I'm currently in locked-down isolation having entered a country with restricted borders, so I'm getting maximum mileage out of testing the accuracy of my new Forerunner 45, doing multiple laps of my exercise yard, multiple times per day!
Initially, I was operating on GPS only (straight out of the box) with acceptably accurate tracking. Two days ago, with overcast sky and rain, I switched to GPS+GLONASS for greater accuracy.... the accuracy has actually decreased as a result, with a mid-run translation of location by several hundred metres. This has happened on two occasions. Images included to illustrate.
In both instances, I have done the same laps as the finish location, from start, but the starting fix has been incredibly off and then rectified mid-run. As a result I'm getting spurious distances of overall run length.
Does anyone have any suggestions as to why the results are worse when using GPS+GLONASS?