SCS PTC-IIex, Manual

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9 Packet-Radio
The most frequently done mistakes according to wrong times are:
•
At connect establishment all attempts of the PTC-IIex are transmitted in very short
distances.
•
On a DAMA-Digi it could happen that suddenly the connection hangs. Digi and PTC-
IIex exchange RR frames only.
Please search for the following commands,
CHeck
,
FRack
,
RESptime
,
SLottime
and
TXDelay
, in the initialization file of your program and check the settings. In any
case you have to adjust the TX delay (
TXdelay
) due to your needs. It is possible to
delete all other commands within the initialization file or take the default settings.
9.3 Robust HF-Packet
For the selection and configuration of the robust modulation for HF-PR no special
commands are necessary. The selection of the modulations type follows the usual way
with the
Baud
command in the pac: menu or
%B
command in hostmode. The transmit
level is taken from the
PSKAmpl
(PACTOR PSK-amplitude, refer to chapter 6.73 on
page 69 and chapter 3.3.4 on page 14 ).
The center frequency of the audio signal is fixed to 1500 Hz. On the receive side the same
side band as the transmit side must be used. We generally recommend USB.
With “Robust PR”-modulation selected the PTC assumes that a connection will be via a
HF Channel and adjusts a few parameters automatically.
MAXFrame is automatically administrated;
the value given by the user does not matter.
RETries is automatically doubled.
TXDelay is automatically divided by 4.
The default setting 100 results in the usual 25 msec for Shortwave.
RESptime is automatically halved.
Following additional Parameters of the
Baud
command are available:
Baud R300: During an X.25 connection automatic / self adaptive selection between
200 bit/sec and 600 bit/sec. UI-Packets (e.g. APRS) are transmitted in
200 bit/sec.
Baud R600: During an X.25 connection automatic / self adaptive selection between
200 bit/sec and 600 bit/sec. UI-Packets (e.g. APRS) are transmitted in
600 bit/sec.
The arguments valid for
Baud
are also available in the same form for the Hostmode
command
%B
.
As the Robust-PR demodulator automaticly detects which modulation is received, e.g. an
APRS network can successively grow or be adapted to the actual requiremens: If only a
few users are present but the distances are large then the longer but more robust
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