[Asterisk-Users] TDM users: modified zttest.c for testing

[Roger Gulbranson]

On Wed, 2005-05-04 at 17:22 -0600, Rich Adamson wrote:
> > > > > TDM & X100P card users:
> > 
> > > > I get average numbers very close to 1.024 (especially if I take some
> > > > rounding error into account).
> > > 
> > > That's a very good point. Now I'm not sure since the only thing I've
> > > got to go by is existing code in zttest.c which implies 8192, and
> > > data arrives in 1024 byte frames. 
> > > 
> > > I'll dig a little deeper to see if I can figure out which one _is_
> > > correct.
> > 
> > I also recommend only printing 3 decimal places for the times.  All of
> > the additional digits are just noise.
> 
> Why do you say 3 when the os call returns 6 places?
> 
> The thought process is essentially oriented around identifying timing
> issues (missed frames) with the TDM card, and it seems from the users
> posting "it works" type responses that six digits _are_ indicative
> of the issue.
> 
> Help me understand...

While the OS may be returning more digits, the interrupt on the card is
only happening on millisecond boundaries (3 decimal places).  A missed
frame will add 0.001 to the time, not something smaller than that.