All, 

I really need some help. I just recently got my FPV stuff and put it on my bird. Anyway, as soon as I turn on the video transmitter the GPS goes dead. If I turn the transmitter off and reset the system GPS comes back full strength. I have searched the site, but no one that I saw has the same problem.

If someone could help the would be great!

Setup:

APM 2.5

Ublox lea6m with the mod.

2w video transmitter 5.8ghz

Hex frame with GPS on one side and video transmitter on the other.

Views: 390

Replies are closed for this discussion.

Replies to This Discussion

Two Watts?  What fpv transmitter puts out two watts?  If correct, then that is your problem.  Separate your antennas as far as possible or reduce the fpv power level.

2000mw does equal 2W correct? 

But that shouldn't interfere with it receiving the signal, they are on two different frequencies. GPS is on 1.5 and this is on 5.8. Am I wrong in thinking this?

Yes, 2000mW is 2 watts. 1mW = 0.001 W.

Regarding the overload of the GPS receiver by the FPV transmitter, even the best receivers made will overload (sensitivity reduces) when a nearby transmitter goes on the air. The GPS receiver has to receive a very weak satellite signal, which means the receiver has to be very sensitive to do so. High sensitivity means even out-of-band signals have the potential to overload the receiver unless it has very good receiver front end filtering, which I doubt the GPS receivers have.

As already stated by a previous poster, use as much antenna to antenna separation as possible. Since vertical separation is much better than horizontal, try to put the GPS unit up high (since it is looking at the sky) and place the FPV antenna down low, under the aircraft if at all possible. The absolute best isolation would be achieved with the transmit antenna directly underneath the receive antenna with as much vertical distance between the two as possible. An aluminum (conductive) mounting plate underneath the GPS would help even more.

HTH,

The GPS band is roughly the third harmonic of the 5GHz of the FPV transmitter.  This is the worst-case as the second harmonic is reduced because of favorable phasing and the higher order harmonics are usually so low that they don't matter.  Aircraft receivers have very selective filters on their GPS receivers because they need to function next to a transponder that has an ERP in the kilowatt range at 1GHz.  But those filters are pretty heavy and expensive.

But, what fpv transmitter puts out two watts?

I will give this a shot right now!

Thanks for the help!

Thought that I should follow this up....

Joe, you were right on.

RSS

Groups

Season Two of the Trust Time Trial (T3) Contest 
A list of all T3 contests is here. The current round, the Vertical Horizontal one, is here

© 2019   Created by Chris Anderson.   Powered by

Badges  |  Report an Issue  |  Terms of Service