Symmetricom Inc
bc620/627AT Time and Frequency Processor
1-1
CHAPTER ONE
INTRODUCTION
1.0 GENERAL
This bc620/627AT Time and Frequency Processor (TFP) User's Guide provides the following
information:
•
Introduction and key feature description.
•
Installation and setup.
•
Detailed operation and programming interfaces.
•
Programming examples.
•
Input and output signals.
1.1 KEY FEATURES
The bc620/627AT has been designed with the following key features:
•
Time on demand (days through microseconds) with zero latency. This feature is
implemented with hardware registers which latch the current time upon host request.
•
Event logging (days through 0.1 microseconds). This feature is implemented with a second
set of hardware registers. Time is captured on a positive or negative input edge or secondary
bus time request.
•
Four operational modes are supported. Modes are distinguished by the reference source.
Mode
Source Of Synchronization
0
Time code - IRIG A, IRIG B, XR3, 2137, NASA36 (modulated or
DC).
1
Free running - on board 10 MHz oscillator (VCXO) used as
reference.
2
1 PPS - synchronizes to external one pulse per second.
3
RTC - uses on board battery backed real time clock IC.
4
GPS - uses Acutime GPS receiver as reference (bc627AT only).
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