US Robotics COURIER - High-Speed Modulation (V.32 bis;HST)

COURIER HIGH SPEED MODEMS
CHANGING SETTINGS
When you change a setting, the modem retains it until you do
one of the following:
•
Change the setting.
• Issue
the A TZ command to reset the modem. If DIP
switch 10 is OFF, the modem resets to the defaults stored
in nonvolatile memory (NVRAM). If DIP switch 10 is
ON, the modem resets to the factory settings stored in
read-only memory (ROM).
• Issue
the AT &F command to reset the modem to its fac-
tory settings.
•
Turn the modem off, and power it on again. The
modem then loads either the nonvolatile memory
defaults (DIP switch 10 OFF) or the factory settings (DIP
switch 10 ON).
HIGH SPEED MODULATION: V.32 BIS/HST
At high speeds, USRobotics modems use either V.32 bis
modulation or HST modulation, unless they are Dual Standard
modems that have both capabilities. By high speeds we mean
calls at 16.8K (HST-to-HST only), 14.4K, 12K, 9600, 7200 or 4800
bps. (The modems use identical, standard modulation at 2400
bps and below.)
Modulation Settings-an
The modems are set at the factory as follows:
V.32 bis modulation-BO. V.32 bis modems are always set to BO.
Dual Standard modems are factory set to BO so that they connect
with both V .32 bis modems and HST modems.
HST modulation-Bl. HST modems are usually set to Bl. How-
ever, they can be set to BO to answer international calls.
Under V.32 bis modulation, data flows at the same rate in both
directions. Under HST modulation, data flow is asymmetrical:
the high speed in one direction and 450 bps in the other. The
modems switch the fast and slow channels when the volume of
4-2 Interface Controls
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