nanog mailing list archives
Re: Cost-effectivenesss of highly-accurate clocks for NTP
From: Bruce Simpson <bms () fastmail net>
Date: Sun, 15 May 2016 08:21:05 +0100
On 13/05/16 20:39, Eric S. Raymond wrote:
In 2012, nearly three years before being recruited for NTPsec, I solved this problem as part of my work on GPSD. The key to this solution is an obscure feature of USB, and a one-wire patch to the bog-standard design for generic USB that exploits it. Technical details on request, but what it comes down to is that with this one weird trick(!) you can mass-produce primary time sources with a jitter bounded by the USB polling interval for about $20 a pop. The USB 1 polling interval is 1ms.
What about USB 3.1 (assuming the device is not intended to be backwards compatible with the polling model) ? I should point out Intel intend to retire EHCI/UHCI and implement only xHCI.
Current thread:
- Re: Cost-effectivenesss of highly-accurate clocks for NTP, (continued)
- Re: Cost-effectivenesss of highly-accurate clocks for NTP Eric S. Raymond (May 15)
- Re: Cost-effectivenesss of highly-accurate clocks for NTP joel jaeggli (May 15)
- Re: Cost-effectivenesss of highly-accurate clocks for NTP Mel Beckman (May 15)
- Re: Cost-effectivenesss of highly-accurate clocks for NTP Lamar Owen (May 16)
- Re: Cost-effectivenesss of highly-accurate clocks for NTP Mel Beckman (May 16)
- RE: Cost-effectivenesss of highly-accurate clocks for NTP Jameson, Daniel (May 16)
- Re: Cost-effectivenesss of highly-accurate clocks for NTP Valdis . Kletnieks (May 15)
- Re: Cost-effectivenesss of highly-accurate clocks for NTP Måns Nilsson (May 15)
- Re: Cost-effectivenesss of highly-accurate clocks for NTP Lamar Owen (May 16)
- Re: Cost-effectivenesss of highly-accurate clocks for NTP Eric S. Raymond (May 15)
- RE: Cost-effectivenesss of highly-accurate clocks for NTP Chuck Church (May 16)
- Re: Cost-effectivenesss of highly-accurate clocks for NTP sthaug (May 16)