SSB

Tuning to a single sideband transmission

For some, the R20 might be your first experience of SSB. This can seem a little finicky at first and it does take a certain knack. Hopefully, with this advice and a little practice, you'll be away in no time.

First, bit of background. SSB stands for Single SideBand. It is a transmission mode that is the same as AM except that the constant carrier frequency is removed. When you generate an AM signal, you transmit a constant frequency called the carrier. The modulation causes that carrier to contain two "sidebands" that are a product of the modulation and the carrier wave. It is a simple matter to receive an AM signal. However, it is rather inefficient because a lot of power is wasted in the carrier. Single sideband removes the carrier and one of the two sidebands. This drastically reduces the average power required for a given transmission, but it also makes it necessary to regenerate that carrier in the receiver. You also need to set the receiver so that it is able to receive the one sideband that is actually transmitted.

SSB requires fairly precise tuning as well as the correct USB/LSB selection. However, with a bit of practice you can get a feel for which direction to tune and whether you have the correct USB/LSB setting. Basically, all non-ham communications will most likely be using USB. Ham communications below 8MHz will be LSB. Above 8MHz, it will be USB.

SSB sounds highly distorted if you try and receive it in AM mode. In SSB mode, it sounds like pitch shifted, garbled Donald Duck until you tune close to the correct frequency and have the correct USB/LSB setting. If it sounds high pitched and shrill, tune to make it lower in pitch, or vice versa. If nothing produces intelligible voice, change to the other sideband setting and try again. If you tune in 1KHz steps, you might fly past the correct frequency unless the transmission is exactly on a 1KHz step. If you can't get it, try shifting to 100 Hz steps and try again.

>Do you need to set this *before* listening to USB/LSB? >I've checked and mine tunes through on 1KHz steps. You need to do it before you attempt to tune in 100Hz steps ;) Note that my R20 is pretty accurate and I can get away with tuning in 1KHz steps.... most transmissions are pretty close to being on even 1KHz frequencies. If yours is a bit off, you may not be able to get it right until you go to slammer steps. Note that it isn't a matter of not being able to hear anything unless you are "right on frequency". You will hear the transmission.... it will just sound too high or low pitched until you are tuned precisely. You can get a feel for it by tuning an AM station in USB or LSB mode. It will sound the same as an SSB signal except there will be a tone that increases in frequency as you tune away from the correct frequency. In a SSB receiver, you set it for upper or lower sideband as required. Then you tune it so that it is tuned to exactly the same frequency that the carrier would be on if it was transmitted. The result is a signal that sounds like it would if it was AM. If you are not tuned quite right, you can understand the transmission but it will sound either too high pitched or too low. On the HF bands, there is not a lot of SSB, so don't be too concerned if you don't find anything right away. Your best bet for starters are the ham bands..... 80 meters (about 3.8MHz LSB) at night and maybe 20 meters (about 14.25MHz USB) during the day would be good places to look. There are others but they are harder to find because there isn't continuous activity. Also, the HF bands are not in real good shape right now due to the fact that we are at the bottom of the sunspot cycle. Remember that you can tune around in AM mode because tuning is far less critical.... you can use 5KHz steps and still not miss anything. If you hear Donald Duck, switch to USB (LSB in the 80M and 40M ham bands) and re-tune using 1KHz or 100Hz steps. >If I find a 'regular' copy on USB/LSB, can I save the freq & the KHz >steps to memory? Yes. I think the mode is stored automatically when you store any frequency you are tuned to. Paul Paul Goelz Rochester Hills, MI USA paul at pgoelz dot com www.pgoelz.com

See 'A beginners guide to Scanning' for more on transmission modes.