Send a calibration signal on a specified radio/port/channel
Syntax: CAL <ch> <mins> <CR>
The CALIBRATE-Command turns on the TX of a specified port (parameter
<ch>) for one minute. While this time the carrier is modulated by a continuous
sequence of 0 and 1, producing a "diddle" tone with a 50:50 ratio. The command
is useful in 2 cases: - It makes it possible for the link partner to set his antenna to
the right direction. - The symmetry of the modulation may be checked and the modem maybe
adjusted for best results. If there are frames in the buffer, they are sent before the
calibration starts. To trigger the PTT watchdog the CAL signal is interrupted every 15
seconds for a short time. Optionally, the calibration time in minutes may be given.Default
is one minute. With the command "CAL <ch> 0" the CAL signal is cancelled.
