[Gb-ccb] forwarded message from John Ford

[Brian Mason]

Correction:  better than ms accuracy...

I agree with John that it is probably important to at least be able to
identify if a sample was somehow dropped.

On Thu, 22 Jan 2004, Brian Mason wrote:

> 
> hi Rich et al.- I think we certainly do want to do as you say below,
> however note that Tim's comment pertains to the dump mode which is meant
> as a CCB diagnostic mode.  For astronomical data collection we can collect
> data at rates >> 10 Hz and timestamp with milliSecond accuracy.
> 
>  Brian
> 
> On Thu, 22 Jan 2004, Richard Lacasse wrote:
> 
> > Tim,
> > 
> > I wonder if at some point in time we may want to tie the data to the 
> > instantaeous telescope position with higher accuracy than 1 second can afford. 
> > The gbt is fairly big and floppy and we are outfitting it with devices like the 
> > quadrant detector which can give an instantaneous position for part of the 
> > telescope at a 10 Hz rate.
> > 
> > Rich
> > 
> > Tim Pearson wrote:
> > 
> > > On Wed, 21 Jan 2004, Martin Shepherd wrote:
> > > 
> > > 
> > >>This brings up a dump-mode issue that I hadn't thought about yet.
> > >>Whereas the time-stamps of the 1ms integrations didn't need to be any
> > >>more accurate than about 0.5ms, dump-mode samples will presumably need
> > >>much more precise timestamps. So yes, your point about using a 10MHz
> > >>signal synchronized to 1PPS may be important.
> > > 
> > > 
> > > I do not think that accurate time-stamping of the dump data is a
> > > requirement. An approximate time (better than 1s) of the start or end
> > > of the dump is all that is needed, assuming the sequence of samples is
> > > really a continuous one. Higher accuracy would be nice, but not
> > > necessary. This is for diagnostics, not pulsar timing.
> > > 
> > > - Tim
> > > _______________________________________________
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> > > 
> > 
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> 
> 

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