NTPNTPNetwork Time ProtocolNetwork Time Protocol

What is NTP and to what extent is it currently useful for Video Occultation Observations?What is NTP and to what extent is it currently useful for Video Occultation Observations?

ByByDave GaultDave Gault

Presented toPresented to88thth Trans-Tasman Symposium on Occultations Trans-Tasman Symposium on Occultations

Monday, 21Monday, 21stst April 2014 April 2014Melbourne, AustraliaMelbourne, Australia

What is NTP?

Network Time Protocol (NTP) is a networking protocol for clock synchronization between computer systems over packet-switched, variable-latency data network.

Source= Wiki

NOT the Windows Clockfor Occultation Timing

While the windows system clock uses NTP technology, it is only good for “every-day” use, like system file maintenance records.

Not suitable for occultation work. Shown here is a 0.4442 second delay

after a recent re-sync operation. UT supplied by IOTA-VTI.

For NTP to be accurate:It needs to cope with asymmetric speed and network latency.

Network latency dependson network load

This cheap and nasty speed test can be found at…http://www.auditmypc.com/broadband-speed-test.asp

Network speed is asymmetric

BeeperSyncDesigned to synchronise a BeeperBox – OK for Visual Occultation Observations.

Designed to synchronise it’s own clock using NTP and then to synchronise a BeeperBox using a parallel port.

Does not attempt to synchronise the PC clock. Reports on timing accuracy; essential to gauge quality of NTP fix.

Distant server versus local server

OccuRec and NTP

OccuRec and NTP testing

Reference TimeOCR’d IOTA-VTI display

Red = Windows clockGreen = OccuRec clock

Raspberry Pi + GPS with 1pps= Stratum 1 NTP Server?