6 Commands
47
If
AP
is set to 200, the PTC-IIIusb will never set the PSK output level below 200 mV.
That means that with a PSKA value of 140 (setting of the maximum PSK amplitude
value, refer to the
PSKAmpl
command, chapter
) and an
AP
of 200 the
power never will be reduced.
If the
PSKA
value is 140 and the
AP
is 70, e.g. the amplitude of the
PSKA
output signal of
the PTC-IIIusb will at a maximum be reduced by the factor 2 (maximum power reduction
by the factor 4).
The setting of the minimum amplitude allows a limitation of the auto power adjustment
range. This is sometimes obvious and necessary: Some transceiver only operate proper in
a limited power range. This can also increase the average throughput in rapidly
fluctuating channels.
In most of all cases the auto power can be switched on with
APower
1.
6.5
AQrg
Default setting: 1
Parameter: 0 Automatic carrier frequency compensation switched off.
1 Automatic carrier frequency compensation for PTC-IIIusb switched on.
The PTC-IIIusb uses two totally separate compensation methods for frequency error
during DPSK operation. The phase error on receive caused by frequency offset is always
relatively quickly compensated, switching off this function, which is essential for PSK
operation, is not possible.
AQrg
1 activates the second, additional compensation method:
The PTC-IIIusb pulls the two carrier frequencies of the modems (DSP) slowly towards
the set value. This, in contrast to the pure error phase compensation, also influences the
focusing indicator (The QRG-Display LED, which slides slowly back to the center
position). To prevent completely drifting away from the chosen frequency, the PTC-
IIIusb uses Master/Slave tracking. This means that the Slave station (Called by the master
station) only adjusts its receive frequency, but the Master station (initiating the contact)
adjusts synchronously both the RX and TX frequencies (relative to the measured offset of
the RX frequency to the set value). Depending on the cycle length and actual signal ratio,
as well as on the size of the QRG error variegates the frequency adjustment speed. On
average it tends to be around 15 Hz per minute.
6.6
ARX
Default setting: 1
Parameter: 0 AMTOR phasing disabled.
1 AMTOR phasing enabled.
With
ARX
0 it is not possible to obtain an AMTOR connect in the standby mode. Also
the reception of AMTOR FEC and NAVTEX is disabled.