Signal Strength and RST reports
I was talking to Daniel, KD0GWR, last night simplex on 146.460. I was stationary at my QTH and he was mobile downtown. This was maybe 10 miles of distance but he was experimenting with antennas and power. I was giving him RS reports and he was a little confused about what those mean, so I think it bares some discussion.
RST (and the related RSQ for computer-based comm) are fundamental to AM, CW and SSB, particularly on HF but just as valid on VHF and UHF. With FM it's not quite as popular, particularly the 'R' part, but it's still useful I think.
First, without going into too much detail, keep in mind that what we are talking about is your transmitted or received field strength. This conceptually is the relative strength of the electromagnetic (EM) field that you are generating on TX or picking up on RX. Think of a pond of still water into which you throw a rock. The rock when it kurplunks makes a bunch of ripples. This is pretty much visually exactly what happens with EM fields when your antenna is resonant with RF energy. It is making 'ripples' (or literally 'waves') in space. Those waves can cause differing responses to objects elsewhere on the pond.
So understand this water analog by substituting free space electrons for water, the rock for your TX antenna and the responding objects as RX antennas. You then have the concept of field strength which is basically the size of the waves that are created. A stronger field is just like bigger waves. Also stronger waves travel farther, again just like with radio, and can create a strong signal at the receiving object.
"Stand your ground. Don't fire unless fired upon, but if they mean to have a war, let it begin here." -- Capt. John Parker
Last edited by DaveInDenver; 04-22-2011 at 06:42 AM.