Timing Cable Specifications For The Ds1 Circuit; Timing Cable Specifications For The E1 Balanced Circuit - Nortel Passport 15000 Hardware Description

Using custom or prefabricated timing cable assemblies for the building
integrated timing supply (BITS) is described in 241-1501-240 Passport
15000, 20000 Hardware Installation, Maintenance and Upgrade.
Timing cable specifications for the DS1 circuit
The DS1 BITS interface is a digital clocking (SF (D4) framing is default, ESF
(Fe) is also supported) format interface - no signals or analogue modes. It
must have the following operational characteristics into the alarm/BITS
module.
• The BIT rate/accuracy is 1.544 kbits/sec +/- 50 bits/sec (+/- 32 ppm) or
better in self-timed, free-running mode.
• The Pulse Amplitude is between 2.4 to 3.6 V peak at the source for a
"mark" isolated pulse, across a 100 Ohm impedance (cable run is
dependant on line build out).
• See the ITU-T G.703 Section 5 for other details with respect to pulse
mask, power levels for all ones, and other considerations.
The functional specifications for the DS1 receive (RX) circuit for a 100-ohm
twisted pair of the A or B timing reference interface are
• two 475-ohm resistors for over-voltage protection
• two surface-mounted fuses for current protection on the network side
• a diode bridge for voltage protection
• 33-pF capacitors used as a high frequency filter for immunity to noise
• two 49.9-ohm resistors for matching impedance
• generally, a 1-to-1 step-up transformer is added to interface to the
transceiver
Timing cable specifications for the E1 balanced circuit
The E1 balanced BITS interface is the digital clocking source with the line
format called common channel signalling (CCS)- no signals or analogue
modes. Zero suppression is HDB3, CRC-4 is enabled. It must have the
following operational characteristics into the alarm/BITS module.
• The operating frequency is 2,048 kbits/s with a tolerance of +/- 50 ppm
or better.
Passport 15000, 20000 Hardware Description
Chapter 3 Shelf assembly 123
5.2S2