Black Box 32144 Manual page 161

3.16.3 D P
ATA UMP
Phase Reversal in Answer Tone
All modes
When enabled, the Phase Reversal
in Answer Tone option signals the
telephone network to turn off its
echo cancelers. For virtually all
applications, phase reversal should
be enabled (the default setting).
Satellite Delay
208, V.32/208 modes
This option facilitates
transmission over satellite links
(but does not permit fast-turn-
around operation). When the
Satellite Delay option is on, RTS
is inhibited for 275 ms after the
answer tone stops and after the
DSR signal comes on. This delay
occurs at both the originating and
answering modems, allowing the
echo suppressors on the telephone
link to be enabled.
Turnaround Delay
208, V.32/208 modes
This option is intended for circuits
where echo is a problem. It pre-
vents the modem from receiving
an echo of its own transmitted data.
When the Turnaround Delay
option is on, CD (pin 8) is held low
for 150 ms after RTS is turned off.
If the modem detects an energy
loss during the delay, it turns CD
on 52 ms after detecting the loss. If
CHAPTER 3: Options: Customizing the Modem Setup
O
PTIONS
the modem does not detect an
energy loss, it turns CD on 52 ms
after the end of the delay. The
modem ignores any energy loss
during the first 8.5 ms.
V.32 Mode
Hayes, V.25 bis, Dumb, Leased-line
modes (except V.33)
This option is used to select
CCITT V.32 bis operation or V.32
extended operation.
V.32bis. When V.32bis mode is
selected (factory-default setting),
the following are available: Rate
Renegotiation Procedure (RRP),
a data rate of 7200 bps, and a
RATE screen that allows the user
to manually initiate RRP.
RRP enables the modem to
automatically fall back or fall
forward to a lower or higher data
rate during data transmission in
response to changes in signal
quality. Selecting V.32 bis mode
makes RRP available as an option;
however, RRP will not function
unless it is enabled. (Enabled is the
factory-default setting.) RRP is
described fully in Section 4.3.2.
When V.32 bis mode is selected,
a RATE screen is available from
MAIN MENU screen 3. The RATE
screen can be used to manually
initiate RRP for diagnostic
purposes. For additional
information, see RATE CHANGE
SCREEN in Section 8.7.
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