Lots of Qns - maybe I should read the FAQ
I'm still working on a FAQ. Soon come, as they say in the Caribbean..
Where in NZ are you?
Tauranga. Drop by if you ever get out here.
How likely would it be to interface the design into other devices? I assume it is currently set up to DMA into the BBB…
Yeah, I get asked this a lot. Everyone want to pump out raw IQ and use existing client software. That's fine, but it will take a little work. Right now I just use a 48 MHz SPI to move the 8 channels of audio + spectrum baseband IQ to the Beagle. But there are 10 unused Beagle GPIO lines hooked up to the FPGA so you could implement a higher bandwidth parallel port. Some folks want a PCB spin that puts a gigabit Ethernet PHY and magnetics on board so they can do "Direct Fourier Conversion" (DFC) which is what Twente WebSDR essentially does. But that's a lot of work and is really getting away from what I wanted to do.
Will it also work with Beaglebone Green?
Yes. In fact the $299 reward "kit" ships with a BBG.
I assume that I could download custom bit files into the Artix FPGA do do my own bidding? How much of the current SDR stack is implemented in the FPGA?
The DDCs and some buffering are in the FPGA. Also a cute little embedded processor from Andrew Holme's Homemade GPS Project to help do the housekeeping. All the baseband stuff is done in the Beagle (FIR filtering, demod, FFTs). Take a quick look at some of the diagrams in the design document that show how the tasks are partitioned.
Is there a link to a PDF of the schematic in the GitHub? I can only find Gerbers and/or CAD files…
Sorry, I'll fix that. Until then look here:
http://www.kiwisdr.com/docs/KiwiSDR/kiwi.schematic.pdfCan you recommend a suitable wide-band antenna design?
I have an active antenna with bias tee in development but it's not ready. I'm going to write a whole separate article about antennas. I'm using a PA0RDT-style mini-whip on the NZ KiwiSDR right now. I soldered it together in an hour or so. What took longer was tracking down all the local noise sources.