Re: [Discuss-gnuradio] UHD support for USRP1

[Jesper Kristensen]

Hi all

Thank you for your replies.

We are at Aalborg University using the Karlsruhe Simulink interface together
with Simulink code supporting inband signalling on the FPGA. Our interest
would be to code a new interface based on the UHD. We handle tx samples by
embedding timestamps into packets send to the USRP as well as de-embedding
timestamps in the RX direction.

If possible we would be most interested in gaing insight into the concept of
metadata and how to use it in connection with inband signalling and the UHD.
Any references to information are most welcome :-)

Our interest is to be able to easily move applications between USRP1&2 as we
have both platforms available.

Kind regards

Jesper Kristensen
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Message: 13
Date: Tue, 10 Aug 2010 02:19:44 -0700
From: Josh Blum <address@hidden>
Subject: Re: [Discuss-gnuradio] UHD support for USRP1
To: Sylvain Munaut <address@hidden>
Cc: address@hidden
Message-ID: <address@hidden>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed



On 08/10/2010 01:49 AM, Sylvain Munaut wrote:
> On 08/10/2010 01:32 AM, Josh Blum wrote:
>>> Say that I want to interface the USRP1 to Simulink using the UHD and
>>> supporting timed TX samples. Would that be feasible with the anticipated
>>> state of the USRP1 support?
>>
>> The USRP1 does not feature timed samples,
>
> Well, there is a firmware that does (the so called 'inband signalling'
> one, even tough it's a misnomer).
>
> I was hoping that with the UHD api featuring timing control, that it
> would become the default firmware.
>

The UHD will use the same images that gnuradio uses for fpga and 
firmware because its known to work and there is source code for it. I am 
not opposed to future enhancement once the basic features work. And I 
hear there is some hobbyist interest in implementing a VRT like packet 
structure and time control...

I dont know anything about the state of the 'inband signalling'. It 
works but its not stable? There is an fpga image but no source code? 
Chime in if you know!

>
> If there is an underflow during a RX capture, will the samples just be
> missing (and therefore potentially desyncing the receiver) or have a
> 'hole' of zeroes of the correct length (it would be way better as a sync
> at least would be preserved).

The USRP1 under uhd will behave like the gnuradio USRP1 driver. So 
samples will just be missing and maybe an 'O' is printed.

If the packets had timestamps, it would be easy to integrate with the 
uhd's rx_metadata. :-)

-Josh