SCS PTC-IIex, Manual

Page: 153 / 220

10 Hostmode
the PC program too low), the buffer is automatically cleared again (4096 samples are
lost). Besides that, the FAX buffer is always cleared automatically when hostmode FAX
reception is activated.
When hostmode FAX reception is active, all PACTOR relevant functions/tasks are
blocked, i.e. PACTOR calls can neither be initiated nor be accepted. (Not all
corresponding commands are blocked. The user itself must be aware of this if a PC
application program does not already limit the command set available during hostmode
FAX operation.)
All other processes which do not access the HF port (UHF/VHF Packet Radio,
particularly the TRX control) are still availble during hostmode FAX reception.
The “extended hostmode” logic (channel 255) includes channel 252.
10.4.23 @K
The KISS-Mode is activated with the commands
KISS
or alternatively
@K
out of the
normal command mode. This usually happens automatically by the KISS-PC-software or
a KISS capable controller (e. g. TNC3). The KISS-mode is terminated by a system reset
(power off/on cycle), but can also be terminated by software with sending the decimal
byte sequence 192, 255, 192. The termination by sending the byte sequence is usually
done automatically by the software as well, and may just once be configured correctly in
the setup of the program.
10.4.24 @S
If hostmode FAX reception (refer to 10.4.22 , Page 138 ) is activated, the additional
hostmode command @S is available. It allows access to the 16 bit wide audio samples
from the A/D converter on the HF port. The @S command does not require a parameter.
The audio sampling rate is 9600 samples per second and cannot be changed. As soon as
the modem recognizes a @S command, it starts acquiring 1024 16 bit samples on the HF
port. The samples are directly (no filtering, no AGC) written to a data buffer and can be
retrieved from there on hostmode channel 251. Thus the modem generates 8 hostmode
data packets (with data field length 256) per @S command. Every 16 Bit sample is split
into 2 bytes, the less significant byte (lower half of the 16 bits) appears first.
The @S command can be used for displaying the frequency spectrum of the input signal
on the HF port.
The “extended hostmode” logic (channel 255) includes channel 251.
10.4.25 @T2
Default setting: 500
Parameter: X 1... 30,000, response time delay
Sets the value for the AX.25 timer 2 (T2) in milliseconds.
After receiving a packet the PTC-IIex waits the time T2 to check if another packets
follow. If so, all packets can be confirmed with only one control packet.
139