Engineer Data

Jeffrey.cc.chang [at] gmail [dot] com

Jeffrey C Chang 650-***-****

Objective:

Seeking a position in research and development; to prototype, design, and evaluate interesting hardware technologies for scientific

or commercial applications.

Summary:

● Extensive experience in building analog and digital electronics systems under tight time and cost constraints.

● 13+ years experience in embedded electronics and high-sensitivity scientific instrument design, development, and deployment,

from prototyping and PCB design and layout, through circuit board bring-up, testing, and characterization, to system debugging

and field deployment.

● Proficient in Altium, OrCad/Cadence, and PADs, as well as Python, C/C++, MATLab, Perl, Java, Verilog and VHDL. Also

proficient in web pages with AJAX components, and development on LAMP stack.

● Excellent team player with experience managing small teams, but also disciplined to work independently.

● Quick to learn and adapt, open to new technologies and techniques, and attentive to details.

Education:

Stanford University: MS Electrical Engineering, 2003

The Ohio State University: BS Electrical and Computer Engineering, Magna Cum Laude, 2001

Experience:

Stanford University, Electrical Engineering Research and Development Engineer

Very Low Frequency (VLF) Group July 2003 to Present

Ground-based receivers (2003-Present):

Lead Engineer: Atmospheric Weather Electromagnetic System for Observation, Modeling, and Education (AWESOME)

Instrument (2003-Present)

Designed, built, and deployed second and third generations of ELF/VLF/LF radio receivers (~90 in worldwide network) for

remote sensing, radio-science experiments, and lightning detection. These are some of the most sensitive VLF receivers in the

world and currently used in commercial lightning detection.

■ Transformed a graduate student project into industrial quality product within 6 months.

■ Designed receiver systems to be easily adaptable for different uses with different input requirements.

■ Improved system survival rate due to close-proximity lightning strikes and harsh weather from 75% in second generation up to 98% in

third generation VLF receivers.

■ Simplified field installation for end user in remote locations under harsh conditions.

■ Lowered production costs 10% by minimizing components count and transitioning to surface mount parts.

■ Lowered overall system noise floor by 20 dB through careful PCB layout practices.

■ Improved sampling accuracy to better than 1 ppm by building GPS disciplined voltage controlled clock circuitry in beta fourth

generation receivers.

■ Redesigned chassis using Solidworks in conjunction with Altium’s 3D features.

■ Responsible for parts inventory and logistics for building, repairing, and redeploying with quick turnaround. Built a browser based

(AJAX) tracking tool for all hardware pieces manufactured and shipped to field sites in order to collect performance statistics.

■ Upgraded data acquisition software interfacing to receivers from Python 2.5 to Python 2.7.3. Rewrote several modules to take

advantage of multiprocessing and new features of Python. Restructured code so that each submodule can restart on detection of errors.

Current software versions have significant better uptimes, ensuring almost continuous data collection.

■ Took the initiative to implement an internally-used web page to display world-wide field-sites’ operational status on a Google map with

real-time updates of housekeeping data, and to track useful pieces of information for each site. Stanford personnel can now monitor

receiver network health all in one place.

■ Managed VLF data storage and compute servers since 2012. Directed overhaul of data servers to streamline data flow from 90+ field

sites. Guided infrastructure upgrades and direction, doubled size of compute cluster and pushed for building of redundant storage.

Currently also working on rewriting the VLF data access portal and defining API.

Satellite based receivers (2007-Present):

Payload Engineer: VLF Wave and Particle Precipitation Mapper (VPM) experiment (2012-Present)

Responsible for design, construction, and testing of three out of four electronic boards in payload, including:

■ Designing a dual channel VLF receiver board with Stanford designed LNA and ADC, and Actel FPGA.

■ Data processing board with Actel FPGA, memory, bus interface, and housekeeping mux.

■ Spacecraft interface board, with power conditioning and GPS interface.

Lead Engineer: SpriteSat VLF Receiver (2007-2012):

Designed and built engineering/flight models of single channel VLF receiver for satellite-based observations.

■ Designed complete VLF receiver in compact form factor (100mm x 70mm x 10mm), with full upgrade path to radiation-

hardened components, for multiple satellite missions.

■ Developed testbed interface to vacuum chamber for qualifying thermal cycles and bake-in tests.

■ First module flown in 2009 on SpriteSat mission. Second module installed on the International Space Station in 2012 as part of

GLIMS mission.

Autonomous Systems (2003-2011):

Engineer: Penguin Systems (2008-2011):

Ultra-low power (sub-watt, ARM based), fully autonomous VLF Receiver, designed for long operational life over Antarctic

winters with average temperature down to -100F.

■ Helped redesign and qualify analog preamps to support several iterations of Stanford designed low noise amplifier chips.

■ Overhauled entire battery system so that battery pack can be serviced quickly without any risk of starting lithium battery fires.

■ Redesigned mechanical structure and thermal insulation for instrument enclosures.

Lead Embedded Engineer: Buoy II (2005-2008):

Upgrades to new electronic systems around COTs TI DSP module. Responsible for all aspects of system redesign, integration

and testing, and deployment.

■ Designed and built CPLD-based ADC board to minimize power requirements, programming overhead, and to control the

desired sampling rate. This also simplified the preamplifier and filter designs.

■ Redesigned CF system so that up to six compact flash cards can interface directly to DSP IO bus via memory mapping,

increasing data bus to full CF card bandwidth.

■ Tested and qualified a journaling file allocation system for data storage on CF cards, which drastically reduced memory and

storage overhead on previously used FAT16 file system.

■ Adapted and recompiled C-based versions of decimation and filtering routines for signal extraction, data compression, and

post-processing. Also heavily tested jpeg compression for data snapshot products.

■ Built mechanical structure for all electronics payload.

■ Specified and built cabling and interconnects to power, GPS, and IRIDIUM modems.

■ Tested and qualified eight complete systems, eventually deploying four systems in two buoys.

■ Successful recording and retrieval of data of 1 hop echo with triggered emissions from HAARP transmissions.

Hardware Engineer: Buoy Project (2003-2005):

Low power VLF receiver system for remote sensing application, deployed in south Pacific ocean (500 mi south of New

Zealand).

■ Main processor based on COTs TI DSP module. Data digitized via COTs ADC module, and stored via firewire bus hosted CF

cards. Data transmitted via IRIDIUM satellite link to Stanford servers.

■ Designed all custom PCBs for interfacing to DSP and ADC modules.

■ Designed microcontroller-based system to interface to IRIDIUM modems as smart UARTs.

■ Designed GPS interface module to acquire data from three GPS simultaneously to calculate roll, pitch, and yaw.

■ Worked on integration of electronics to buoy chassis.

Engineer: VLF Interferometer (2001-2005):

First fully autonomous, battery powered, VLF receiver, based on embedded i586, with CF and microdrive storage.

■ Designed and layout PCBs for CF data storage, analog preamp cards, and lowpass filter cards.

■ Debugged and tested field setups. Managed team for first remote setup in Alaska during summer of 2002. Part of the field team

which deployed nine sites during winter of 2003.

Antarctic Projects (2003-Present):

Field Engineer (2003-Present):

Member of engineering field team for AGO (Automatic Geophysical Observatories) in Antarctica from 2004-2008.

■ Responsible for yearly maintenance of science instruments at four remote field sites on Antarctic plateau. Repairs of instruments often

required clever solutions with limited parts on-hand during expedition. Awarded the Antarctic Service Medal.

■ Helped upgrade observatories from propane to wind and solar-powered, allowing for full year operation.

■ Presently a member of stateside phone support team for VLF instrument.

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