milf said:
OK here is the best place to debate whats really the best way to talk about all these matters.
OK, since we have to for some reason start a NEW thread about this, let's start off on the right foot:
Let's list some industry standards first.
Wide FM = +/- 75 kHz deviation, or about 200 kHz bandwidth.
Standard FM = +/- 15 kHz deviation or about 40 kHz bandwidth.
NarrowBand FM = +/- 5 kHz deviation or about 16 kHz bandwidth.
SuperNarrow FM (AKA SNFM) = +/- 2.5 kHz deviation, or about 11 kHz bandwidth.
Of these four, Wide FM is used by FM and TV broadcast. (that's about it)
Standard FM is almost extinct, being used by a few hams as links and by the military.
NarrowBand FM is used by nearly everyone, and has been for the past 30+ years when the switch was made from standard FM to NarrowBand FM. There are even some transceivers out there marked "Converted to NarrowBand FM - 5 kHz".
SNFM started showing up a few years ago and is used on the new "7.5 kHz channels" on VHF (such as 155.1675 MHz), and on some 12.5 kHz splinter channels (as well asa few standard channels) on UHF. It is called narrowband FM by some manufacturers, but that does little but confuse most users - especially those in the industry and those who have been around when NBFM came into wide use in the 60s. It is unfortunate that one scanner manufacturer has chosen to use the term 'NFM' for what is really SNFM, and FM for what is NBFM, but everyone can see the confusion that is causing.
When the switch from FM (40 kHz BW) to NFM (15 kHz BW) was made in the 60s, it more than cut in half the bandwidth of every signal. As you can see, going from NBFM (16 kHz BW) to SNFM (11 kHz BW) does not yeild a doubling of the available frequencies per se. At best, it gives you nearly 1/3 more spectrum. Of course, the problem is that until all the users convert from NBFM to SNFM, NBFM users will greatly interfere with operations on SNFM channels.
Things are bad enough trying to use 16 kHz BW signals on 15 kHz BW channels. Many people know this listening to scanners and hearing strong adjacent signals blead over to the channel they are trying to monitor. But, they will be much worse when (or IF) the conversion is complete and people are using 11 kHz BW signals on 7.5 kHz BW channels. Someone does not know simple math at the FCC, I guess.
The reason you can't use simplistic 'wide' and 'narrow' terms for talking about NBFM and SNFM (respectively) is because you leave no room for describing more than two FM modes unless you invent completely new terms for Standard FM and Wideband FM as well. Even IF you do that, there will then be two sets of terms - one used by the industry, and another used by hobbyists. That will only serve to make hobbyists sound like a bunch of fools who can't understand industry standards enough to use them right. The standards are out there - we should ADOPT THEM, NOT MAKE UP OUR OWN :!:
If someone comes on asking if the PRO-96 receives Wide FM, how do you know what he is asking about? Is he asking about industry standard Wideband FM (such as TV broadcast audio), or standard NarrowBand FM (which some people are calling Wideband FM)? The only way to keep everyone on the same page is to use the SAME TERMS, and it may as well be the same terms the industry uses.
As I said before, if you use only Wide FM and Narrow FM for talking about NBFM and SNFM (respectively) is that you are then faced with issues such as:
The BC296D receives Narrowband FM, Wideband FM,
AND Wideband FM :!: :shock: :roll:
Joe M.
