EDIT: This question can be closed due to figured out the problem was in the NTP configuration.

While the gps device is no gps data received, gps device is send gps time to server as zeros ("00000000000000") or starting of the unix time (1970-01-01 00:00:00) depending on the model of the gps device. If I get time data like this, I have to override it before record it to database as in current UTC time.

After this datas when the gps is starts to receiving gsp signals and begin to send GPS time, a problem apearing because of the 90 seconds difference between gps time and ntp time.

Say, If I get no time data from device I record data as:

2016-01-01 12:53:00
2016-01-01 12:53:10
2016-01-01 12:53:20

When device start to send GPS time records are looks like this:

2016-01-01 12:53:00
2016-01-01 12:53:10
2016-01-01 12:53:20
2016-01-01 12:51:30
2016-01-01 12:51:40
2016-01-01 12:51:50

If the device is change it's location before start sending the correct gps time, device is displayed as moved back and forth on the map.

Does this 90 seconds difference between with gps and ntp time normal and I have to make adjustment for this in my codes, or is something wrong with my system.

Additional Information:

  • This problem occurs once if device is newly mounted and powered until faced with power failure.
  • We have many different tracking devices but unfortunately I'm not allowed to give more information.
  • Devices are sent various information like vehicle status, location information etc. as in HEX based based data packages. I am pretty sure that I process data accurately.
  • I process data by splitting each information piece in data package and process each part as described in devices document.
  • 1
    can you add what device(s) you are using, and how you fetch time information from them – Ian Turton Jan 6 '16 at 11:43
  • I've made some additions to bottom of the question. – Sencer H. Jan 6 '16 at 12:21
  • Which of the two, ntp time or gps time, do you believe is correct? Can you confirm this via a third party service? (radio-signal synced clock?) – Spacedman Jan 6 '16 at 13:03
  • OK, I was think they both should be correct but somehow, I think GPS has send information late. I checked servers ntp poll service configuration and I think the server is out of sync. Thank you for showing me to how I was blind, guys :D This question can be flagged for close. – Sencer H. Jan 6 '16 at 14:00

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