Smiths Industries (2)

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Basics

Employer	Smiths Industries Aerospace Systems Ltd., Cheltenham
Dates	July 1997 - March 1999
Business area	Civil Aircraft Instrumentation (Fuel Measurement)
Position	Principal Engineer

Engineering Tasks

Cost Reduction / Obsolescence Mitigation	Redesign of an existing board with the aims of cost reduction, reduce future component obsolescence problems.
Future Fuel Measurement Systems	Invent and evaluate ideas for the next generation of fuel measurement system. Provide technical support for proposals to potential customers.
TDR Techniques	Evaluate the usefulness of TDR (Time Domain Reflectometry) as a potential fuel gauging technique for aircraft.
Other Minor Activities	The normal practice of sharing good ideas and difficult problems around an engineering group.

Cost Reduction / Obsolescence Mitigation

Project	Fuel Measurement System for the Boeing 777 Airplane
Sphere of Work	Product design. Civil aircraft avionics, medium grade safety critical system. Hazardous environment involving jet aviation fuel.
Responsibilities	Post-design work on an existing system, with two aims: cost reduction, overcoming of component obsolescence issues - especially with regard to Mil-Spec. devices. provide total compatibility with the old design, such system and board level testing as necessary to overcome the poor documentation of the existing system. This was to be accomplished by a moderate re-design of a challenging mixed-signal circuit board Discussions with and presentations to the customer (Boeing Commercial Airplane Group).
Notes	This work was done while the question of commercial spec. components in aircraft systems was being re-evaluated, and the problem of obsolescence of Mil-Spec. devices was beginning to bite. Hence it was not a case of re-design to established procedures - rather one of working out the rules on-the-fly, and dealing with changing parts approval criteria mid-design.
Hardware Skills	Analogue and Mixed Signal accurate analogue and A to D circuits; very complex accuracy analyses using MathCad, 1MHz ultrasonics (the fuel gauging technology) - up to 30Vp-p in the transmit circuits down to few mV on receive; associated switching, gain control, thresholding and control, Digital standard logic, arithmetic logic in ASICs, ASIC - technical management and support of work done by specialist ASIC group, understand and comment on VHDL. 68020 microprocessor serial inter-processor links External Interfaces operation in a serious EMC environment. aircraft interfaces - worked around ARINC 629.
Software Skills	Working with embedded real-time software, in ADA / 68020 assembler.
Debug/Test Skills	System level and board level testing. Analogue and real-time digital oscilloscopes Logic analysers for ASIC characterisation Signal generators to 10MHz for analogue circuit characterisation
Support Activities	Detailed thermal measurements of the unit to establish the actual component requirements. Laboratory PC for terminal emulation and test equipment data retrieval.

Future Fuel Measurement Systems

Project	Research - consider new ways of applying existing fuel gauging technologies. Provide input into proposals to potential customers.
Sphere of Work	Possible future product architecture paper design. Civil aircraft avionics, medium grade safety critical system. Hazardous environment involving jet aviation fuel.
Responsibilities	Invent and evaluate new fuel gauging techniques and systems architectures. Assist in designing systems architectures, and other technical support for proposal work.
Notes	This work build on experience gained in the Cost Reduction / Obsolescence Mitigation task.
Hardware Skills, etc.	Basically paper design exercises.

TDR Techniques

Project	Research the possibilities of using Time Domain Reflectometry (TDR) as an aircraft fuel gauging technology
Sphere of Work	Techniques research, associated test rig design and operation. Hazardous environment owing to working with aviation fuel.
Responsibilities	Investigate TDR as a fuel gauging technology. At the end of the project there was a demonstration/presentation of conclusions to potential customers and other interested parties.
Notes	There were four main areas of work - design, build and integrate a small TDR equipment suitable for use with aviation jet fuel and write associated software. carry out a series of experiments to obtain sets of representative TDR traces design novel DSP algorithms for deducing an accurate fuel height from a TDR trace initial sketch designs of how a TDR fuel gauge would be implemented in an aircraft.
Hardware Skills	Analogue economical GHz bandwidth video, sub-ns pulses, mismatched small signal transmission lines viewed in the time domain. Digital standard logic, timing critical logic design, analogue pulse generation using logic circuits.
DSP Skills	Process aperiodic signals - extract the surface height from a TDR trace. Implemented in MathCad for initial algorithm development/test, then code in C++ for a general purpose processor.
Software Skills	Large (>10000 line) desktop programme to provide DSP functions and human interface. Written in C++ using OOP methods; hosted on PC-WinNT4 running in console mode. Small programme to provide remote control of GPIB; controlled from the large program using a file-based communication scheme. Written in C++ using OOP methods; hosted on PC-DOS. Small programs to control test equipment in a manual mode and save oscilloscope trace data via GPIB. Written in C++ using OOP methods; hosted on PC-DOS.
Debug/Test Skills	General testing. Analogue and real-time digital oscilloscopes Sampling scopes to 6GHz (Tek TDS820), very fast probing Logic analysers for ASIC characterisation GPIB control of test equipment from a PC, associated software
Support Activities	All mechanical design issues - including test fuel probes and jigs.

Other Minor Activities

Project	The normal practice of sharing good ideas and difficult problems around an engineering group
Sphere of Work	Some research work, some civil aircraft avionics, medium grade safety critical systems. Equipment for us in a hazardous environment.
Notes	The most noteworthy involvement under this heading was helping in research into the possibilities of using DSP techniques to process the signal traces generated using the existing ultrasonic fuel gauge probes. There were several other activities that came up - mostly in the analogue electronics or system architectures fields.
Hardware Skills	Analogue and Mixed Signal general analogue circuits, 1MHz ultrasonics; fast D to A and A to D converters - for generating and receiving ultrasonic signals. Digital standard logic, FIFOs for A to D and D to A data buffering.
DSP Skills	Detection of a received ultrasonics pulses using correlation algoroithms. Implemented in MathCad
Debug/Test Skills	Board level testing. Analogue and real-time digital oscilloscopes Signal generators to 10MHz for analogue circuit characterisation

Support Environment

Desktop Computer Systems	PC-WinNT4
Desktop Software - General	MS Office (Word, Excel, PowerPoint) MS Schedule Lotus cc:mail MS Internet Explorer Adobe Acrobat

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Curriculum Vitae > Career ... > Smiths Industries (2) / John Dubery / 8 April 2000