<div dir="ltr">Hi<br><div class="gmail_extra"><br>Are you using a common clock?</div><div class="gmail_extra"><a href="http://kaira.sgo.fi/2013/09/16-dual-channel-coherent-digital.html">http://kaira.sgo.fi/2013/09/16-dual-channel-coherent-digital.html</a></div>
<div class="gmail_extra"><br></div><div class="gmail_extra">I've modified some of the RTL dongles, played with GNURadio and Octave.</div><div class="gmail_extra"><div class="gmail_extra">The results are promising, sample level correlation (2.4M/10, FM radio signal).</div>
<br><div class="gmail_quote">On Mon, Dec 30, 2013 at 9:38 AM, Jiao Xianjun <span dir="ltr"><<a href="mailto:putaoshu@gmail.com" target="_blank">putaoshu@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
<div dir="ltr"><div><div>Hi guys,<br><br></div>For the multiple dongles synchronization in signal level instead of bits/packets level, I setup a working repo in github, and write a initial demo framework. See below:<br><br>

<a href="https://github.com/JiaoXianjun/multi-rtl-sdr-udp-relay.git" target="_blank">https://github.com/JiaoXianjun/multi-rtl-sdr-udp-relay.git</a><br><br></div>You may find information and instruction of demo quickly by reading the README.<br>

<div><p style="margin:15px 0px;color:rgb(51,51,51);font-family:Helvetica,arial,freesans,clean,sans-serif;font-size:15px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:25px;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px">

My initial purpose is performing in-fly calibration for multiple dongles according to some pre-known signal (GSM, ADS-B?) to let them work together coherently.</p><p style="margin:15px 0px;color:rgb(51,51,51);font-family:Helvetica,arial,freesans,clean,sans-serif;font-size:15px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:25px;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px">

An ideal scheme may be that we should generate a very narrow band and very week signal in (or just located at the edge of) target working band of dongles, and perform the software in-fly calibration in background (or driver level). This would be user friendly.<br>
</p></div></div></blockquote><div><br></div><div>Cheap (8USD+PP), simple, computer-controlled and legal FM band "marker"<br></div><div><a href="http://blog.palosaari.fi/2013/08/naked-hardware-12-usb-audio-transmitter.html">http://blog.palosaari.fi/2013/08/naked-hardware-12-usb-audio-transmitter.html</a></div>
<div><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div dir="ltr"><div><p style="margin:15px 0px;color:rgb(51,51,51);font-family:Helvetica,arial,freesans,clean,sans-serif;font-size:15px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:25px;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px">

</p><p style="margin:15px 0px;color:rgb(51,51,51);font-family:Helvetica,arial,freesans,clean,sans-serif;font-size:15px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:25px;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px">

I know it is far from final state currently, and many things are not clear yet (See TODO). But please join me if you also think this is a good idea. Just check out the demo and run it to have a look.</p></div></div></blockquote>
<div>Testing it and I'll let you know.<br></div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
<div dir="ltr"><div><p style="margin:15px 0px;color:rgb(51,51,51);font-family:Helvetica,arial,freesans,clean,sans-serif;font-size:15px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:25px;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px">

Currently I just test the demo in Ubuntu-Linux.</p><p style="margin:15px 0px;color:rgb(51,51,51);font-family:Helvetica,arial,freesans,clean,sans-serif;font-size:15px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:25px;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px">

</p><p style="margin:15px 0px;color:rgb(51,51,51);font-family:Helvetica,arial,freesans,clean,sans-serif;font-size:15px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:25px;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px">

BR</p><span class=""><font color="#888888"><p style="margin:15px 0px;color:rgb(51,51,51);font-family:Helvetica,arial,freesans,clean,sans-serif;font-size:15px;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:25px;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px">

Jiao Xianjun<br></p></font></span></div></div><div class=""><div class="h5"><div class="gmail_extra"><br><br><div class="gmail_quote">On Mon, Sep 2, 2013 at 8:23 PM, Sylvain AZARIAN <span dir="ltr"><<a href="mailto:sylvain.azarian@gmail.com" target="_blank">sylvain.azarian@gmail.com</a>></span> wrote:<br>

<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div dir="ltr">Thanks. <span><font color="#888888"><div><br>
</div><div>sylvain</div></font></span></div>
<div><div><div class="gmail_extra"><br><br><div class="gmail_quote">2013/9/2 Sdr Guru <span dir="ltr"><<a href="mailto:sdrguru1@gmail.com" target="_blank">sdrguru1@gmail.com</a>></span><br>


<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div dir="ltr"><div>The second way, use MLAT enabled dump1090</div>
<div><a href="https://github.com/antirez/dump1090/pull/23" target="_blank">https://github.com/antirez/dump1090/pull/23</a><br>


</div><div><a href="http://www.satsignal.eu/raspberry-pi/dump1090.html" target="_blank">http://www.satsignal.eu/raspberry-pi/dump1090.html</a><br>
</div><div class="gmail_extra"><br><br><div class="gmail_quote">On Sun, Aug 25, 2013 at 4:13 PM, Jiao Xianjun <span dir="ltr"><<a href="mailto:putaoshu@gmail.com" target="_blank">putaoshu@gmail.com</a>></span> wrote:<br>




<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div dir="ltr"><div><div><div>Hi,<br><br></div>I want to use multiple rtl-sdr dongles to do some multi-antenna experiments.<br>




<br></div>Is it possible to read IQ samples from multiple rtl-sdr dongles in a synchronized manner?<br>
<br></div><div>I already have a glance at dump1090 codes, which is a project using rtl-sdr to decode aircraft broadcasting ADS-B messages in 1090MHz.<br><br></div><div>Seems that I should use rtlsdr_read_async() instead of rtlsdr_read_sync(), because that if rtlsdr_read_sync() is used, I have to call it multiple times sequentially. That looks not synchronized.<br>





<br></div><div>But rtlsdr_read_async() function only accept one rtl-sdr device as input parameter, and it will be blocked after it is called. So seems that it also can't be used for my purpose directly.<br><br></div>




<div>
Also welcome any opinion on how to improve rtl-sdr lib/driver to support this feature.<br><br></div><div>Thank you.<br><br>BR<span><font color="#888888"><br><br>Jiao Xianjun <br></font></span></div></div>
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