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Steve,<br>
<br>
It may be right that SDR is not capable to run time sensitive
applications.<br>
I was scoping 10Mhz WWV today, output shows that real time/SDR time<br>
varies, escpecially while minimizing and maximizing PowerSDR window<br>
which causes higher CPU load. IIt was @ 48kHz sampling rate all
over<br>
the path, biggest buffers, no audioble drop-outs, max DPC latency
170<span class="Apple-style-span" style="color: rgb(34, 34, 34);
font-family: arial, sans-serif; font-style: normal; font-variant:
normal; font-weight: normal; letter-spacing: normal; line-height:
16px; orphans: 2; text-align: -webkit-auto; text-indent: 0px;
text-transform: none; white-space: normal; widows: 2;
word-spacing: 0px; -webkit-text-decorations-in-effect: none;
-webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;
background-color: rgb(255, 255, 255); font-size: small; ">μs.<br>
Anyway, it's now clear why's there are drop-outs while listening
DRM, why's<br>
there are out of sync line blocks in SSTV, why's digital SSTV
misses the blocks.<br>
I'm not struggling with it anymore. All the other, CW and SSB
works just fine.<br>
<br>
<br>
<br>
<br>
<br>
73's,<br>
Riho, ES7AAZ.<br>
</span><br>
<br>
29.09.2011 23:56, Steve Bunch kirjutas:
<blockquote
cite="mid:198ED828-6C7C-4EEF-8C71-094E5905EBBE@ameritech.net"
type="cite">Riho,
<div><br>
</div>
<div>I can't answer your question exactly, but this can happen
because of buffering somewhere in your sample chain, when the
sampling rate of your system is slightly slower than realtime so
the samples aren't being consumed as fast as they're generated.
The unread samples are saved up somewhere, and accumulate
there. I had this happening to me in an ALSA-based Linux system
-- I would over time be listening several seconds behind
realtime when using a USRP to listen to FM radio. Restarting
the chain will clear out the buffered data; when you restart it
will grow again. </div>
<div><br>
</div>
<div>I don't know if the Ozy/Mercury sample chain is capable of
buffering this much data (someone familiar with it should be
able to tell you exactly how much can be buffered there), but in
my case it was in my audio system. Unfortunately, I don't know
the various Windows audio systems well enough to give you any
help, but that is where I would look first.</div>
<div><br>
</div>
<div>Steve, K9SRB</div>
<div><br>
<div>
<div>On Sep 29, 2011, at 3:07 AM, Riho B., ES7AAZ wrote:</div>
<br class="Apple-interchange-newline">
<blockquote type="cite">***** High Performance Software
Defined Radio Discussion List *****<br>
<br>
<meta http-equiv="content-type" content="text/html;
charset=ISO-8859-1">
<div bgcolor="#FFFFFF" text="#000000"> Hi,<br>
<br>
I have a program called Faros which is a beacon monitor.<br>
Faros gets his time sync from ntp GPS time servers.<br>
<span class="apple-style-span"><span
style="font-size:10.5pt;font-family:"Tahoma","sans-serif";background:#FCFAEA">NCDXF</span></span>
network beacons have GPS dicsiplined controller<br>
which allows path delay calculation and Faros does it.<br>
<br>
After 2h running I see 120ms latency growth (linear graph)<br>
and it's growing on. Which means that radio waves are
traveling<br>
about one more circle around the world. It can't be so.
Restarting<br>
PowerSDR brings the latency back to its initial state.
Exactly the same <br>
effect with CWSkimmer console. It's almost same vith VAC
and with<br>
analog audio cable.<br>
<br>
The question is not even about latency itself or how much
it is.<br>
The question is why's latency growing and how much it
does?<br>
Is it somewhere in USB connection ? I'm Ozy user.<br>
<br>
<br>
<br>
73,<br>
Riho, ES7AAZ<br>
</div>
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