Broadband-Hamnet™ Forum :: VoIP
Board Index Latest Posts Welcome Guest   [Register]  [Login]
 Subject :Call Quality.. 2014-10-09- 01:01:17 
GM4WZG
Member
Joined: 2013-06-26- 13:19:20
Posts: 6
Location: 


Hi,


We have a mesh network up and running on both sides of the Forth Estuary in Scotland. The VOIP works very nicely on nodes that are within a few hundred yards of the one containing the asterisk server.


However VOIP on nodes at around 10 miles distance is poor. We brought about a significant improvement by changing the distance setting from automatic to a suitable fixed value but audio is still broken up at times.


Default ping tests show good performance.  But pinging with a 10K payload gives us times of around 100-130ms and alarmingly, some 6 percent packet loss.  The latency is just within spec for a VOIP link but this packet loss is what I guess is doing the damage.

Just wondering if others have had the same experience ?


73


Bernie

GM4WZG
IP Logged
 Subject :Re:Call Quality.. 2014-10-09- 01:45:57 
AD7QF
Member
Joined: 2012-04-16- 05:51:12
Posts: 23
Location: 
This is a wild guess on my part, but are the times on the nodes synchronized. If one of them has an internet connection then they should be. Otherwise they all come up starting a a zero start time. As is probably the case, each node has a different time one it. Asterisk does have some time synchronization issues. A quick search on Asterisk time sync will show some of what I mean. As I said, a guess on my part.
IP Logged
 Subject :Re:Call Quality.. 2014-10-09- 01:58:52 
GM4WZG
Member
Joined: 2013-06-26- 13:19:20
Posts: 6
Location: 
Excellent - I never thought of that and it might catch me out at some point. Alas, that's not the current issue though - all are synched via an internet gateway connection to a time server and I just checked them. I guess we should put our own time server somewhere in case the internet fails (we're an Emcomm group and don't want to rely on public comms). Thanks ! Bernie GM4WZG
IP Logged
 Subject :Re:Call Quality.. 2014-10-09- 05:57:55 
KF5JIM
Future Astronaut
Joined: 2013-07-17- 12:13:36
Posts: 250
Location: Nederland

You might also want to set it up to use G729 instead of G711 (alaw and ulaw). The amount of bandwith drops by a factor of 10. G729: 8kbps (inc. overhead) vs. G711: 80kbps (inc. overhead) per each audio channel. Each call has two audio channels (1 send + 1 recieve). This also helps drasticly with call quality and chop. Plus, G729 does a passthrough with Asterisk so efficiency also improves too.
IP Logged
My opinions and views expressed here are solely my own.
Page # 


Powered by ccBoard


SPONSORED AD: