UHF radios are used for short range communication within a convoy. These radios are not considered an emergency radio as longer distance communication is usually required in an emergency (but don’t ignore the possibility that help might be closer than you think.)
Radio Setup for CTCSS:
We prefer to use a radio feature called CTCSS. This allows us to communicate within the convoy without receiving interruptions from other groups. If your radio does not have CTCSS, we are not asking you to replace it – simply let the Trip Leader know and he won’t use it for that trip. If you do have CTCSS (check in your manual) then we ask you to put in a bit of time to set it up. Most radios are easy to set up but we have had one GME which had an option called Silent Mode which first needed to be turned on. The four basic steps are underlined below. Please note that we need everyone in the convoy to have the system programmed correctly in order to use it. If you have any problems, please let us know before your next trip.
How do I set up CTCSS? We use channel 28 and a CTCSS code of 107.2 Hz. If you use channel 28 in another group please speak to us first.
1. Look in your user manual for a table with a similar title to “CTCSS Codes and Frequencies” (usually found in the appendix). If you don’t have a user manual you will need to download a copy (or we can do it using trial and error).
2. Under the column heading “Frequencies (Hz)” search for 107.2 and make a note of the corresponding Code Number. (The Code Number should be in the vicinity of “14”). Not all radios support all the standard frequencies. If your radio does not support 107.2 Hz please let us know. Also make sure you are using the correct manual for your radio as the code numbers vary depending on the supported frequencies on your radio.
e.g.
3. Turn on your radio and select channel 28.
4. Press the CTCSS button (or it may be in a Menu System) and select the Code Number you recorded above. You may need to refer to your manual on how to enter the code, save your selection and exit the menu.
Channel 28 on your radio is now programmed to only hear other radios with the same CTCSS code and should display a “C” or some other code (see your manual) on CTCSS enabled channels.
Why use CTCSS? - With CTCSS enabled on a specific channel you will only hear other radios (i.e. our convoy) which have the same code on that channel. This means we won’t be interrupted by other users. They can still hear our conversation unless they also have CTCSS enabled in which case neither group would know that someone else is using the same channel unless we both happen to transmit at the same time. This should eliminate the need for us to change channels or to put up with 3rd party chatter.
What is CTCSS (Continuous Tone Coded Squelch System) and how does it work? You may be familiar with the squelch system on your radio. It blocks out (mutes) unwanted background radio “noise”. The more you turn the squelch up, the stronger the incoming signal has to be to turn the muting off and allow the signal to enter your radio. CTCSS uses this squelch system to completely block all incoming signals on your selected channel ( in our case, channel 28) unless it also receives a sub audible frequency ( in our case, 107.2 Hz). This frequency is transmitted the whole time the PTT ( Press To Talk) button is pressed. Although this tone is very difficult to hear, it is usually filtered out by the radio before it reaches the loudspeaker.
There is another system called DCS (Digital-Coded Squelch) which works in exactly the same manner as CTCSS but uses a digital code.
Handheld: If the convoy is not spread out then often a handheld unit will do the job. Two watt is a common size and one watt will also work but anything less is not recommended. Five watt radios are also available but battery life may be a problem. Having a handheld unit is often very helpful in a vehicle recovery situation but do not use them for critical instructions such as “Go” in case of miscommunication.
In-Car: In-car units that produce 5 watts are recommended as they give a much greater range of up to 10 km and 50 km in perfect conditions on a mountain top. Be careful when selecting a radio which has the controls in the handpiece as some units are prone to changing channel too easily if the handpiece is bumped.
Antennas – long vs short: A long antenna (approx. 6 dB) is used in flat outback terrain where a convoy can be spread out due to dust. This type of antenna concentrates the radio wave to produce a flat disc like pattern which can achieve greater distances but if the vehicle is on an incline then the signal can be shot straight over the top of the other vehicle even though it may be quite close. In mountainous country we use a short 3 dB antenna which produces a spherical radio pattern which is more suited to these undulating conditions. It has a shorter range but this is not usually a problem as the vehicles are normally traveling closer together. If it does become a problem then the trip leader can appoint someone in the middle of the convoy to relay messages. Recommendation – buy an antenna which has interchangeable long & short antennas.
Poor radio signal. This can often be due to moisture getting into the coaxial cable of the antenna. External connections should be sealed with either Self-amalgamating Tape or Denso Tape for maximum protection.