This post is to introduce my new open source Trimble Thunderbolt Monitor v1.0. It is based on the Netduino hardware platform. It displays the status of the Thunderbolt on a 4×20 LCD screen. It is purely the first iteration of the code and I have a number of extra features to add in point releases.
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.
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.
TSIP stands for Trimble Standard Interface Protocol, and it is used in products from Trimble such as the Thunderbolt and differs from NMEA which is a lot simpler and only contains status data.
The TSIP protocol is based on the transmission of packets of information between the user equipment and the GPS receiver. Each packet includes an identification code that identifies the meaning and format of the data that follows. Each packet begins and ends with control characters.
I decided I would like to start a new construction project for 2012. Having thought carefully I finalised on a 10MHz reference which can be used as a standard for test equipment, or to lock the master oscillator (TCXO) of a rig/transverter to a solid, accurate source. I did quite a bit of research over Christmas and concluded that the best bet would be to start with something commercial and add to it. It is possible to start from scratch but with the surplus market so cheap why not spend the time adding the sugar and actually using it.
My research eventually pointed me to the Trimble Thunderbolt which is a commercial GPS disciplined clock and readily available on eBay. This was to be the basis of the project. I ordered one and it arrived today.