tl;dr: footpod increases the distance measurement accuracy of the gps sportwatch.
Track distance: 1.71km +- 0.01km (3x measurements with garmin vista hcx and polar m 400 = 6 measurements), urban environment.
Hardware:
- Garmin Forerunner 945 (GPS+Glonass, 1s track saving)
- adidas Mi_coach footpod (ant+ version)
- Garmin Vista HCx (as a reference)
- Polar M400 (as a reference)
tl;dr garmin with footpod measured almost the exact distance of the loop (1.71 km).
Three runs with three settings of garmin forerunner: (1) GPS+footpod, (2) GPS only, and (3) footpod only. All runs accompanied with two other gpses as a reference. Track distance: 1.71km +- 0.01km.
| Round | distance Polar (reference) | distance Vista (reference) | data source | distance | time | average pace | error | place |
|---|---|---|---|---|---|---|---|---|
| 1 | 1.72 | 1.70 | GPS+footpod | 1.71 | 9:40.5 | 05:40 | -0.10% | 1 🥇 |
| 2 | 1.70 | 1.71 | GPS | 1.67 | 9:31.8 | 05:43 | 2.24% | 3 |
| 3 | 1.72 | 1.70 | footpod | 1.68 | 9:28.7 | 05:38 | 1.66% | 2 |
- garmin with footpod measured almost the exact distance of the loop (1.71 km, -0.10%).
- garmin with gps only was the worst, with error +2.24%
- foot pod only (no GPS!) was 1.66% wrong
tl;dr: garmin+footpod offers more "stable" and consistent pace/speed
Raw data plots. Garmin device + polar m400 as a reference.
Smoothened data (5s window average). Garmin device + polar m400 as a reference.
Distribution of speeds:
And some statistics:
| speed_calc | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| count | mean | std | min | 25% | 50% | 75% | max | ||
| hardware | source | ||||||||
| footpod | garmin | 569.0 | 2.958910 | 0.105325 | 1.99 | 2.940002 | 2.960083 | 3.000000 | 3.639984 |
| polar | 574.0 | 2.999651 | 0.492067 | 0.00 | 2.900024 | 3.000000 | 3.199951 | 4.500000 | |
| gps | garmin | 572.0 | 2.917657 | 0.770542 | 0.00 | 2.580013 | 2.894989 | 3.209970 | 7.880005 |
| polar | 576.0 | 2.957465 | 0.302476 | 0.00 | 2.800049 | 3.000000 | 3.099998 | 4.100006 | |
| gps+footpod | garmin | 580.0 | 2.940086 | 0.085252 | 1.49 | 2.910004 | 2.949951 | 2.980042 | 3.070007 |
| polar | 606.0 | 2.852475 | 0.672028 | 0.00 | 2.799988 | 3.000000 | 3.100002 | 4.199997 | |
Results:
- garmin with footpod: very stable pace.
- garmin with gps only: high variability of speed
- foot pod only (no GPS!): very stable pace.
- polar m400: pace is more stable than forerunner in gps-only mode. This may be due to averaging [citation needed].