2024.9.22 23:45
By 김민준
There are 4 main FPV systems in the market, which are divided to Digital and Analogue. Both options have their pros and cons, and it is up to the user to select that they want. However, quite a lot of goggles support both so if you would like to use both, it is completely possible.
FPV systems are mainly 5.8ghz transmission, so do check with regulations and make sure it doesn’t interfere with other 5g wifi networks.
HD FPV is quite common these days, with more and more people adopting HD FPV. HD FPV’s great as it is a digital protocol, allowing for much higher quality footage shown to the user while flying. This improves the overall experience and immersion of flying, but also costs more and has more latency. Furthermore, HD systems are not intercompatible so if you choose one system, you are unfortunately stuck with it. HD systems also seem to have a limit on how many pilots can fly at once, as there is only 8 Channels. There are 3 main systems for Digital FPV systems, and 1 new system.
DJI FPV is what quite a lot of newcomers use. It’s simple, reliable, and offers excellent quality. It’s easy to use as you just need the goggles and an Air unit or VTX. A lot of FPV FCs have dedicated plugs for DJI Air units, which show how well it’s getting adopted into the market. DJI FPV also has two-way communication, which allows for better image quality as if an image fails to send due to RF signal losses, the air unit will retransmit the image. DJI is the gold standard for image quality, but it also lacks versatility. Currently, DJI has 3 goggles, the DJI goggles, Goggles v2, and Goggles 2. Confusing naming aside, with those 3 goggles that does not easily support other input methods, there is the Air units and O3 air unit. DJI’s air units are large and expensive, costing up to 300,000 krw+ for the O3. Due to this, the per unit cost of each drone increases and it isn’t fesable for smaller drones.
DJI’s breakdown pattern when there is low reception or interference can be distracting, when large parts of the image start to pixelate. However, this may be preferable as it keeps some parts of the image usable. DJI’s reception is quite good and reliable, but there is a hard limit on it’s range set by DJI. Further than the range, the goggles and air unit will just refuse to connect even with upgraded antennas. Finally, DJI also has variable latency where depending on the reception and link quality, the latency may vary from the standard 20~30ms to longer. This can be undesirable to some who need consistent low latency.
Walksnail avatar is a more adaptable version of DJI FPV. Both operate similarly and share similar ups & downs in terms of video quality. However, the DJI FPV system does have better image quality and the breakdown patten on WS system is more smeary and can have jitters. However, the main benefit to WS system is the fact that it’s first, cheaper, and second, has multiple VTX options. I personally didn’t go for DJI HD as I didn’t want to be limited to larger drones due to the size of the DJI air units. I personally love small whoop or toothpick style drones (about the size of your hand) and fitting an air unit on those kinds of quads are basically impossible. Plus, I didn’t want to spend 300,000krw+ on every drone I built. With WS system, they have a small 1s VTX that weights under 8 grams and it ‘only’ costs ~120,000 krw. WS also has a much larger VTX that can transmit up to 2W of power, which allows much longer ranges. Also, WS does not lock your range like DJI does so with the right antennas, you can go further than the 10km(I think 20~30km) limit that DJI places. However, some users can find the breakdown pattern of the WS system not ideal, and same as DJI, may not like the variable latency.
WS supports a variety of resolution, framerate, and bitrate. As low as 540p 100fps and as high as 1080p 60fps, with bitrates at 25 or 50mbps. This allows the user to choose between different resolutions, prioritizing image quality but lacking latency and range, or prioritizing latency and range while sacrificing image quality. Talking about range, WS has good penetration so you can fly in areas with obstacles, and pretty decent range.
Finally, WS also sells a separate VRX that can be used with monitors or other goggles, but the support for different modes can vary depending on the monitor’s performance.
HDZero is a digital system designed for latency. Both DJI FPV and WS systems are focused on image quality, while HDZ is focused on latency. DJI FPV and WS have variable latency of 22~50ms where depending on the reception and other factors, the latency can spike. This is due to the two-way communication and retransmission of the images. HDZ systems have a one-way video transmission where the VTX just sends the footage, and the goggles or VRX takes what it can from the footage. HDZ’s footage doesn’t look as good as DJI FPV or WS, but if latency is what you need HDZ is the way to go. HDZ can have latency of as low as 15ms, which is actually faster than some analogue systems. Most people won’t need HDZ’s low latency, as it really only matters for racers or freestylers who want the lowest latency to avoid obstacles. However, it’s impressive that HDZ can have digital HD image transmission at a lower latency than analogue. HDZ system’s breakdown pattern is similar to analogue, where static appears on the screen. This can be distracting to some, but it is similar to how analogue systems breakdown. HDZ is also much more compatible than WS, where there are even AIO FCs(FC with 4in1 ESCS designed for whoop or toothpick style quads) and higher power VTXs suitable for bigger drones. HDZ also has a external VRX so you can use it with a monitor or different goggles.
HDZ has several ranges of resolution and framerate. As low as 540p 90fps and as high as 1080p 60fps mode. Like WS, this allows the user to select different resolutions to prioritize different aspecs. However, HDZ doesn’t have as good penetration and range as the DJI FPV or WS system due to it’s protocol.
OpenIPC is a HD system that is quite new. It’s main fame is that it’s open source, which should allow for extremely cheap hardware. There isn’t much info available on this system as it only recently started getting adopted for FPV purposes.