When I started flying the first FPV drone I built I always had issues. I remember being so happy when I flew all of my 3 packs and my quad was still alive. Many issues I had was regarding the analog FPV feed. The video signal was bad and sometimes completely gone. In this article, I’ll give you tips on how to improve your FPV range and video signal.
Good soldering and right connections
I have to admit when I started my soldering was really bad. I was happy when the wire just stuck to the pad instead of having a proper soldering and fluent connection. For the video quality and reliability of the video transmitter, it is important to have proper connections. Bad connections can come loose in-air by the vibrations of the motors. You really do not want the video to go black while doing a power loop. Check out my article about soldering. It’s also a good idea to use a good soldering iron like the MINI TS100.
It’s getting hot!
Because video transmitters are using a lot of power for such little devices. they can get quite hot. Place the transmitter somewhere on the quad where it can ventilate. Some transmitters are meant to put on the stack and have 30.5×30.5 or 20×20 mounting holes. Different video transmitters have to be placed somewhere else. Do not place them directly on your carbon frame, this can distort your signal. I recommend using special double-sided tape that can resist high temperatures to stick it on and lock it with a cable tie. Do not use hot glue as it will become soft because of the warmth the video transmitter produces.
Antenna placement is key to improve FPV range
The placement of the antenna is very important. The carbon frame and the LiPo can interfere with the VTX connection dramatically. You want to place the antenna as far as possible from the frame. The antenna or SMA adapter should not touch the carbon. The easiest way to mount a video antenna right is by using a (TPU) 3D print. If your antenna is flexible try to bow it a little up so it will be higher than a top-mounted LiPo. You can find 3D files for almost every frame on Thingiverse. I’ve also made some custom ones.
LHCP or RHCP
Most 5.8GHz video antennas are available in RHCP and LHCP versions. The difference between these antennas is the way these are winded. RHCP stands for ‘Right Hand Circular Polarized’ and LHCP for ‘Left Hand Circular Polarized’.
RHCP is mostly used, however, LHCP is the standard for the DJI FPV system. It does not really matter which type you choose, as long as you make sure the antenna on the receiver uses the same polarisation as on the transmitter. If you use different types you will have no or a really bad connection.
If you are flying with multiple pilots it could be beneficial if some pilots use LHCP antennas and some use RHCP. This will result in less interference between the channels.
Changing the transmitter’s output power
Last but not least, the output power. I’ve put this one last for a reason. It is very important to take a look at the upper items and apply them to your quad before you higher the output power of your VTX. Once you have one or more of those items not fixed right you have no reason to update the output power, you could even damage the video transmitter.
But yes, most video transmitters do have the option to change the output power. This is done by pressing a button on the VTX for a certain time, this can be different for each VTX so you should check the corresponding manual for your video transmitter. The better way to do this is by using TBS Smart Audio or IRC Tramp protocol. This requires you to connect an extra wire from a free UART TX port to your transmitter that lets you change your channel, band, and output power through Betaflight Configurator and the Betaflight OSD settings. It’s also needed for the use of pit-mode.
Using more output power also means the VTX uses more battery and it even gets hotter so you have to make sure the video transmitter gets enough ventilation. Not on every location more output power will give you a better signal. In some circumstances, you are better off with 25Mw output power to improve the FPV signal because of reflections.