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 12, page 161.
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