Nortel Networks Circuit Card - Manual (Page 750)

Page 750 of 906 NTAK79 2.0 Mb PRI card
553-3001-211 Standard 3.00 August 2005
Switch SW1 – DCHI Configuration
This switch enables/disables the on-board DCHI and sets the operating mode
of the DCHI. DPNSS1 mode is not supported at this time. For all other
countries that do not use DPNSS, use Q.931 mode.
Switch SW2 – Carrier Impedance Configuration
This switch sets the carrier impedance to either 120 ohms or 75 ohms.
Twisted pair cable is usually associated with 120 ohms. Coaxial cable is
usually associated with the 75 ohms setting.
Switch SW3 – Clock Controller Configuration
This switch enables/disables (H/W) the on-board Clock Controller. Disable
the SW 3-2 if the on-board clock controller is not in use.
Table 240
Switch SW1
Switch Down (On) Up (Off)
SW 1-1 enable DCHI disable DCHI
SW 1-2 DPNSS1/DASS2 Q.931
Table 241
Switch SW2
Cable Type SW 2-1 SW 2-2
75 ohms Up (Off) Down (On)
120 ohms Down (On) Up (Off)
Table 242
Switch SW3
Switch Down (On) Up (Off) Note
SW 3-1 — — Spare
SW 3-2 Disabled Enabled