FPV: Technical Area

Radio Frequencies

 

fpv-audio-frequency

27 MHZ Band:

This frequency is illegal to use for all radio controlled craft – don’t even think about it!

35 MHZ Band:

The most frequently used band in the FPV sector, this band benefits from a very long range and can span over 1 mile with standard FPV equipment.

The disadvantage of this particular band is that another pilot can end up on the same frequency by mistake, which can then result in crashing your signal dropping and your craft crashing. A good idea to avoid this happening is to make a note of all pilots assigned channels.

Here’s a table that shows the channels and frequencies –

Channel 55 34.950 Channel 67 35.070 Channel 79 35.190
Channel 56 34.960 Channel 68 35.080 Channel 80 35.200
Channel 57 34.970 Channel 69 35.090 Channel 81 35.210
Channel 58 34.980 Channel 70 35.100 Channel 82 35.220
Channel 59 34.990 Channel 71 35.110 Channel 83 35.230
Channel 60 35.000 Channel 72 35.120 Channel 84 35.240
Channel 61 35.010 Channel 73 35.130 Channel 85 35.250
Channel 62 35.020 Channel 74 35.140 Channel 86 35.260
Channel 63 35.030 Channel 75 35.150 Channel 87 35.270
Channel 64 35.040 Channel 76 35.160 Channel 88 35.280
Channel 65 35.050 Channel 77 35.170 Channel 89 35.290
Channel 66 35.060 Channel 78 35.180 Channel 90 35.300

 

Here’s some information on how to correctly identify the channel number of an untagged crystal:

If the crystals state the frequency but not the channel how are you able to define the correct channel?

This depends on what the crystals mark up with.

A little bit of subtraction is used to work out the correct channel –

If marked 34._ then subtract 40 after the decimal point – if marked 34.950 subtract 40 off of the 95 leaving you with 55. This gives you 55 so it is on channel 55.

If marked 35._ then add 60 after the decimal point – if marked 35.180this would be 18+60=78-channel 78. 35.240 is 24+60=channel 84.

An approval sticker or official CE marking is needed for all 35 MHZ equipment. If your 35 MHZ equipment does not have this marking it may be deemed illegal for UK use.

The 2.4 GHZ Band:

2.4 GHZ is an excellent choice of band and has gained highly in its popularity over the years. 2.4 GHZ has a decent range which doesn’t make flying with other 2.4 users an issue. The 2.4 uses what’s called Frequency Hopping Spectrum Spread Technology (FHSS) which means the transmitter output changes between several channels back and forth by not being tethered to one band channel. This is set up to stop confliction with other channel users. If you do happen to be using the old 35MHZ radio and would be looking to upgrade to a 2.4ghz this can be quite easily done. You can purchase a 2.4GHZ upgrade kit that blends telemetry connection with your FPV craft allowing you to monitor things such as battery condition.

I found a video on frequency hopping which nicely simplifies the theory:

UHF Band:

The 433 MHZ UHF band is used for long range flying. It has even been known to spread at full control to the excess of 25km away with some claiming up to 70km!

This frequency range is not actually legal in the UK and is more commonly used abroad.

As a result there are no UHF radios to buy straight off of the shelf.

You would need to check compatibility with your current radio and connect the UHF unit to it. Normally this would just be the power wires for the UHF system combined with a PPM signal enabling the UHF system for broadcast.

Here’s a great video about FPV long range and how you can modify your equipment to achieve it.

View the next category: Video Frequencies >>>>>>