Symmetricom 5071A, Operating And Programming Manual

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Preface
Operating and Programming Manual xvii
Introducing the 5071A
This introduction describes the 5071A‘s features, providing information to
better understand them so you can operate the instrument effectively. The
following is a functional narrative description. For specific details such as
signal levels, accuracy, stability, etc., see the specifications in Chapter 6.
The 5071A is a source of extremely accurate and stable output frequencies.
The accuracy of the 5071A is within a few parts in 10
13
of the
internationally accepted definition of frequency. This accuracy is made
more usable and practical by the 5071A's excellent environmental stability.
The 5071A uses a fundamental property of the element cesium to define
frequency. Inside the cesium beam tube assembly, an applied microwave
signal causes energy-level transitions to occur in the cesium atoms. The
microwave signal is synthesized from a 10 MHz Voltage-Controlled
Crystal Oscillator (VCXO).
Patented Cesium II circuit and software technology detects departures of
the microwave frequency from the cesium energy-level transition
frequency and corrects them by tuning the VCXO to run precisely at the
proper rational-fraction of the cesium frequency. The microprocessor (an
integral part of this servo loop) performs the error determination and
correction several times a second to ensure that the VCXO is always
closely locked to the cesium-transition frequency.
Many functions within the 5071A are under Cesium II software control.
The software manages the initial warm-up and alignment, then
continuously monitors the appropriate signals using this information to
control all key operating parameters for optimum performance. Starting
the 5071A merely requires connecting ac or dc power (see pages 5 and 6).
After a typical warm-up time of 15 minutes, the standard is fully
operational and the operator may optionally press three keys to
display a continuous operation signal. There are no maintenance
procedures or adjustments needed even when necessary to replace the
cesium beam tube. The 5071A meets all specifications within 30
minutes of power connection at room temperature.
Overview
What is the 5071A
Primary Frequency
Standard?
How Does the
5071A Work?