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

[Marcus D. Leech]

On 04/26/2010 01:41 PM, Josh Blum wrote:
> 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
>
My main "looking forward to's":

    o n-bit OTW format, to facilitate higher bandwidth: n=4,8,16
    o a generic method for setting/getting auxillary
TTL/LVCMOS/LVTTL/whatever control bits
       if the daughtercard has 'em, without necessarily giving up data
bits. 

My radio astronomy work could benefit greatly from both of these, as
well as time-stamped sampling.
  Actually, I do have a question about time-stamping.  Are individual
samples timestamped, or just
  blocks of samples?




-- 
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org