David Dunbar Email and Phone Number

Test, and troubleshoot, transmit receive modules for use on satellites to provide broadband internet access from space. Analyze test data to identify failure modes. Reviewed lab test setups and made improvements to reduce false failures which increased production yields.

Responsible for the design, implementation, and testing of RF circuits (such as frequency multipliers, mixers, filters, phase locked loops, frequency synthesizers, and low noise amplifiers) with discrete, lumped, microstrip, and stripline structures. Owned various RF subsystem CCAs. Perform impedance matching between sections to minimize noise figure, reduce RF losses, and to minimize EMI. Prototype RF circuits to optimize performance prior to final layout. Worked on various R&D programs to increase reliability and reduce cost. Utilize RF and digital test equipment and circuit simulators to design and test RF, analog, and digital circuits and mixed signal CCAs. Worked in an interdisciplinary team to design CCAs, mechanical housings, and assemblies to withstand various vibration, shock, temperature, EMI, and radiation flight profiles. Assisted programs with EMI detection and mitigation, reduced self jamming to lower noise figure and lower MDS. Assisted with the design and integration of RF CCAs into flight systems (guided munitions and GBUs). Participated in the entire development cycle (proposals, planning, trade studies, simulations, design, schematic capture, PCB layout, component geometry creation, component research, assembly, trouble shooting, production testing, and rework).

Supervised the layout, implementation, and testing of an anti-jam CCA for GPS receivers for use in various unmanned aerial systems. Designed, laid out, built, and tested numerous RF prototype circuits and evaluation cards. Located and eliminated sources of EMI and RF leakage in RF circuits and assemblies. Setup and calibrated an 8-channel GPS simulator and GPS jammer inside of an anechoic chamber. Performed testing and troubleshooting on RF systems. Documented the test results of GPS receivers while in a rolling airframe GPS jammed environment. Provided mentoring and guidance to fellow engineers and technicians.

Responsible Engineering Authority for a GPS receiver CCA for the Enhanced Paveway III GBU-24.Made design improvements to the PLL frequency synthesizer, and built-in test circuits. Worked closely with factory technicians in order to maintain high rate production. Worked component obsolescence issues, worked with vendors and suppliers to resolve vendor related design and quality issues. Reverse engineered and documented a complete factory test station.

Responsible for CDMA / spread spectrum transmitter design and development in the 902-928 MHz band under FCC part 15. This included RF and digital circuit design and simulation, circuit prototyping and testing, schematic capture, PCB design & layout, Monte Carlo analysis, and device verification testing. Conducted experiments on transmitter and receiver hardware. Utilized RF test equipment to design and test filters and impedance matching networks (with discrete components and microstrip structures), BPSK modulators, frequency multipliers, amplifiers, and microstrip antennas. Created a semi-anechoic chamber where I performed pre-FCC compliance testing.

Worked closely with RF and digital design engineers in a team environment to implement and test new circuit designs. This included PCB layout, fabrication, assembly, and debugging. Developed a “Magnetic Programmer” which OOK modulated a 1 MHz carrier with serial data. Partially designed and fully implemented a digital control loop DC/DC converter/voltage regulator which was then implemented in an ASIC. Utilized a PCB milling machine for rapid RF PCB prototyping. Performed antenna research, measured antenna radiation patterns, component research, analyzed test results, created and performed device verification test procedures and documented results.