[ntp:questions] How bad is USB? (was: Re: Can the line audio out of HF radio be used to sync ntp. Trying to get a cheap ($) radio method.)

[David J Taylor]

Garrett Wollman wrote:
> In article <K9WdnS4y5pIuymfUnZ2dnUVZ_t2dnZ2d at giganews.com>,
> Richard B. Gilbert <rgilbert88 at comcast.net> wrote:
>
>> USB is nearly useless for NTP!  USB has latencies sufficiently large
>> and variable to render it unsuitable for use with NTP.
[]

Garrett, Richard,

You've both commented that USB has drawbacks, but in reality what 
performance might be obtained?  Not everyone needs microsecond precision, 
and USB might allow millisecond precision - i.e. possibly better than what 
might be obtained by Internet access alone, or by using a radio source.

Has anyone made any actual tests or measurements?  Are there any results 
available from an actual installation of USB on either Windows or UNIX?

Thanks,
David