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last updated 18 Jul 2003

Scanning - legally

27MHz CB was the first system that the public were free to use for business purposes, with a license of course, and that anyone else with a CB could legally listen to. The business users attempting to use a channel sensibly were all too aware that they were using CB sets, and that the channels were wide open to abuse from other 'breakers'. Combine that with long periods of overseas SSB interference during summer days (or almost every day towards sunspot maxima every 12 years) and this use of CB clearly wasn't a viable option.

PMR446 on the other hand is very suitable for businesses looking for low range communication, possibly replacing formerly licensed 'on-site' systems. These user groups will seldom hear any other activity on what they perceive to be 'their channel', what with over 300 'channels' available. Many may believe that they are using equipment that cannot be monitored, and any using the more serious gear (not the cheap yellow stuff) may even believe they are using proper exclusive channel. Some of them will not even be aware that no license at all is needed for PMR446.

As with CB, there is nothing in the regulations to prevent you listening to others using these radios. The scanner crowd have been monitoring various channels and trying to work out who is who for years - and now PMR446 users can do the same, legally! Without having to conceal their radios in deep pockets etc ;o)

Scanner folk over the years have found that it is possible to identify channel users in several ways :

Careful listening.
Often clues are there, from the callsigns (if any are used!) and from other references in the messages. This kind of "communications intelligence gathering" is something many folk really enjoy, though it is an offence to do this with private channels.

Tracking.
Hunting down the source of the PMR446 transmissions, a direction finding skill, or just trial and error travelling in different directions while keeping an eye on the signal meter. Some scanner folk even use frequency counters to 'capture' nearby frequencies, much easier as they're already there in the right place!


Other techniques apply to Private VHF/UHF channels which is against the law in the UK but perfectly legal in some other countries...

Direct evidence.
Sometimes you may get to handle a handheld radio, and find that the frequencies are written in some way on the back of the set! There is no known law against this one, hehe. Or maybe you find yourself in a firm's office and there on a noticeboard is a license or some note with the relevant frequencies on it.

The easy and legal way.
Of course, it is perfectly possible to obtain frequency infomation by word of mouth, it may be being mentioned on a CB channel, and in fact many thousands of private frequencies all over the spectrum are listed in one freely available book in particular which can tell you a great number of your local channels such as taxis, fire, police, ambulances, even the military base a few miles down the road. Some such information is even found in magazines, or in books stocked by the local library.
You can surf the web, read the newsgroups, and subscribe to a few relevant mailing lists. A lot of frequency information is available.

Antenna clues.
An expert will have seen various business vehicles, handheld radios, antennas on premises etc., and so have an idea from the size of the antennas as to which band is used. A three element beam on a building pointing towards a local tower or mast will be a dead giveaway that the firm uses a Common Base Station repeater service, the base station using "Reverse Frequency Working" - i.e. like a fixed position mobile unit. A folded dipole base antenna is directly related in size to the band in use, being about half a wavelength. Such knowledge gives the scanner offender a good starting point. A real expert will recognize the different types of handhelds or mobile sets and know which bands they are usually used with.

'Taxi Hunting'.
Sometimes it's difficult. It may be known that a channel is used by a building firm, by the type of messages. However, they are all old pros and don't give anything away. "The office" and "the yard" give no clues. In these cases, some may resort to another favourite activity - known by some as "taxi hunting" as a general term. Any channel that dispatches mobile units to specific locations is ripe for this. Some will listen in the car until a place that is known is mentioned... then off they drive and wait to see who turns up!

Telephone technique.
One very last resort, is quite despicable and I hope no-one would try it. When really desperate, some may have a shortlist of suspects for an unknown channel. They then dial most of the suspect's phone number and wait for the base to start talking. Then the final digit is dialled and they listen to the scanner for the sound of the telephone ringing in the background! There's no real harm done of course, but it does seem a little outrageous.

No, no, no!
The worst option is something I hope you'll NEVER stoop to. Some people with no morals wouldn't mind making a false booking to a taxi firm and seeing which channel passed the details. That is quite offensive as it costs time and money to the taxi firm. Some would justify this by making the destination close to the firm in question and not during a busy time, and think that kids play this prank quite often so they're used to it - BUT PLEASE DO NOT TRY this! This is supposed to be for your amusement, and not a suggested tip. Honest!


This page is intended to show how some people have made a hobby out of this sort of thing, quite legally in the USA (although most relevant information is actually PUBLISHED by the FCC themselves!). I cannot stress highly enough though, that in the UK you'd be making a criminal of yourself...
THIS PAGE IS provided for interest/curiosity only, and is not intended to support, condone, or encourage any illegal activities. If you listen in the UK without permission/licence to anything other than licenced Broadcasting or Amateur Radio (& CB) you are breaking UK law. Under Section 5(b) of the Wireless Telegraphy Act 1949 it is an offence to use radio equipment with intent to obtain information as to the contents, sender or addressee of any messages, whether or not the information is passed on, which the user has not been authorised to receive.