laobeylu

That's actually sort of what I did. I didn't explain it to someone else, but went through it in my head, talking to myself explaining the design. Explaining it to someone else must be even better!

Thanks -- you're right. I've added a link and spelled it out completely in the first sentence now.

Thanks! Actually, doing 4 layers first really helped me save cost on the first prototypes while still allowing me to verify almost the complete design. But that's a difficult question. I think it's inevitable for some things to slip through like they did (the wrong valued resistors...) and 3 revisions to get it right were not that many. One thing I'd certainly do is starting with the FPGA design early on, so I'd not just blindly pick a part that looked suitable like I did this time. That would have also eliminated the mistake where I didn't route clocks to clock capable pins.

That's true, I'll update the USRP price on the website.

Thanks!

Well, I'm currently working on a new version that I'm hoping to sell. I also still need to work on the software.

This won't be an addon, but the next revision will include an expansion header so you can add addons. Should be pretty neat to make an LCD+battery pack "shield" so you can use the SDR as a stand-alone spectrum analyzer.

What I'll actually use it for: I built it because I wanted to learn more about signal processing and the different protocols that common devices use, so I'll be tinkering with all those protocols.

No idea what I'll do after this, maybe that LCD addon I was talking about?

That'd be a cool project... The link is working for me, the schematics should be here: https://s3.amazonaws.com/freesrp/prototype-r2/freesrp-sch.pd... Are you sure it's broken?

Thank you for the kind comment. Not selling them yet, though, and the small batch might end up being a little more expensive than that (but I'm really trying to keep it under $400).

Hey! I'm Lukas, the guy who made this. Just discovered someone posted it on Hacker News, pretty exciting for me. If you want to ask me any questions or make comments, I'm here and on reddit: https://www.reddit.com/r/electronics/comments/4uic5r/sdr_pla...