In this article I will share some tips on how to avoid and fix FPV video issues. They way you connect and power VTX and FPV camera affects how clean the video signal is. With good practices you can minimize noise in the FPV feed.
Table of Content
- How to power VTX and Camera
- LiPo is noisy
- Every ground pin is different
- Signal ground
- White lines
- Black lines
- Connect camera to VTX directly
- LC Filter
|All FPV Cameras Compilation in this spreadsheet.|
|All 5.8GHz VTX Compilation in this spreadsheet.|
Best Way to Power VTX and Camera
The safest way is to power your FPV camera from the VTX. A lot of VTX’s these days have 5V output dedicated for FPV cameras. If you are already using filtered power source for your VTX, the additional regulator on the VTX is extra filtering for your FPV camera.
If your can’t power the FPV camera directly from VTX for any reason, the next best thing to do is to power both VTX and camera from the same filtered and regulated power source.
Most noise related issues are caused by powering either the FPV camera or VTX, or both, directly from the main LiPo battery.
Power Directly from LiPo is Noisy
The majority of FPV cameras and VTX’s these days can be powered directly by a 4S LiPo battery, some even support 6S. But the raw voltage tends to be noisy because of the ESC’s and motors it’s connected to. The noise can get passed through the PDB or flight controller to your VTX and FPV camera.
When powering your FPV system directly from LiPo, your video quality will largely depend on how noisy your motors and ESC’s are, and how well your camera and VTX can filter out the noise.
Some VTX’s have beefier power filtering, but FPV cameras generally don’t. Perhaps you can get away by powering your VTX directly from LiPo, and power the camera from your VTX.
To minimize noise in your FPV video feed, you want to protect both of your camera and VTX from exposing to noise. It’s best to power them from a filtered and regulated power source.
Where to Add Capacitors
Additional capacitors are often used at the input power of a device to clean up the electrical noise.
Where to add the capacitor depends on where your VTX is getting power from. If it’s getting power from 5V then you should put the cap on the 5V rail, if it’s 12V then put the cap on the 12V rail. If it’s powered directly from LiPo, then put the cap on XT60 pads. This is the most effective way to clean up noise.
I see a lot of people always add the capacitor at the XT60 pads, regardless how the VTX is being powered. It might work, but it’s not the most effective.
Twisting Signal and Ground Wires
It’s a good practice to twist the video signal and ground wires together, this acts like a shield against induced external noise from ESCs and BEC inductors. Because of this, also keep signal wires and power wires away from BEC inductors.
Keeping ESC aways from FC BEC
The MOSFET on your ESC switch many times a second, and that creates EMI that can affect BEC on your FC. If you use this affected BEC to power your FPV setup, you will get noise. In some extreme cases, the noise can even get to your 3V3 regulator and affects your gyro performance (as well as OSD chip).
Therefore, be mindful when mounting your 4in1 ESC and FC (not as much a problem with singla ESC on the arms), avoid having the side of the FC with the 5V BEC to face the MOSFET side of the 4in1 ESC.
Every Ground Pin Is Different
Ideally, all ground pins are the same, but in reality that’s not necessarily true.
Ground pins are connected using a piece of wire or a copper trace on a PCB. Any piece of wire or copper trace has resistance, capacitance and inductance.
Because of this, there will be a voltage difference between two ground pins on a circuit board if there is current flowing through them. Think of this as an extremely tiny resistor.
This is why it’s best practice to connect the grounds of your VTX and FPV camera to the same pin, or to two ground pins as close to each other as possible.
Signal Ground Is Important
There is current going through the power and signal wires, and eventually it has to return to its source via the ground wires. It’s a complete cycle, that’s why it’s called a “circuit”.
When you don’t have signal ground connected, the signal can only return to its source through the power ground. Therefore the signal will be “more vulnerable” to the noise in the power. By having a signal ground, you can better “isolate” the signal from the power.
This is especially important when you are powering your FPV system directly from the main LiPo battery.
“White Lines” in Video?
“White lines” are usually a sign of excessive electrical noise in the power to either the FPV camera or VTX, or both. Adding a low ESR capacitor to the ESC power, or XT60 pads should usually fix it.
Further Reading: why and where to add low ESR capacitor in a mini quad?
When you are getting lines in your FPV video, try to fix your FPV setup’s power first by powering your FPV camera from your VTX. If that doesn’t work, then you can try adding a capacitor in your battery lead.
“Black Lines” in Video?
“Black lines” are usually power related, which are commonly caused by a power hungry VTX. Some VTX don’t do well with stepped-down voltage, and they might struggle to deliver the desired output power.
If you are getting black lines in the video feed, you might find the issue to be worse at a higher output power such as 800mW than a lower power such as 25mw. If that’s indeed the case then it’s definitely related to insufficient power or voltage to the VTX.
You can try powering your VTX directly off of the battery voltage without any BEC (voltage regulator). If this does not solve the issue with black lines, you might just have a defective VTX or camera.
Connecting FPV Camera to VTX Directly
Don’t wire things you aren’t using, such as OSD or camera control. Unnecessary wiring might introduce noise to your FPV system. If you are not using OSD, simply wire your camera’s video output straight to your VTX and bypassing the video signal pads on the FC.
Another solution to cleaner video feed is to use an LC filter between the power and your FPV system. It blocks some of the noise in the power getting to your FPV system, but it doesn’t reduce the amount of noise in the power like a low ESR capacitor does.
Jello on Well-Tuned Quad
Most FPV cameras these days have CMOS sensors, which means they are more prone to jello effect than CCD cameras. You should not have jello in your FPV video if your quad is performing and tuned probably. If you do not hear noticeable oscillations from the quad, but there is jello, check the follow things:
- loose camera screws?
- loose camera lens – is the lens lock nut broken?
- loose camera sensor inside the camera?
If none of these is the cause, try using TPU mounts for the FPV camera. The flexible and soft material absorbs some of the vibrations.
- Mar 2018 – Article created
- Apr 2019 – Updated
- Jul 2019 – added “where to add cap” and “twisting signal/ground wires”