UK Radio Transmitter Legalities

Jon_

Member
Hi,

This is sort of picaxe related and I am sure it will help future users who are not sure, if someone can answer the question ;-)

I have been looking at a number of different radio transmitters and receivers from a number of different websites, both AM and FM, UK and non-UK. I am aware that in the UK 433mhz is an unregulated band so ideally a transmitter and receiver on that band would be great, however, it comes at the cost that it is a very crowded band as everyone is using it for garage remotes, model helicopters etc, you name it and it is on that band.

I notice there are loads of radio chips on RS which broadcast on many different frequencies which are of course short range, normally 500m-ish. There are also chips on sparkfun on 315mhz. So here is the question, what frequencies can I broadcast on short range in the UK?

Thanks for the help!
 

manuka

Senior Member
Jon:Aside from regs, just what exactly are you wanting to do, & over what range & environment?

Licence free 433 MHz ASK gear is dirt cheap & most is so PICAXE friendly that you'd be mad not to at least give it a whirl. Sure - that band can be crowded, but suitable code preambles,slow data rates and receive antenna etc can usually cut the mustard for most needs. Superior GFSK (Gaussium Freq. Shift Keying ) transceiver units are capable of marvellous performance when the going gets tough. Stan.
 

Dippy

Moderator
Uh oh, I feel an advert brewing
:)
Read the links given for full details. Some details can be obtained if you search through places like Radiometrix site.
Most decent manufacturers will give good guidance.
 

MFB

Senior Member
The best place to look into radio legal issues is the OfCom web site and download their guide to frequency band allocations. The rules can be quite complicated. For example, 433MHz can be used for telemetry from a radio control aircraft but does not allow this frequency to be used to control aircraft.
 

srnet

Senior Member
For example, 433MHz can be used for telemetry from a radio control aircraft but does not allow this frequency to be used to control aircraft.
A requirement which is ignored of course.

UHF remote control systems are used for long range remote contol, Dragonlink is the name. 433Mhz frequency hopping at 500mW. Gives a remote control range (for model planes) of 15-20 miles.
 

manuka

Senior Member
Hey Dippy- advert time! Dragonlink technology is certainly appealing, BUT even they point out that their power levels mean a ham radio licence is expected.
 

ciseco

Senior Member
"what frequencies can I broadcast on short range in the UK?"

433, 868, 2.4ghz are all common. As you say 433 is rather a busy place, we use 868 by default on our radios, other picaxe users are using them, rev ed have suggested they will stock them at some point. I know of people using them in demanding applications of UAV's, planes, copters, even a bomb disposal tank as well as the more normal micro to micro or micro to pc link. 500m is possible, if you did a search for haku on here he got over 3Km without having to resort to external antennas. One guy claimed he could get 10km but I guess he failed.

I think I'm right in thinking both manuka and dippy have them

They can also be used as end nodes, here's an example of a light switch running on a coin cell http://www.openmicros.org/index.php/component/kunena/7-communications-and-protocols/131-modding-a-standard-light-switch-with-an-xrf?Itemid=0

Dippy will remember building something very similar PIC based a while back that used an Xbee and bigger batteries.

Miles
 
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hippy

Technical Support
Staff member
So here is the question, what frequencies can I broadcast on short range in the UK?
The primary short range device (SRD) frequencies are 433MHz and 866MHz, see Annex B ...

http://stakeholders.ofcom.org.uk/binaries/spectrum/spectrum-policy-area/spectrum-management/ukfat2010.pdf

I don't believe 413MHz is licensed for SRD use these days and additionally may not work as that frequency is close to TETRA ( emergency service digital radio ) which can drown it out.

A good rule of thumb is that if a reputable manufacturer in the UK sells a specific frequency device then it is legal and if they don't have anything for a particular frequency or of a particular power output then it almost certainly isn't legal to use unlicensed.
 

ciseco

Senior Member
Is anyone using 413? pehaps you were refering to Jon's 315, this is a common frequency for FCC based regulations (US etc), 315 shouldn't be used within ETSI regions (mostly europe)
 

hippy

Technical Support
Staff member
Thanks Graham O.

I would guess that needs to be taken in its entirety as while "Non-specific short-range devices : Equipment may be used airborne, 433.05-434.79 MHz" seems to allow radio aircraft control on 433MHz the later "Model Control : For telemetry to provide data from the model only, including airborne models, 433.05 - 434.79 MHz, 1 mW" precludes it.

Likewise "Non-specific short-range devices : 433.05-434.79 MHz, 10 mW, duty cycle limit 10%" and "Non-specific short-range devices : 433.05-434.79 MHz, 1 mW" taken together introduce a continuous transmission limit of 1mW and only allows 10mW with 10% duty, which doesn't seem to have been in previous regs.

I've no idea what 10% duty is but imagine they did not intend it to mean could be used continuously for a whole month if not used for the rest of the year, nor that you could have ten transmitters and cycle between them :)

Added : I would also expect frequency hopping within the band to still be considered continuous use, and even if not, 500mW as used by the Dragon Link is well outside the allowed limits for the UK.
 
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Graham O

Member
There is a lot in that document and it must be read in it's entirety. "Model control" allocations can be used for model control, but "non specific" cannot be, as I understand it. So you have to identify your application, then find out which frequencies are available and then see if they are feasible for your application. 10% duty cycle means that it can be transmitting for 10% of the time over a 1 hour period, i.e. 6 minutes. But I like your thinking, I hadn't considered the possibility of 10 transmitters and cycling between them.

Fortunately, there is no definition of "short range". High altitude balloon transmitters routinely get ranges of 300km+
 

Dippy

Moderator
Oh it's confusing stuff.
Search on ETSI EN 300 220-1 pdf - I downloaded a copy a little while back as I was going round in circles.
There's info in it that might help ... or hinder.
 

Jon_

Member
Well there is a lot of information here! It will take me a while to read it all...

To answer somebody's earlier question, the project I have in mind to start with will effectively put picaxe in a radio network - star topology I suppose. Each node will have a specific task around the garden and each one will check in with the master on a regular basis to make sure it is doing what it is supposed to be doing, i can't imagine a node being more than 200m away from the master. My first task is watering, a node will be connected to an electric valve and will water the garden at specific times when the master tells it.....there are a number of other tasks that other nodes will be doing eventually ;-)
 

ciseco

Senior Member
If you wanted to save time and effort then either XBEE API (not nice) or XRF (LLAP, dead easy) can drive your output (sprinkler valve) without need for a micro at every node. There's a dual relay board on everyone's favorite auction site for such a use. If using LLAP from a PICAXE connected to an XRF, takes just one line of code - serout "aXXRELAYAON-" to turn relay A on, OFF does as you'd expect and TOG wiggles in back and forth. Can support 676 nodes and there's sample code to build nodes on picaxe's. Here's an 08M as a temp sensor example, complete LLAP device in 39 lines of code, means you can build custom networks in a matter of hours. LLAP will run on any micro or PC. IBM even have it running with MQTT (telemetry queuing protocol). I have a picaxe doorbell and gate opener sounder (tranmitter is an XRF + coincell + bell push + microswitch) took me under 20 mins to do both ends in code and soldering, took longer to figure out how to mount the box and the switches and what sounds to play :)

http://www.openmicros.org/index.php/articles/78-microcontroller-projects/70-picaxe-08m-wireless-aprotocol-sensor
 
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Zizka

New Member
The 433 / 868MHz / 2.4GHz bands are the commonly known ISM allocations, but in the UK we also have a 173MHz (10mW, narrowband) allocation and a 458MHz (458.525-459.1MHz) half watt band. In addition, the 458MHz band can be used for model control (with a power limit of 100mW: I've seen 3 miles out of a 100mW 458MHz system). It's worth looking around a bit.
 

Goeytex

Senior Member
US FCC regulations are just as complicated and difficult to understand. A good rule of thumb is to configure your Transmitter
for the minimum output power to get the job done.

If around the house / garden is all you need, then a 433 mhz GFSK transceiver system setup at 5 - 10 dbm max TX power should be more than adequate and will not likely create any problems with the neighbors.

2.4 GHZ modules are also an option, but range can be an issue in circumstances where there are obstacles between the modules.
 

john2051

New Member
Hi,
I've been a licenced ham for over twenty years, and unless things have changed, 433MHz is allocated to the mod as primary user status, amateurs use the band on a secondary
basis, meaning we have to accept interference from the mod and ism users. Problems arise when these 433 mhz units are close by to an amateur radio repeater.
From my location here in lincoln, the lincoln 70cms repeater swamps alot of the cheap am and fm modules modules. Amateurs (all secondary users?) are subject to unattended notice of variation licence conditions. One of which you cant use the lower portion of 70cms within 100km radius of Charing Cross. Also, at times the MOD tests various radio activities,
at which 70cms becomes un-usable. My recommendation would be to use the highest frequencies that are useful..

regards john
 
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