Author Topic: Audio Transfer Short Interrupts  (Read 3872 times)

dj4kw

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Audio Transfer Short Interrupts
« on: 2011-06-18, 16:14:32 »
Hello
using ICOM 706 MK II and RRC-1258 MK II, I notice that the received sound is interrupted with a slight klick very shortly from time to time.  Interrupt is less then 0.1 seconds, but enough to make CW hard to read, e.g. a Dit of the Morse signal is split into two short ones.

Is this a known problem?  Can I change settings to avoid this?  For example Audio Quality (presently set to 2 Lin 16 bit 8 kHz on both units)?

Or is it a problem of my DSL provider (25 MBit/s) ?

Regards
Gerd

dj4mz

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Re: Audio Transfer Short Interrupts
« Reply #1 on: 2011-06-20, 09:37:09 »
Hello Gerd,

I also have seen (or heard) these short interuptions. As you already mentioned interupts are very short and, in my case, only occur seldom. So I didn't care about it. I think it is related to SIP, as I also know this behavior from IP telephones. Can you configure or do you use QoS in your Router?

It would be interesting if some of the SIP settings can influence the probablility of occurence.

CU in FN next weekend,
Simon

sm2o

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Re: Audio Transfer Short Interrupts
« Reply #2 on: 2011-06-20, 10:30:19 »
if you have short interrupts, Increase the the jitter buffer settings, see manual

73 de mike

SM0UXX

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Re: Audio Transfer Short Interrupts
« Reply #3 on: 2011-07-30, 11:39:06 »
I also experienced this, both on TX and RX. Especially on TX it was hard to find the reason...

In my case it seems there were two things causing this;
1. First I tried to use wireless LAN at control site (home). Although the signal was very strong, and the speed seemed OK (54Mbits over wireless, about 90Mbits to internet), there were still too many bits lost. I guess other routers, microwave owens and so on caused the QRM. So the solution was to simply install an ethernet cable to the control-shack from my router.

2. However I still had some occasional audio dropouts, and more annoying - my TX sound would occasionally start to "stutter". However this was solved when upgrading RRC firmware (I canīt say exactly which version did it, since I missed a few versions since I eventually upgraded to v2.34). My theory is that there was some conflict between one of the RRCīs and one of my routers. In one of the firmware updates several ethernet issues were adressed (Iīm not updated on exaclty what was done).

Hope this can give some clues?

73 de  Erik

dj4kw

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Jitter Parameter / Re: Audio Transfer Short Interrupts
« Reply #4 on: 2011-10-26, 13:39:14 »
Mike, thank you for directing our attention to a proper setting of the jitter-parameter.  As mentioned earlier, I use an ICOM-706 MK II.

Erik, thanks for mentioning that the same effect can take place in the reverse direction.  I have a question concerning the TX side where my CW dahs and dits seems to have no equal length.

In an activity day with over 100 CW QSO's it happened twice (< 2 %) that during reception of a call sign I heard a clicking noise and I missed one dit.  Remote and local Remetorig are connected with ethernet cable, no WLAN; providers supply 25 MBit/s one side, 30 MBit/s the other.  But there was additional activity by VNC/VPN with the remote computer and I do not complain about the RX side.  Nevertheless my question, if I can improve parameter settings.  The TX was keyed from two sources, (1) a PC contest program at the remote site, controlled via VNC and (2) manually with a paddle connected to the local Remoterig.  Some stations thought I would use a semi-automatic key, my dahs were not with uniform length.   

Is that also a Jitter-problem or what parameters should i check?

73
DJ4KW


sm2o

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Re: Audio Transfer Short Interrupts
« Reply #5 on: 2011-10-26, 18:27:13 »
If you use the internal keyer function int the RRC the length of dit and dah are not at all depending on the internet connection, they are generated at the remote side and the ratio between dit and dah are constant, the ratio can be set in the keyer setup.

The key delay can be increased to improve the tolerance against Jitter, you set side tone to 0 then you can hear the side tone from the radio eg. what is actually sent from the radio when testing what value you need for the key delay

73 de mike