24. RADIO CONTROL TECHNICAL INFORMATION

The BMFA is an active member of the UK Radio Control Council (UKRCC).  This is the body recognised by the Government Agency Ofcom as representing all modelling use of radio frequencies in the UK.

24.1    Official Frequency Allocations
The specific frequency bands available for the use of radio controlled models are shown below, with the maximum effective radiated power output of the transmitter measured in milliwatts

Frequency (MHz) Bandwidth (kHz) e.r.p. (mW) Use
26.96 to 27.28 10 or 20 100 General model control
34.945 to35.305 10 100 Air model control
40.66 to 41.00 10 100 Surface model control
49.82 to 49.98 10 General model control (SRD)
433.05 to 434.79 25 1 Data telemetry (SRD)
434.04 to 434.79 25 10 Data telemetry (SRD)
458.50 to 459.50 25 100 General model control
2.4 GHz Wideband 100/10* General model control
5.8 GHz Wideband 25 Airborne video

 

* NOTE: 100mW e.i.r.p and 100mW/100kHz e.i.r.p. density when frequency hopping modulation is used.  10mW/MHz e.i.r.p. density when other types of modulation are used.

This and other information concerning modelling use of radio frequencies can be found in the Ofcom document OfW 311. You can view the latest copy on www.ofcom.org.uk  (use the search box).

24.2    The 27 MHz Band
(a)  Identification is by coloured ribbon attached to transmitter aerial in the colours as listed when using 20 kHz spacing and a   white flag with channel number in black when using 10 kHz spacing..

(b)  The channel spacing on this band is 10 kHz and all modern sets, with the CE mark, should meet this specification. However, many older specification sets are still in use and these have a minimum channel spacing of 20 kHz. This situation will remain for a number of years so if you are operating narrow band 27 MHz then be aware of the danger.

(c)  You must not use an old 20 kHz split crystal in a new set. Even if you wish to transmit on the same frequency, a new narrow band crystal will be required in a narrow band set.

(d)  The 27 MHz band is legally shared by other users, in particular, model cars, model boats, citizens band operators and an increasing number of radio controlled toys. It therefore cannot  be recommended for use by airborne models.  In fact many clubs have already found it necessary to ban it completely.

(e)  If you really must use it take great care particularly near urban areas and remember when you fly a model aircraft you are personally responsible for the safety of the flight.  So think very carefully before proceeding because of the many sources of potential interference.

Chan. Frequency. Old Colour Chan. Frequency. Old Colour
1 26.965 17 27.125 Orange-Yellow
2 26.975 Black 18 27.135
3 26.985 19 27.145 Yellow
4 26.995 Brown 20 27.155
5 27.005 21 27.165
6 27.015 22 27.175 Yellow-Green
7 27.025 Brown-Red 23 27.185
8 27.035 24 27.195 Green
9 27.045 Red 25 27.205
10 27.055 26 27.215
11 27.065 27 27.225 Green-Blue
12 27.075 Red-Orange 28 27.235
13 27.085 29 27.245 Blue
14 27.095 Orange 30 27.255 Blue
15 27.105 31 27.265
16 27.115 32 27.275 White or Purple


24.3    The 35 MHz Band
(a)  The 35 MHz band is SOLELY for model aircraft and under no circumstances must it be used for any other purpose, such as the control of surface vehicles. Transmitters must not be airborne.

(b)  Identification is by orange flag with black or white channel numerals.

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

(c)  To Identify the Channel Number of an Untagged Crystal,

(1)  If the crystal is marked 34.xxx you subtract 40 from the first two numbers after the decimal point of the frequency marking, (i.e. 34.960, subtract 40 from 96 giving channel 56)

(2)  If the crystal is marked 35.xxx you add 60 to the first two numbers after the decimal point of the frequency marking, (i.e. 35.260, add 60 to 26 giving channel 86).

24.4    The 40 MHz Band.
(a)   This is for surface vehicles only and band identification is usually by green flag with white channel numeral. The band will use the last three numerals of the actual transmitted frequency as the channel identification, for instance,

40.665 MHz will be channel 665

40.825 MHz will be channel 825

(b)   This  band is SOLELY for surface vehicle use and under no circumstances must it be used for the control of model aircraft

24.5    The 49 MHz Band
The very low radiated power of this band would limit it to indoor use only.  As far as is known no commercial equipment for model use is available, although it is widely used by the toy industry, including for indoor model aircraft.  Transmitters may not be airborne.

24.6    The 433 MHz and 434 MHz UHF Bands
These are data telemetry bands for short range devices (SRD) and may be used to transmit data back to the transmitter.  However they are not exclusive to model controllers and are shared with other users who are permitted to radiate relatively higher powers, so you must take care when selecting a channel for use in a particular locality. All equipment used must be type approved (ETSI 300 200-1) and therefore show the CE mark.

24.7    The 459 MHz UHF Band
Identification will be by channel numeral.

458.525    channel 1 458.850    channel 14 459.175    channel 27
458.550    channel 2 458.875    channel 15 459.200    channel 28
458.575    channel 3 458.900    channel 16 459.225    channel 29
458.600    channel 4 458.925    channel 17 459.250    channel 30
458.625    channel 5 458.950    channel 18 459.275    channel 31
458.650    channel 6 458.975    channel 19 459.300    channel 32
458.675    channel 7 459.000    channel 20 459.325    channel 33
458.700    channel 8 459.025    channel 21 459.350    channel 34
458.725    channel 9 459.050    channel 22 459.375    channel 35
458.750    channel 10 459.075    channel 23 459.400    channel 36
458.775    channel 11 459.100    channel 24 459.425    channel 37
458.800    channel 12 459.125    channel 25 459.450    channel 38
458.825    channel 13 459.150    channel 26 459.475    channel 39

The 459 MHz is shared with various industrial telemetry and telecommand devices between 458.5 and 458.95 and to specialised telemetry beween 458.95 and 459.1, so users of these channels should be aware of the possibility of interference being present. The use of frequencies above 459.100 MHz (channel 24) is recommended. Transmitters may not be airborne. 

24.8    The 2.4 GHz Band.
This is a worldwide Industrial/Scientific/Medical (ISM) band, similar in scope to the 27 MHz band.

There are two currently available types of equipment. One uses spread spectrum technology and does not operate on a fixed frequency. There are 80 channels available and each set uses two channels during operation. They automatically set themselves to a pair of  unused frequencies when switched on. Operation is constantly self monitored and the set will move to an unused frequency if any interference is detected.

The other technology in use is frequency hopping which operates in a similar manner to mobile ‘phones.

All should be self regulating when it comes to selecting frequencies to use and the two different operating systems can co-exist with each other. Consequently, no direct frequency control is required for the band.

This band is useable for most regular R/C applications.  It is also used by many computer applications such as wireless networking and Bluetooth devices but the method of operation of the equipment in this band means that the possibility of interference from such devices is extremely low.

The band may also be used by video equipment but only at a maximum radiated power of 10 mW.

24.9    The 5.8 GHz Band
The band covers 5.725 GHz to 5.875 GHz.

This band is used by most FPV video equipment.  It has been divided into four bands A, B, E, and F, each band having 8 channels as the table below.

1 2 3 4 5 6 7 8
A 5865 5845 5825 5805 5785 5765 5745 5725
B 5733 5752 5771 5790 5809 5828 5847 5866
E 5705 5685 5665 5645 55885 5905 5925 5945
F 5740 5760 5780 5800 5820 5840 5860 5880

As you can see the grey channels are illegal for use in the UK. Some commercial manufacturers may use a different range of channels some of which may also be illegal.  Check very carefully the frequencies used by any video equipment you intend to purchase.

24.10  72 MHz Equipment
Contrary to some people’s belief, 72 MHz IS NOT A LEGAL FREQUENCY FOR MODEL CONTROL IN THE UK. A manufacturer’s development license is available (under very strict conditions) to bona-fide designers/manufacturers from the DTI. Anyone using 72 MHz without such a current special licence is operating illegally and may face a fine and confiscation of the equipment. This licence is for genuine development work only and does NOT give the operator the right to use the frequency for normal R/C flying.

72 MHz is very widely used in the UK for communications purposes.

24.11  R/C Equipment Type Approval
In October 1998, harmonised standards for low power radio control equipment were introduced into European Union Countries. From that date all new equipment either manufactured or imported into the UK has to comply with the requirements for the issue of a CE marking

The European standards which apply to all newly introduced R/C equipment are ETSI 300 – 220 For Equipment pre 2.4 GHz and ETSI 300 440 covering Wideband (2.4 and 5.8 GHz) equipment. For full details see ofw 311 and IR 2030 available at www.ofcom.org.uk These also reference the above ETSIs.

It is therefore essential that any radio control equipment you buy and use carries an official CE marking.The CE marking is your only assurance that the equipment you own, or are intending to purchase, complies with the standards laid down by the Government.  When purchasing your next R/C equipment, make a special point of looking for the CE marking; this is the only way you can be sure the equipment you are using is legal.

Notes:

(a)   From October 1998 all newly introduced 27 MHz equipment must also carry a CE marking and be capable of operating at 10 kHz spacing.  27 MHz equipment manufactured before that date is exempt from this legislation.

(b)   The 1998 legislation noted above was not retrospective so all 35 MHz equipment which was previously tested against the old SAME/MHTF Type Approval standards remains legal to use.

(b)   Current legislation allows the CE mark to appear on the equipment itself, the instruction leaflet or on the box.

24.12  Synthesised Frequency Equipment
(a)   35 MHz synthesised frequency transmitting equipment is legal in the UK as long as it has been tested and carries the CE mark. There is, however, a limitation to its use in the UK that has been agreed with Ofcom and also at international level by the FAI.

(b)   This is that any synthesised transmitter must have a two stage switch-on process. The first switch-on stage must NOT transmit but must give a clear indication of the frequency that will eventually be transmitted. This is to enable you to select frequencies safely and, more importantly, to obtain clearance from the site frequency control system.

(c)   Only after you have done this should you activate the second switch-on stage which enables transmission.

(d)   Synthesised frequency equipment will give you much greater flexibility in your frequency selection but it also has many pitfalls and you should take great care if you use such equipment. Remember that most people you are flying with will not have the same facilities and your operations must fit in with what is accepted as normal operating procedures.

(e)   For instance, you should be showing a frequency flag and be prepared to change it if you change frequencies. You must take extra care when using the frequency control system as your opportunities to reserve the wrong frequency will be much greater. You may find that the ability of your transmitter to select any frequency will be viewed with suspicion by some and, in the event of interference being suspected, you could find that you are the first person checked. The only way to avoid problems is to be scrupulously careful in your operations.

(f)   Finally, although synthesised sets have the potential to be more reliable and cheaper to produce than plug-in crystal sets, remember that they still use a fixed crystal in the transmitter module and the receiver and that any crystal can drift over time. You will still need to have your radio equipment checked occasionally as a master crystal drifting will affect all the other frequencies synthesised from it. Curing the problem will be a job for the importer/manufacturer and will not be as simple as just plugging in a new crystal.

24.13  Grey Imports
There is a small but increasing trend, driven in many cases by the ease of internet shopping, for flyers to directly import equipment from sources outside the EU for their own use. All frequency bands are affected by this and sets on both 35 MHz and 2.4 GHz are especially involved.

Now most of us are not familiar with EU and UK law on this subject but you should consider the following very carefully.

It is a fact that the onus for making sure that the equipment meets EU standards rests not on the manufacturer but on the original importer into the EU. This applies whether the equipment carries a real or bogus CE mark or no CE mark at all.

This means, of course, that equipment bought through the normal model shop chain is warranted to be legal by the major importers who do the original importing into the EU. However, if you have imported equipment directly from outside the EU for your own use then you are personally responsible for it’s legal operation within the UK.

This is extremely important to you as a user because you may inadvertently find yourself in serious trouble if you are involved in an incident.

Just to take two instances;

(1)   The application of bogus CE marks to equipment manufactured and supplied from certain parts of the far east is not unknown. If you have one of these sets you have no idea whether it is legal to operate or not.

(2)   The USA and Canada have higher power limits for 2.4 GHz equipment than we do and it is known that most Spektrum sets sold there have been built to take advantage of these higher powers. If you have personally imported a set from the USA then it will almost certainly be illegal to operate in the UK unless it has been re-calibrated by the official importers.

24.14  Radio Control Licence
From 1.8.1981, model control equipment is exempt from the requirement of a Licence under Section 1 (1) of the Wireless Telegraphy Act 1949 subject to the terms, provisions and limitations set out in parts 1 and 2 respectively of the Statutory Instrument 1980 No. 1848.

Next Section 25. THE BMFA COUNCIL OF MANAGEMENT

 

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