Timewave DSP-232, Operating Manual

Page: 170 / 271

Chapter 9 AMTOR Operation
Mode: AMTOR ARQ Host: Ao
“
n ” 1 to 5, specifying a relative tolerance for bit boundary jitter.
ARQTOL controls the tolerance for received bit boundary jitter in the AMTOR ARQ mode. “ n ” is a number from 1
(tight tolerance) to 5 (loose tolerance). The number signifies how far away from the expected bit transition time the
actual received transition may be, in tenths of a bit (mS). If the transition occurs further away than expected, the
received block is counted as an error, even if all three characters in the block appear to be valid AMTOR characters.
The default value of
ARQTOL 3 is the equivalent of the fixed tolerance of previous firmware releases.
ARQTOL should be set to a low number (tighter tolerance) for applications that require nearly error-free
communications. The tradeoff is that good received character blocks are counted as bad if the bit transitions are
suspect, thereby causing retransmissions and lowering the effective character rate.
ARQTOL
doesn’t affect
FEC
,
SELFEC
or
ARQ
Listen modes.
ARXTor ON|OFF
Default: OFF
Mode: AMTOR, PACTOR Host: Ar
OFF Disables the automatic detection of non-selected operating modes.
ON Enables automatic detection and switching between AMTOR and PACTOR modes.
ARXTOR allows the automatic switching from PACTOR Listen mode to AMTOR FEC receive and from PACTOR
Standby to AMTOR ARQ. It also allows the automatic switching from AMTOR Listen to AMTOR FEC receive.
With
ARXTOR ON
, an AMTOR FEC signal is detected by
ALIST
and
PTLIST
modes as well as AMTOR
Standby mode. AMTOR Standby, ALIST and PTLIST all use FEC idles to recognize FEC transmissions. In the
AMTOR Standby mode, however, FEC text patterns are recognized as an additional quick recognition method
which may speed locking onto a FEC signal.
ARXTOR ON
enables
PTLIST
mode to monitor AMTOR ARQ transmissions. It also means an incoming AMTOR
ARQ call is recognized in PACTOR Standby mode. Only a call for the selcall in MYSELCAL is recognized;
PACTOR can’t detect ARQ calls to
MYALTCAL
or
MYIDENT
.
When a PACTOR mode detects an AMTOR transmission, there is an added delay before the text is shown. Your
TNC must switch from PACTOR to AMTOR, where the signal is again detected. For fastest detection of AMTOR
FEC, your TNC should be in the AMTOR Standby mode. For fastest syncing on AMTOR ARQ signals, the TNC
should be in
ALIST mode.
At the end of the new mode (AMTOR ARQ or FEC), your TNC returns to the original monitoring mode (
AMTOR
,
ALIST , PACTOR or PTLIST ).
ARXTOR is defaulted OFF to accommodate old application programs that have no provision for handling a
spontaneous change of modes from PACTOR to AMTOR.
Here’s a summary of the AMTOR/PACTOR mode switching:
Original Operating Mode
Target mode detection AMTOR ALIST PACTOR PTLIST
AMTOR FEC if RFEC if ARXT if ARXT
AMTOR ARQ ( MYSELCAL ) always if ARXT
AMTOR ARQ (
MYALTCAL
) always
AMTOR ARQ ( MYIDENT ) always
Monitor AMTOR ARQ always if ARXT
September, 05 9-11