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<p class="MsoNormal">Hello All:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I have a prototype of a process working for moving (raw) spectrum data from the TangerineSDR to the Central Host; I would like any interested colleagues to review and comment on it, since it is such an important piece of the system. I have
a mockup running in Ubuntu on a virtual server, but the final Central Host process will run under CentOS and Django. Here’s how the process works:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<ol style="margin-top:0in" start="1" type="1">
<li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1">When in Ringbuffer mode, the TangerineSDR collects one to 16 bands of spectrum data, saving it in a ring buffer in Digital RF format. (Typical actual use would probably be the ~ 5
bands of WWV).<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1">Every so often (say, 120 seconds), the TangerineSDR sends a heartbeat packet to the Central Host.
<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1">If the Central Host has been given a data collection command (by a superuser), it will reply to the heartbeat with a Data Request that has a start and end time.<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1">The TangerineSDR finds all the files and metadata collected during the requested time frame and uses tar to put into a single file (optionally compressed).
<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1">The upload file gets named according to the (still being refined) CWRU naming convention (except that band info will not appear in the file name since a DRF file will usually contain
multiple bands).<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1">The TangerineSDR optionally sets the maximum upload rate (“throttle”) and uses the utility lftp to send the file to the sftp server running on the Central Host. Each user has their
own “incoming” directory. <o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1">The Central Host checks the incoming directories at certain intervals; when it finds a file package, it moves it to a central collection and puts a cross-reference into the relational
database.<o:p></o:p></li></ol>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Notes: I thought about a number of different ways of moving the data from TangerineSDR to the Central Host; this way seems promising because it offers the following benefits –<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<ul style="margin-top:0in" type="disc">
<li class="MsoListParagraph" style="margin-left:0in;mso-list:l1 level1 lfo2"><span style="font-family:"Courier New"">lftp</span> is restartable in case the upload is interrupted. Some uploads will run for a long time.<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l1 level1 lfo2">Using sftp as the protocol protects the data in transit.<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l1 level1 lfo2">The Central Host can handle a lot of uploads at once without burdening the website.<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l1 level1 lfo2">Since each user has a unique UID and password, and data travels encrypted, we should be able to minimize hackers uploading garbage.<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l1 level1 lfo2">The TangerineSDR has another mode (“snapshotter”) which pre-processes raw spectrum into frequency domain data – this will be handled differently (more to come on that).<o:p></o:p></li></ul>
<p class="MsoListParagraph"><o:p> </o:p></p>
<p class="MsoListParagraph" style="margin-left:.25in">I’m sure I have not thought of everything though; if you have a suggestion on how to do this better, it is most welcome – thanks for your help! -73- Bill AB4EJ
<o:p></o:p></p>
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