That's interesting ...What I'm referring to as "narrowband" is the new NTIA
channeling plan for public service band beginning at 162.0125 and
progressing at 12.5 KHz intervals to create 942 channels through 174 Mhz.
Everybody calls it narrowband but nobody can explain why its any different
than what's in use now except for the channelization.

I know that I can set my TH-D7AG to the 4th decimal (e.g., a 6.25 KHz
increment), but I don't know if it's really doing what NTIA refers to a
"narrowband."


"Steve Nosko" wrote in message
...
The term has changed over the years and has a couple of definitions.

There is a 'mathematical' or technical definition where it depends upon
the
modulation index. I don't remember the number, but I think it may be
where
the modulation index produces sidebands such that those past the first
(Bessel order 1) have levels that are considered insignificant. [[ Be
advised, FM has sidebands to infinity...always]]

Then there is the practical or colloquial. Right now, 2.5 KHz peak
deviation is called "Narrow FM" because 5KHz is/was the 'norm'. When 30
KHz was the norm, 15 KHz was called narrow or "split channel". After 15
KHz
was established, 5KHz was split channel or narrow. And so it goes. Then
there was the QST article about "Micro band FM" with extremely little
deviation (An April spoof since it is not technically viable).

The multi-band Kenwood TH-F6 / F7 (144/222/440) is NFM capable. However,
I
suspect that they only cut the Tx deviation and leave the RX filtering the
same as 5KHz deviation...

By the way. The 15 KHz channels currently used by US hams are not what
the
5KHz deviation is designed for. 15 KHz. is actually "alternate" channel
operation and is only intended for systems with enough physical separation
to keep the adjacent channel energy low enough to cause trouble.
A 5 KHz system can not 'normally' handle 15 KHz spacing. The sidebands
are not, and the required Rx filtering can not be made compatible with 15
KHz spacing. The two are mutually exclusive. 5 KHz deviation has
significant sideband energy in the adjacent 15 KHz channel and the RX
filtering required for the 5 KHz deviation must be wide enough to accept
this energy in order to provide acceptable distortion on channel.

--
Steve N, K,9;d, c. i My email has no u's.




"Richard G Amirault" wrote in message
...
What is "narrow-band FM"??? Some could say that *all* FM ham radios use
"narrow-band" ... compared to a FM broadcast station.

Richard in Boston, MA, USA

N7RX wrote:
: I need a multi-band HT that does cross band repeat and has narrow-band
FM
: capability. Look like the IC-w32a is the only one that meets this spec.
: Anybody know of another?

: If not cross-band capable, how about a multi-band that is NBFM capable?

: 73 Neal N7RX