Senior Design Projects
National Radio Astronomy Observatory
Richard Prestage, Jason Ray, Justin Richmond-Decker,
Vereese van Tonder
At 100 m, the GBT is the largest fully steerable telescope
in the world.
305 ft
485 ft
2.3 acre collecting
area
Characteristics of the GBT
Large Collecting Area
Sensitive to Low Surface Brightness
Sky Coverage & Tracking (>85%)
Angular Resolution
Frequency Coverage
Radio Quiet Zone
Unblocked Aperture
state-of-art receivers & detectors
modern control software
flexible scheduling
The Advantage of Unblocked Optics
Dynamic Range
Near sidelobes reduced by a factor >10 from conventional antennas
Gain & Sensitivity
The 100 meter diameter GBT performs better than a 120 meter conventional antenna
Reduced Interference
A telescope for cosmology
The origin and destiny of the Universe
Studying black holes and
extreme environments to
determine the fate and
age of the Universe
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A telescope for fundamental physics
The fastest pulsars test
our understanding of
matter at the most
extreme densities
Timing of pulsars gives the
most stringent tests of
theories of gravity
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Kramer et al 2006 Science
A Telescope Designed to be Enhanced
We have an ongoing development program to ensure the
GBT remains a vibrant, cutting-edge instrument for years to
come
All development is done in conjunction with college &
university groups around the country
A Telescope Designed to be Enhanced
Digital signal processing
Pushing the state of the art
in bandwidth and resolution
Green Bank FPGA lab building
digital signal processing hardware
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A Telescope Designed to be Enhanced
Software Engineering
Advancing astronomical software
through technologies, visualization,
and high performance computing
Upcoming data rate of >10Pb/day;
Take advantage of web-based technologies
e.g. GWT, AJAX, JAVA, Genshi
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NRAO / WVU Senior Design Projects
• We are keen to continue joint-supervised NRAO / WVU Senior
Design Projects.
• Students would be co-supervised by a WVU faculty member and an
NRAO staff member.
• We have a range of projects available; we will highlight three here.
• One project will involve computer science and development only.
• Two projects are more cross-disciplinary within electronic
engineering.
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The Projects
• GBT Active surface control system upgrade
• Design and implementation of a new “artificial pulsar”
instrument test fixture
• A data streaming upgrade for the GBT
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WVU Senior Capstone Project –
Active Surface Controller Upgrade
Jason Ray
Green Bank Telescope Digital Engineer
GBT Active Surface
• The GBT is so large that the shape of the primary reflector changes over
elevation, mainly due to gravity.
• To correct this problem, the GBT has an active surface comprised of 2209
actuator assemblies, which can adjust the 2004 surface panels as needed to
bring the surface back to the required parabolic shape.
• The hardware components for this system were originally procured
starting in early 1992, now making them over 20 years old, and at this
point obsolete.
• Given the importance of the active surface for high frequency observing,
the control system should be upgraded with modern hardware, software,
and communications protocols.
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Existing Hardware
• The current system is based on three MV167 VME computers, with
custom VME IIOP (Intelligent Input Output Processor) boards, which
communicate with the H-Drive modules and LVDT modules.
• The H-Drive modules allow for bidirectional on/off control of 16 actuators
each. The LVDT modules are analog input modules that can monitor 16
LVDT position sensors each.
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Existing Hardware
• The actuator assembly consists of a small DC motor for movement up or
down, and an LVDT for position sensing.
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Upgrade Project
• The scope of this project will be to design and develop an upgraded and
modernized control system for the GBT Active Surface. Tasks will include:
– Picking up where the previous group left off
– Planning the project
– Gathering and defining the requirements
– Designing the hardware, software, and control system
– Testing and documentation of the finished device
• The VME computers and IO cards shall be replaced by a modern computer
running Linux Redhat 64.
• The proprietary IIOP interface, for communicating between the computer
and the control modules, shall be replaced by a standard, ethernet based
interface (i.e., telnet).
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Upgrade Project
• The H-Drive and LVDT modules shall be replaced by microcontroller
based modules that will provide control/monitor for 16 actuators each.
• The current H-Drive modules only allow for simple “on/off” control of the
motors. It is desirable for the new motor control module to have a higher
quality control mechanism, such as pulse width modulation (PWM).
• The new control system hardware, software, and communications
protocols shall all have wide commercial acceptance in order to stave off
obsolescence for as long as possible. The hardware components shall be
highly reliable and readily available from standard parts suppliers.
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Work Experience
This project offers the opportunity to gain valuable, real-world work
experience in the following areas:
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Project planning
Electronics circuit design
Printed circuit board design
Control systems design
Embedded firmware design
Software design
Mechanical packaging & RFI mitigation design
Hardware construction, troubleshooting, & testing
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Current Status
• This year’s group has:
– Developed test circuit boards to use for the control system design.
– Successfully implemented control of a single actuator using a
microcontroller development kit and a prototype PCB.
– Completed the design for the module adapter boards required to
interface the new control modules to the existing wiring.
• This next steps include:
– Expanding their design to control 16 actuators in a single module pair.
– Develop the circuit boards needed to implement this design
– Mechanical packaging of the module into an RFI enclosure
– Documentation
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Project Information
• WVU project team
– Dr. Parviz Famouri – WVU supervisor
– Jeffrey Smith
– Charles Taylor
– Gregory Thurston
• NRAO Supervisor – Jason Ray
– jray@nrao.edu
– (304) 456-2125
• Project documentation
– https://safe.nrao.edu/wiki/bin/view/GB/PTCS/ActiveSurfaceUpgrades
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WVU Senior Capstone Project –
Wideband Artificial Pulsar
Vereese Van Tonder, Digital Engineer
Randy McCullough, Head of GBT Digital Electronics Group
Wideband Artificial Pulsar
• GBT have various high performance digital back-ends (DBE)
– Search for pulsars
– Investigate pulsar timing
• The DBEs are designed in-house using the open source “CASPER” toolset
• Need to test the DBE off-line before employment
• Therefore need HW and SW to emulate a pulsar
?
WBAP
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Pulsar Properties
• Emulate pulsars with ms periods
• Emulate pulsar frequency dispersion through ISM
• Higher frequency components arrive first
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WBAP Project Overview
• An extended project
• Research & documentation
– Set target specifications
– Project schedule
– Bill of materials
– SW & HW design proposals
• Design review by multidisciplinary panel
• Design implementation and verification
– SW development (C coding)
– Board layout using Eagle PCB
– Various SW packages
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WBAP System Overview
• 100MHz – 1000 MHz
• Command line interface
• Variables
– Pulse amplitude, width, period
– Pulse polarization
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WBAP System Requirements
Emulate ISM
use dispersive TL
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Required Interests & Outcomes
• Work within a multidisciplinary environment
– Pulsar astronomers
– SW, RF, and digital engineers
• Integrating system components
• Various SW packages will be used:
– Autodesk Inventor for instrument packaging
– Eagle PCB (schematic capture and Printed Circuit Board Layout)
– Microwave Office (RF/Microwave design, modelling, etc.)
– Vector Network Analyzer
– Portable Spectrum Analyzer
– Portable Digital Oscilloscope
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Software Development at NRAO
Justin Richmond-Decker
Green Bank Software Development Division
What Do We Do?
Develop and support software
for scientific achievement
Programming Methodology
• Agile programming
• Shared code
• Free software
• Git revision control
Design Goals
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Sensitive, low-noise observing platform
Expandable and upgradable
Minimal interdependencies
Allow experts to use all hardware capabilities
Allow novices to think about astronomy, not devices
A laboratory of instruments, not a black box
Monitor and Control
• M&C system is the GBT’s software backbone (C++)
• Interface with telescope’s hardware/firmware
• YGOR, GB, GBT
• Managers
• Parameters / Samplers
GBT Signal Path
Frontend
Backend
FITS Files
• Managers store data in FITS format
Weather
FITS
Antenna
FITS
VEGAS
FITS
sdfits
SDFITS
Pipeline
ASTRID
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Astronomer’s Integrated Desktop
Written in Python
Monitor/Control observations
Edit and validate observing scripts
Real-time (or offline) data display
GBT Status display
Command console, logs
ASTRID Observation Management
ASTRID Data Display
ASTRID GBT Status
FPGA Programming
• Many backends (signal processing) use FPGAs
• Firmware controls circuit behavior
• Can easily load/reload different firmware
• Software reads and writes to FPGA
• Versatile behavior using identical hardware/software
FPGA Firmware
Some Projects I’ve Worked On
• Monitor and Control
– CalibLamp_3mm Manager
– Rotator Manager
– RA_Mark5 Manager
• Astrid
– Data display updates
– GBT Status upgrade
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Potential WVU Senior Capstone Project
• Data Streaming
– Using ØMQ
– Any number of applications can receive this data
– Currently can only monitor telescope
– Want to implement control
Thank you for your attention!
For more information, contact:
Richard Prestage (rprestag@nrao.edu)
Natalia Schmid (Natalia.Schmid@mail.wvu.edu)
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