Software-defined GPS receiver: BeagleBone Black + FPGA

Beware the cursed  waters of RF, Here Be Dragons!  (I studied them ...)

And I also have a copy of Puff The Magic Dragon, which struck terror into the hearts of even the most bold.

Maybe the best part of SDR is that you don't have to do much in the RF domain, especially if you can buy in the front end.

I see that simply put that is what he's done with that highly integrated solution !

Drew On the original  Radio he made the reciever prity much from the base parts and then did the baseband stuff in the FPGA using a soft CPU to do the lifting.

On this guy's design he's used one of the high integration recievers with a seperate SAW filter and a few L's and C's. Did he then copy the other guy's CPU or did he roll or customise his own ??

This part seemed to be missing which in fact may of been the most interesting part given the Radio integration, I was lookin forward to a description of the FPGA contents.

Also what parts did he use for the SAW and the inductors I see that most of those SAWs have 2 or 40ish BW not 20 Mhz which is what the chip's data sheet states or is this a typo ??

I'm all very interested in this cheers

Geri Elsworth did a bit on FPGA based SDRs in which she did a load of Dead bugging and Manhattan style construction .

I'm sure you can manage it Drew I'd lay off the coffee for a day or two to let the shakes go down also some practice before hand saves you from soldering your nose whilst using a microscope

A link to a nice little Soldering technique talks:

http://www.edaboard.com/thread197551.html

I think he may have use Andrew Holme's FPGA+code. I've been a long-time reader of A. Holme's web pages - he's done some very impressive stuff, especially with frequency synthesizers. If I was to follow any design, it would be his : )

It's amazing how integrated some ICs are, containing virtually the entire radio, whereas Andrew's one is more discrete and very sophisticated (and he's using a passive mixer). Some approaches are more harder to design into the IC, although I'm not sure at these extremely high frequencies like GPS.

Also it is down to 0402-sized parts at these frequencies (and it looks like it from Andrew's photographs).

Incidentally, I took apart a USB SDR dongle recently, inside it just had two main ICs, and hardly any passive components at all. It didn't pick up many local FM stations, maybe it just needs some filtering (it may be picking up wifi, or other stuff nearby and that may be overloading it).

I think E14 is in need of a FPGA tutorial

Once I saw a complete prototype radio built as individual modules all on little boards with square pads, all stuck to copper-clad board offering the ground plane, and it was about a meter long :-) Apparently it did function (with little performance of course, but to prove aspects of the design) before a PCB was created.

Hehe sounds like a challenge...  I will try to convert some notes sometime soon, although maybe there are others with more experience in this area. Regarding devices, I like Xilinx, but I'd love to try Lattice after what John Beetem was mentioning on another thread, and also revisit Altera devices someday (Billabot is experimenting with that for now).

The Xilinx stuff would be fine !!