Request Expert

Expert has extensive experience in several types of spread spectrum systems, including slow, medium, and fast frequency hopping, direct sequence, chirp, and an innovative noise modulation technique which transmits a sinusoid-free waveform. These systems have been used for anti-jam, low probability of intercept, and ranging applications, and have been successfully implemented and tested. Operating bands have ranged from VHF (30 MHz) to S-band (2.3 GHz). Expert's role has been in the areas of spread spectrum waveform design as well as detailed design, simulation, and implementation of synchronization algorithms, both acquisition and tracking.

Expert has been involved in the research, design, development, and production of a wide variety of communication systems since the mid-1970s. These systems have employed AM, FM, and PM analog modulations, as well as broad range of digital modulations including BPSK, QPSK, 8-PSK, MSK (binary, 2-ary, and 4-ary), FSK (binary, 4-ary, and 8-ary), 16-QAM, 32-QAM, 64-QAM, 49-QPR, Orthogonal Frequency Division Multiplexing (OFDM) partial response modulations, Shaped BPSK (SPBSK), Tamed Frequency Modulation (TFM), and GTFM, among others. His role in the development of these systems has been primarily at the system design, analysis, and simulation level; however, his firm's staff of over 40 circuit designers and programmers provide practical implementations of his system designs. These systems have operated over ground-to-ground, ground-to-air, air-to-ground, air-to-air, and satellite link configurations at frequencies from less than 1 MHz to several GHz. In addition to detailed design of the modems listed above, he has been heavily involved in all levels of synchronization, data squelch algorithms, IF filter characterization, AGC behavior, PLL implementations, and synthesizer design.


Over the past fifteen years, Expert has written over 50,000 lines of FORTRAN code to develop a powerful modular communications channel modeling program incorporating the effects of modulation, noise, nonlinear amplifiers, multiple stages of filtering, fading channels, AGC, bit synchronization, carrier recovery loop, IF and baseband equalizers, demodulation, jammers, and adjacent channel interference. Because these models have been used in the design of real production hardware, they are far more detailed and realistic than the simplified analytical descriptions provided by commercial communication system simulator packages.

Expert's background in DSP techniques dates back to the late 1970s (before commercial digital sound processors). He has worked with many members of the Texas Instruments TMS320 family, including the 32010, 320C20, 320C25, and 320C30. He also has experience in DSP with non-DSP type processors such as the 8031 and the 68HC16. Algorithms that Expert has developed for these processors include digital filters, Fourier transforms, carrier recovery loops, phase detectors, adaptive equalizers (both linear and decision feedback), modulators, demodulators, bit synchronizers, and error correcting coders/decoders.


Expert has developed a wide variety of synchronizers for use in communication systems, including carrier recovery loops of several types, bit synchronizers which significantly outperform conventional approaches, frame sync preambles, and detection algorithms which perform reliably at bit error rates as high as 15 percent and spread spectrum acquisition and tracking algorithms which acquire at signal to noise ratios as low as -30 dB in the spread spectrum bandwidth.


Since the early 1980s, Expert has been involved in the design and implementation of several types of direct and indirect synthesizers, including conventional PLL, fractional N (DigiPhase), direct digital synthesizers (DDS), and hybrids of these. Particular emphasis in these designs has been on the very low power consumption, small size, and fast switching speeds even with small frequency step sizes.


Over the past 20 years, Expert has worked on the design, development, and production of a wide range of communications systems. These systems have employed many different modulation and demodulation techniques including AM, FM, PSK, QPSK, 8-PSK, hybrid AM and FM modulations, Quadrature Amplitude Modulation (QAM, orders 16 through 256), partial response modulations including duobinaryk, 9-QPR, and 40-QPR, and Orthogonal Frequency Division Modulation (OFDM).


Expert performed system, RF, and digital engineering for ADC Telecommunications' Homeworx HFC telephony system.He performed system, RF, and digital engineering for Mobil Oil's Speedpass RFID system. Expert performed system engineering for Cincinnati Electronics' TDRSS transponder.