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ATS-6501 Users Guide
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1 General Information
1.1 Introduction
The ATS-6501 Tflex is a state-of-the-art GPS Disciplined time and frequency reference.
It utilizes an internal rubidium (Rb) atomic clock and low noise synthesizer (LNS) in conjunction
with GPS measurements to provide outputs that are characterized by the short-term stability of
the atomic clock and the long-term stability of the GPS constellation. Additionally, it provides
the user with the capability to enhance the frequency stability and holdover performance of the
unit by using an external cesium (Cs) clock as the reference. This provides a scalable architecture
that allows users to fulfill a wide range of current and future requirements with a single unit. The
ATS-6501 is suitable for a variety of precise time and frequency applications.
The 1 Pulse per Second (PPS) accuracy and frequency stability of the ATS-6501 is
further enhanced by using a dual-frequency (L1/L2) GPS receiver. The dual-frequency receiver
applies corrections to the GPS timing signals that remove a significant portion of the errors due to
ionospheric delay. The measurements can also be made available to users for the purpose of
modeling the total electron content (TEC) of the ionosphere.
In applications where reliability is a must the ATS-6501 is capable of operating from an
AC (100 – 240VAC, 50-60 Hz) or DC Power -48 VDC (SELV type) (-18 to -60 VDC) source and
comes with two fully redundant power supplies. The unit is capable of operating from a single
supply in the event one of the two power supplies fails.
The ATS-6511 is a fiber distribution system that derives its references and stability from
at least one ATS-6501. The ATS-6511 has two fiber I/O connections that allow for two-way time
transfer between the two systems. This capability allows the ATS-6511 outputs to be set on time
in relation to the ATS-6501 providing the reference signals and also provides for precise
calibration through the two-way time transfer. A 4372A module can be ordered and installed in
an ATS-6501 to supply the fiber signals to a ATS-6511. The fiber connection includes all timing
signals to provide the same capability and performance of the ATS-6501 in the ATS-6511. A
TSC-4340 distribution amplifier can be connected to a 4372A output to provide up to 8 more
outputs to ATS-6511s. The 4372A module includes input capability to monitor the status of each
ATS-6511 connected either directly to the 4372A module or through a TSC-4340 distribution
amplifier.
1.2 Ordering
Information
ATS 6501A (Tflex): Standard dual frequency GPS time and frequency standard. Dual AC
input supplies included. Requires external frequency reference or internal Rubidium
reference and includes two 1 PPS/DC IRIG, one 10 MHz, and one AM IRIG output module.
A dual frequency GPS antenna is included with unit.
Option D (DC Power Input): Provides DC input (-48 VDC (SELV type) (-18 to -60 VDC))
capability instead of AC for one of the supplies. The second power supply is still AC.
Option D2 (Dual DC Power Input): Provides dual DC input (-48 VDC (SELV type) (-18 to
-60 VDC)) capability instead of AC.
