What to look for in an FPV monitor
FPV monitor with dual receivers
Ideally, you want the monitor to have an FPV receiver built in. This way, you will not have to buy an additional receiver and you also avoid the hassle of having to deal with too many wires.
Another advantage of using a monitor with a built-in receiver is you do not have to worry about having enough batteries to power up a separate receiver and a monitor separately. You can use one set of batteries to power up both the FPV transmitter and receiver.
You would also want the monitor to have a video output which would allow you to plug in your FPV goggles. This way, you can use your goggles for the best possible FPV experience while another person watches on the monitor.
While a single receiver built into the monitor should be good enough for most users, this may not always work well. At times, your receiver may lose signal from the drone's onboard FPV camera and the screen may go blank. You certainly do not want this to happen. It's better to use a monitor that has two receivers instead of one. Monitors with two receivers are called diversity monitors.
These two receivers work in tandem. The monitor figures out which of the two receivers is receiving a stronger signal and sources the feed from the one that's getting the stronger signal. This improves both range and performance of the system. If you want to increase the range of your FPV setup, you would want to use a helical antenna - in addition to the stock dipole antennas you may be using. Dipole antennas are good enough for short ranges, but not if you want a range of more than a kilometer.
- Easy to setup and transport
It should not be a hassle to setup and transport your FPV system. If you use integrated systems that have several components built in, you will have to deal with fewer wires and fewer batteries, making moving and setups easy and fast.
- Attached sun shield/shade
You want the monitor to come with an attached sun shield. This reduces setup time. You do not want monitors that do not come with a sun shield as it would be hard to view the display outdoors during the day.
Your FPV receiver and transmitter should be compatible. You will be using either a 2.4 GHz or a 5.8 GHz FPV transmitter. Most likely a 5.8 GHz FPV transmitter as 2.4 GHz is more commonly used for the radio control transmitter that controls the drone. So the receiver you use should be 5.8 GHZ. You would want to check for compatibility before you buy.
FPV monitors with 1024x600 resolution can be expensive. The cheaper ones - mostly those that cost less than $100 - have a resolution of 800x480 or lesser.
- Does it have DVR built in?
Not everyone may want this, but this can be a great feature to have. You will be able to record video on a microSD card. This can be useful in locating your quadcopter should you crash it.
- What's the brightness or luminance?
This is a very important thing you would need to consider if you are going to be using the monitor outdoors during the daytime. You would want the luminance to be at least 200 to 250 cd/m2 (candela per square meter). Anything that's far less than 200 cd/m2 would not be suitable. Some of the better monitors have a luminance of more than 400 cd/m2 (candela per square meter).
You want the horizontal and vertical view angles - or the viewing cone - to be as large as possible. A horizontal viewing angle of 140 deg and a vertical viewing angle of 120 would be very good. But what's common is a viewing angle of between 70 to 80 degrees. Outside of the viewing cone, the video may appear too faint and of very poor quality. Older LCD monitors used to have very narrow viewing angle, but monitors today have much larger viewing angles - thanks to vastly improved technologies.
It can happen that you may lose video signal from the drone. If this happens, some FPV screens go blue. And they take a while to display the picture when the signal does resume.This can be bad as you might end up crashing the drone. You do not want the screen to go blue if you lose video signal.
Instead, you want the screen to display at least a partial picture even if you are getting a lot of static. That way, you will be able to see through the static and this can help you stay in control and avoid crashing.
This is a measure of the time it takes for a new image from your quadcopter to appear on your screen. For most people, a latency of 100 milliseconds would be acceptable. But if you are into FPV racing and need to fly very fast between obstacles, a latency of 100 milliseconds might be too large and unacceptable. But very few manufacturers would give you this data - and you will need to make your own tests and figure out which monitor is best suited for you.
If you want the smoothest videos, you would want to consider mounting the camera on a gimbal.