Wednesday, 2 September 2015

Electronics and Propulsion System in RC Flying - Part 6 - FPV Flying

6. FPV (First Person View).
FPV flying  - Video display for the pilot/operator - 1
 FPV flying - Video display for the pilot/operator - 2
FPV flying  - Video display for the pilot/operator - 3
  • What are the equipment required for basic FPV system ?
  • Where to start and how to build a FPV system ?
I will try to explain on how to build a basic FPV system and what are the minimum equipment required.
  • You can find very expensive FPV gear, please do not start out with the expensive items.
1. Deciding on a FPV platform (airplane or multirotor)
  • If you are new to FPV flying , then you should start out with an easy, stable and tested model airplane or multirotor.
2. RC Tx - Rx.
  • You should have a 6 channel and above Tx Rx.
  • To increase the Tx power for long range, you can use a 2.4GHz amplifier.
  • A standard RC Tx will  have an output on 10mW - 30mW.( around 1.5 km range) with a booster you can have an output on 500 - 1000 mW.
  • Do not use video TX on 2,4 Ghz when you use a RC Tx on 2,4 Ghz.
3. Camera.
  • A variety and types of cameras are avialiable for FPV application.
  • Select one which suits your budget.

4. AV Transmitter and Receiver.

  • AV (Audio Video) Tx is used to transmit video and OSD information from camera and OSD module fitted on the aircraft  to the ground station consists of AV Rx and Video display for the pilot to control the aircraft.
  • Again a verity of models are avialiable with different transmission power and frequency.
  • Carefully select the power and frequency for your AV TX-Rx equipment.
  • Different countries have different rules for the power and frequency for armature use.
5. Video goggles or Display.

  • Video goggle is not a first choice for a beginner.
  • FPV flying with Video goggles requiters a lot of experience in LOS flying .
  • So start with a simple video display.
  • Even you can use your laptop as FPV display.
6.  FPV Minimum OSD (On Screen Display)
Information displayed on screen - 1
 Information displayed on screen - 2
 Control board and GPS module for OSD display
  • For easy navigation when you are flying, you also need a OSD (On Screen Display).
  • This item will show you your home location, speed, battery volt and more.
  • It is not a must to have OSD installed in your FPV plane, but if you want to  fly long range missions beyond visual range , you will find this very needy to know about the status of your Aircraft.
  • OSD board takes information from your flight control board, GPS module and battery module and mix it with the video signal for transmitting to the ground station.
  • Mid segment and above flight control boards will have built in OSD terminal for connecting OSD module.
  • In many cases OSD module will not be part of Flight controller board, you have to purchase it separately.
7. Additional Antenna for long range wireless video transmission.
  • If you want to fly beyond line of sight (LOS) then normal antenna fitted in your AV Tx-Rx may not be sufficient to cover the distance.
  • In such cases you have to add additional antennas on your Aircraft and ground station.
  • For a beginner this is normally not required. 
A complete FPV system will cost you around Rs : 25,000/- to 30,000/- .

FPV System Setup.
  • If you are a scratch builder who has experience in flying RC airplanes, or you read about the basics of RC flying, this page will help you in setting up your first FPV system.
Finding Your Equipment
  • In the recent years, various vendors have started to sell kits that contains the minimum FPV system needed to outfit an RC-Aircraft for FPV flight.
  • In some cases, these kits are comprised of good quality parts, but same times the combination may not be good enough.
  • Then you can do better by selecting the components individually.
  • The company or supplier you select to purchase your FPV system equipment depends on where you are located.
  • In India we have to pay hefty shipping fees  and customs duty for batteries and all other parts from overseas.
  • But now, there are many more options for domestic shipping and purchasing.
  • If you want items from overseas, you will have to find a vendor with a large stock of items and reasonable shipping rates. 
  • Hobby King has an international warehouse and is a good option. ( I have good experience with Hobby King).
  • You can take a look at some other companies also, to see if they will suit your needs and budget.
FPV System Minimum Requirements
  • We have seen  the various items you will need to upgrade your RC-Aircraft for FPV use. See the picture below to understand how these items work together.

 1. Camera
  • The cameras used in FPV are the same as those used as security cameras without heavy enclosures to reduce weight.
  • When you select a camera, you need to be aware of its power requirement., its weight and size.
  • Try to to select a camera with a wide input voltage range, so that you can use it with different voltage batteries.
  • I use cameras with a 5-18 V input, so that I can use the main flight battery (2S 7.4 V – 4S 14.8 V max) for power.
2. Aircraft
  • A basic trainer or well turned quadcopter is a very good selection to start FPV flying.
  • Experienced RC pilots who are used to line-of-sight (LOS) flying also want to stick to something basic for the first few FPV flights.
  • If you are comfortable flying a quadcopter or another type of aircraft, you could use that as your FPV platform.
  • The best starter aircraft for FPV flying  is the aircraft  you are most comfortable in LOS flying.
3. RC Transmitter and Receiver
  • If you are having a simple RC transmitter, it is better to upgrade to a mid segment or high end Tx-Rx to have better FPV flying.
  • You requires additional channels to control different functions in FPV flying.
4 & 5. Video Transmitter and Antenna
  • The video transmitter takes the signal from the camera and OSD system to send it out through an antenna.
  • The transmit antenna is an omnidirectional antenna.
  • An omnidirectional antenna sends the signal out in all directions. 
  • Video transmitters are designed for use in several frequency bands.
  • A selector switch on the transmitter will set the exact frequency for the video signal transmission. 
  • Your choice of frequency will depend on several factors, such as the frequency of your radio, permitted frequency for such application in your country.
6 & 7.  Ground Station with Video Receiver and Antenna
  • A ground station includes several components that receive and display the video feed send from your aircraft.
  • Ground stations can be simple or complex.
In the picture above you can see  a larger tripod setup with two antennas and video receiver to the side of the monitor.
8. Video Display: Monitor and FPV Goggles
  • FPV  goggles have two small displays inserted into a small headset.
  • You will  get an experience that will be  like sitting in the front row of a movie theater or in a flight simulator 3D theater watching space travel.
  • Even  the video looks great, you should have a very good experience in normal flying to undertake FPV flying using goggles.
  • I will recommend starting  with  your laptop or a simple 7 inch video display monitor to get the feeling of FPV flying.
How to do the wiring of a basic FPV System
  • If you have selected the aircraft,  RC Tx-Rx  and video Tx-Rx,  purchased the necessary components to  start your FPV project.
  • Now it is time to connect all these items together into a wireless video system.
  • First step to help this process go smoothly is to confirm  the operating voltage of each component.
  • Video transmitters and receivers typically operate at 12 V. 
  • Many cameras also have an operating voltage range that includes 5-15 V.
  • By using components that operate at 12 V, it will be easier to use  a 3S Lipo (12.6 V max) main battery supply. 
  • You will have to use additional voltage converters to step down the voltage if you plan to use 4S batteries (16.8 V max).
Here’s a wiring diagram for a simple FPV system:
  • We can use standard servo wire for all connections, except from the battery to the ESC, and from the ESC to the motor.
  • Servo wire is 22-26 AWG, and can take  several amps of current.
  • ESC- BECs  are typically rated for 3 to 4 amps output.
  • Servo wires will carry this current without any problem.
  • The UBEC output powers the servos and RC receiver.
  • The above diagram shows a single battery powering both the video link system and the control / power system.
  • If you use a single battery to power both, a power filter is recommended.
  • The position of the power filter is between the split to the ESC and  to the camera / video transmitter.
  • While the power filter is optional, if you use one in such setups, your video will be much clearer .
  • The ground station is connected  much the same way, except you have a video receiver and a monitor instead of a video transmitter and a camera.
Next Step
  • If you understood the various components that make up a basic FPV system and how to connect those components into a circuit, you should be ready for your first ground test and maiden flight.
Example of a full kit for- FPV Quadcopter.

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