As you look deeper into FPV flying you soon realise there are lots off different brands of equipment available and whats more lots of different frequencies open to buy.
The equipment available is for use world wide. But as with all countries the UK has only a select few that we can legally use, that are open to us.
Not only are there certain frequencies that we are legal to use but there are also constraints on what power levels we can transmit legally on as well. The transmission levels though are another subject entirely. In this article ill concentrate on frequencies only
So what frequencies can you get video equipment for :
So whats the difference ?
The lower the frequency band, the larger the waveform produced. The larger the waveform the further it travels, the better it can get round or penetrate objects such as small buildings, trees and people.
So in that case the obvious choice is go out and buy 900mhz video equipment ? Not that easy I’m afraid
The 900 Mhz band
Nope, if only it were that easy…….. Unfortunately the government opened the 900mhz band to the mobile phone industry in 2009 so that the 3G phones could be used in this country.
Ok so so that 900 ruled out, how about 1.2ghz, well again as a resident of the UK again this band is not available for us to legally use.
The 1.3 Ghz band
The myth regarding 1.3GHz comes mostly from our American cousins, because, if they have a ‘Ham’ licence, they can use 1.3GHz for FPV. A Radio Amateur can use 1.3GHz for transmitting video/audio (Amateur Television or ATV) only from a ground based station.
The moment it is used for aerial work, it becomes illegal in the UK.
Not so straight forward is it ? …….. So now we get to 2.4ghz systems :
The 2.4 Ghz band
2.4Ghz video equipment is very popular. Its the most commonly made equipment and generally is the cheaper of all the bands to buy. It has good range / power ratio and is sought after by many.
Hip hip…………… Hang on………..
Yes you guessed it, there’s a problem. The problem with 2.4ghz is that with the launch of the Spektrum and Futaba 2.4ghz radio control equipment you cant use your 2.4ghz video equipment around any 2.4ghz radio user.
Their equipment will interfere with yours and spoil the picture being broadcast.
Another downside of the 2.4ghz video is it has poor object penetration properties and buildings trees and people can all have adverse effects even completely loosing picture.
So when you fly with 2.4ghz video you have to remain in Line Of Site to the plane.
So this brings us alone to …………………..
The 5.8 Ghz band
5.8 Ghz is growing in its popularity. This band is useful because its off the 2.4ghz that most flyer’s will be on so that’s that problem solved. Its got a decent range / power ratio but again as the 2.4ghz has very poor penetration properties so Line Of Sight flying only. It did have poor reception due to polarization and multipath, this now has been solved with the rise of the circular polarized antennas. It can now be used practically to great ranges without issue and has now proven itself well worth considering amongst FPV pilots. It is most useful for multicopter pilots as the vtx can be in close proximity to everything else with no adverse effects, which is the only option on multicopters.
So lets sum up :
900 Mhz :
Pros – Brilliant range, great penetration
Cons – Illegal for use in the UK, band used by mobile phones
1.2 Ghz :
Pros – Great range, good penetration
Cons – Illegal for use in the UK, band used by other sources
1.3 Ghz :
Pros – Good range, good penetration, very clear band
Cons – Not legal for airborne use in the Uk
2.4 Ghz :
Pros – Good range, cheap equipment price, lots of none FPV equipment on the 2.4ghz band can be used with FPV equipment such as antennas
Cons – Bad penetration properties, band used by other flyer’s, wifi equipment, bluetooth etc.
5.8 Ghz :
Pros – Good range, cheap equipment price, band very clean due to low amount of other users. with circular polarized antennas no loss in reception quality.
Cons – Very poor penetration
So what do we all do ?
Most popular method is to adopt 35mhz radio control for our platforms. This gives us good range and faultless results as the 35mhz doesn’t effect the video signal at all. Although with UHF ( 459Mhz ) on the increase this then opens up to possibility of using 2.4Ghz video if not club flying.
This keeps us all legal, we have good control, good video quality and providing we respect other 2.4ghz flyer’s and keep away enjoy the best compromise we possibly can