Re: [Discuss-gnuradio] USRP1 Inband rework, request for features and comments

[Eric Schneider]

Echoing some feedback to the list...
 
On Mon, 2010-01-25 at 08:47 -0700, Eric Schneider wrote:

> 1. I do not intent to implement VRT over USB.  Only to implement a VRT
> compatible interface on the host.  The USB inband protocol will simply
> serve to make that possible in the most efficient way possible.

There seems to be differing views about implementing VRT over USB.  Some
like it for the standard, others oppose it from a complexity
perspective.

I haven't had any feedback regarding bandwidth efficiency specifically,
which I thought was a complaint regarding the original inband code.  VRT
would increase overhead, does anyone care?

> Do timestamps really need to be 32 bits?  That allows scheduling
> transmission 33 seconds in advance on a 64MHz clock, which seems
> excessive to me.

This is a non-issue, there is no practical gain from reducing the
timestamps by a few bits.  16 bits is too small, next stop 32.

> I'm leaning towards a 16 or 32 bit trailer with optional, per packet,
> meta data.  Less than 16 bit alignment of trailer/meta would fragment
> individual (16 bit) samples, and 32 bits would keep I/Q interleaving
> order constant between packets.  I am open to entertaining the idea of
> tiny (8 bit?) trailers, so long as we can reliably detect and recover
> from buffer overruns and such.

Just disregard this babble...

--ETS