[App_rpt-users] Audio Clipping with IAXRPT / Web Transceiver Client

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Hi Kieth, In the usbradio.conf  have you got the "txlinonly = yes'?

This should limit TX audio coming from the URI.

txlimonly=yes        ; Audio limiting with no pre-emphasis on output 
channel: no,yes
             ; no - Audio is not limited.
             ; yes - Audio is  limited.
             ; Suitable for transmitters with no limiting but with 
pre-emphasis.

You can also tell the IAX users to cut back their mic gains. I would 
start here first. Like a lot of people on Echolink they dont have the 
computer set up properly. I find that head sets sound the best rather 
than using the internal mics on lapatops.

I would leave the codec as Ulaw. dont bother with GSM, has crappy watery 
audio.

Jon VA3RQ

On 3/3/2013 11:31 AM, Keith Goobie wrote:
> Good day All.
>
> We have had our node up at VE3LSR / VE3UOR for a few months and we all 
> have learned a lot about configuration and operation.  It is ACID 
> install and version id is 300.3.
>
> On our asterisk system, we support three nodes:
>
> 27211 -- VE3UOR UHF repeater
> 29133 -- VE3LSR coupled through a RLC-DSP404 controller (often 
> connected to VE3UPS and VE3UHN), and
> 29154 -- VA3LSR remote link for VE3LSR into VE3MUS -- not too active 
> -- ad-hoc RF link.
>
> I have also been testing out iaxrpt and the WebTransceiver clients.
>
> I am on these systems and the results have been promising.  I do 
> notice some clipping on the audio on some stations.  Initially I 
> thought it was amplitude related -- over-driving the URI-FOB, but I am 
> now beginning to suspect that it may be network related and in my 
> research I hear the term jitter being used -- which if activated, 
> adjust operation on the receiving end only.
>
> It may be that the system is not powered enough to drive the three 
> uri-fobs.   CPU show about 25% busy.
> [root at VE3LSR etc]# cat /proc/cpuinfo
> processor    : 0
> vendor_id    : GenuineIntel
> cpu family    : 15
> model        : 4
> model name    : Intel(R) Pentium(R) 4 CPU 3.00GHz
> stepping    : 3
> cpu MHz        : 2992.898
> cache size    : 2048 KB
> physical id    : 0
> siblings    : 2
> core id        : 0
> cpu cores    : 1
> apicid        : 0
> fdiv_bug    : no
> hlt_bug        : no
> f00f_bug    : no
> coma_bug    : no
> fpu        : yes
> fpu_exception    : yes
> cpuid level    : 5
> wp        : yes
> flags        : fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca 
> cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe lm 
> constant_tsc pni monitor ds_cpl est cid cx16 xtpr
> bogomips    : 5985.79
>
> We do think that the system is sufficiently powered.
>
> We are looking for comments & guidance.  Are we expecting too much 
> from the system having three fobs connected?  We do have good 
> bandwidth into and out of the site.
>
> I am listening to other systems -- most not to busy, so I am not yet 
> able to get a good reference point.
>
> I have not dabbled with the codecs much, but have been focused on 
> using ulaw.  I am also testing with GSM -- lower bandwidth.
>
> So as I said before, thoughts or suggestions are welcome.
>
> Keith / VA3YC
> -- 
> keith at goobie.org
> Keith Goobie
> Richmond Hill, ON, CANADA
>
>
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