Neoclock-4X driver removal

[Eric S. Raymond]

Achim Gratz via devel <devel at ntpsec.org>:
> Eric S. Raymond via devel writes:
> > * It has 2ms jitter, way worse than a cheap GPS these days.
> 
> That is actually much better than what most of the cheap GPS deliver
> when connected over USB.

You may be a bit behind the curve on this.

I've measured 1ms jitter with the Macx-1, the device I designed in
conjuction with Navisys back in 2012.  That was a bog-standard
GPS+PL2303 design with 1PPS from the engine connected to the DCD 
line on the PL2303.

That's how I know that it already took very little effort to pull down
that jitter figure seven years ago. Another way to put this is that as
far back as 2012 you had to be screwing the pooch pretty determindly
to get as bad as 2ms.

There's a realistic prospect of that jitter dropping to 0.25msec as
people who make USB-to-serial chips stop bothering to support USB
1.1. This may already have happened - I haven't been tracking that
area closely because 1ms jitter is just bartely low enough not to be a
real problem for an NTP source exoecteds to deliver WAN
synchronization.

> > * All the usual signal-propagation and interference problems that
> >   have caused most other longwave time receivers to be replaced by
> >   GPSes.
> 
> Except that GPS still needs clear view of a relatively large portion of
> the sky and VLW doesn't, aside from all the interference and signal
> propagation issues that it has too, because it is operating just on a
> different band of RF.

What you say in true in theory. In practice, experience in the U.S.
tells us pretty clearly that the tradeoff is in favor of GPS.

How do we know this?  After the WWVB modulation change in 2012, all
the Amwerican clock-radio vendors moved to GPS-conditioned units *and
never looked back.*  Longwave receivers are no longer worth the NRE
to build them here.
-- 
		<a href="http://www.catb.org/~esr/">Eric S. Raymond</a>