In article <MSMed.9418$6q2.8375@newssvr14.news.prodigy.com>,
Rob Dekker <rob@verific.com> wrote:

I never understood this remark (you made it several times). Isn't it true
that any
signal, broadband or narrowband, always has 'adjacent channels' ?
I mean if a signal is 1Hz wide, and we conclude that because the adjacent
1Hz

channels show lower (noise) power, then is that not similar to a signal of

1MHz with
adjacent channels of 1MHz showing lower (noise) power ?

Using adjacent channels as a reference works for narrowband signals, because
there are no natural narrow band signals.  It doesn't work well for broadband
signals as, on that scale, natural signals could be contained within the
bandwidth, so you cannot assume that the in channel noise is identical to
the adjacent channel noise.