improving TX clarity

[Patrick Perdue]

A while back, Chris, VE3RWJ made a suggestion to add an optional clarity
boost to improve TX audio, with a bit of a slight boost in a couple of
bands around 1.5 and 2..5 kHz or so, which I think is a great idea.

I was just playing around with some audio recorded to my parrot node
(55553) from Repeaterphone using an old version of SoundForge. Turns out
that, when at 8 kHz, the smooth/enhance preset "boost high frequencies"
is pretty much exactly the kind of curve that would work well for
getting some user's audio out of the mud. I think this would especially
be useful when audio processing is enabled, as it would be for almost
all use-cases.

I've attached two short pink noise samples here, each is 1 second long.
The first is with no processing, the second is with smooth/enhance
applied. Both wave files are at 8 kHz sampling rate, 16-bit mono, just
so you can hear, and especially see the difference in equalization
between the two, if you want to try creating a similar EQ curve yourself.

73

N2DYI