Kai Schulte wrote:
>
> On Mon, 13 Sep 1999, Thomas Sailer wrote:
>
> > And if HAPN works on your HT, then you were lucky, it won't
> > work with most HTs.
>
> Why not? The spectrum vanishes at 0 Hz, so the PLL should have no
> trouble. What else might be a problem?
>
> I used to do 4k8 HAPN duobinary with a c528, and it worked ok (provided
> the afsk1200 people using digital squelches weren't trampling on my
> signal...)
My HT's start to cut off very sharply at aroudn 2.4kHz, that's where
the maximum of the HAPN spectrum is.
That doesn't mean that there are no chances recovering the signal
if you are willing to do a lot of work. I've successfully sent
a 9k6 G3RUH like signal over a c701 and was able to recover it with
an acceptable bit error rate i.e. something that could have been
recovered with a high rate ECCode.
However, no HAPN modem I know of does this and also the HAPN modulation
does not include known training bits for an equalizer which makes the
task even more difficult. And then there's always the startup delay
problem.
Tom
