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<DIV><FONT size=2 face=Arial>Hi Riho,</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>You may care to do some tests on you system using
KISS Konsole since I suspect you are dropping packets between the PC and HPSDR
hardware. If you are only losing the odd packet then you are not going to
hear them.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>The Metis Ethernet code has a packet number
included in each data frame both to and from the PC. KK will indicate if a
packet is lost and what the expected and received packet numbers
are. Similarly Metis will light a LED if it misses a packet.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Using KK with Metis at 192ksps I have never seen a
missed packet in either direction - in fact I had to deliberately send incorrect
packet numbers to check the code was working!</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>I'm also currently doing some work that involves
time stamping the data from Mercury via Metis - again no dropped packets.
</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>The PC has absolutely no idea what the sample rate
is of the data it is being sent. It's not acceptable that an SDR can't be used
for DRM, SSTV etc - this needs to be investigated and corrected.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>73 Phil...VK6APH </FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=es7aaz@gmail.com href="mailto:es7aaz@gmail.com">Riho B., ES7AAZ</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=hpsdr@lists.openhpsdr.org
href="mailto:hpsdr@lists.openhpsdr.org">hpsdr@lists.openhpsdr.org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Saturday, October 01, 2011 6:00
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [hpsdr] about latency growth
with HPSDR</DIV>
<DIV><BR></DIV>***** High Performance Software Defined Radio Discussion List
*****<BR><BR>
<P>
<HR>
<P></P>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
style="WIDOWS: 2; TEXT-TRANSFORM: none; BACKGROUND-COLOR: rgb(255,255,255); TEXT-INDENT: 0px; FONT: small/16px arial, sans-serif; WHITE-SPACE: normal; ORPHANS: 2; LETTER-SPACING: normal; COLOR: rgb(34,34,34); WORD-SPACING: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px"
class=Apple-style-span>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>
<DIV text="#000000" bgcolor="#FFFFFF">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-FAMILY: 'Tahoma','sans-serif'; BACKGROUND: #fcfaea; FONT-SIZE: 10.5pt">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>_______________________________________________<BR>HPSDR
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