check if you have a ground loop. If yes, this is probably the cause of this hum. Open the loop. Best Regards, Francois BERGERET France ___ --Bandwidth and Colocation Provided by http://www.api-digital.com-- asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
Re: [asterisk-users] Help 60Hz Hum?
Maybe approach this problem at the wall socket? Could there be ground issues in the building that the telco has filters for but asterisk's box doesn't? A line conditioning UPS might help. Moj Mark Bell wrote: Hey guys, I am trying to diagnose a hum in my FXO lines I am using an Adtran 750 with 8 FXO ports. I am getting a pretty bad hum on the line during a call. I have checked the Telco side of the 66 block and there is no hum there so it’s my problem to fix. I have tried to lower the gain but that reduces the call volume to much. Where else should I be looking? Setup as follows Dell PE1950 server Redfone Quad port fonebridge2 Asterisk 1.2.18 Zaptel 1.2.18 From redfone Adtran 750 Channel Bank with 8 FXO and 16 FXS Two PRI connections to fonebridge TIA Mark ___ --Bandwidth and Colocation Provided by http://www.api-digital.com-- asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users ___ --Bandwidth and Colocation Provided by http://www.api-digital.com-- asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
Re: [asterisk-users] Help 60Hz Hum?
If necessary a 1:1 transformer on the voice lines might clean your audio up for you. One transformer on each line. On 10/6/07, Mark Bell [EMAIL PROTECTED] wrote: Hey guys, I am trying to diagnose a hum in my FXO lines I am using an Adtran 750 with 8 FXO ports. I am getting a pretty bad hum on the line during a call. I have checked the Telco side of the 66 block and there is no hum there so it's my problem to fix. I have tried to lower the gain but that reduces the call volume to much. Where else should I be looking? Setup as follows Dell PE1950 server Redfone Quad port fonebridge2 Asterisk 1.2.18 Zaptel 1.2.18 From redfone Adtran 750 Channel Bank with 8 FXO and 16 FXS Two PRI connections to fonebridge TIA Mark ___ --Bandwidth and Colocation Provided by http://www.api-digital.com-- asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users ___ --Bandwidth and Colocation Provided by http://www.api-digital.com-- asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
Re: [asterisk-users] Help 60Hz Hum?
Mark Bell wrote: Hey guys, I am trying to diagnose a hum in my FXO lines I am using an Adtran 750 with 8 FXO ports. I am getting a pretty bad hum on the line during a call. I have checked the Telco side of the 66 block and there is no hum there so it’s my problem to fix. Is there hum on the line ONLY when the FXO port has closed the loop? At the demarc? When the buttset closes the loop? Or is the hum introduced on the Asterisk end? All of the FXS ports clean and clear? Are you sure it is 60 Hz and not 120 Hz? Longitudinal imbalance introduced by a defect in one port on the FXO card? All 8 ports on 2 cards? Remember that standard analog Central Office lines ( loop start ) are very much like a balanced audio line with DC superimposed for supervision. The DC is introduced at the CO end with one side grounded at the CO and the other at ( open circuit ) -48VDC, and a ground on the subscriber end will introduce hum, or if low enough resistance will keep the line in an off hook condition. Swap the Adtran cards if only on some circuits, and make sure the 750 is well grounded. John Novack -- Dog is my co-pilot ___ --Bandwidth and Colocation Provided by http://www.api-digital.com-- asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
Re: [asterisk-users] Help 60Hz Hum?
Thanks for the tips John. I also forgot to mention the Adtran is a DC unit. The hum is introduced at the asterisk end. If I pull the bridge clips and test the telco side of 66 block the line is fine. I will swap some cards around and see what happens -Original Message- From: [EMAIL PROTECTED] [mailto:asterisk-users- [EMAIL PROTECTED] On Behalf Of John Novack Sent: Monday, October 08, 2007 2:59 PM To: Asterisk Users Mailing List - Non-Commercial Discussion Subject: Re: [asterisk-users] Help 60Hz Hum? Mark Bell wrote: Hey guys, I am trying to diagnose a hum in my FXO lines I am using an Adtran 750 with 8 FXO ports. I am getting a pretty bad hum on the line during a call. I have checked the Telco side of the 66 block and there is no hum there so it's my problem to fix. Is there hum on the line ONLY when the FXO port has closed the loop? At the demarc? When the buttset closes the loop? Or is the hum introduced on the Asterisk end? All of the FXS ports clean and clear? Are you sure it is 60 Hz and not 120 Hz? Longitudinal imbalance introduced by a defect in one port on the FXO card? All 8 ports on 2 cards? Remember that standard analog Central Office lines ( loop start ) are very much like a balanced audio line with DC superimposed for supervision. The DC is introduced at the CO end with one side grounded at the CO and the other at ( open circuit ) -48VDC, and a ground on the subscriber end will introduce hum, or if low enough resistance will keep the line in an off hook condition. Swap the Adtran cards if only on some circuits, and make sure the 750 is well grounded. John Novack -- Dog is my co-pilot ___ --Bandwidth and Colocation Provided by http://www.api-digital.com-- asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users ___ --Bandwidth and Colocation Provided by http://www.api-digital.com-- asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
[asterisk-users] Help 60Hz Hum?
Hey guys, I am trying to diagnose a hum in my FXO lines I am using an Adtran 750 with 8 FXO ports. I am getting a pretty bad hum on the line during a call. I have checked the Telco side of the 66 block and there is no hum there so it's my problem to fix. I have tried to lower the gain but that reduces the call volume to much. Where else should I be looking? Setup as follows Dell PE1950 server Redfone Quad port fonebridge2 Asterisk 1.2.18 Zaptel 1.2.18 From redfone Adtran 750 Channel Bank with 8 FXO and 16 FXS Two PRI connections to fonebridge TIA Mark ___ --Bandwidth and Colocation Provided by http://www.api-digital.com-- asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
