[time-nuts] Fwd: CGSIC: FW: New NANU 2014090

[Gregory Maxwell]

On Wed, Dec 17, 2014 at 12:01 AM, Jim Lux <jimlux at earthlink.net> wrote:
> On 12/16/14, 3:36 PM, Magnus Danielson wrote:
> what about one of the software receivers? I would think that making  L2 and
> L5 filters isn't that tough, so all you need is the back end.

I'm pretty sure GNSS-SDRLIB supports L2C,  you can see it working with
a ~$400 bladerf

http://www.rtl-sdr.com/real-time-gps-positioning-bladerf/

Though getting dual band, in phase, requires something like a $1100
USRP B210... and that that point you're getting in to the price-points
where you can find surplus survey receivers and such.

>From a timenuts perspective, it may be more interesting to go the SDR
route, since the survey receiver is not likely to have a lot of
affordances for timing applications and there is a lot of interesting
things you could do in software.

There have been some people talking about GNSS targeted SDRs, e.g.
things with 4x  in phase down mixers and backing ADCs that could
simultaneously capture every current/known GNSS signal and send them
down to the computer, at a reasonably low price... but I think none
have moved past the prototyping phase.

The nearest I'm aware that seems actually available is
http://www.onetalent-gnss.com/ideas/software-defined-radio/sdrnav40
but I don't really know anything about it. (e.g. if it's real, what
the software support story is, etc.)