TP3404 Quad Digital Adapter for Subscriber Loops (QDASL)
General Description
The TP3404 is a combination 4-line transceiver for voice and
data transmission on twisted pair subscriber loops, typically
in PBX line card applications. It is a companion device to the
TP3401/2/3 DASL single-channel transceivers. In addition to
4 independent transceivers, a time-slot assignment circuit is
included to support interfacing to the system backplane.
Each QDASL line operates as an ISDN “U” Interface for
short loop applications, typically in a PBX environment, providing
transmission for 2 B channels and 1 D channel.
Full-duplex transmission at 144 kb/s is achieved on single
twisted wire pairs using a burst-mode technique (Time Compression
Multiplexed). All timing sequences necessary for
loop activation and de-activation are generated on-chip.
Alternate Mark Inversion (AMI) line coding is used to ensure
low error rates in the presence of noise with lower emi
radiation than other codes such as Biphase (Manchester).
On #24 AWG cable the range is at least 1.8 km (6k ft.).