[RTTY] AE4JY HF path simulator

[f6irf at free.fr]

re my previous email

If you try "pathsim" don't be surprised to find out that you are able to decode
CW down to -19dB in 3kHz BW, while K1JT chart shows the human limit around
-14dB in 2.5Khz BW for 12WPM CW... (AWGN channel)
It does not mean that you are "superman" or that K1JT is wrong or that there is
a bug in AE4JY simulator, just that K1JT graph obviously takes the peak-power
values(1), while pathSim additive noise level responds to a slow AGC, which
means according to the signal "mean power" as defined below(2)
The ratio between mean power and peak-power is about 4.5dB for a typical
CW-message at normal "weight", thus the difference...
Of course it has almost no impact on RTTY for which peak and mean power values
are very close.
Patrick

(1)it has the advantage of not being "message dependant" even for modes like CW
or Feld-HELL.
(2)mean power (of a radio transmitter): The average power supplied to the
antenna transmission line by a transmitter during an interval of time
sufficiently long compared with the lowest frequency encountered in the
modulation taken under normal operating conditions.