View Full Version : Signal Strength and RST reports
04-21-2011, 12:52 PM
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.
04-21-2011, 03:21 PM
Great info, Dave. This thread should be stickied.
04-21-2011, 03:42 PM
I could hear you guys from boulder yesterday. I was mobile in the 60 with the tiny Comet SB1 on the lip mount.
Daniel was an R2/R1 S2/S3 depending on my location
Dave was an R3/S3.
Is that the way to give a report?
I had to have the squelch all the way off to pick either of you two up.
Thanks for the explanation Dave!
04-21-2011, 06:26 PM
That's an awesome explanation.
04-21-2011, 07:38 PM
Cool. Now Marco - I just need to know how to get my radio so i could have talked to you in Boulder.
Were you talking with Nakman, because I was able to hear him a bit and Dave heard him well.
04-21-2011, 08:58 PM
I had my little antenna on. I bet if I had my 5/8 wave antenna I could have talked to you just fine. I could BARELY hear you (R1S2) at my house, so we could try from my house with my big antenna sometime. Right now the 60 is back in the garage without the antenna on it so we'll have to wait a bit. I would like to try it though
04-21-2011, 09:30 PM
Name your time. Sunday evening or some evening next week. I have two antennas. A short Diamond and a 5/8 Larsen 150. The Diamond has a spring loaded center pin to make contact. The 150 has a bent piece of metal, like a spring (or the contact for the bulb of an old D cell flashlight) and I am wondering if it is making a good contact.
04-21-2011, 09:47 PM
Nice explanation dave. Took me a time or two to read it but I get it now. I wish there were more folks closer to my side of town with the radio on, whenever I drive home I make a few calls but nothing. I know simplex is a far shot but even on the repeater I only reach others but no RS folks.
04-24-2011, 04:16 PM
Those are fine Marco. For phone all you need to say is like "You're 59" or "I copy 5 by 9". You always give them in R-S-T order and 59 is tip-top, 36 would be a middle of the road and 22 would be about the lowest above noise.
I am not sure that this was explained, but the "59" Dave uses is part of the RST code. RST stands for
The R stands for "Readability". Readability is a qualitative assessment of how easy or difficult it is to correctly copy the information being sent during the transmission. In a Morse code transmission, readability refers to how easy or difficult it is to distinguish each of the characters in the text of the message being sent; in a voice transmission, readability refers to how easy or difficult it is for each spoken word to be understood correctly. Readability is measured on a scale of 1 to 5.
The S stands for "Strength". Strength is an assessment of how powerful the received signal is at the receiving location. Although an accurate signal strength meter can determine a quantitative value for signal strength, in practice this portion of the RST code is a qualitative assessment, often made based on the S meter of the radio receiver at the location of signal reception. "Strength" is measured on a scale of 1 to 9.
The T stands for "Tone". Tone is used only used in Morse code and digital transmissions and is therefore omitted during voice operations. With modern transmitter technology, imperfections in the quality of the transmitter modulation that can be detected by humans are rare. Tone is measured on a scale of 1 to 9.
Readability is kind of a seat-of-the-pants thing. If someone is down in the weeds, he or she is a 1-2. If you can barely make out what they are saying, but not every word, then maybe 3-4. 5 indicates that each word is understandable.
Strength is right in front of you. Just estimate it off of the meter on your radio.
Most contest operators just give 5-9 more as a courtesy and to be quick. No one wants to hear anybody argue over signal. Plus, once you have 5-9 (or for code 5-9-9) down, its easy.
For our purposes, we just say the two numbers together. Like apple pie and ice cream. 5-9 means you're golden.
"Full quieting" is another term someone might hear on the FM side. Full quieting is when there is no static heard when a station is using a repeater. If the repeater doesn't miss any of the transmission, it is full quieting.
04-24-2011, 07:09 PM
This is awesome info. 95% of the time (and I guess for most of us in the club who use Ham in our rigs) I'm either talking on trail or looking to see who I can reach, how far it is and how clear I'm coming through and sharing that same info back and likely on 2M FM.
04-25-2011, 07:17 AM
Dave, great explanation.
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