The FPV video receivers are used to pick up radio signals coming from video transmitters (VTX) on our drones and to turn them into a video we can watch on our goggles and displays. They are typically in the 5.8Ghz range, most of them have around 48 channels, divided into a couple of bands each including 8 channels.
Diversity and Singular Modules
They come in different shapes and sizes. Before the fpv goggles became a hit, there were AV video receivers that could be mounted on a tripod like the Eachine RC832.
Nowadays modular receivers are more popular. They are designed to fit into a „standard Fatshark" module bay. That shape of a receiver is used more and more and so you can find the same slot on almost all goggles that have the capability of having an external module.
New kinds of receivers usually come in a diversity package. Diversity means that there are 2 receivers, both measuring for signal strength. In that case, a typical diversity receiver would constantly output the higher strength value signal to your fpv goggles screens.
There is also something called a Rapidfire mode that comes with the ImmersionRC receiver.
Rapidfire mode combines two pictures into one giving you the highest possible quality. There is also a legacy mode if you want to use the standard diversity but We highly prefer the rapidFIRE one.
There are also singular receivers that are not used as much anymore because of the very affordable price of the diversity ones nowadays. A good example of a singular receiver is the RX that you would get with old FatShark Dominator goggles. It didn't even have a screen! How silly is that?!
Some goggles have an internal receiver built-in. While searching for them, you might see some very cheap goggles like the Eachine EV100s with two antenna connectors.
That could make you think that it has to have some kind of diversity but that just became a marketing strategy, making beginners believe that they are getting a diversity receiver built-in while it is just two antenna connectors connected to one receiver.
That is not for all of them of course, We are talking about the low end here…
In this article, we will be discussing modular receivers, differences between them and antenna options.
Types of FPV Receivers
Stand Alone Receivers
As we earlier said, some receivers are built-in and receiver modules. There are also stand-alone receivers that were used at the beginning of the hobby and some of them had a 1/4 inch thread so you could mount them on top of a tripod to have the maximum range possible.
Independent receivers were used with old monitors and goggles like the Quanum DIY KIT. Some of them had a thread so you could put them on a tripod to place them exactly how you wanted to get the maximum range out of your UAV.
Built-in receivers can be found in goggles like the Eachine 800D, Eachine 800DM, Eachine VR006, Skyzone SKY02, SKY03, Aomways, Topskys, etc. They can be really good, like ones in the Skyzone SKY03 but there are the bad ones as well.
For example, my old EV100 goggles had such a terrible built-in receiver that I couldn't go as far as 10 meters away without losing video. You always have to check for reviews before buying these types of goggles.
Receiver modules like ImmersionRC RapidFIRE, LaForge, TBS Fusion, OWLRC, True-D are used in goggles that support external receivers. They have a „standard Fatshark" module bay that has a 9 pin female header to which you can connect your receiver module.
Some of the goggles that support an external receiver module are Fatsharks, Orqas, Eachine 200D, 300D, and others.
If your goggles have an internal receiver and you wish to have let's say a rapidFIRE, you can always buy an AV IN adapter that you can attach to your goggles and connect an RX module to them.
FPV Video Receiver Frequencies
In analog FPV we mostly use the 5.8Ghz spectrum for video. There are up to 72 usable channels in that spectrum and they are split into different bands each including 8 channels.
Some examples of the bands are Boscom A, Boscom B, Boscom E, Fatshark band, Race band, etc.
Old Fatshark goggles were coming with receivers that could receive signal only on Fatshark band so be sure to look for that if you are buying old dominators...
If you have that problem, it can be simply fixed by swapping the stock receiver with a more up to date module.
The mostly used band is raceband. Not all channels output the same power. If you fly alone then you don't have to worry about what band or channel you are on but if you have friends flying around you, you have to see what channels are free to use.
If you fly with your buddies, never plug in your quadcopter while someone is in the air because most of the video transmitters switch to the highest power on startup and that could make your nearby pilots blind for some time and you could blast them out of the air.
Some video transmitters may have different frequencies than others so you always need to check the frequency table that comes with most of them.
Best FPV Video Receivers
Furious FPV True-D and OwlRC are great modules if you want to spend up to 100 USD.
For around 150 USD, you can get ImmersionRC RapidFIRE which could be easily called the best one on the market. It has a special Rapidfire mode that combines two pictures into one to get better quality, range, and penetration.
The most expensive receiver comes from Clearview. It currently sells for around 220 USD. It was very popular when it came out because of its diversity that wasn't as widely spread as today.
If you are looking for a receiver module on a budget, then Eachine Pro58 might be a good choice. You can flash a lot of different firmwares on it and see what works best.
The antenna is a crucial part of your FPV video system. There are a lot of situations where you would want to use a different antenna setup, like on a race or around trees, you would probably have two omnidirectional antennas. If you are flying long-range you would have a patch or a directional antenna.
There are linear, circular polarised (omnidirectional) and patch antennas.
Linear antennas can receive a full package of information only if transmitting antenna and receiving antenna are both at the right angle, that is why they are not used as much anymore. You can find them on video transmitters on smaller drones like tiny whoops.
They are used there because of their low weight and indestructibility. The antenna angle isn't that important because you would probably have an omnidirectional antenna on your receiver that would be able to pick up the video even if your quadcopter is at a weird angle.
For bigger quads, we use circularly polarised antennas on video transmitters and a combination of circular polarised and patch antennas on our receivers.
Circularly polarised antennas
Circularly polarised antennas come in two variants, there are cloverleaf and PCB antennas.
They have one problem and that is that they can't pick up or transmit a signal from the top and the bottom of the antenna. That is why you can see some people having two identical antennas one at a small angle from another.
Pagoda antenna is an open-source PCB design that was created for 5.8Ghz frequency by Maarten Baert.
If you looked up for the files, you could order yourself a printed circuit board, an assembly jig and make your own Pagoda at home.
They work well, are cheap and are being made by lots of different companies.
An example of a cloverleaf antenna is the classic Fatshark omnidirectional antenna. They are also being made by lots of companies but they don't have a standard like Pagoda. They can be easily tuned for a specific frequency and are also being handmade and sold at a steep price.
PCB omnidirectional antennas, other than a Pagoda, weren't a thing before Orqa released their omnidirectional antenna that outperformed Pagodas and some of the more expensive antennas.
A patch is a directional antenna that has a bigger range than circular polarised one. The thing with it is that it can pick up signals only in the facing direction. That is why most of the pilots run one circular polarised and one patch antenna. Circular polarised is used for flying around the pilot and a patch is used when you want to go in one direction a bit further.
FPV Receivers are used to turn the RF signal from your drone into a video you see on your goggles. You can choose between modules and tripod-mounted receivers for the ground station, although more and more pilots are using a module and built-in receivers because of their compact size.
Ground stations are used on races so everyone can see what every pilot is receiving. They were used before when you wanted to get a lot of range but nowadays it can be done straight from the goggles with a proper receiver and antenna setup.
Author: Bruno Džambić Nađ