Transcript Digital Control and Data Acquisition System for the QUIET

Digital Control and Data Acquisition System for the
QUIET Experiment
Mircea Bogdan, Dan Kapner, Dorothea Samtleben, Keith Vanderlinde
•QUIET (Q/U Imaging ExperimenT ) is meant to characterize the
signature of gravitational waves in the polarization of the cosmic
microwave background. These gravitational waves are thought to
originate from Inflation, the exponentially accelerating expansion of the
very early universe.
•QUIET Phase I will operate arrays of 91 4-channel W-band (90GHz) and
19 4-channel Q-band (40GHz) polarimeter receivers, placed on 1.4m
telescopes, in Chajnantor, Chile.
•QUIET polarimeters are integrated elements of High Electron Mobility
Transistor (HEMT) RF amplifiers, phase-switches, passive phase
discriminators and RF detector diodes. The polarimeters require biasing
of their monolithic microwave integrated circuits (MMIC), detector diodes,
and phase switches.
•QUIET Digital Control and DAQ is responsible for controlling and
monitoring the polarimeter biases, environment monitors and the ADC of
the signal channels.
7 W-band polarimeter modules with
representative optics attached to one.
QUIET Digital Control and DAQ System
Polarimeters
Functions (Phase I):
•Setup and Control of over 1500 current and
voltage bias levels;
•Acquisition and real time processing of about
400 analog signals.
Specifications:
Data
Biases
Bias
Electronics
Data
Cryostat
Housekeeping
Electronics
40 LVDS Communication
Lines
•DAQ with up to 13 custom-made ADC boards,
each with 32 channels of 18-bit, 800kSPS.
•Digital signals processed with local FPGAs,
demodulated and averaged over 10ms intervals.
•VME read out at a 100Hz rate.
•Full scale input of +/-2V;
•1 pole input filter – configurable;
•Input noise voltage ~ 15uV RMS;
•Simultaneous sampling;
•Channel-to-Channel Skew ~ 5ns.
Master ADC Board
Data
VME Backplane
VME Crate
Controller
Data
Network
PC Frontend
Block Diagram for the QUIET Digital Control System