SSB CB Radios
Although access to its 27 MHz frequency was originally planned to be a short-term solution for Australia back in the 1970's, SSB radio has been a key part of the CB revolution for decades now. CB became legal in the 1970's after truckers campaigned for a viable two-way radio to provide a short-range communications solution for highway use. The original idea was to transition Australian CB to the 477 MHz UHF bands after five years, but the 27 MHz frequency became so popular that the government was never able to officially close it down. While most radios are built into vehicles, handheld CB radios are also popular.
What is Single Sideband?
In the early days of radio, AM transmission worked by applying a modulation to a carrier wave. Technological limitations meant that you actually ended up with a triple wave situation where the carrier took up the centre with two sidebands on either side carrying the modulation. Single side band radios save power and boost effective signal strength by putting all the power into just transmitting the modulations for one of the sidebands. The receiver generates its own internal carrier wave and then superimposes the sideband on it to reproduce the signal.
How Different are AM and SSB from UHF CB Radios?
While both AM and SSB use the same bands, they offer very different performance characteristics. UHF not only uses a different frequency, but also works on different principles. Each has its own advantages and tradeoffs in comparison to the others:
- AM: Simple and short ranged, Australian AM CB originally offered 18 channels for voice communication and later expanded to 40. In most cases it offers a range of up to 15 kilometres, and requires no special equipment beyond the radio.
- SSB: Sideband uses the same frequencies as AM, but is more efficient and can usually reach up to 30 kilometres, with 3,000 kilometres being possible when the conditions are right. It's also popular on the water where it gains extended range from the lack of terrain and buildings.
- UHF: UHF's higher frequencies limit it to line of sight, but its use of frequency modulation offers clearer voice communications than the AM bands. Before 2011, UHF CB radios limited to 40 channels, with the allotment doubling to 80 channels thereafter.
Using SSB Radios
Whether you prefer land-based or marine SSB radio, they are fairly simple to use, although marine radios authorise under the same license as CB. The key is knowing which sideband to use. In most cases, you want to use LSB, the lower sideband, rather than the upper sideband, which is confusingly but logically known as USB. Once you have your system set up you can enjoy communications across Australia and occasionally to Tasmania or New Zealand.