RS(T)N signal report
Table of Contents

For short explanation, see RSN


Radio experimenters, as we once were, have an important duty to give reliable signal reports so that we can gauge propagation, the efficiency and radiation patters of our antenna systems, etc. However, the RST system was devised long ago when we did not suffer from "local noise" from all types of electronic junk. Instead, in those days, others suffered from our interference.

Our most pressing problem that is threatening "Amateur Radio" is probably the rising noise levels that make our communication on any mode more and more difficult. Yet, we have no way to inform the other station of the real signal strength of their signal, if their signal is below our local noise level. Nor do we have a way to express the current local noise level which would be of interest to the other station, and also for the general collection of data about rising noise levels, and noise in city locations, and some countries where it is worse e.g. China and Korea.

Those active on short waves will notice that it is not possible to have QSO with stations in BY and HL unless you have a very strong signal, they just will not hear you with a local noise level often above S9. The same is the case for some hams in western cities too, and many YB hams and other countries where there are, as in Australia, no enforcement of manufactured or imported gear EMC specifications.

The T in the RST system is now perhaps superfluous, since 99.9% of CW signals now have a T9. Also one may argue that the S meter system is ambiguous since different radio gear give different S meter readings for the same signal strength, and, almost always HF amateur radio signals have QSB that makes the S meter signal strength vary by at least one, and often two or three S points or more. Does one give the "average" S value? Or the one at the start of the QSO? Or the maximum value? Some will even give the range e.g. RST 55/79 meaning from S5 to S7. I wrote about a simpler 5 point signal strength reporting system the same as the QSA code where it is easy by ear to judge the signal strength 1 being barely audible, 2 is weak, 3 average, 4 strong, and 5 exceptionally strong.

However, after talking with my friend Tim VK3IM this evening, we arrived at the conclusion that we really need a new "N" value to determine the (S meter) level of noise. Thus, in an SSB signal a report of RSN 498 would indicate readable without difficulty, signal strength S9, and a local noise level of S8. Or in CW, RSTN 4998. Or, RSN 498 as the T value is always 9 in any case.

Take as example, a local noise level of S5. How far below the noise will you be able to hear? Perhaps S3, but not less. I conducted tests with a sound engineer ham in PA-land and discovered that myself and other very experienced and skilled telegraphists could copy signals up to 13dB below noise level provided they were not too fast, and with some repetitions, and 10dB below noise without too much difficulty. Given that an S meter unit is supposed to be 6dB (but could be 4dB on some radios designed to trick buyers into thinking they are more sensitive), this means around 2 S points. So with a noise level of S5 one would be unable to copy a signal less than S3 (in CW) and SSB is worse, one cannot copy SSB below noise level.

Therefore a signal report of RSN 357 would make a lot of sense: you are having difficulty to read the signal (R=3), the signal is estimated to be S 5 as you can barely copy it, with the local noise level at S7. This is far more meaningful than RST 359 — why is your signal R=3? Because of other stations QRM? If yes, they can add QRM. If due to atmospherics they can add "QRN". But if it is local noise, there is no real code for it (and there should be) but also, how much local noise? Knowing the other station has a local noise level of S7 is interesting and puts it all into perspective.

Likewise, if you are on an amateur band with the current local noise level on an empty frequency at S3, then you will give a report for that same S5 signal as RSN 553 or RSTN 55N3 (5593).

What do you think? Is it not time that we start measuring and sharing (optionally, should we wish) our local noise levels? Would that not be interesting? The RSN (RSTN) system would be, we think, the easiest way to do this without re-inventing the RST system. CW stations may optionally leave out the T and send an RSN report, just as those on phone, since T is always 9 anyway.

I'd be interested in your replies, and some of us may like to start giving RSN reports — I am sure hams would be very interested to receive an RSN report of say 586 and would quickly work it out what it means. It may be quite fun to start using it and see if others also adopt it, or comment on it. In any case, it will not be difficult to publish and popularise this method of RS(T)N signal reporting via such means as Wikipedia and other reference points.


I think you have an interesting idea here. Posted on my blog KB6NU.comDan, KB6NU, CW Geek, Ham Radio Instructor, Author of the "No Nonsense" amateur radio license study guides

The Tone element of any report would appear to be unnecessary in the 21st century — Doc, VK5BUG

What a great idea and how long overdue is this reform !
I virtually never send Morse these days but I do copy stations sending 5nn over and over [especially during contests] and I think, what a nonsense report.
Getting the idea over amongst a few Morse stalwarts may take quite a bit of time and would be confusing if used on DX so I would suggest that you bounce the proposal off the ARRL, RSGB and WIA / RASA. — Steve, VK3HK

That all makes good sense to me. RSN, would soon be understood by most cw ops. — Dave, VK4YD

Read Lou's comments with interest and i am inclined to agree with his findings. I have long given Signal reports which are not really S meter readings (they are pretty meaningless) but what one gets "between the ears"
Noise is certainly a factor which is seriously affecting most folk who have near neighbours.
I like the idea very much… If I ever find anyone sending me this new type of RSN / RSTN I might realise what it is and reply accordingly/RSTN —David, VK3DBD

I have been dubious about RST reports for some time. I have three receivers side by side (FT817ND, FT891 AND TS680S) and from the same antenna the noise level varies between 817 S7, 891 S1 and the 680 S5. So I always give S reports empirically. I believe most CW operators have little confidence in the RST system hence the ubiquitous 'RST 5NN' report.
It probably makes sense to give the RSN at the start of the QSO as part of the confirmation of the contact, along with the call sign and name of the operator. If the report drops back significantly during the QSO perhaps you could send 'RSN now 356'. — Tony, VK3TP ex VK3CAB

Agree with all your logic. Every time I send a report such as 359 I feel I need to explain it, but even following it with "QRM" isn't adequate, because the other op might well wonder why I choose to operate on a freq with such bad QRM! The answer of course is that the QRM might be 50kHz wide (often OTHR or RFI) meaning I need the other station to be strong enough to get over the interference.
So it would be great to have a more useful signal reporting system, such as you propose.
As the challenge would be around education (breaking long-established traditions) and getting adoption, I wonder if you ought to submit your ideas as an article to QST and/or some other magazines? I bet it would create a lot of discussion and maybe generate the sort of support needed to change habits. — Neil, ZL1NZ

It could even be useful in a CQ to add Nn (e.g. N9) so callers would know the noise level and why they may not be heard - Lou, VK5EEE

Wonderful post on KB6NU! I toss laurels & accolades to your thinking, dedication & Elmering! "Communication" carries the burden/responsibility of communicating information; useful, important, needed data. Guess what chart now hangs in my shack :o) — Phil, WF3W

A great idea for the conditions and circumstances of current day radio communications. From my point of view and with the situation of daily QRML that I face and further more it seems to me that the "responsible" authorities are doing nothing to assist us, at least if one adopts this system of reporting in a QSO the other person in the contact will know in more detail what is happening with our signals. I am 100% totally in agreement with your explanation and recommendations. I hope that our colleagues will take up this idea and adopt it in the near future. I am in complete agreement with your opinion that in these times in practice as you clarified it the T isn't necessary. — Manolo, VK3DRQ

I really like the RSN/RSTN system and sure won't mind if it catches on. — Chas, VK8HW

Today I was pleasantly surprised on two occasions in QSO with JL1MUT and later with VK8HW to receive RS(T)N reports. It's interesting looking in the log at the history of my local noise levels. I like that this is optional, voluntary, and does not contradict with the existing RST system. In electronic logs allowing only 3 fields for RST one could use the T field for N - it would be clear that numbers that are not 9 are Noise level numbers. — Lou, VK5EEE

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