[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 david-taylor at blueyonder.not-this-part.nor-this.co.uk.invalid
Fri May 1 05:49:14 UTC 2009

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?


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