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.
| Byte | Bit | Item | Type | Value | Description |
|---|---|---|---|---|---|
| 0 | Subcode | UNIT8 | 0xAB | ||
| 1-4 | Time of Week | UINT32 | GPS seconds of week | ||
| 5-6 | Week Number | UINT16 | GPS Week Number (see above) | ||
| 7-8 | UTC Offset | INT16 | UTC Offset (seconds) | ||
| 9 | 0
1 2 3 4 | Timing Flag | Bit field | 0 1 0 1 0 1 0 1 0 1 | GPS time UTC time GPS PPS UTC PPS time is set time is not set have UTC info no UTC info time from GPS time from user |
| 10 | Seconds | UNIT8 | 0-59 | (60 for UTC leap second event) | |
| 11 | Minutes | UNIT8 | 0-59 | Minutes of Hour | |
| 12 | Hours | UNIT8 | 0-23 | Hour of Day | |
| 13 | Day of Month | UNIT8 | 1-31 | Day of Month | |
| 14 | Month | UNIT8 | 1-12 | Month of Year | |
| 15-16 | Year | UINT16 | Four digits of Year (e.g. 2012) |