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<p class="MsoNormal">Following up from discussions at the GNU Radio conference, it seems that many USRP users have a need for flushing the DSP chain (interpolation filters, CIC filter, etc.) in the FPGA when using the transmit burst interface. Using metadata
 headers for setting transmit time_specs and starts/ends of bursts is useful and works very well, but information and guidance about how many zero samples are needed to flush the DSP chain is sparse and undocumented. (To my knowledge, at least). Some things
 that would be helpful, in increasing level of effort:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="mso-list:Ignore">1)<span style="font:7.0pt "Times New Roman"">     
</span></span><![endif]>Documentation about how many zero samples must be transmitted to flush the DSP chain: if host sample-rate dependent, a formula or lookup table<o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="mso-list:Ignore">2)<span style="font:7.0pt "Times New Roman"">     
</span></span><![endif]>A tool/utility to automatically determine this number through a loopback test, etc.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks,<o:p></o:p></p>
<p class="MsoNormal">Sean Nowlan<o:p></o:p></p>
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