What Is FMN & NFM and Are They Equal or They Different?

[paulears]

Sadly, you totally miss the point, and I doubt I can explain it to you. I understand the point you're trying to make, but the first mass market use for the FM mode was broadcast radio. Every one had the letters FM emblazoned on the front. Using today's nomenclature, it should have said WFM. Advancing technology realised the problem of description. In the 80s, comms FM was F3E - now we have much more tightly defined terminology for what we consider to be the same thing.

My point was that WFM and NFM do signify something - or maybe point towards the need for prodding a button? FM, without any first character is a generic term and not a specific guide to deviation level.

I suspect we're both being a bit pedantic about something we both know quite well, but describe differently?

 

[Voyager]

My point was that WFM and NFM do signify something - or maybe point towards the need for prodding a button? FM, without any first character is a generic term and not a specific guide to deviation level.

I suspect we're both being a bit pedantic about something we both know quite well, but describe differently?

OK. Maybe broadcast FM was the first FM mode. I won't debate that point.

But, FM without any other designation (letter/s) also denotes a specific guide to deviation level (specifically, 15 kHz deviation).

Let me ask you this: What do you use for the FM mode that is emission designation 36K0F3E? For example, 16K0F3E or 20K0F3E is Narrowband FM (NBFM) per the EIA. 11K0F3E (or 11K2F3E) is Super Narrowband FM (SNFM) per the EIA.

What is your term for the 36K0F3E mode which was used by Land Mobile and ham radio until the 60's? (that mode used 15 kHz deviation).

(and yes, I know I errantly said 30K0F3E above - corrected to 36K0F3E - 30 kHz was the channel spacing at the time)

 

[paulears]

This is the problem - the key feature is that over the years one part of the spec has remained constant - the F3E component in the modern spec - this is FM. In the 70s, 36K0F3E was NFM, and it didn't get any narrower. SNFM is a designation that's creeping in now, because we have it. My point is that we've never had a sub divider called FM. We've had for all of my life two as the minimum. WFM and NFM - both being FM. Now we appear to have WFM, NFM, and now SNFM. This is fine. I cannot subscribe to the fact that there is an FM in between N and W, that's all. FM always denotes mode, the extra letter designate, or at least attempts to describe the type. If it's not narrow, it's wide (or supper narrow).

36K0F3E if it has existed back then would have been called narrow, because back then, it was!

 

[Voyager]

Yet - I've never heard it called NFM - only FM. Is there any documentation for the "NFM" 36K0F3E mode?

There is also the ever-popular NBFM which was not called NFM - ever. NBFM (NarrowBand FM) is the technical designation for those modes 16K0F3E and 20K0F3E. I still recall all the stickers "Adjusted to Narrowband FM +/- 5 kHz deviation".

SNFM has been around since the 90s. It just never got very popular, but is technically the correct term for the mode 11K2F3E per the EIA.

 

[paulears]

You are making the very common error of using current jargon as a a technical 'standard' - something that has accurate and definitive boundaries and definitions. The problem is that jargon like this only relates to contemporary use. So only now will it be accurate with the current understanding. we've done it for years - and as long as the jargon is used correctly, it's no big deal. USB is a good example. There is SSB, which has two variants, of which USB is one. The bandwidth of USB communications was always a bit hit and miss, so we could now be using terms like EUSB - where the E stood for extreme - where the useful part was shifted further from the centre nominal frequency, and perhaps MUSB where a moderate amount of shift was used instead. Nobody had a need for discrimination so it never happened. It was even dafter with domestic radios when they added the new VHF band. We had LW, MW and SW - but they added FM? It could, and perhaps should have been called VSW for Very short wave, but they chose FM instead.

As for the designators, we've traditionally in the UK followed the ITU system for categorising emissions, but the American standard creeps into designs originating over there. This is why you cannot really go backwards in time and re-categorise old techniques using US systems. Well, you can, but what's the point?

If you want to take this off the forum to PMs, it's fine with me - because we're wasting people's time here. Your profile doesn't say where you are. So we may just be arguing about a transatlantic difference. After all if we cannot agree on what the word 'pants' means, it's a bit silly arguing about FM. Pants, by the way are what you wear underneath trousers. You may never have heard FM used as I describe simply because you're in the wrong place (or I am). Here in the UK, FM is the modulation type, and has never had a bandwidth implications - that's what, as I've said, the extra letters are for.

Interesting to a few, perhaps but ultra dull to most I guess. Shall we call it a draw? Cultural differences is a good explanation that works for me - I understand how difficult it is for Americans to handle English. (That is a joke, honestly).

 

[Voyager]

So you are saying the nomenclature is as follows:

NFM = 36K0F3E
NBFM = 16K0F3E (or 20K0F3E)
SNFM = 11K0F3E

Is that what you are saying? If so, please provide a source for the NFM designation for 30K0F3E becasue I've always read it as follows:

FM = 36K0F3E
NBFM = 16K0F3E (or 20K0F3E)
SNFM = 11K0F3E

I'm in the USA, so there could be a cross-pond variation involved.

I know in your area they are now using NAM for aircraft while we still use AM, and I'm quite certain it is and always has been called AM. But, as yet there are only two AM modes. Maybe in 50 years two guys will be having this discussion and one will say there was never an AM - only NAM and WAM.

 

[nd5y]

I know in your area they are now using NAM for aircraft while we still use AM, and I'm quite certain it is and always has been called AM. But, as yet there are only two AM modes.

They didn't change the bandwidth. It's still 6 kHz (6K00A3E). All they did was change the channel spacing from 25 kHz to 8.33 kHz. There are some examples of this in the US already but not for air traffic control.

 

[Voyager]

OK. I know there is a NAM mode on some receivers as well as an AM mode.

Maybe it just uses tighter filters (like 7.5 kHz rather than 15 kHz).

 

[paulears]

I'm not sure I can respond any more clearly than I have. I am saying that the new and current assignment of codes to bandwidth seems to work now, but is difficult to re-apply to the past, although it does do that - I'm uncertain of the point though?

AM, on it's own, like FM means nothing whatsoever until it sits in a context. So If you say AM airband, then you can go ahead and have an inferred bandwidth. You can say, up until just a short while ago that airband is AM. We now have to add NAM - but that's just a limiter. Narrow in this case is different from the Narrow in FM systems. It means narrow. I'm just going round in circles. You want to tie down specs to descriptors and this is a contemporary useful system. I do not subscribe to the fact that the letter means anything other than Wide, or narrow, teeny-weeny, or maybe miniscule. Feel free to ascribe whatever code you think fits. I think what you are doing is attempting to be ultra-prescriptive to what is simply a helpful guide. All the licenses I have, have specifics, either in numeric values or our Internationally agreed designators. At the moment, this is all that really matters. for convenience, I use WFM NFM - I use NFM for 25 and 12.5KHz channels - you don't. We don't agree - this is fine.