gps-guides
Max’s Tracks
GPS Device
Garmin Vivoactive 3 - firmware 7.70.
20210428
Big Spike - 43 Knots
The positional speeds contain a spike of 42.96 knots, likely caused by a crash or falling in. Fortunately it was automatically filtered because of the rate of deceleration.
Spikes that are more subtle may not be high enough to be filtered out but can still be large enough to elevate the reported result, sometimes by several knots.
Non-Doppler vs Doppler
Comparison of the non-Doppler figures posted to GP3S against the non-Doppler and Doppler actuals from the FIT. The 250m posted was at least 0.57 knots too high.
It is impossible to determine whether the Doppler speeds are accurate or too high.
| GP3S | Non-doppler | Doppler | Diff | |
|---|---|---|---|---|
| 2 sec | 29.11 | 29.13 | 28.59 | 0.54 |
| 5 x 10s | 27.28 | 27.28 | 26.93 | 0.35 |
| 100m | 28.82 | 28.83 | 28.22 | 0.61 |
| 250m | 28.46 | 28.46 | 27.89 | 0.57 |
| 500m | 27.53 | 27.53 | 27.06 | 0.47 |
| 1852m | 24.89 | 24.89 | 24.67 | 0.22 |
| 1/2 hour | 12.45 | 12.38 | 11.58 | 0.80 |
| hour | 0.00 | 0.00 | 0.00 | 0.00 |
| alpha | 17.18 | 0.00 | 0.00 | 0.00 |
20210505
Non-Doppler vs Doppler
Comparison of the non-Doppler figures posted to GP3S against the non-Doppler and Doppler actuals from the FIT. The 250m posted was at least 0.41 knots too high.
It is impossible to determine whether the Doppler speeds are accurate or too high.
| GP3S | Non-doppler | Doppler | Diff | |
|---|---|---|---|---|
| 2 sec | 29.86 | 29.86 | 29.65 | 0.21 |
| 5 x 10s | 29.19 | 29.19 | 28.77 | 0.42 |
| 100m | 29.54 | 29.54 | 29.28 | 0.26 |
| 250m | 29.39 | 29.39 | 28.98 | 0.41 |
| 500m | 28.32 | 28.32 | 27.99 | 0.33 |
| 1852m | 26.08 | 26.08 | 25.75 | 0.33 |
| 1/2 hour | 17.24 | 17.24 | 17.04 | 0.20 |
| hour | 15.94 | 15.94 | 15.62 | 0.32 |
| alpha | 20.12 | 20.12 | 19.77 | 0.35 |
Doppler vs Positional
The top 20 runs over 250m show that non-Doppler is faster than Doppler in this session:
- Average of 0.36 knots faster
- Maximum of 0.76 knots faster
Speed Resolution
Confirmed speed resolution to be 1 cm/s.
20210505
Non-Doppler vs Doppler
Comparison of the non-Doppler figures posted to GP3S against the non-Doppler and Doppler actuals from the FIT. The 250m posted was at least 0.15 knots too high.
It is impossible to determine whether the Doppler speeds are accurate or too high.
| GP3S | Non-doppler | Doppler | Diff | |
|---|---|---|---|---|
| 2 sec | 30.27 | 30.23 | 30.20 | 0.03 |
| 5 x 10s | 27.97 | 27.97 | 27.76 | 0.21 |
| 100m | 30.15 | 30.15 | 29.96 | 0.19 |
| 250m | 29.86 | 29.86 | 29.71 | 0.15 |
| 500m | 28.89 | 28.89 | 28.72 | 0.17 |
| 1852m | 23.81 | 23.81 | 23.56 | 0.25 |
| 1/2 hour | 16.48 | 16.48 | 16.30 | 0.18 |
| hour | 11.93 | 9.44 | 9.32 | 0.12 |
| alpha | 18.59 | 15.74 | 15.37 | 0.37 |
Summary
Non-Doppler vs Doppler
This is a graphical view of all the sessions posted vs the FIT results.
In all categories the results posted to GP3S are higher than the Doppler speeds.
It is impossible to determine whether the Doppler speeds are accurate or too high.
Track Data
You can find all of the tracks on GitHub under sessions/contacts/beam/tracks.