Is GPS data recording at equal time intervals possible in practice? I know that GPS loggers can be set to automatically record position at equal time intervals (e.g. 10-seconds intervals), but in my experience the resulting logs still contain location data recorded in varying intervals. What could be causing this? Does it have to do with hardware/software (I used GPS Logger for Android combined with Active GPS application installed on Samsung Galaxy J3 2017 smartphone AND Holux RCV 3000 in built-up urban areas)? OR with the fact that a number of factors can cause a blockage or a loss of a GPS signal resulting in a lack of or a significant inaccuracy of the recording?
Hi
there are another methods in order to resolve this problem such as using interpolation between each GPS readings or predicting the data using either Intelligent technique or Extrapolation
Best Regards
GPS data recording at equal time intervals is possible in practice with appropriate hardware and software.
if you miss data sometime; you may need to change recording parameters of your logging device, and you will know what causes the miss.
But if you see data at irregular intervals, you need to change your device.
Without the help of Internal Measurement Unit (IMU) any set intervals may only be interpolated if signals are missed from satellites. The added value of an IMU is it gives you a better estimate and more accuracy than just interpolation. Some softwares can use existing magnetic compass and accelerometer from the smartphone to act as an IMU. Your Android Samsung Galaxy J3 does not have a compass and does not have an accelerometer. I dont think the Holux has an internal IMU but your unit may have an option to include one or provide software if your smartphone has a compass & accelerometers (software IMU). It may be best to contact Holex for a better answer if you want more accurate set intervals.
Dear Ahmed Hasan, Abdul Malik Khan, Reuben Reyes, thank you all for your helpful comments. I’ll consider interpolation and other techniques, and take a closer look at the Holux’s technical specification. The original software is pretty basic. I think I have to look for more sophisticated alternatives.
My own opinion is that it is possible for GPS data to be recorded at equal interval. This is possible during GPS configuration. For GPS observations, we have different mode of operations. It may be static, stop-and-go, or kinematics.
If static is selected, under the recording mode, one may select compacted or sampled. But for static compacted is recommended.
Under observation/ recording rate or Recording Interval, we have many options like: 2 seconds, 5 seconds, 10 seconds, 15 seconds, 20 seconds and others. For static one may select 15 seconds or 20 seconds. If it is Stop-and-go 2 seconds is recommended.
Once these settings are done, the instrument has no choice but to recording at the stipulated time interval selected.
But the instrument may its own index error or cyclic error apart from GPS error like Ionospheric error, Topospheric error, Ephemeris data error, Satellite clock drift error, multipath error, cyclic error and measurement noise error.
Thanks.
GPS data recording at equal time intervals is impossible because there is always a small drift between the satellites atomic clocks and the receivers clocks (bias). In other words, the satellites and the receivers clocks are not generally synchronized. That is why pseudoranges are used instead geometric ranges.