Adding an On Screen Display for FPV
Posted on February 4, 2010 by aaronredbaron
One of the recent advancements in the world of FPV (First Person Video) flying is the widespread availability of OSD (On Screen Display) systems. With a surprising variety on the market, hobbyist have a wide range of options from a simple display of battery voltage to a complete HUD (Heads Up Display) with return to home autopilot capabilities integrated. While adding a complex OSD system is hardly turn key, the final result can be very rewarding.
Features
OSD systems take input from a variety of sensors and super-impose graphics on your video signal to give you “instruments.” Adding a current sensor to an electric powered model gives the operator an accurate indication of the batteries health and remaining capacity. RSSI (resonant signal strength indicator) readings can offer a percentage value to indicate the signal strength of the RC system. Temperature, RPM, and a second battery voltage indicator can often be added as well giving the pilot a good information about flight time and battery health. GPS is a popular addition to an OSD. With a GPS receiver on-board, the model locks a home position before launch, and then provides directional aid during the flight to guide you home. GPS information can also provide speed and altitude readings, but these readings are not ideal. For an accurate indication of the model’s speed and altitude, some OSDs offer barometric pressure sensors; static pressure changes provide altitude readings, or they can be configured with a pitot tube for airspeed. A few OSDs even use a thermopile sensor to provide an horizon indicator.
Autopilots and Antenna Trackers
With all of these sensors on board, its only natural these systems began to offer return to home autopilots. Using the thermopile sensors to keep the model level, and GPS information to provide altitude and heading, a lost link with a long range FPV plane doesn’t have to mean it flies away. Although they must be properly configured, adding an OSD with a RTH (return to home) feature can help prevent lost models. Another feature becoming more popular is using GPS information on the ground to run pan and tilt servos for an antenna tracker. Some OSDs work in concert with a ground based antenna tracker and more are being developed to use them. With an antenna tracker you can use a higher gain direction antenna on your video receiver and get much better video signal.
Some flyers prefer to fly with an unobstructed, uncluttered view without the complexity of an OSD, but OSDs don’t have to be horribly distracting. If you want a complicated setup with all the bells and whistles, the technology is available at reasonable prices to satiate your cravings. Whether you just want simple battery data or a full F-16 simulated cockpit, the FPV community is evolving to meet your needs.
The following video uses the RVOSD from RangeVideo. This is version 2 with a 5hz GPS. New V3 RVOSDs come with a 10 hz GPS, providing more accurate altitude and speed data. This RVOSD is not set up with thermopile sensors, and RTH functions are not available for helicopters.
I’d love to see some of the size and weight comparisons and photos of some of the different options out there. Can you turn just about any rc plane into an first person view (FPV) flyer or are there some definite winners out there to work with?
Chris