I just saw these posts on RC Groups:
http://www.rcgroups.com/forums/showpost.php?p=29542578&postcount=620
http://www.rcgroups.com/forums/showthread.php?t=2244017&page=2
This looks like it could be serious but could go undetected unless the Hdop is checked before /during each flight.
I have been using 8XR's since I switched to Taranis from Spektrum radio last year.
I can not say for sure if I have experienced the issue for first hand, as this does NOT completely knock out the GPS just a momentary loss/glitch or higher Hdop...
It looks like its worth experimenting with other Rx's (I have an orange Tx module for the Taranis) and monitoring the Hdop. It appears (from what I have read..) it is the Tx side of 8XR that causes the GPS glitch. It might be worth trying non-telemetry enabled Rx's from FrSky.
Replies
Simple demonstration video about the effect of electromagnetic interference (EMI) of the FrSky telemetry receivers on the reception of the signal from the GPS satellite. That test was made with a D8R-XP telemetry receiver but I think that could be the same problem. You can see the shielding efect of a simple antistatic bag improving signal reception. Obviously, the best solution is to keep your GPS antenna as far as possible from any EMI source but shielding them is a good thing to have in mind.
https://youtu.be/zzybeDj8wlw
I have several multirotors using APM, Pixhawk and Vector all with D4R-II receivers (they output 8 channels in PPM mode) and they all have fine GPS performance. Separation between the GPS and receiver antennas is on the order of 6-8 inches on all of those models.
They all use A2 telemetry for the flight battery so they are transmitting.
I have a few X8Rs but frankly I've never used one since the D4R-IIs are so much smaller, lighter and have built-in A2 support so they only need a simple voltage divider for main battery monitoring.
If the X8R really causes you issues, I recommend you try a D4R-II.
Did you find out any more information on this?
I have the same gear and haven't noticed anything but also have not done any specific tests.
Well I have just started using ArduPilot with gps/compass on a mast this last week for the first time with a Tricopter.
I previously used the kk2 board but needed gps as I lost model a few times, was found but not something I want to repeat.
Not sure what HDOP is considered acceptable, but I am getting 1.91, max was 2.01 I think, and sometimes its lower at 1.40ish.
NSats 10 most of the time.