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Plan Outline
Brief overview the idea is to attach an SDR receiver & GPU to and LWA antenna to see if we can make decent (time and frequency resolution), cheap spectrometer. Could also be an interesting idea for our VLF observations amp + phase I think.
SDR obtains time domain samples in a given frequency band -> transferred quickly (USB3) to GPU memory (DMA) -> use GPU to do polyphase filtering/fft -> write to disk-> loop over a series of bands to obtain coverage from ~10-90 MHz
Get a working prototype, currently obtain spectrograms using laptop and the SDR need to look at attaching to GPU, and GPU processing.
- SDR - LimeMini SDR (https://limemicro.com/products/boards/limesdr-mini/)
- GPU - Nivida Jeston Nano (https://developer.nvidia.com/embedded/jetson-nano-developer-kit)
- Antenna - small whip antenna
Test how fast the SDR can acquire the time domain samples and transfer to the GPU for polyphase filtering Develop software to run the SDR and GPU combo and output spectrogram is some reasonable format Long duration tests - acquiring spectrogram 24/7 or at least during daylight with crappy whip antenna (I realise prob won’t see any solar events).
At the moment I’m pretty worried about overheating (damage) and fire risks so need to purchase few parts:
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Jetson Nano case + fan https://www.waveshare.com/jetson-nano-case-c.htm https://ie.rs-online.com/web/p/development-tool-accessories/2237610/?cm_mmc=IE-PLA-DS3A-_-google-_-PLA_IE_EN_Raspberry_Pi_%26_Arduino_%26_Development_Tools_Whoop_HI+(2)-_-(IE:Whoop!)+Development+Tool+Accessories-_-2237610&matchtype=&pla-329920080133&gclid=CjwKCAjwzaSLBhBJEiwAJSRokjy4ResfiyWaJhDv_6wwCjlIfEPTDUel0NhBVKFF5s8gFQxcFNy1zhoCIDIQAvD_BwE&gclsrc=aw.ds https://www.seeedstudio.com/DeskPi-Nano-for-Jetson-Nano-p-5093.html
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Jetson Nano barrel power adapter one of the one listed here https://forums.developer.nvidia.com/t/power-supply-considerations-for-jetson-nano-developer-kit/71637
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Lime SDR cooling (it can run very hot) https://www.hackmod.de/LimeSDR-Mini-Cooling-Case https://www.crowdsupply.com/hackergadgets/lime-ac-case DIY get heatsink and thermal mat e.g. https://github.com/gasparka/spectrogram/blob/master/doc/all_cools.JPG
- LWA Antenna - needs to be moved to Dunsink tested if possible and perhaps cleaned up?
- LWA antenna power coupler (https://reeve.com/RadioScience/Antennas/ActiveCrossed-Dipole/LWA_PowerCoupler.htm) The SDR mini only has one RX channel so need to combine polarisations, can we just combine output voltages directly?
- Cables from antenna to power coupler (spare/extra LOFAR cables?)
- Adapter/s from SMA to miniSMA for lime SDR
- Deploy and test at Dunsink