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<p class="MsoNormal">I finally have a simulation which I believe is faithful to the design target for the speed of the Tangerine.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The Red Pitaya (in HPDSDR emulation mode) is able to output 2 (I/Q) channels, each at 48 ksps (for a total output of 96 ksps). To simulate 192 ksps, in Digital RF we specify 192,000 as sample rate, duplicate the data 8 times, and save
each buffer twice. Data output is 96,000 x (2 data saves) X (2 antennas) X (8 bands) X (8 bytes per sample) = 24,576,000 bytes/sec. The msec/file is set to 4000; so every 4 seconds, the system outputs a file of size 98,311,608 bytes. Since the payload is
98,304,000 bytes, we see that Digital RF adds very little overhead. The compression is set to zero, so missing data is not removed (if it occurs); the system will save NaN (not a number) in the missed values.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Speed test results:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Every buffer save introduces enough delay to make the program miss a few buffers (even when saving to ramdisk). The percentage of missed data is quite small; for example, in today’s benchmark, we have the following:<o:p></o:p></p>
<p class="MsoNormal"><span style="font-family:"Courier New""><o:p> </o:p></span></p>
<table class="MsoNormalTable" border="0" cellspacing="0" cellpadding="0" width="1079" style="width:809.0pt;border-collapse:collapse">
<tbody>
<tr style="height:15.0pt">
<td width="132" nowrap="" valign="bottom" style="width:99.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal"><span style="font-family:"Courier New";color:black">buffer# sent<o:p></o:p></span></p>
</td>
<td width="143" nowrap="" valign="bottom" style="width:107.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal"><span style="font-family:"Courier New";color:black">buffer# saved<o:p></o:p></span></p>
</td>
<td width="139" nowrap="" valign="bottom" style="width:104.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal"><span style="font-family:"Courier New";color:black">buffers sent<o:p></o:p></span></p>
</td>
<td width="135" nowrap="" valign="bottom" style="width:101.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal"><span style="font-family:"Courier New";color:black">buffers missed<o:p></o:p></span></p>
</td>
<td width="139" nowrap="" valign="bottom" style="width:104.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal"><span style="font-family:"Courier New";color:black">percent lost<o:p></o:p></span></p>
</td>
<td width="137" nowrap="" valign="bottom" style="width:103.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal"><span style="font-family:"Courier New";color:black">success rate<o:p></o:p></span></p>
</td>
<td width="255" nowrap="" valign="bottom" style="width:191.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal"><span style="font-family:"Courier New";color:black">missed data (microseconds)<o:p></o:p></span></p>
</td>
</tr>
<tr style="height:15.0pt">
<td width="132" nowrap="" style="width:99.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">5425<o:p></o:p></span></p>
</td>
<td width="143" nowrap="" valign="bottom" style="width:107.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">5409<o:p></o:p></span></p>
</td>
<td width="139" nowrap="" valign="bottom" style="width:104.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">5425<o:p></o:p></span></p>
</td>
<td width="135" nowrap="" valign="bottom" style="width:101.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">16<o:p></o:p></span></p>
</td>
<td width="139" nowrap="" valign="bottom" style="width:104.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">0.29%<o:p></o:p></span></p>
</td>
<td width="137" nowrap="" valign="bottom" style="width:103.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="color:black">99.71%<o:p></o:p></span></p>
</td>
<td width="255" nowrap="" valign="bottom" style="width:191.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">12000<o:p></o:p></span></p>
</td>
</tr>
<tr style="height:15.0pt">
<td width="132" nowrap="" style="width:99.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">10766<o:p></o:p></span></p>
</td>
<td width="143" nowrap="" valign="bottom" style="width:107.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">10757<o:p></o:p></span></p>
</td>
<td width="139" nowrap="" valign="bottom" style="width:104.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">5341<o:p></o:p></span></p>
</td>
<td width="135" nowrap="" valign="bottom" style="width:101.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">9<o:p></o:p></span></p>
</td>
<td width="139" nowrap="" valign="bottom" style="width:104.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">0.17%<o:p></o:p></span></p>
</td>
<td width="137" nowrap="" valign="bottom" style="width:103.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="color:black">99.83%<o:p></o:p></span></p>
</td>
<td width="255" nowrap="" valign="bottom" style="width:191.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">6750<o:p></o:p></span></p>
</td>
</tr>
<tr style="height:15.0pt">
<td width="132" nowrap="" style="width:99.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">16107<o:p></o:p></span></p>
</td>
<td width="143" nowrap="" valign="bottom" style="width:107.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">16098<o:p></o:p></span></p>
</td>
<td width="139" nowrap="" valign="bottom" style="width:104.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">5341<o:p></o:p></span></p>
</td>
<td width="135" nowrap="" valign="bottom" style="width:101.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">9<o:p></o:p></span></p>
</td>
<td width="139" nowrap="" valign="bottom" style="width:104.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">0.17%<o:p></o:p></span></p>
</td>
<td width="137" nowrap="" valign="bottom" style="width:103.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="color:black">99.83%<o:p></o:p></span></p>
</td>
<td width="255" nowrap="" valign="bottom" style="width:191.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">6750<o:p></o:p></span></p>
</td>
</tr>
<tr style="height:15.0pt">
<td width="132" nowrap="" style="width:99.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">21469<o:p></o:p></span></p>
</td>
<td width="143" nowrap="" valign="bottom" style="width:107.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">21440<o:p></o:p></span></p>
</td>
<td width="139" nowrap="" valign="bottom" style="width:104.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">5362<o:p></o:p></span></p>
</td>
<td width="135" nowrap="" valign="bottom" style="width:101.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">29<o:p></o:p></span></p>
</td>
<td width="139" nowrap="" valign="bottom" style="width:104.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">0.54%<o:p></o:p></span></p>
</td>
<td width="137" nowrap="" valign="bottom" style="width:103.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="color:black">99.46%<o:p></o:p></span></p>
</td>
<td width="255" nowrap="" valign="bottom" style="width:191.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">21750<o:p></o:p></span></p>
</td>
</tr>
<tr style="height:15.0pt">
<td width="132" nowrap="" style="width:99.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">26803<o:p></o:p></span></p>
</td>
<td width="143" nowrap="" valign="bottom" style="width:107.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">26801<o:p></o:p></span></p>
</td>
<td width="139" nowrap="" valign="bottom" style="width:104.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">5334<o:p></o:p></span></p>
</td>
<td width="135" nowrap="" valign="bottom" style="width:101.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">2<o:p></o:p></span></p>
</td>
<td width="139" nowrap="" valign="bottom" style="width:104.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">0.04%<o:p></o:p></span></p>
</td>
<td width="137" nowrap="" valign="bottom" style="width:103.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="color:black">99.96%<o:p></o:p></span></p>
</td>
<td width="255" nowrap="" valign="bottom" style="width:191.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">1500<o:p></o:p></span></p>
</td>
</tr>
<tr style="height:15.0pt">
<td width="132" nowrap="" style="width:99.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">32151<o:p></o:p></span></p>
</td>
<td width="143" nowrap="" valign="bottom" style="width:107.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">32135<o:p></o:p></span></p>
</td>
<td width="139" nowrap="" valign="bottom" style="width:104.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">5348<o:p></o:p></span></p>
</td>
<td width="135" nowrap="" valign="bottom" style="width:101.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">16<o:p></o:p></span></p>
</td>
<td width="139" nowrap="" valign="bottom" style="width:104.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">0.30%<o:p></o:p></span></p>
</td>
<td width="137" nowrap="" valign="bottom" style="width:103.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="color:black">99.70%<o:p></o:p></span></p>
</td>
<td width="255" nowrap="" valign="bottom" style="width:191.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">12000<o:p></o:p></span></p>
</td>
</tr>
<tr style="height:15.0pt">
<td width="132" nowrap="" style="width:99.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">37499<o:p></o:p></span></p>
</td>
<td width="143" nowrap="" valign="bottom" style="width:107.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">37484<o:p></o:p></span></p>
</td>
<td width="139" nowrap="" valign="bottom" style="width:104.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">5348<o:p></o:p></span></p>
</td>
<td width="135" nowrap="" valign="bottom" style="width:101.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">15<o:p></o:p></span></p>
</td>
<td width="139" nowrap="" valign="bottom" style="width:104.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">0.28%<o:p></o:p></span></p>
</td>
<td width="137" nowrap="" valign="bottom" style="width:103.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="color:black">99.72%<o:p></o:p></span></p>
</td>
<td width="255" nowrap="" valign="bottom" style="width:191.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">11250<o:p></o:p></span></p>
</td>
</tr>
<tr style="height:15.0pt">
<td width="132" nowrap="" valign="bottom" style="width:99.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
</td>
<td width="143" nowrap="" valign="bottom" style="width:107.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Times New Roman",serif">Total
</span><span style="font-size:10.0pt;font-family:Wingdings">à</span><span style="font-size:10.0pt;font-family:"Times New Roman",serif"><o:p></o:p></span></p>
</td>
<td width="139" nowrap="" valign="bottom" style="width:104.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">37499<o:p></o:p></span></p>
</td>
<td width="135" nowrap="" valign="bottom" style="width:101.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">96<o:p></o:p></span></p>
</td>
<td width="139" nowrap="" valign="bottom" style="width:104.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">0.26%<o:p></o:p></span></p>
</td>
<td width="137" nowrap="" valign="bottom" style="width:103.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="color:black">99.74%<o:p></o:p></span></p>
</td>
<td width="255" nowrap="" valign="bottom" style="width:191.0pt;padding:0in 5.4pt 0in 5.4pt;height:15.0pt">
<p class="MsoNormal" align="right" style="text-align:right"><span style="font-family:"Courier New";color:black">72000<o:p></o:p></span></p>
</td>
</tr>
</tbody>
</table>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">It is interesting to note that, during this test, I started the drf mirror utility, which copies the data from ramdisk to spinning disk (I found that setting the process priority of drf to -5 [higher than pihpsdr] was necessary to get the
data save to work. It was able to keep up with the amount of data being moved, so I conclude that this is a workable solution; the science users will have to weigh in on whether this amount of data loss is acceptable. I’m not sure how to speed this system
up any further with this hardware. Attached is source code for the part of pihpsdr which I modified to save the Dgitial RF data; if anybody spots any bug, I am interested to know,.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">W. D. Engelke (Bill), Asst. Research Engr. AB4EJ<o:p></o:p></p>
<p class="MsoNormal">Center for Advanced Public Safety<o:p></o:p></p>
<p class="MsoNormal">Cyber Hall<o:p></o:p></p>
<p class="MsoNormal">The University of Alabama<o:p></o:p></p>
<p class="MsoNormal">Tuscaloosa, AL 35487<o:p></o:p></p>
<p class="MsoNormal">Desk: (205) 348-7244<o:p></o:p></p>
<p class="MsoNormal">Mobile: (205) 764-3099<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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