- Dragon Link
- Purchasing the Dragon Link
- Important information
- Dragon Link Installation
- Binding the RX and TX
- Range Testing
- LED indications
- Questions, support, and further assistance
When you start FPV, you probably already have, or had a plane with a radio control system. This aim of this page, is to help you check if your radio is going to be trouble free during your FPV experience, and to explore reliable alternatives or new radio control systems if you have currently none.
The radio control is the link to your RC aircraft, vehicle and is therefore very important. Should it fail you, recovering your model can be very difficult and not always successful.
While we are going to go into some more details, the recommended beginner radio is a FM radio, later extended by a UHF radio system.
There are many kinds of radios, however, in most cases you will want to privilege the programmable ones with 8 or 9 channels PPM, and supporting extension modules.
While none of the arguments in this list are requirements for FPV, they are recommended for the following reasons:
A short introduction on the most common signal types:
Analog / PPM (FM)
Older radios, no interference resistance. However, you will see the signal usually degrade nicely when you are reaching the maximum range (glitches).
PPM 8 channel signal has historically become a standard, and newer digital systems generally have an extra PPM input/output, or use the PPM modulation on top of their digital signal.
By design, PPM has a frame time of 22.5ms, which means the minimum control latency (delay between you push the sticks and the model moves) is around 22-25 ms.
PCM (FM) PCM is a digital coded signal that is often used on older radios. Often, both PCM and analog PPM signal are provided. This signal is stronger against glitches, but does not resist interferences particularly well compared to more recent digital systems.
Uses a wider part of the band than necessary to transmit the signal. If part of the band is interfered, the copies of the signal are still going through. However, if the whole DSSS band used is interfered, you're out of luck. Some radios, like the Spektrum/JR DSM2 use 2 DSSS channels. These channels are sometimes selected next to one another and might be interfered with by wifi traffic and cameras relatively easily.
Jump through the band in a random but predictable order (hopping). The complete band has to be interfered to cut the RC link from these systems. Therefore, they're very good at resisting interferences.
Futaba FAAST and all UHF systems are using FHSS. Some other radios also use FHSS or variants, like AFHSS which also ensure it won't use already in use channels for hopping.
FPV abilities: Good
These radios are the “good old” 72 mhz, 35 mhz, 40-41 mhz and 27 mhz radios. It emit on a fixed frequency and is not convenient when many RC users use this type of radio at the same location. Each RC user has to use a unique frequency which is selected prior usage, and there's a table of frequencies assigned in your location, club, or area, and interferences. This lead to frequent human errors and interferences which break your RC link completely.
In these conditions, the regular FM radios are a good choice. They provide medium range (2 to 4km, or more) and can be found for cheap on eBay and other such websites.
The Futaba 9CAP is an example of very popular radio among FPV users.
FPV abilities: Mixed bag
These radios have generally replaced the FM radios in clubs and are the most popular radios. They usually are able to pick clear frequencies and resist interferences well, even if someone else start his transmitter on the same frequency.
While this sound good, there are quite a few drawbacks on these radios:
While there are many other brands, Futaba FAAST radios are recommended over Spektrum radios for reasons seen in the above “Signal type” section.
FPV abilities: Excellent
UHF radios are usually emitting on the 433-435 mhz band. The UHF radios are the best of both worlds: lower frequency, relatively unpopulated and enough bandwidth to provide good interference resistance.
They also usually emit at higher power (500 mW average) than the other radios (80 to 200 mW average).
These radios are found in the form of extension modules, which can be plugged on your radio. Again, the Futaba 9CAP is very popular, as well the the cheap imax/turnigy 9x radios.
However, these radios usually require an Amateur_radio_license to use legally due to the frequency and power used.
An example of UHF radio is our Dragon Link, which has been tested over 25 km.