Speed Sensor vs GPS

I am setting up an "alert" service in my Data Field to inform the cyclist of certain lost signal conditions. I can easily detect GPS, Power Meter, HR Sensor, and Cadence Sensor signal issues.

But on a MTB, a speed sensor is much more accurate than GPS. GPS can lose 10% of speed and distance on twisty single tracks (for whatever reason, Garmin watches are much better than the Edge devices on twisty trails). But a Garmin device simply restort to GPS if the speed sensor stops sending a signal. I'm not sure how to tell if my speed data is based on GPS or the speed sensor. Any ideas on how to determine this? I'd like to inform the rider if their speed sensor is not working or the signal is intermittent during a ride. Usually indicates a battery needs replacement. And can buy them 10% more miles and speed if they can address that issue.

FlowState over 6 years ago

I'm don't think there's any way for CIQ data fields to determine the data source for various things in ActivityInfo, such as HR / speed / cadence / elevation, although this has been requested in the past. I suppose you could pair directly with the speed sensor in your app, but then of course you would lose all the benefits of pairing natively, like having the sensor data override native speed data.

jim_m_58 over 6 years ago

And if the sensor is BLE, you can't even try a direct connection... With CIQ you'll see "best source", so on watches with OHR, you'll get that if there no external HRM connected, you'll get watch cadence if there's no footpod connected, etc.

DaveBrillhart over 6 years ago

And if the sensor is BLE, you can't even try a direct connection... With CIQ you'll see "best source", so on watches with OHR, you'll get that if there no external HRM connected, you'll get watch cadence if there's no footpod connected, etc.

That is nice, in that the "service" is more reliable with automatic fail over. However, it really would be a very useful bit of info to know the source. My use case is a prime example, where the source makes a significant difference, and alerts the athlete to an opportunity to fix the sensor issue.

Of course, adding GRADE to the Activity.Info is another very obvious feature request and a valuable metric. Garmin developed a pretty sophisticated algorithm to create a responsive, accurate, and smooth grade metric. Those three characteristics are pretty impossible to achieve using barometric and distance readings, as the barometer tends to be noisy and updates in leaps. So you need to smooth it out over many seconds, which then reduces the responsiveness. Anyway, Garmin has decided some things should not be exposed to CIQ developers for some reason. Like sensor source, grade, etc. Ugh.