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CXR Larus 80-100-400 Issue 1, July 2006 1-9
1.33
Stratum 1/PRC System
1.331 A redundant Stratum 1 or PRC system is made up of a 54500-17 (T1) or
54500-16 (E1) shelf, two 54511-2 T1 or 54512 E1/2.048 MHz or 54513 Input
Cards, and either two 54591 GPS Track and Hold Clock Cards or two 54593
GPS Track and Hold Clock Cards. Up to ten output driver cards may be
selected, consisting of any mix of T1 (54571-2), Composite Clock (54572-3),
European Standard (E1) all ones (54573-4), 2.048 MHz Square Wave (54574-
2), 1.544 MHz EIA RS-422 Square Wave (54575-4), 8 kHz EIA RS-422 Square
Wave (54575-5), and 5/10 MHz (54577) cards. A Network Time Server Card
(54580) is available as an option only with the GPS system.
1.332 The system may also include one or two 54541-2 T1 or 54542-3 E1 cards for
synchronization measurements, one 54550-21, -22, -23, or -24 Information
Management Card with either TL1/ITL1 or menu interface, and one 54560
Alarm Interface Card.
1.333 The 54591-2 and 54593-2 GPS cards are provisioned with AB input
architecture only. AA input architecture is not supported with GPS. Track and
hold cards in any combination must provide the same input architecture, either
AA or AB.
1.34
General GPS Information
1.341
The 54591 and 54593 cards incorporate a GPS receiver and timing processor.
The receiver normally requires a rooftop antenna to furnish adequate signal
strength for dependable reception and tracking. The antenna should be
located for the 'best view of the sky.' The antenna cable connects to the rear of
the 54500 shelf at the GPS antenna connector. Inside the shelf, the coax is
routed to the GPS receiver unit within the 54591/54593 GPS card.
1.342 The standard antenna kit contains the following:
·
GPS antenna [weatherproof and less than 5 inches (13 cm) in height]
·
Vertical surface mounting bracket with hardware
·
50 feet (15 meters) of RG-58 coaxial cable with connectors
1.343
The GPS receiver uses a sophisticated technology which simultaneously tracks
signals from multiple nongeostationary communications satellites. The U.S.
military originally mandated this global system primarily for precision navigation.
Its secondary role is that of an accurate frequency source. The U.S. military
maintains daily calibration of the primary frequency reference, an atomic clock
traceable to Coordinated Universal Time (UTC), in each healthy satellite.
