"Telstar Electronics" wrote...
I suggest you review
http://en.wikipedia.org/wiki/Frequen...dulation_index
for details.

And I suggest that you learn the theory, rather than relying
on Wikipedia to try outwitting techs.
Some important things to note...
1. Wikipedia is only as accurate and complete as the
information put in by the public.
2. Wikipedia is no substitute for proper training.
3. One line or paragraph does not explain everything.
4. The real clue may be in the text - "approximately".

Your linked reference suggests that when the modulation
index is below 1, the bandwidth is approximately twice the
modulating frequency.
Bandwidth = 2Fm

If you are relying on such a simple, crude and innacurate
approximation, it only serves to show that you have neither
true technical knowledge or experience of FM CB.

If only you had read a little further, you would have
spotted another approximation that appears to dispute
the above method:
Bandwidth = 2 (Fd + Fm)

Note that the first approximation method does not include
deviation, and does not appear to define bandwidth.
As the sidebands are infinite, using the term bandwidth
without defining a level is like using dB without a reference
or level.
The second method includes both deviation and modulating
freqency, and does define bandwidth within the text.

But those are only approximations, a better idea of bandwidth
may be obtained from real figures...

With the CB audio bandwidth, the second sideband spreads to
over half way to the next channel, while the third sideband
spreads out to just below the adjacent channel carrier frequency.
A receiver cannot block these without blocking the wanted signal.
So while we can ignore the first sideband, anything above that
should be kept to insignificant levels.

At a modulation index of 1:
Second sideband = 11.5%
Third sideband = 2%
At a modulation index of 0.8:
Second sideband = 7.6%
Third sideband = 1%

These are NOT insignificant levels. Here in the UK, because
of legal restrictions of the day, many people once run on
just 10% (400mW) total power - and got decent distances
on it.


Bottom line...

Bottom line is that you are only interested in sales, and
you will say whatever it takes to get those sales.

Some of us, who have had FM CB from the beginning
in 1981, have already seen the sales tactics used. The
deception, selective facts, bending of reality and
outright lies used to make a sale.


Regards,
Peter.