Getting rid of Mumbo Jumbo in preparation for availability long range CB radio equipm

[Lightspeed]

Regulation of License free CB radio in the UK will, by July 2014, will be relaxed to permit the legal use of SSB and AM transmission for the first time.

This is good news for UK preppers as SSB will give greater range to emergency communications, and hopefully the allowance of SSB CB for the first time in the UK will stimulate equipment sales and increased usage of that equipment across the country.

Our friend Northern Raider has pointed out that for a vast majority of preppers, radio is just a tool, and it needs to be like all the rest of our preferred tools. Strong, reliable and easy to use. I agree with him. CB is just that, but until the new regulations come into force it is rather limited in terms of communication range. These new regulations will give us license free access to equipment capable of much improved range ( actually global range when conditions are right). But as always, one advantage compromises another. In this instance the increased communications range is accompanied by a greater level of operating complexity.

This thread is to intended to make sense of the additional complexity by making sense of the jargon and new terminology that are intrinsically linked to the improved technology that will available to us.

Making sense of Jargon

Frequency:
This section gives a simple description of the technical words Frequency, Megaherz (Mhz) and wavelength. The good news is that CB radios take care of all this stuff for us. You can skip this section if you wish.

Frequency is the fundamental jargon to radio technology. It describes the rate (frequency) of vibration of the transmitted and received radio signal. Radio frequency is at least 1000 times highr than human hearing limits and is inaudible and invisible to us. It is measured in Mega Herz (Mhz). which mean millions of vibrations per second. Both transmit and receive stations must be on exactly the same frequency for their transmissions to be mutually receivable. This is exactly the same as conventional transistor radios which, in order to hear our favourite music radio station, we have to tune ( align frequency) of the receiver to that of the transmitter.

You will hear talk of wavelength. Wavelength is directly proportional to frequency. It is usually used descriptively in two ways. Firstly in a general way to describe a whole bunch of closely spaced frequencies (UK CB has a wavelength of 11 metres in this context… you will sometimes hear it referred to as the 11 metre band). The second is the precise wavelength of a specific frequency, this is used in the calculation of antenna lengths that are critical to proper resonance of an antenna, which is important for the proper transmission of the radio signal.

Channels:
CB radios effectively simplify the whole Frequency and wavelength techno mumbo jumbo. They do this by using Channels.

Set channels are used for the tuning and matching of transmitting and receiving frequencies For example in the UK standard 27/81 27.6125 Mhz is allocated as Channel 1. Such radios 40 available channels all of differing standard frequencies.

Operators simply click to agreed channels to talk to one another. There is no need to remember complicated frequencies, nor to fiddle with ultra-sensitive tuning knobs. Just a click of the channel up/down buttons like changing channel on a TV.

In the UK we are permitted use of 80 channels with pre-set frequencies. 40 of these channels are UK only, the other 40 are compatible with the pre-set frequencies used across EU, USA and rest of world.

Mode
OK so we now understand frequencies and that these are simplified into set channels.

Currently Mode is not an issue to us as all UK legal CB equipment uses just one mode ( FM) so there is no choice to make.

The new generation radios that will take advantage of the relaxed regulations will keep the FM only mode on the 40 channels ( 1 thru 40) specific to the UK. But offer the option of up to 4 modes ( FM/AM/USB/LSB) for each of the second batch of 40 channels (Ch 41 thru 80). It is important to understand what this means.

On each of channels 41 to 80, transmission will be able to be made in any of 4 different modes. You will hear/see reference to them as FM, AM , and SSB (of which there are two flavours USB and LSB) . CB radios that are capable of operating in these additional modes are termed Multi-mode radios.

We’ll ignore the technicalities of each of these modes, and just look upon them as 4 distinctly different technical languages used by the CB radio’s electronics . If we visualise CB radios talking to one another in various of these invisible, inaudible technical languages ( modes). When we talk into the microphone, the CB Radio immediately translates our spoken words into one of its technical languages ( modes) and transmits that language as radio waves. While all CB radios tuned to the same channel will be able to hear the radio waves, only those set to the same technical language ( mode) will be able to understand the message they are hearing and translate it back to human speech for the receiving operator to hear.

We need to understand that, to achieve radio communication by CB, both radios must be on the same channel and set to the same mode.

So, which Mode is best?:
For short range and ease of use FM and AM are easiest as they are simple click and go channelized frequencies. Range will be in the order of 2 to 5 miles. Greatest number of potential contacts will be found on FM only equipment. So use FM for greatest number of potential contacts and AM to restrict the number of contacts.

SSB ( LSB and USB) Have greatest range. Typically 3x the range of FM or AM stations, and with greater possibility to bounce signals of the atmosphere to achieve long distance and even global communications. LSB and USB modes require far greater skill from receiving station operator. Not only must correct channel and mode be selected, but also the receiving station operator has to delicately fine tune the received signal to render it intelligible. This can be frustrating process, and sometimes needs constant adjustment throughout a conversation.

A technical note about range and coverage from an SSB capable CB radio.
Visualise a polo mint laying on a table top. The CB radio is at the centre.

The CB station at the center will be able to make local contact with stations as far as away as the inner circumference of the mint. This will be between 5 and 50 miles. It will not be able to make contact with any stations located under the mint ( the mintiness obstructs radio waves)

BUT, and this is the cunning thing about SSB, contacts will be able to be made to areas beyond the outer circumference of the mint. That is approximately 400 miles from the transmitting radio station, and extends worldwide.

But don’t get too excited about the 400miles and beyond thing. Its very doable with almost all of the equipment that will be available, but its ultra-dependent on the state of the 11 year solar cycle, atmospheric conditions, time of year, and time of day. At times reliable daily communications from Southend to Cape Town can be achieved day after day, at others the best the Scunthorpe station will be able to get is the end of the pier…. Its very much in the lap of the gods.

With knowledge of propagation, its possible to improve odds for long haul communication, and that knowledge comes with much practice and experiment.

Generally the land covered by the polo is masked from the central station's transmissions . Under even less frequent conditions than the Southend to Cape Town scenario described communication into the minty zone can also be achieved. These are rare and mysterious events belied to be associated with defects in the mint making process........