| Advanced Communications In Transportation |
| Designing Up-to-Date Telephone Switch Networks |
| By John Maurer, Atlanta, Georgia, 1-404-870-3213
c/o mjohnson@ogc.itsmarta.com |
| The key elements of MARTA·s updated system-wide
telephone and communications systems provide for superior communications
now and in the future. |
|
Our task was to provide an up-to-date design for the Metropolitan
Atlanta Rapid Transit Authority’s (MARTA’s) systemwide
telephone switch network. The system is controlled from the Rail Service
Control Center (RSCC) satellite switch located at the Avondale Station
on MARTA’s East Line, which interfaces to a primary switch at
the system headquarters located adjacent to the Lindberg Station.
MARTA Vehicle |
Upgraded Telephone Switching Network
The new updated telephone switching network is made possible by using
electronic, non-blocking switch devices at the RSCC and at outlying
site locations. These locations are connected at Type 1 (T1) carrier
transmissions rates of 1.54 megabits per second (Mbps) via pulse code
modulation (PCM) dedicated carrier systems or via leased Megalink
private circuit paths, which provide optimum voice and data operation.
Transmission interfacing for these switches is via:
- High frequency copper span lines for the
original MARTA stations
- Single-mode fiber-optic facilities for the three most recent
stations, two stations schedule for opening to revenue service
in December 2000, and sites scheduled for future construction
and inclusion to the MARTA system.
An electronic telephone switch for the new rail yard that is under
design and due for construction in the near future will be made compatible
and interfaced with the existing telephone systems.
The updated switching network provides for the following telephony
features:
- Automatic Call Distribution
- Automatic Number Identification
- Call Detail Recording
- Direct Inward Dialing
- Direct Outward Dialing
- Directory Lookup System
- Conference call capability
- Diagnostic testing both local and remote.
Fiber-Optic Media System
The installation and implementation of a MARTA system-wide fibe- optic
network is also underway concurrent with the telephone switch upgrade
project. This new system will allow for replacement of the existing
high frequency copper transmission components and the capability of
high-speed dissemination of voice, data and video.
A MARTA criterion establishes that transmission of intelligence should
be SONET (Synchronized Optical Network) for present and future transfer
of information.
With this system in place, MARTA has the advantage of a modern switching
system that provides superior communications now and that can be updated
easily to take advantage of future telecommunication system enhancements
that are being developed at a fast pace. |
|
| John Maurer·s background in telecommunications
goes back to 1951 when he designed and put seventeen telephone community
dial offices into operation in western Oregon. He has extensive experience
in telecommunications, including telephony, satellite earth stations,
terrestrial microwave point-to-point systems, troposcatter radio long-range
systems; and experience on several rapid transit systems across the
U.S. |
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