Symmetricom TM7000, Руководство пользователя

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THEORY OF OPERATATION
Figure 4.1.2 shows a simplified diagram of a typical Time Code Translator. The significant
points of a Time Code Translator are:
•
Input Amplifier – Usually this is an AGC (Automatic Gain Control) type amplifier.
Its function is to provide a constant amplitude signal to the decode and detection
circuitry.
•
Serial-to-Parallel Converter – This is the heart of the unit. It’s function is to detect
digital data in the input format and assign it to storage in the Time Accumulator. This
portion contains the necessary circuits to synchronize the frequency dividers.
•
Frequency Dividers – These counters divide the carrier frequency. Once
synchronized by decoding circuitry in the Serial-to-Parallel section, this counter
provides the terms necessary to index the digital data contained in the input code.
This allows the locating of each code bit and the proper assignment to accumulator
storage. They also provide a 1PPS signal to update the Time Accumulator.
•
Time Accumulator – This counter stores the value being read from the input code. It
is updated with the 1PPS signal from the Frequency Dividers and is permuted to
count in the format of the input Time Code (usually Seconds, Minutes and Hours).
Day-of-Year is provided if it is contained in the input Time Code. The Time
Accumulator is the basis for most outputs provided by the unit.
•
Display – This section takes the Time Accumulator data and displays it to the user.
INPUT
AMPLIFIER
SERIAL TO PARALLEL
CONVERTER
DISPLAY
TIME
ACCUMULATOR
f N
+
t 1
SCAN TERMS
SYNC
1PPS
f
t
MINOR TIME MAJOR TIME
FREQUENCY
DIVIDERS
Figure 4.1.2
Typical Time Code Translator
Symmetricom, Inc. TM7000 TymMachine TCG/T (Rev D) 4-3