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<div class="elementToProof"><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">Tnx Bryan.</span></div>
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<div class="elementToProof"><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">I'm not doing any compensation for the rolloff. That's why this is mostly useful for</span></div>
<div class="elementToProof"><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">RX skimming purposes. There is still a lot of useful bandwidth for SDR skimmer clients</span></div>
<div class="elementToProof"><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">such as cw/rtty skimmer and sparksdr.</span></div>
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<div class="elementToProof"><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">I was trying to get as many receivers as possible in the FPGA of Mercury with a goal</span></div>
<div class="elementToProof"><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">of hitting 8 for 8 band skimming. With the FIR it didn't have enough room for even 4.</span></div>
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<div class="elementToProof"><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">-Rick / N1GP</span></div>
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<span style="font-family: Calibri, Helvetica, sans-serif;">Very cool Rick!</span></div>
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<div><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">If you're not using compensating FIR filters after the CIC filter in the DDC, how are you compensating for the rolloff in the CIC?</span></div>
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<div><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">73,</span></div>
<div><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">Bryan W4WMT</span></div>
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<div dir="ltr" id="divRplyFwdMsg"><span style="font-family: Calibri, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);"><b>From:</b> Richard Koch <n1gp@hotmail.com><br>
<b>Sent:</b> Tuesday, February 6, 2024 1:00 PM<br>
<b>To:</b> hpsdr@lists.openhpsdr.org <hpsdr@lists.openhpsdr.org><br>
<b>Subject:</b> 8 DDC Skimmer Receiver firmware for Mercury/Metis</span>
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Hello list,</div>
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I've attempted to put some new life into my Atlas boards. I wanted to use</div>
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the Mercury / Metis pair to do some receiver skimming. I was able to get</div>
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8 DDCs working with one Mercury by using an NCO -vs- Cordic (inspired</div>
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by the Hermes-Lite2 folks) and only using CIC filters in the DSP (no FIR).</div>
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It is also limited to a 0-30MHz range and is Protocol 2 based.</div>
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It seems to work pretty well for me and I thought I would put it out there</div>
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to share with the community, hopefully someone will find it useful.</div>
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I put the firmware up on the github TAPR site:</div>
<div style="direction: ltr;"><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);"><a href="https://github.com/TAPR/OpenHPSDR-Firmware/tree/master/Protocol%202/Atlas/Skimmer_Receiver" id="OWA944fb7b9-4388-7116-7894-2998965172aa" class="OWAAutoLink" data-auth="NotApplicable">https://github.com/TAPR/OpenHPSDR-Firmware/tree/master/Protocol%202/Atlas/Skimmer_Receiver</a></span></div>
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<div style="direction: ltr;"><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">-Rick / N1GP</span></div>
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