FPV and GPS antenna

[afernan]

I built a setup for FPV using a CL antenna 1.3Mhz (so, big size) and I located it close of AQ GPS antenna... but no way!

Each time I switch on the video Tx, the GPS signal was loose. Obviously there was a big interference caused by the FPV Tx antenna. Now I´m thinking to put as much away as possible, but since in the arms is not possible, I thought a conf like in the image attached.

I guess that in order to use the antenna upside-down I´ll need to put also the Rx CL antenna also upside-down in order to maintain same circular polarization sense on both antenna. Is it correct?

Please any help on that is wellcome. Thanks.

[joebar.rc]

Makes sence, 1.3Ghz and GPS is often a no go (just read some of the FPV forums) and also 1.3Ghz is a harmonic of 2.4Ghz so without precaution (filters etc) you could suffer from TX-RX problems too.
Quite often the video freq is 2x the control freq is used, so with 1.3Ghz video, you need 433 control, 2.4Ghz control -> 5.8Ghz video.

Menno

[Kisssys]

Angel,

I have had 1.3ghz TX ( Lawmate ) that didn't cause any problem but that's not saying your's is not bad. I have found the Video Camera itself will effect the GPS even without it hooked to the transmitter. They radiate RF all over the spectrum and if close to the GPS or even a 2.4 receiver they will effect the operation.

I like to set the copter out in a open area and let the gps lock on, then I plug and unplug the camera and tx to see how it effects my Hacc and Vacc. It can only cause a major change in Vacc.

A lot of people think that because they get a 3D lock that things are ok and that's not true at all. There are many threads on RCgroups about camera and TX interference.

[bluuu]

1.2GHz may affect RC signal (second harmonic), you can use low pass filter and move antenna far far away from RC RX

I had a problem with FRSKy TFRSP (for Futba FASST) and Fox 800 VTX. Max range to loss RC was about 80m. (on my fpv quad, distance between RX and VTX is 52cm)
The same setup with FRSky RC link (ACCST) was +800m.

[afernan]

Yes, I think best is test on field. I´ve read GPS signal is at 1575.42 Mhz, so quite close to my 1.3MHz.

The idea shown with the antenna upside-down maybe is not so good since to put the Rx antenna upside-down will shadow some area with the Rx methallic box. Other posibility is to put it in one of the legs upside.

[afernan]

With the Tx antenna lower in the leg (se immage) it works perfect. No interference in GPS

Angel

[afernan]

Small mod for FPV:

while flying FPV, I use to be always in PH and move with DVH. In that case LED 2 (I have in front side) is always quick flashing that makes get cracy the FPV camera, specially in dawn or night flights.

So I´ve changed the led2 patterns of PH and DVH to something more convenient for FPV, with LED2 ON all time for PH or while moving in DVH

The compilation attached also has also implemented WLR (Waypoint Live Recording). I´ve longly tested without any problem. Enjoy
Angel

[SuperSharpShooter]

A change I've been meaning to make is to change the low battery pattern of LED 1 so that it's long on, with a short off. With the current long off, short on pattern, reaching low battery stage 1 can make things dicey when flying in low light.

[Kisssys]

I turned off all my LED's and just put a couple of red led strips in the front for eyes. When I FPV I usually don't have any lights. You can use a 1uf cap to couple from a PWM output set for speaker to give audible warnings to your Video TX audio input. This was a test hop before I did Halloween nighttime FPV.
[youtube]watch?v=zur7cF9a3Eg&list=UUvyI6dkgSbra4VDVHOdIzgw[/youtube]

[afernan]

Whoouu! . Really a nice idea, very funny and well done. I take the idea for next year to do in my comunity.

Angel