6 Commands
84
sequence in the received SYNC packet, or for a
MASTER start no later than the begin of the data
packet.
0 1 1 AMTOR-FEC
1 0 0 PACTOR-FEC
1 0
1
RTTY / CW
1 1 0
LISTEN
AMTOR
or
PACTOR.
1 1 1 Channel-Busy RF
channel
busy.
Table 6.4: PTC status information, Bit 4-6
In STBY condition the PTC-IIIusb analyzes the HF channel and differs between
busy
and
free
.A
busy
channel is defined as all signals that are audibly distinctly different from
noise, but, however, having a speed < 250 Baud. Packet-Radio (300 Baud) is virtually
ignored. Furthermore, strong carriers on the channel are not evaluated as
channel busy
.
Even the very hard to detect PACTOR-2 signals were recognized. The PTC-IIIusb reacts
well even to short QPSK/BPSK sections, so that even the short PACTOR-2
acknowledgement signal is sufficient for the channel to be recognized as busy.
This function is essential for automatic stations, e.g.
WinLink
systems.
An occupied HF channel is indicated by a status value of 247 (Channel busy) being given
over the serial interface. After the PTC-IIIusb channel busy status has been activated, it
remains so for at least 3.5 seconds. An optical output is also given, with the
TFC
-LED
lighting up when the channel is busy.
The Channel busy status is only given in the STBY condition,
not
in Listen mode (L=1)!
6.91
SYStest
The system test is not normally required by the PTC user, but has been included here
for the sake of completeness.
SYStest
is purely a tool to diagnose and rectify faults
in defective PTCs'. In normal operation this function is not needed.
The command
SYStest
(without argument) activates the system-test menu. (
sys:-
menu). The command prompt takes the form
sys:
.
Within the
sys:-
menu the following systemtest commands are allowed:
Audio, AUDPerm, DD, Fsk, Help, Kill, Led, MONitor, PLl, Ptt,
Quit, Ram, SERNum, Trxtest.
All other
normal
commands are not available! The
sys:-
menu may be ended with
Quit
or
DD
.
The
SYStest
command may also be followed by an argument, which should be a
command from the
sys:-
menu. In this case, the PTC carries out only that given system
test command, without switching to the
sys:-
menu. The command virtually has been fed
through.
This command for example would show the PTC-IIIusb RAM expansion.
cmd:
SYS
Ram <Return>
For a detailed description of the SYStest commands see chapter
.