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<div>Michelle - Thanks for posting. I'll frame some of the questions.<br></div><div><br></div><div>Typical 10 GHz terrestrial contesting rigs are Heterodyne; that is a Mixer works with a Local Oscillator (LO) to take the RF down to an IF (Intermediate Frequency).</div><div>For an SDR, that IF can be digitized by an Analog-Digital Converter.</div><div><br></div><div>The most popular IF for contesting/SSB rigs is 144 MHz. </div><div>For a data BW of 10 MHz that may or may not be a fast enough IF carrier. If we can digitize and recover the data, it would allow a lot of re-use of existing equipment.</div><div><br></div><div>I've heard suggestions/proposals up to the 1.2 GHz Ham band.</div><div>In some sense, the IF carrier could be 144/220/440/915/1200 MHz, or even any Non-Ham frequency in between.</div><div><br></div><div>There are a lot of proof of existence designs for a 10 GHz Mixed down to an IF; and lots of off the shelf ADC dev-boards. (catch me off thread for details).</div><div><br></div><div>Some questions I have are: </div><div>---from an FPGA side of the SDR, what data rate(s) can the FPGA absorb in to a decimator? </div><div><br></div><div>Must we decide upfront on a single frequency; or </div><div>preferably allow flexibility in the RF front end design (ie, Mixer, PLL and Local Oscl hardware choices) by allowing a wide and programmable variety of ADC and decimation rates?</div><div><br></div><div>{This is where RF and Digital folks must communicate across walls.} ;-)</div><div><br></div><div>Comments welcome.</div><div><br></div><div>regards,</div><div>David</div><div>KI6CLA</div><div><br></div><div><br></div>
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On Friday, January 25, 2019, 2:41:54 PM PST, Michelle Thompson via Ground-Station <ground-station@lists.openresearch.institute> wrote:
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<div><div id="ydp40e62e6byiv6388574106"><div dir="ltr"><div dir="ltr">While we are striving to enable all sorts of wonderful designs by putting prototypes into GNU Radio, a central goal is to design our own hardware.<br><br>We've had a lot of progress on the protocol and algorithm front (GSE, LDPC, some of the polyphase). <br><br>Some fundamental decisions about our own hardware need to be made.<br><br>When we receive, we expect to have to decimate. This is because we are receiving at a relatively high frequency (10GHz).<br><br>Our bandwidth is (up to) 10MHz. For DVB-S2/X, we fix our sampling rate, depending on what bandwidth we want to support. We have a lot of freedom here.<br><br>Picking the right frequencies for the receive chain is therefore important.<br><br>What are our options? <br><br>What options make the best sense?<br><br>I'd like to build and test as soon as possible, so let's get some discussion going.<br><br><div><div dir="ltr" class="ydp40e62e6byiv6388574106gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div dir="ltr">-Michelle W5NYV<br><br><div dir="ltr"><br></div></div></div></div></div></div></div></div></div></div></div></div>_______________________________________________<br>Ground-Station mailing list<br><a href="mailto:Ground-Station@lists.openresearch.institute" rel="nofollow" target="_blank">Ground-Station@lists.openresearch.institute</a><br><a href="http://lists.openresearch.institute/mailman/listinfo/ground-station" rel="nofollow" target="_blank">http://lists.openresearch.institute/mailman/listinfo/ground-station</a><br></div>
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