reprint from digitalradio digest number 3758

"David Freese" <w1hkj@...>

Being so close to another net frequency is not going to work unless you
provide a proper filter.

Using flarq efficiently you need to
* use a 500 Hz filter or better
* use a distance of 500 Hz.

We have tried to put 2 pskmail servers on a 250 Hz distance but they
qrm'ed each other in such a way that is was not feasible. We had to
increase the distance to 500 Hz.

To use a broad filter and let the DSP do the filtering is basically wrong.
The AGC will wipe out the flarq signal to the effect that all packets
are damaged and no transfer is possible.

To take advantage of the small bandwidth of PSK63 you need to have a
matched (100 Hz)
filter. If you don't have that it makes more sense to increase the
speed to PSK250.
That has the added advantage of being less frequency-critical.

Just some of the experience we gathered with pskmail...


Rein PA0R

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