Chapter 12
Technical Specifications and
Operating Parameters
NOTE: Specifications are subject to change without notice.
12.1
Functional Description
12.1.1
Front Panel Interface
Each “B” clock has eight buttons, eight annunciator LEDs and one LED backlit display. Each “C” clock
adds a large six character LED time and date display, which may be adjusted for mm/dd/yy or dd.mm.yy.
The only front panel control is the display backlight for convenience.
12.1.2
Processing
The Model 1200B, Model 1201B, and Model 1201C both operate under the same principles and use the
same basic components. Differences are: the Model 1200B does not have a holdover oscillator and only the
1201C has a large LED display in addition to the backlit LCD display. Supervision of these clock systems is
under the control of several microprocessors dedicated to separate tasks. The main clock processor governs
the overall operation of the clock, including the user interface, and input and output control. Two other
processors manage the network card (NTP/PTP) and a final processor, called the Time Base Processor
(TBP), manages the composite oscillator.
The specific processor used in the TBP is designed for hard, real-time requirements, as well as extremely
fast execution of critical code. Additionally, since the TBP does not have to support the system-level clock
operation (user interface and I/O control), the TBP does not have changes in the system level impacting
the TBP operation. This chosen architectural separation also allows easy porting of TBP functionality into
different time products. Some of the key features implemented by the TBP are:
Inner-loop PLL: This is an N.f hardware loop that locks the VCXO to the high-stability hold-over
oscillator (HO) in a unique, proprietary configuration that provides superior stability and reliability.
Outer control loop: This is a pure software DLL that locks the composite oscillator (VCXO / HO) to
the reference signal: the 1 PPS from the GNSS receiver for current products.
Hold-over operation:
The TBP implements a multi-parameter estimator that allows accurate
prediction of hold-over oscillator drift, thus allowing the oscillator to be accurately compensated,
minimizing drift effects during hold-over.
Agile antenna support (future): The TBP will implement the real-time algorithms required to support
the operation of the agile antenna, when it becomes available.