Specifications

Excalibur Multirate DAP Installation and Operation
5-40
Speed
This parameter specifies the speed the DAP automatically switches to when it originates
a dial backup connection. The answering unit adapts to the originating unit's speed if the
answering unit is set for a higher speed than the originating unit. If the answering unit is
set for a lower speed, the connection will be made at the answering unit's speed except
when it is set for 2.1, 2.4, 4.5, or 9.0 Kbps. Although the lowest data rate at which the
modem in the IDBU can operate is 4.8 Kbps, the unit is able to support a synchronous
DTE operating at 2.1, 2.4, or 4.5 Kbps. When the dial backup connection is made, the
IDBU automatically sets up the call at 4.8 Kbps and performs rate adaption so the DTE
port continues to operate at its current speed. When the DTE is operating at 9.0 Kbps, the
IDBU automatically sets up the call at 9.6 Kbps and performs rate adaption so the DTE
port continues to operate at 9.0 Kbps. Rate adaption and CCITT V.14 compliant
asynchronous/synchronous conversion are provided only when the dial backup
connection is between two Excalibur DAPs.
Transmit Clock
This parameter specifies the source of timing signals for the dial backup port's transmit
clock. This clock determines the rate at which data is transmitted across the dial-up
telephone line. The available options are:
• Internal - data is transmitted synchronized to the DAP's internal crystal.
• External - the transmit clock derives timing from an external clock source. If an
external transmit clock source is selected but is not present, the port
automatically reverts to internal transmit clock mode. This option is not
available when the speed is set for 2.1, 4.5, or 9.0 Kbps.
• Slave - receive (Rx) channel timing is slaved to the dial-up Rx line and transmit
(Tx) channel timing is slaved to the Rx channel timing. Data is transmitted
synchronized to a clock derived from the receive line.
Dialer
This parameter specifies the method of dialing used by the DAP. When Autosense is
enabled, the DAP automatically determines the proper dialing method. It begins by
dialing the stored telephone number using tone dialing. If a dial tone is detected after the
first digit, it redials the number using pulse dialing. If your calls are placed through a
PBX system that does not provide standard dial tones, you must then select Tone or
Pulse, depending on your calling facility.