Diagnosing and Fixing FPV video noise is a tedious task. You may notice the diagonal lines in fpv feed or black lines in fpv video or vtx cuts out in the middle of flight. The sheer number of factors coming into picture makes it challenging to fix. Common reasons why a Bad FPV Feed occurs include electrical and/or mechanical issues in the drone.
FPV VIDEO ISSUES POSSIBLE CAUSES
Bad Video feed like noise, power filtering, vtx connection can be attributed to various factors like human errors- bad soldering joints, voltage spikes from LiPo batteries, problems emanating from the Video Transmitter among various other things. Read below as we break down the list of possible fpv video problems.
Cold Solder Joints
If you are new to soldering be sure to read our drone soldering guide.
Cold Solder joints are solder joints where the wires and the contact pads on the PCB are not making contact. This may disrupt the flow of electrical current between the wires and the pads, thereby causing a discontinuity in the circuit. The solder connections is the only means of power and data transmission, an incomplete circuit will result in loss of power and data signals abruptly.
Loss of signals may occur, when the power delivery to the Video Transmitter stops abruptly. No power going to transmitter means it is not transmitting the video. Ensuring a good solder joint between the power wires and the pads, and signal wire coming from the FPV Camera and the pads, resulting in the optimal working of the Video transmitter.
Have you read this article detailing the fundamentals of FPV Antennas?
Another common yet mess up by pilots is using an LHCP on the quad and an RHCP antenna on the FPV Goggles. This is common and easy overlooked because, some antennas come with plastic covering that disguise the antenna, making it hard for pilots to figure out. On the bench the antennas might look like they are working normal because of their close proximity to the Video receiver, but when some distance is put between the quad and the receiver, the video cuts out leaving the pilots blind.
As a general rule of thumb, if you are getting into FPV and are looking to buy a bunch of antennas, stick to one type of polarization, either LHCP or RHCP, and this way no matter which antenna you use the antennas would be matched. We recommend getting a RHCP antenna for the sole reason being that most pilots run RHCP antennas and spectating would be fun.
Electronic Speed Controllers are one of the most fundamental and the most important component on a quad. ESCs mediate large amounts of current from the LiPos to the Brushless motors. Every wire, that carries current creates a magnetic field and the same physics applies for quads too. The ESCs create large magnetic fields at higher throttles and these magnetic fields interfere with Video Transmitters causing distortion in the video.
How to combat this issue? Place the ESCs as far away from the VTXs as possible thereby reducing the interference from the ESCs. Placing ESCs on the arms might also reduce the interference with the drone flight controllers.
Inadequate Power Supply
Inadequate power supply might also be one of the causes for you having a bad video quality. The 5V power supply coming from the Flight controllers might not have adequate current outputs to support the power hungry VTX at higher power outputs. It might be tempting to power the VTX directly off the LiPo battery, but then again the voltage spikes might cause interference. Optimally, 12V power outputs from the Flight controllers must be used and directly powering the VTX off the LiPo battery must be avoided at all costs. Nowadays, ESC’s have power outputs which can also be used thereby reducing the stress on Flight controllers.
Range and Power Outputs
To determine which power supply is best for powering your FPV camera and VTX, you need to know what voltages they are able to receive. Most FPV cameras nowadays have a wide operating range usually between 5V and 30V or even higher than that. Safest option for powering your FPV camera is from VTX. Most VTX’es these days include a filtered 5V output for running FPV cameras. Most video noise problems are caused by powering either the VTX or FPV camera directly from the LiPo battery. Fluctuating power conditions from ESC’s and motors make the raw voltage from a battery noisy.
Low ESR Capacitors
Capacitors can eliminate ripples in a circuit. If a line carrying DC voltage has ripples or spikes in it, a big capacitor can even out the voltage by absorbing the peaks and filling in the valleys. It acts like a tiny battery, when there is a spike in voltage, the capacitor absorbs it like charging a battery; and when there is drop in voltage, the capacitor discharges itself by releasing the stored energy. Voltage spikes from lipo batteries can be combated by using Low ESR capacitors.
Voltage spikes are bad for electronic components because they stress the electronic components. When using 6S LiPo battery, the voltage can spike in excess of 30V, way above the maximum operating voltages of components and thereby damaging them. Capacitors help maintain a constant voltage.
Heat kills electronics, heat is their biggest enemy. Electronic components are built to last a long time, but it is heat that kills them prematurely. A Drone Video Transmitter can overheat when it has inadequate cooling. Overheating transmitters work sub optimally, than when they are cool.
A small VTX transmitting constantly at higher power outputs will kill it faster than a VTX that has adequate cooling. If you plan to do long range FPV, a 2g VTX is not the ideal choice to transmit video at 600mW constantly. Instead opting for a larger VTX that can adequately handle this excess heat will make the VTX last longer.
A heat sink is one way to help cool off the transmitter, but placing it on the top plate with the cold air directly blowing onto the VTX is the preferred choice.
Upgrading the Video Receiver
I know! Barely anyone uses RC832 receivers anymore. But this is a possibility too, maybe the VTX is working optimally but the fault might be on the fpv video receiver. The video receiver might not be sensitive enough to be picking up the video signals being transmitted. A diversity receiver is twice as much as sensitive than a single video receiver module. Trust us, if you are still using a single receiver module, upgrade to a diversity module ASAP. It’s totally worth it!
FPV Channel Interference
FPV channels in a band usually have good separation between them, but neighbouring channels might still overlapp with each other and cause interference. Before you fly with a group, the best thing to do is to check which frequencies they're using, so you can see if there are any open ones available for you to use. Choose a channel that is as distant as possible from the occupied ones so as to minimize interference. Also, If both people use ie. RHCP antennas, then they could be interfering with each other. Using opposite polarization ie. LHCP would reduce interference between pilots.
Jello and PID Tuning
If you watched the above video carefully, you can see that the quad vibrates. The vibration from the motors is transferred to the quad frame causing the whole drone to vibrate. These vibrations can be eliminated by PID Tuning it, watch this video by Joshua Bardwell, and soft mounting the motors help too. Quadcopter Propellers can be attributed to causing vibrations in quads too. It is easy to use different sized on quads and thereby causing an imbalance in the thrust produced by the motors. Double checking the propellers to be of the same size and if the propellers aren’t damaged in a crash help ensure a Jello free flight. Another cause for Jello might be a loosely mounted FPV camera, tightening it down might help with the vibrations.
Fixing FPV video noise is a tedious task. The sheer number of factors coming into picture makes bad fpv feed a frustrating fix. The learning in FPV is a never ending process, you keep learning everyday. After few deep fpv problem diagnosis you're going to pinpoint the problems faster, don't give up 🙂
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