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GPS Polling Rate

dustinsterk
Hello,
I am the developer of HotLap, and am very interested in the ability to change the GPS rate from the default 1Hz to 5Hz or greater.  It sounds like this is already a firmware capability for the default Downhill biking/skiing/snowboarding activity (which bumps it to 5Hz) for the Fenix 8 and other models, but there is no way to use/set the rate from the API that I have found.  Does anyone have any information or know of ways take advantage of the higher sampling rate as my app can dramatically benefit from these higher sampling rates for Motorsport use (at high speeds in cars/on track, etc).
Thanks in advance.

  • 5 Hz recording is one of the most desirable features of the speedsailing (aka speedsurfing) community, many of whom own a Garmin and wear it on the water (typically using the APPro Windsurf app). Without the 5 Hz data from the GNSS chipset (or suitable low pass filter that smooths the 5 Hz data prior to downsampling to 1 Hz) we see erroneous "max speeds", which people naturally assume to be true. 

    I have written a couple of articles touching on why it is so important that speeds can be recorded at 5 Hz (or higher). The first simply discusses the implications of sampling rates, and aliasing - https://logiqx.github.io/gps-details/general/aliasing/

    The image below is taken from the first article and shows how indiviual readings are scattered around the true speed, but once in a while outliers are wrong by several knots. I don't expect anyone outside of the community to understand that our speed doesn't change by multiple knots in a split second, but it doesn't. The implication is that people are claiming speeds that they never achieved in reality, just errors. 

    The second article is more of a warning to speed sailors about how "max speed" can be misleading -  https://medium.com/@mikeg888/what-to-make-of-max-speeds-b83c05569e6c

    It would be really, really useful if Garmin provided an option to record 5 Hz data, and it doesn't even need 5 Hz logging to the FIT file. Simply store 5 values within an array, just like IMU data (e.g. accelerometer and gyroscope) can already be recorded in FIT files at 125 Hz. This example of 125 Hz accelerometer data is from a Forerunner 255.

    5 Hz data inside the FIT file allows us to sort out these issues during the post-processing. I see no real reason why Garmin cannot provide 5 Hz logging of speeds, especially via the API. It would also allow them to provide better 1 Hz speeds for sports where it matters.

    Popular speedsailing websites:

    - https://www.gps-speedsurfing.com/

    - https://speedsurf.app/

  • in reply to Mike K888

    This is fantastic...so many applications could benefit from 5Hz or greater, please Garmin consider this feature!