The Swift Navigation Piksi project may be of interest: http://swiftnav.com/piksi.html
It has an FPGA for correlation with an ARM Cortex-M3 for tracking loops and navigation. The hardware and ARM firmware is open source, but the FPGA design is closed-source at the moment. However, I don't see why the FPGA would need adapting for use with L2C & L5. I know the Swift Nav folks are looking into a multi-frequency product. One of the main obstacles is a commodity front-end solution, and antennas at reasonable prices. Henry On Tue, Dec 16, 2014 at 5:01 PM, Magnus Danielson <mag...@rubidium.dyndns.org> wrote: > Jim, > > On 12/17/2014 01:46 AM, Jim Lux wrote: >> >> On 12/16/14, 4:29 PM, Magnus Danielson wrote: >>> >>> Jim, Bob, >>> >>> >>> There is a fair amount of work along the full path. >>> >>> LNA with some L2 and L5 filters is pretty easy. >>> >>> I think you still want to have a correlator baseband processing in say >>> an FPGA. >>> >> >> well, yes.. but I don't know if there's any handy open source free cores >> out there for that. >> >> I do know <grin> of an implementation that does the acq and track in a >> pair of Xilinx 2-3000 parts and does the nav solution in a SPARC V8, but >> it's not open source and it's definitely export controlled. > > > For that application it needs to break both the limits at the same time, for > sure. > >> Seems that what's out there is mostly "record bits" and "postprocess in >> C++ or Matlab" Several textbooks even include it. > > > It's good for many purposes as you get yourself up to speed. > >>> There is naturally stuff to be done on the L2C and L5 modulated signals, >>> but it goes in a relatively slow paze so that even modest processors can >>> keep up with it. >> >> >> Indeed.. we do 24 channels (where channel is one PRN at one frequency) >> with a 3 frequency solution without making a 66 MHz LEON2 based SPARC >> sweat too much. >> >> >> That's why it would be intriguing if someone had the FPGA stuff out there. > > > Indeed. I did a GPS correlator core once, but it had issues to fit the FPGA > I had at hand at the time. The software receiver I did was not at all doing > real-time, but it did do many of the crucial points and was a nice exercise. > >> It would still be an expensive project, I suspect. Either you'd have a >> few $50-100 boards that would need interfacing and a lot of time, or a >> $1000 board with less time. >> >> >> One hopes that in a few years, multifrequency stuff will become available. > > > Indeed. Maybe a complete implementation just needs to hit the web.. > > Cheers, > Magnus > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.