IntroductionFPV = First Person View In its simplest form a camera and video transmitter on the model sending a live real-time video signal to a receiver and display for the pilot and/or spectators. This allows the model to be flown or operated (also works for cars and boats) as if you were in it and driving. Other than longer ranges, it allows you to fly closer to trees and into places that are not possible flying traditional line-of-sight. I’ve been experimenting with cameras and FPV on RC models since 2007. Since then, the equipment has become better, smaller and cheaper. Originally using 2.4GHz video limited where it can be used and didn’t produce the best video quality due to wifi interference and poor off-the-shelf antennas. This is all based on my own research and experience. There are other opinions and options, many of which I’ve considered or experimented with. |
Simple and Low Cost – Starter System
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The Next Step UpStepping up from a basic system or beginning with a more expensive system. Improvements include
Goggles vs Monitorprovide a more imersive experience; you feel more on-board as the pilot. The standard are FatShark goggles due to reasonable cost, availability and function. Goggles are more expensive than a LCD monitor. Goggles can fog up during flight and don’t work for some people wearing glasses. A monitor allows you to easily switch between FPV and direct visual control. Monitors are not so good outside in bright light; monitor sun shades do help. Camera Type or QualityCameras have improved a lot and dropped in price. Most FPV cameras are security cameras with settings changed to suit rapidly changing light levels and wider dynamic range (WDR). The most important requirement for a FPV camera is that it respond quickly to changing light levels, dark ground, bright sky and occasionally looking into the sun. A reasonable camera will show detail on the ground while looking directly at a bright horizon. Good WRD allows the camera to show detail in the foreground while looking at a bright sky. The Diversity ReceiverThis is simply 2 or more receivers working at the same time to provide one video signal to the monitor or goggles. It allows multiple antennas to operate at the same time. A good diversity system will take all the best bits of signal and make one better image either of the received signals. Diversity receivers are nice but expensive and not really normally worth the cost and complexity. The best use may be for when flying in all directions in a difficult environment, such as quad racing in a forest. Unwanted signals can trick a diversity receiver in to looking the wrong way and causing loss of signal. AntennasAntennas will make or break the FPV system. The small rubber-duckie antennas provided with transmitters and receivers are very limiting. Circular polarized (CP) antennas provide a much better signal as they naturally reject a lot of interference and reflected signals. The cloverleaf (3-lobe) and skew-planar (4-lobe) type are omni-directional or work equally around 360 degrees (the doughnut pattern). The Helical is another CP antenna that is directional. It will greatly improve range in one direction and cut interference from other directions. CP antennas must be matched transmitter and receiver, left-hand or right-hand. Video RecorderRecord the received video at the ground station. This can be entertaining and useful when searching for a downed model, even nearby in long grass. There are stand-alone recorders as well as receivers with recorders built in. On-Screen DisplayVery handy. A small device that collects information within the model and overlays it on the FPV video feed. Often attached to a GPS receiver, the OSD can show power state, position, altitude, speed, direction to home an more. Much of this is calculated from the GPS receiver. Note: if the camera fails or comes un-plugged, many OSDs stop working. IMO many OSDs display too much information on the video, complicating it. Many OSDs allow you to configure the display. |
Actually Flying FPVFlying FPV is not difficult but can take some getting used to. Planes vs multi-rotors are quite different. Planes must be moving forward to fly and can only move forward. This simplifies what is going on. Multi-rotors can stop and move in any direction. When stopped it can be unnerving at first as the machine drifts, which can be in any direction. With some practice it is easier to more accurately position the model, than with LOS flying. ObserversA good observer is very handy when flying with others, simply to keep everyone informed, including the FPV pilot. But the observer is never as aware of where the FPV model is and where it’s going as is the pilot, especially at lower altitudes. For the observer to take over in a “situation” would normally increase the chances of a crash. When there are other models flying in the same area, the observer has a better idea of what’s coming up behind, but the pilot has a better idea of where the model is regarding distance at all altitudes and excellent positional awareness at low altitudes. Flying FPV without an observer is easy and I think safe enough if you normally operate safely. A part time observer is handy, someone to point out the obvious, but this also applies to LOS flying. Where is it?FPV pilot confusion occurs when switching from FPV to LOS. The model is often not where you expect it to be. I think this is due to the changing perspective. The FPV view provides a reference that doesn’t match expectations as the pilot now has to estimate distance and altitude. A good observer makes for a quicker transition. Flying with other modelsI don’t think there is a greater risk of mid air collision mixing FPV and LOS flying than there is if all the models were flown LOS; possibly less risk. It’s unlikely the FPV pilot will fly into someone as he knows exactly where he’s going and can take more precise evasive action. Judging distance from the LOS pilot doesn’t come into it. The LOS pilot has to maintain greater separation to be sure of not colliding. If any model flys into the back of another model, road-rules probably apply and the one behind is to blame; following too close. If you look at Youtube collision videos as examples, many are a slower model being run down by a faster model. A faster LOS pilot is concentrating on the model and may not be aware of what is out front that he is catching up on. The FPV pilot is more likely to see and avoid as he can almost ignore his own model and concentrate on where it’s going; and looking at the view . |
The Usual Questions
- What does it cost?
- How far and how high can it go?
- Is it legal?
- Is it safe?
- Is it difficult?
- What video frequency can I use?
- What sort of RC should I use?
- The Other Gear?
- What equipment tricks/traps are there?
2. What does it cost?
There is an initial cost to buy equipment and then you can improve performance with many hours of work or if cost is not an issue, buying better equipment
Reasonably reliable short range (to 300 meters) can be achieved for about NZ$100 using low cost HobbyKing camera and video transmitter/receiver on 5.8 GHz video. You’ll need a LCD display or goggles. A small LCD TV is good to get started.
To increase the distance reliably and safely the cost increases. Out to 1000 meters can be achieved with a better antenna on the plane and a directional video receiver antenna; add $100.
Beyond about 500 meters reliability of the plane, RC and video link become more important and the price goes up. Prices vary considerably:
Plane with motor, esc, battery, RC etc. camera video transmitter on screen display (OSD) stability controller autopilot (RTL = return to launch)
Receive antenna, receiver, tripod, diversity controller, 2nd antenna and receiver, video splitter, LCD display goggles, video recorder, suitable power supplies and cables.
500 to 1000 meters is a lot easier with a stability controller and OSD. This can add another $200+.
Staying within 1000 meters is not too expensive and doesn’t stress the legality too much or create a lot of argument. Depending on the area you can have more fun within 500 meters than out at 1000 meters.
3. How far and how high can it go?
Do not exceed 400 feet above ground level. Flying above 400 feet is illegal and will attract unwanted attention from authorities and the wrath of other FPV flyers.
I don’t recommend more than 1000 meters out and 100 meters high, BUT…
As we’ve seen on Youtube, with the right video and RC equipment and a suitable airframe, many Kilometers is possible. BUT… (again), to do it responsibly requires a lot of setup and testing and I’m not recommending it.
To exceed 1-2 Km I highly recommend you have a full compliment of autopilot, RTL and OSD, and stay well away from people, buildings, roads and wherever there may be full sized aircraft.
Video is probably the weakest link followed by RC. Better antennas and a video diversity system can improve video reliability. Long range RC requires more exotic and expensive equipment. The RTL is an insurance system against loss of video or RC.
Loss of video or RC can occur at any distance due to interference which is beyond the control of the pilot and spotter. This applies to any RC plane but with FPV there are 2 major systems that must both be working correctly.
Beyond about 300 meters a spotter is very handy and provides some backup and confidence. Often just a running commentary can keep the pilot on the right track. Binoculars are handy but should be kept on the plane throughout the flight. It’s often difficult to find the plane at a distance with binoculars. Be aware that it’s impossible to judge distance looking through binoculars.
4. Is it legal?
Yes, within limits. There are guidelines existing and being written – MFNZ guidelines are based mostly on the UK guidelines/rules. Basically:
- Must be flown by two MFNZ members with buddy-box. PIC = non-FPV.
- Limited to the pilot in command’s visual line of sight.
- Limited to designated flying sites and approved overfly areas.
- Limited to a maximum of 10 pounds and 60 miles per hour.
The Rules are being revised……. We are hoping that if everyone uses common sense and flys safely we won’t be saddled with restrictive rules.
5. Is it safe?
Yes, with common sense – As with almost everything in life. FPV is no less safe than any other type of RC flying. IMO it is probably safer than some. Assuming the equipment is working, an FPV pilot with a few hours of experience has more precise control over the model than a pilot looking directly at a model 300 meters away.
The FPV pilots ability to judge distance and position is the same at 50 meters and 1000 meters.
Attempting FPV with poor planning, testing and little practice will get expensive and therefore somewhat self regulating.
To be safe:
- Know the aircraft, flight characteristics, stall speed etc.
- The aircraft must be well built and maintained
- Careful flight area selection and familiarity
- Flight planning
- Checking and testing, before and during each flight
- Know your FPV equipment and limitations
- 30 to 100 meters AGL is generally pretty safe
As you will be flying in a safe area the worst that happens is that you have to go and get the plane and do some repairs.
Out to maybe 500 meters (normal visual range) you are unlikely to have any problems. Beyond that, consider that a minor failure could cost you the plane and the expensive on board FPV gear. Even if (as you should be) flying in an area where a crash doesn’t matter there is a chance that you won’t get the plane back or you’ll spend 3 days hacking through gorse on a remote hill side.
6. Is it difficult?
Yes and No
A simple short range (to 300 meters) system off-the-shelf on 5.8GHz is pretty simple to get going. To go beyond this range becomes more complex. Generally a lot more DIY.
To begin with have a designated spotter help by keeping track of the plane and giving a running commentary. One spotter; other spectators – keep quiet. Once familiar with the plane, equipment and flying area a spotter is only really needed as a silent backup to point out approaching people, animals etc.
The most difficult thing to get used to is video interference. Your first thought will be to ditch the video and look for the plane. It’s hard to do but stay with the video.Interference is generally of short duration and you can still fly on a noisy picture. Often an FPV aircraft won’t be very high; probably lower than a normally piloted plane at the same distance. This doesn’t give much time to acquire it visually and continue flying.
It takes a bit to get used to the new perspective, the limited peripheral view and possible depth distortion from the camera. It’s not difficult if the plane is stable and predictable and you are familiar with the area. It helps to have easily recognizable landmarks. There can be a perception that the plane has travelled further than it actually has. It may also appear that the plane is further away from things than it actually is.
Switching from fpv to visual can be heart-stopping as the plane is often not quite where you expect to see it. A spotter helps here.
An OSD with GPS helps as it can indicate distance, direction home, and altitude. To begin with it’s taxing to concentrate on the scene and keep track of the OSD data. Don’t put all your trust in the data. GPS altitude is often unreliable and if for any reason the GPS looses signal you loose the help it’s providing. Don’t have too much data on the screen.
7. What video frequencies can I use?
ISM bands = industrial scientific medical. 2.4GHz and 5.8GHz are ISM bands allocated for general unlicensed use within limits. They do allow video transmission up to 1 watt and 200mW respectively.
Here in NZ there are 3 basic options:
- 900MHz NO – NOT “easily” LEGAL in NZ
- 2.4GHz interference with RC and from RC and wifi etc.
- 5.8GHz ensure the transmitter is within the band (some are not)
- 1.280GHz requires a HAM Radio License (only 1 channel)
SRD = Short Range Devices
GURL License – General User Radio Licence for SRDs
A list of frequencies and applied conditions : link.
ISM Band Notes
| Band 1 | Frequency | Width | Notes |
|---|---|---|---|
| 27.12 MHz | 26.957 – 27.283 MHz | 0.326 MHz | . |
| 433.92 MHz | 433.05 – 434.79 MHz | 1.74 MHz | shared (HAM) |
| 921.5 MHz | 915 – 928 MHz | 13 MHz | data |
| 2.45 GHz | 2.4 – 2.5 GHz | 100 MHz | wifi bluetooth etc. |
| 5.8 GHz | 5.725 – 5.875 GHz | 150 MHz | wifi phones |
| 24.125 GHz | 24.00 – 24.25 GHz | 250 MHz | ? |
| 122.5 GHz | 122 – 123 GHz | 1000 MHz | ? |
| 245 GHz | 244 – 246 GHz | 2000 MHz | ? |
Note: the 433MHz ISM band allows -16 dBW EIRP maximum power = 16mW and a 2dBi gain antenna. Effective Isotropic Radiated Power (EIRP) depends on transmitter power and antenna gain. 100mW of TX power and a 2 dBi antenna gain = about 150mW EIRP = -8 dBW.
The 5.8 GHz ISM band is 5725 to 5875 MHz. The centre frequency is 5800 MHz. It appears that licensed users can operate fixed links (FRL) of up to 200 watts eirp. The 5.8 GHz band can also be used for WLAN systems up to 4W eirp.
FRL systems can operate at higher effective power levels and can interfere with low power systems. There may be another area at 5250 to 5350 MHz ???. The Ministry was/is considering making 5470 to 5725 MHz available for low power WLAN systems.
The HobbyKing 200mW 5.8G transmitter/receiver set that costs about US$60 has 8 channels. As supplied, none of these channels are within the NZ ISM band and it should not be used. See later post RE. mods for frequency compliance.
- 1. 5705 = below ism – (53.81mm – 13.45mm cloverleaf antenna dimensions)
- 2. 5865 = TYPO on the Hobbyking site – should read 5685 MHz and is below the ISM band.
- 3. 5665 = below ism –
- 4. 5645 = below ism –
- 5. 5885 = above ism –
- 6. 5905 = above ism –
- 7. 5925 = above ism –
- 8. 5945 = above ism –
Putting these in order: 5645 – 5665 – 4685 – 5705 – 5885 – 5905 – 5925 – 5945
Note: The American 5.8G channels (used by Fat Shark) are different and RX/TX gear is not compatible with most of the low cost Chinese gear.
Note: Imported 900MHz gear is not legal as it operates in band space allocated to cellphones and aircraft navigation.
The lower frequencies go further for the same power transmitted but require larger antennas. More power transmitted does not directly relate to increased range. Better receivers or receive antennas are much more effective than transmit power.
Power over 500mW can introduce other problems in the aircraft; high current draw and interference with other electronics.
2.4GHz works but suffers from interference from other systems and cannot be used with nearby 2.4GHz RC. It is also very effectively blocked by trees. Channels are 2414, 2432, 2450, 2468 MHz. 2468 (ch-4) is the default channel for Airwave modules. The main advantage of 2.4GHz: there is lots of gear available, wifi antennas can be used, and it was (may still be) the cheapest.
1280MHz is usable if you sit a test and get a HAM radio license. It works well but equipment choice is limited, may not be NZ compliant and there is really only one legal channel.
Note: GURL = General User Radio Licence. FRL = Fixed Radio Link. RSM = Radio Spectrum Management : Link,
8. What sort of RC should I use?
This depends on your video frequency and range required. 2.4GHz RC and Video CANNOT be used on the same aircraft, they will interfere. Different channels within the band don’t help enough to matter.
35, 40 or 72 MHz RC works well and frequencies are clearer than they were. 1-2 Km range is possible but can be expensive and/or tricky.
2.4GHz RC can operate to 2Km. Remember – it is a free-for-all band and there are many other users, mostly wifi and cordless phones.
2.4GHz tends to work fine out to a point and then stops. Low-frequency gear is not as smart and tends to get jittery before it stops. the range can be increased with a directional (higher gain) antenna on the transmitter but this does mean you have to point the transmitter at the plane AT ALL TIMES.
9. The Other Gear?
Stability Controller: This uses gyros and accelerometers to work out “level” and then fly the plane. They are very sensitive to vibration and must be mounted correctly. An earlier form uses IR sensors to look for the horizon in all directions to keep the plane level. This looks for the difference in temperature between ground and sky. The FMA Co-Pilot is one example that works quite well – most days.
Autopilot – RTL: A small improvement on the stability controller, it uses GPS coordinates to fly the plane back to where it took off from if RC is lost or it’s commanded to return. This is a good safety backup to the RC and video links. you must still land the plane manually or at worst it’s going to crash nearby.
GPS Logger: A fun addition. Records GPS location and altitude as you fly so that it can be later displayed on Google Earth etc.
Lost Plane Locator: In trees or gorse it could be impossible to locate a downed plane and with FPV it could be 500+ meters away. Considering that it could take a day to get to the plane, a screaming alarm may not be much use as it will be flat when you most need it. There are self powered radio trackers at slightly more cost that can be installed.
10. What equipment tricks/traps are there?
Cameras: You need a camera that handles bright and dark areas at the same time well. It must respond to light level changes quickly. Few do. Price is not always a good indication of quality for FPV. Some cameras have been vetted by suppliers but these are generally expensive. Get a camera that is known to work or be prepared to experiment.
Wider angle lenses provide a bigger view but tend to push the image out, making everything look further away. Narrower angle lenses give a more realistic view of a smaller area with less peripheral vision so you must know the area well.
CMOS cameras tend to handle direct sunlight better than the common CCD types. Vibration can cause a lot of wobble in the image from a CMOS sensor. CMOS is low power compared to CCD.
I’ve found that many cheaper cameras work better indoors or on dark overcast days than in full sun. Some cameras are intended for low light and work well at dusk but trees and grass look white or silver making a nuclear wasteland look. This is because they don’t filter IR well and CMOS and CCD sensors are more sensitive to IR than visible light. This also affects focus.
Video Recording on the Ground and on the Plane: Cameras that record carried on the plane provide a much better quality of recording including HD if you spend some $$$. Recording on the ground can provide useful info if you have to go and find the plane. Both provide much information and entertainment when trying to work out why it crashed.
Many video recorders are not good at recording fast movement involving the whole image. To do with codecs and how they reduce the data stored. The Key-Cam uses MJPEG (motion JPEG) where every frame is a complete image stored. This means quality is good but file size is large.
Audio Recording: Recorded audio is mostly just motor and air noise but can give a clue as to the condition of the plane and controls.
Transmitters: Never power the transmitter without the antenna connected. Don’t mess with the antenna. The transmitter can be destroyed. These get hot and require some air-flow or will fail. A hot transmitter can stop working mid flight until it cools. Keep the transmitter/antenna as far from other electronics as possible, especially GPS receivers and RC receivers.
Video Antennas and Receivers: The plane has to transmit evenly in all directions. This requires a low-gain antenna. Cheap and simple. The receiver antenna can be higher gain so that it focuses its attention towards the plane. This can be a patch, yagi or dish. Higher frequency = smaller antenna and/or higher gain. keep the antenna/s clear of the ground and clear of large objects; people, cars, trees buildings. You need line of sight to the plane at all times.
The video receiver should be close to or directly attached to the antenna. At these frequencies cables soak up the signal. The higher the sensitivity of the receiver and the gain of the antenna, the more sensitive the system will be. Within reason; too sensitive and you’ll pickup the video camera at the local dairy and wifi networks rather than the plane.
As antenna gain increases it becomes more sensitive but over a smaller area, hence directional. 8dbi is a good compromise for directional gain but you don’t have to re-aim it all the time, ie. when landing from behind.
Power: FPV can be powered from the flight battery or a separate battery. From the flight battery, video interference/noise may be more of a problem. Torroidal cores and power filtering may be required to achieve best results from the video and RC. Don’t overload the power supply or a ESC/BEC. Cooling from airflow when flying doesn’t work sitting on the ground pre-flight.
The ground end can have a number of batteries. make sure they are all charged and able to see you through the days flying.
Wiring and Installation: Keep it tidy and professional. If it looks like crap it’ll probably fail. Avoid connectors that come apart easily, and wiring that vibrates or moves. Cables to pan/tilt mounts can fail with continued flexing.
Basic but Complete System
A model that is easy to fly, stale and not too fast. A stability controller is a good idea as it lets you concentrate on where you are going and less on keeping the model in the air.
The other items required are:
- video camera and transmitter
- low-cost CCD camera – there are many to choose from
- 5.8GHz, 200 mW video transmitter – get the 32 channel version
- video receiver to match transmitter – 32 channel version
- display, LCD or Goggles – recommend 800×480 resolution
- video recorder
Note: Fat Shark use different video channels than HK: not compatible. My 1st choice wouldn’t be Fat Shark for the video transmitter/receiver as the channels are different and there’s less choice for equipment, updates etc.
I normally don’t use goggles but they do provide a more imersive experience than a LCD. A LCD monitor works best if you can keep it out of bright light and use a higher resolution screen. I’ve got my setup so that I can fly from inside the car using a 7″ LCD monitor.
Hobbyking can now supply all the parts needed but you can often get better deals and free shipping from Ebay and other suppliers.
My Setup:
Models come and go but the FPV gear gets swapped around.
Plane setup:
I am currently using mostly 5.8GHz FPV with 200mW transmitters operating on frequencies within the NZ ISM band. I still have a system with a 500mW 2.4GHz FPV system that works well when away from wifi and other RC models operating on 2.4GHz.
Ground setup:
I have multiple receivers on a tripod mounts that connect to a DCPAV diversity controller, video splitter (DIY 4-channel) Genius TV-GO VGA monitor driver V-Mate SD card recorder 7″ LCD mainly for the recorder (bad blue-screen) 14 Ah 12V SLA battery (good for 4+ hours) 7″ LCD TV/monitor for flying (normally, no blue-screen) 3″ backup monitor
A second more portable ground station consists of low-res goggles stripped and fitted into ski-goggles and connected to a combined receiver-recorder.
Transmitter is Turnigy 9X (ER9X code) with various TX modules (JR synthesized 35MHz, Corona, FRsky), an internal 433MHz LRS and UHF connector fitted in place of the original antenna. This allows a whip to be plugged in for normal flying or a coax connection to the antenna on the roof of the car or the antenna tripod for longer range. TX battery is a 3-cell LiPo 2650 which lasts very well.
LINKS:
HobbyKing. New stuff often: HobbyKing
DIY Antennas (thanks to IBCrazy): Cloverleaf, Skew Planar, Helical …
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