Amateur radio, programming, electronics and other musings

Archive for Dec, 2012

What is NTP?

Categories: Projects, Trimble Thunderbolt Monitor
Comments Off on What is NTP?

Network Time Protocol (NTP) is a networking protocol for clock synchronization between computer systems over packet-switched, variable-latency data networks developed back in 1985.

NTP provides Coordinated Universal Time (UTC) including scheduled leap second adjustments. No information about time zones or daylight saving time is transmitted; this information is outside its scope and must be obtained separately.

It is usually able to maintain time to within tens of milliseconds over the public Internet and can achieve 1 millisecond accuracy on local area networks under ideal conditions.

The current reference implementation is version 4 (NTPv4), which is a proposed standard as documented in RFC 5905. It succeeds version 3, specified in RFC 1305.

Read more

Netduino Plus 2

Categories: Trimble Thunderbolt Monitor
Comments Off on Netduino Plus 2

Last week I purchased the updated Netduino Plus 2 from Secret Labs.  This version has a network port on it which I have been playing with. It’s given me the nudge I needed to continue with the Trimble Monitor. I have been testing out code to act as a web server and I am currently looking at the spec for NTP (RFC1305). Read more

Report Packet 0x8F-AB Primary Timing Packet

Categories: Trimble Thunderbolt Monitor
Comments Off on Report Packet 0x8F-AB Primary Timing Packet

In an earlier post I posted a sample capture from my Trimble to demonstrate the kind of data packets which would need to be interpreted by the software.  I left it for a little while giving any readers the chance to dig into the documentation and decode it themselves.  I received an email from Sam in VKland who managed to do just that and send me the decoded output.  Not sure if Sam is a radio ham but he has already posted some ideas for the future of the project.

0x8F-AB is an automatic output packet which provides time information once per second if enabled with packet 0x8E-A5. GPS week number, GPS time-of-week (TOW), UTC integer offset, time flags, date and time-of-day (TOD) information is provided. This packet can be requested with packet 0x8E-AB.

Read more