Re: [asterisk-users] Line noise/hiss on Openvox A400P card on FXO
On 01/03/12 10:05, Sebastian Arcus wrote: I have a server with an OpenVox A400P card with 2 FXO modules on it. The internal extensions are SIP Grandstream phones. When making or receiving external calls through PSTN, there is an interrupted hissing like high pitch noise - which might go away for few seconds then start again. Just a follow up to my own post. After taking apart the * server, replacing motherboard, replacing analog card with a usb FXO card from Sangoma - none of the above have helped with the problem. However: 1. I tried disabling echo cancellation on the FXO ports in DAHDI and all of a sudden the line is much clearer. The noise is still there, but because the conversation is clearer, I could drop the gains on the FXO ports to -2db and -5db. This has reduced the background hiss to a certain extent. This was really an important lesson for me - as I would normally set the default echo cancellation (128 I think) and just leave it on - unless more was required. What I really should have done is started with no echo cancellation and just add a bit at a time - up to minimum necessary. I never realised how much harm too much echo cancellation does to the sound quality on the line. 2. I have tested the setup with an old Cisco 7940 phone. To my surprise, although the noise is still there somewhere, it is nowhere near as noticeable on the Grandstream GXP280 phone. It looks like in great part the Grandstream GXP 280 is just too sensitive to line noise - or it picks up / amplifies too much the wrong frequencies. 3. Again, using Ekiga, there is virtually no line noise. They must be using some really good algorithms which clean up the line. Maybe the above will help someone. I just have to decide now if I scrap the Grandstreams and replace them with Cisco phones - or just live with the line quality. Sebastian 1. The noise is not present when calling in between internal extensions (SIP only). 2. The noise is the same on both PSTN lines. 3. The noise is NOT present when I tried two different phones directly in the PSTN line(s) (a Philips DECT phone and a BT Converse phone) Is the noise interference actually on the line, which the phones filter out because of their better electronic design (then the OpenVox card) - or is it generated somewhere in the server or on the OpenVox card? I have tried: 1. Checking the interrupts and making sure the OpenVox card has its own IRQ. 2. Moving the card around on different PCI slots. 3. Changing the second network card with a different model (the first one is integrated in the motherboard). 4. Changing the motherboard, CPU and RAM (one motherboard AMD with Sis chipset, the other one Intel). 5. Placing ferrite cores on the phone cables. 6. Checking to see if the OpenVox card gets 1000 interrupts per second and it does. 7. Upgrading the kernel from 2.6.29 to 2.6.37 8. Ran FXO tune and made sure it starts with DAHDI 9. Disabled and enable software echo cancellation - it makes no difference. The server is virtually under no load during the tests. It does have IDE hard-drives (which apparently can cause problems) - but there is not much I can do about that. I also have a Sangoma USB FXO adapter - which I'm about to install and configure to see if it makes a difference. I would really like to figure out where is the noise coming from - as I'm going a bit in circles. If I can find out for sure that the OpenVox card is either broken or low quality - I'll just have to replace it. But I can't even figure that out for sure. The specs are: CPU: Celeron 2.4GHz Asterisk 10.1.2 Dahdi 2.6.0 Hard-drives: IDE OpenVox A400P analog card Many thanks for any advice. -- _ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- New to Asterisk? Join us for a live introductory webinar every Thurs: http://www.asterisk.org/hello asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users -- Linux vehicle CCTV - www.open-t.co.uk/iroko -- _ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- New to Asterisk? Join us for a live introductory webinar every Thurs: http://www.asterisk.org/hello asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
Re: [asterisk-users] Line noise/hiss on Openvox A400P card on FXO
Hello Are you using a amd server? Sometimes openvox doesn't work fine with amd processor Regards On Mar 1, 2012 2:07 PM, Dave Platt dpl...@radagast.org wrote: 5. Placing ferrite cores on the phone cables. Do either of the phone lines in question have DSL on them? If so, a ferrite core (which will block common-mode RF signals) probably won't help much, if at all. DSL is a differential-mode signal, and its frequency content starts down in the tens of kHz. Ferrite cores are usually intended to block much higher frequency interference, and won't have enough inductance to help much with DSL signals. What I would suggest, is that you get yourself a couple of DSL microfilters... plug them into the A400P FXO ports, and plug the lines into the filters. These sorts of filters are designed specifically to block DSL differential- mode signals from getting into analog-phone circuits, and they will also be fairly effective against other forms of low-frequency-RF noise. -- _ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- New to Asterisk? Join us for a live introductory webinar every Thurs: http://www.asterisk.org/hello 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 -- New to Asterisk? Join us for a live introductory webinar every Thurs: http://www.asterisk.org/hello asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
Re: [asterisk-users] Line noise/hiss on Openvox A400P card on FXO
Hi, I've tried both an AMD and an Intel motherboard - with identical results. Sebastian On 04/03/12 15:32, Carlos Rojas wrote: Hello Are you using a amd server? Sometimes openvox doesn't work fine with amd processor Regards On Mar 1, 2012 2:07 PM, Dave Platt dpl...@radagast.org mailto:dpl...@radagast.org wrote: 5. Placing ferrite cores on the phone cables. Do either of the phone lines in question have DSL on them? If so, a ferrite core (which will block common-mode RF signals) probably won't help much, if at all. DSL is a differential-mode signal, and its frequency content starts down in the tens of kHz. Ferrite cores are usually intended to block much higher frequency interference, and won't have enough inductance to help much with DSL signals. What I would suggest, is that you get yourself a couple of DSL microfilters... plug them into the A400P FXO ports, and plug the lines into the filters. These sorts of filters are designed specifically to block DSL differential- mode signals from getting into analog-phone circuits, and they will also be fairly effective against other forms of low-frequency-RF noise. -- _ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- New to Asterisk? Join us for a live introductory webinar every Thurs: http://www.asterisk.org/hello 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 -- New to Asterisk? Join us for a live introductory webinar every Thurs: http://www.asterisk.org/hello asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users -- Linux vehicle CCTV - www.open-t.co.uk/iroko -- _ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- New to Asterisk? Join us for a live introductory webinar every Thurs: http://www.asterisk.org/hello asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
[asterisk-users] Line noise/hiss on Openvox A400P card on FXO
I have a server with an OpenVox A400P card with 2 FXO modules on it. The internal extensions are SIP Grandstream phones. When making or receiving external calls through PSTN, there is an interrupted hissing like high pitch noise - which might go away for few seconds then start again. 1. The noise is not present when calling in between internal extensions (SIP only). 2. The noise is the same on both PSTN lines. 3. The noise is NOT present when I tried two different phones directly in the PSTN line(s) (a Philips DECT phone and a BT Converse phone) Is the noise interference actually on the line, which the phones filter out because of their better electronic design (then the OpenVox card) - or is it generated somewhere in the server or on the OpenVox card? I have tried: 1. Checking the interrupts and making sure the OpenVox card has its own IRQ. 2. Moving the card around on different PCI slots. 3. Changing the second network card with a different model (the first one is integrated in the motherboard). 4. Changing the motherboard, CPU and RAM (one motherboard AMD with Sis chipset, the other one Intel). 5. Placing ferrite cores on the phone cables. 6. Checking to see if the OpenVox card gets 1000 interrupts per second and it does. 7. Upgrading the kernel from 2.6.29 to 2.6.37 8. Ran FXO tune and made sure it starts with DAHDI 9. Disabled and enable software echo cancellation - it makes no difference. The server is virtually under no load during the tests. It does have IDE hard-drives (which apparently can cause problems) - but there is not much I can do about that. I also have a Sangoma USB FXO adapter - which I'm about to install and configure to see if it makes a difference. I would really like to figure out where is the noise coming from - as I'm going a bit in circles. If I can find out for sure that the OpenVox card is either broken or low quality - I'll just have to replace it. But I can't even figure that out for sure. The specs are: CPU: Celeron 2.4GHz Asterisk 10.1.2 Dahdi 2.6.0 Hard-drives: IDE OpenVox A400P analog card Many thanks for any advice. -- _ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- New to Asterisk? Join us for a live introductory webinar every Thurs: http://www.asterisk.org/hello asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
[asterisk-users] Line noise/hiss on Openvox A400P card on FXO
5. Placing ferrite cores on the phone cables. Do either of the phone lines in question have DSL on them? If so, a ferrite core (which will block common-mode RF signals) probably won't help much, if at all. DSL is a differential-mode signal, and its frequency content starts down in the tens of kHz. Ferrite cores are usually intended to block much higher frequency interference, and won't have enough inductance to help much with DSL signals. What I would suggest, is that you get yourself a couple of DSL microfilters... plug them into the A400P FXO ports, and plug the lines into the filters. These sorts of filters are designed specifically to block DSL differential- mode signals from getting into analog-phone circuits, and they will also be fairly effective against other forms of low-frequency-RF noise. -- _ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- New to Asterisk? Join us for a live introductory webinar every Thurs: http://www.asterisk.org/hello asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
Re: [asterisk-users] Line noise/hiss on Openvox A400P card on FXO
On 01/03/12 19:07, Dave Platt wrote: 5. Placing ferrite cores on the phone cables. Do either of the phone lines in question have DSL on them? If so, a ferrite core (which will block common-mode RF signals) probably won't help much, if at all. DSL is a differential-mode signal, and its frequency content starts down in the tens of kHz. Ferrite cores are usually intended to block much higher frequency interference, and won't have enough inductance to help much with DSL signals. What I would suggest, is that you get yourself a couple of DSL microfilters... plug them into the A400P FXO ports, and plug the lines into the filters. These sorts of filters are designed specifically to block DSL differential- mode signals from getting into analog-phone circuits, and they will also be fairly effective against other forms of low-frequency-RF noise. Hi Dave and thanks for the suggestion. Although the lines don't have ADSL on them (we have a separate line for that) - I've tried ADSL filters on the them anyway. I even chained two filters to see if it will have any effect. I'm afraid the noise is still the same. Regards -- _ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- New to Asterisk? Join us for a live introductory webinar every Thurs: http://www.asterisk.org/hello asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
