Re: [Discuss-gnuradio] Phase-lock across USRP-2 boxes and radar receiver development

Am Fr 08.10.2010 14:57, Mamoru Yamamoto <yamamoto@rish.kyoto-u.ac.jp> schrieb:

> Mr. Josh Blum, Mr. Matt Ettus,
> Friends,
>
> I think that you are following discussion on the mailing list
> that is "phase-lock problem across USRP-2 boxes".
> Mr. Juha Vierinen kindly helped us with the information that
>
> -- USRP-2 FPGA with GNU Radio original does not support "phase-lock
> across USRP-2 boxes".
> -- USRP-2 FPGA with UHD supports that.
> -- The "phase-lock across USRP-2 boxes" is the "NCO phase reset at PPS
> input".
>
> Are these true? We are developing a radar receiver, and already
> have a working program with GNU Radio original FPGA. For us, easiest
> way is to use a revised FPGA with "NCO reset at PPS" over GNU Radio.
> Is there such version of the FPGA image? The other way may be for us
> to switch to the UHD.
>
> What do you suggest?
>
> As our application is a radar receiver. Then in our program,
> we apply the TX pulse to PPS input, and reset the time counter
> at the TX pulses. Is this possible with UHD? This is
> one critical point for us to move to UHD.
>
> I hope your help. Thanks.
>
> Regards,
>
> --
> Mamoru Yamamoto / RISH, Kyoto University
> yamamoto@rish.kyoto-u.ac.jp
> Phone +81-774-38-3814, Cell +81-90-5653-7555
>
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Hello Mamoru,

you can find the code of UHD under the following link:
http://ettus-apps.sourcerepo.com/redmine/ettus/projects/uhd/wiki

The main advantage of the driver (for me) is that it uses UDP as the transport layer protocol, and thus the USRP2 is not Linux-only. There are some announcements from Josh Blum on all the features, and recently there were some posts that it works well with MIMO systems; it should have all the features of the "legacy" version.

In practice, the only change you need in your code is to use UHD sinks and sources instead of the old USRP2 ones (and of cause install the driver and update the FGPA bitstream and firmware on the SD card, as well as gnuradio on the "next" branch).

I have not attempted to use the MIMO capabilities, but I would recommend the switch to UHD.

There is some information on how to install the driver in the manual
http://www.ettus.com/uhd_docs/manual/html/index.html

Regards,
Matthias
[currently in (rainy) Kyoto]

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