Re: [Discuss-gnuradio] USRP for GPS

[Wolfarth, Ryan]

Walter,

Currently the receiver that triggers our USRPs to record the RF data is quite expensive.  We don't use all of its features, but it has a few key parameters that are used in our trigger threshold calculation.  If we deploy this same system to another location we'd like to have a USRP function as the trigger.  In that sense we are interested in using the USRP as a GNSS receiver, but our goal isn't to get a position solution.

As far as performance metrics go, you need to define a few parameters for your receiver before settling on the USRP as a host.  The two that pop into my mind right away are: 1.) which GPS signal(s) do you want to use and 2.) how many channels do you hope to track?  If I recall correctly, there's a thread somewhere on this list where a group used the old USRP1 and modified the FPGA to do 4 channel tracking with fast acquisition.

Regards,
Ryan

On Mon, Oct 3, 2011 at 11:56 AM, Walter Barmak <address@hidden> wrote:

Hi Ryan,

Thanks very much for your answer! You mean you are inetersted in
developing a stand alone receiver "with" the USRP?

I'm sorry, what do you mean by performance metrics?

thanks again,
Walter

On Mon, 2011-10-03 at 15:52 -0300, Wolfarth, Ryan wrote:
> Hi Walter,
>
> My group is using the USRP to record raw RF data at GPS and GLONASS
> frequencies.  We do all of our signal processing in post right now,
> but are interested in developing a stand alone receiver.  If you
> search the mailing list you'll find some other folks who are
> implementing GPS receivers on the FPGA.  What kind of performance
> metrics are you hoping to obtain?  As far as the daughter boards go,
> we use the RFX1200 and RFX1800.  I've also heard of people using the
> SBX.
>
> I have no answer to your question regarding OpenGTS: I'm fairly new to
> this system as well.  If you're going to do real time tracking your
> best bet is probably to modify the FPGA for performance
> considerations.  Hope this helps!
>
> Ryan
>
> On Mon, Oct 3, 2011 at 11:00 AM, Walter Barmak
> <address@hidden> wrote:
>         hi,
>
>         i was wondering whether the usrp can be used as a "gps
>         receiver". if so,
>         1) how can i achieve this?
>
>         2) any link you could provide for me to read?
>
>
>         3) what daughterboards should be used?
>
>         4) Can the usrp be used with OpenGTS (for example) for
>         tracking (usrp as
>         a gps receiver)?
>
>         thanks in advance,
>         walter
>
>
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