Nov 15, 2012, 05:09 PM
Joined Aug 2002
It's probably the most critical aspect of using any UHF system. A single Rf nasty
component can cut the range to virtually nothing.
That's why it's critical to do proper micro-power range checks, first
with just the UHF Tx/Rx powered, and then again with everything
on the plane powered up and operating as it normally would
(including GoPro actually recording etc.. )
I had a really nice solid setup on my X8 with the RL Rx antenna
pretty close to the center of the plane. Then installed a very
popular OSD and my range dropped dramatically. Chased my
tail for a while and finally figured it out. I had made
the mistake of not doing a micro-power range test because
I assumed the OSD was Rf clean because nobody else had ever
reported an issue with it. Discovered that the current sensor
was spewing a lot of noise (maybe it's just mine.. maybe not).
Ended up having to move the RL Rx to the other end of the fuse, and
the RL Rx antenna all the way out in the middle of the wing, to get away from it.
Now my range is back to normal.
Note that Rf noise doesn't always cause the RSSI to drop. Because it's
noise picked up by the Rx, it can actually hold the Rf RSSI value higher
while the Rx simply stops receiving packets. That's why for micro power
range tests, I usually set a failsafe position that'll move one of the servos
and I watch both the blinking light on the Rx (blinking slows as it starts dropping packets)
and for the servo to jump to failsafe as I walk away from the Tx.
Last edited by Daemon; Nov 15, 2012 at 05:24 PM.