by RCModelReviews » Tue Dec 28, 2010 7:14 pm
The Spektrum receivers are still based on a fairly old chipset (from Cypress) that was never designed to cope with very strong out-of-band signals (such as a 1.5Watt transmitter on 900MHz sitting just a few inches away) so it sounds as if your video transmitter is desensitizing the RC receiver.
Desensitizing is kind of like when someone (your RC transmitter) is whispering in your left ear while someone else (the video transmitter) is shouting in your right ear. Because your brain effectively "winds down the volume" to compensate for the shouting in one ear, you can't hear the whispering in the other.
I've noticed that the Spektrum receivers are quite sensitive to out-of-band signals (ie: signals not on 2.4GHz) -- to the extent that they'll sometimes even pick up ignition noise from gas engines -- something I've not observed on any other 2.4GHz systems.
Going 72MHz would likely improve the situation -- but make sure you use a PCM system so you still have failsafe in case you go out of range.
5.8GHz would be your best video option but you'll likely be limited to 200mW and so will need a hi-gain receiver antenna, possibly with tracking.
Alternatively, you could look at some other RC system.
As part of the FPV articles I'm writing, I'll be evaluating the ability of various brands to cope with strong in-band and out-of-band signals from video transmitters. Some definitely do better than others.
RCModelReviews.com, just the facts.