High Speed Transmission Equipment
2002 Teccor Electronics
SIDACtor
Data Book and Design Guide
3 - 11
http://www.teccor.com
+1 972-580-7777
R
Figure 3.12
ISDN Protection
Component Selection
The “SC MC”
SIDACtor
devices and F1250T
TeleLink
fuse were chosen because these
components meet GR 1089 surge immunity requirements without the use of additional
series resistance. An MC is chosen to reduce degradation of data rates. The P2600SC MC
voltage rating was selected to ensure coordination with MLT voltages that can approach
150 V rms. The voltage rating of the P0640SC MC was selected to ensure coordination with
varying signal voltages.
Pair Gain Circuit Protection
A digital pair gain system differs from an ISDN circuit in that ring detection, ring trip, ring
forward, and off-hook detection are carried within the 64 kbps bit stream for each channel
rather than using a separate D channel. The pair gain system also uses loop powering from
10 V up to 145 V with a typical maximum current of 75 mA. (Figure 3.13)
Figure 3.13
Pair Gain Overview
Tip
Ring
P2600SC MC
Power
Source
ISDN
Transceiver
F1250T
TX
P0640SC MC
RX
F1250T
F1250T
Power
Sink
P0640SC MC
RX
TX
ISDN
Transceiver
ISDN U-Interface
ISDN S/T Interface
Switching
System
Line powered
DSL 2-Wire,
160 kbps
2B1Q
POTS
Line 1
Line 2
MDF
Central Office
Terminal (COT)
VF
1
VF
2
HF
VF
1
VF
2
HF
Remote
Terminal
Remote Terminal (RT)
building or pedestal
mounted
POTS
Customer
Premises
(CP)
Central Office (CO)