Publication No. 981049 Rev. B
PXIe-3352 User Manual
Astronics Test Systems
Overview and Features 1-3
Rubidium Block
The major component of the PXIe-3352 is the Rubidium block. The Rubidium
block is a multifunctional Rubidium Frequency Standard. It is one of the smallest
atomic clock standards currently available, where the accuracy and stability are
derived from a quantum energy transition that occurs in a free Rubidium atom.
The unit utilizes a unique advanced technology that allows a reduction in size
without sacrificing performance. The standard unit provides outputs of 10MHz and
1PPS.
The Rubidium is comprised of a unique DFLL (Digital Frequency Lock Loop),
where a high performance crystal oscillator is locked to the Rubidium atomic line
using an embedded microprocessor and a special patented algorithm. The
algorithm improves temperature stability and enables very fine digital frequency
control.
OCXO
(Optional)
Main DDS
Rubidium
Resonator
Multiplier
DAC
Micro
Controller
Pre-Amp
Phase
Detector
1/10
7
DPLL
(Digital Phase Lock Loop)
FLL
(Frequency Lock Loop)
6.84GHz
10MHz
10MHz
Output
1PPS
External 1PPS
TX/RX
Figure 1-4, Rubidium Oscillator Block Diagram
The Physics Package ("Rubidium Resonator" in Figure 1-4) includes a lamp,
subassembly, a cavity subassembly, a "C-Field" coil, and a double magnetic
shield. The lamp is RF-discharged: a Rb87 lamp that emits a light that is directed
into the cavity subassembly. The light is filtered by a Rb85 filter cell, transmitted
