Re: [Discuss-gnuradio] Why you should be be trying out the UHD

[Josh Blum]

In band signaling is a misnomer. But yes, the UHD supports time stamped 
samples down to the precision of the clock. The time spec uses a 32 bit 
integer for seconds and a double for fractional seconds (in 
nanoseconds). The reason for using nanoseconds was to make the time spec 
independent of the usrp device clock rate, since we will want to support 
other clock rates than just usrp2-100Mhz.

The double has about 52 bits of mantissa, only 30 of which are needed 
for the integer part of the nanoseconds. So I dont think there is room 
for ambiguity as to which clock tick a time spec will refer to (for a 
clock rate in 10s of Mhz).

-Josh

On 04/26/2010 04:31 AM, Sylvain Munaut wrote:
> Matt Ettus wrote:
> > Things are starting to stabilize on the UHD front and everything is
> > moving forward rapidly.  You should really be trying out the UHD *now*
> > if any of the following applies to you:
>
> > - You want to use USRPs with software other than GNU Radio (like
> > OpenBTS, OSSIE, SCARI, LabVIEW, Simulink, Matlab, or anything else),
> > especially if you are a developer of one of those systems
>
> What about support for timestamped packets (inband signalling for usrp1)
> ? Is that something UHD supports ?
>
>  From looking at the API it seems so (time_spec) but that uses 'double'
> and not an integer sample count. Isn't there a risk of imprecision /
> shift / gap of +/- 1 sample ? Especially if we use non standard clock
> rates that don't have nice # samples per seconds ...
>
>
> Cheers,
>
>
>      Sylvain
>
>
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