A class of decoding algorithms that utilizes channel measurement information, in addition to the conventional use of the algebraic properties of the code, is presented. The maximum number of errors that can, with high probability, be corrected is equal to one less than d, the minimum Hamming distance of the code. This twofold increase over the error-correcting capability of a conventional binary decoder is achieved by using channel measurement (soft-decision) information to provide a measure of the relative reliability of each of the received binary digits. An upper bound on these decoding algorithms is derived, which is proportional to the probability of an error for dth order diversity, an expression that has been evaluated for a wide range of communication channels and modulation techhiques. With the aid of a lower hound on these algorithms, which is also a lower hound on a correlation (maximumlikelihood) decoder, we show for both the Gaussian and Rayleigh fading channels, that as the signal-to-noise ratio (SNR) increases, the asyniptotic behavior of these decoding algorithms cannot be improved. Computer simulations indicate that even for low SNR the performance of a correlation decoder can be approached by relatively simple decoding procedures. In addition, we study the effect on the performance of these decoding algorithms when a threshold is used to simplify the decoding process.

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In this study, a test methodology was developed for the measurement of spur gear efficiency under high-speed and variable torque conditions. A power-circulating test machine was designed to operate at speeds to 10,000rpm and transmitted power levels to 700kW. A precision torque measurement system was implemented, and its accuracy and repeatability in measuring torque loss in the power loop was demonstrated. Tests were conducted on gears with two values of modules and two surface roughness levels, operating in a dry sump jet-lubrication environment with three different gear lubricants. These tests were used to quantify the influence of these parameters on both load-dependent (mechanical), load-independent (spin), and total power loss. Trends in mechanical gear mesh efficiency and total gearbox efficiency were discussed in terms of rotational speed and transmitted torque. Finally, recommendations were made for the design of spur gear pairs, surface roughness, and lubricant selection for improved efficiency.

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In this study, a test methodology was developed for measurement of spur gear efficiency under high-speed and variable torque conditions. A power-circulating test machine was designed to operate at speeds to 10,000 rpm and transmitted power levels to 700 kW. A precision torque measurement system was implemented and its accuracy and repeatability in measuring torque loss in the power loop was demonstrated. Tests were conducted on gears with two values of module, and two surface roughness levels, operating in a dry sump jet-lubrication environment with three different gear lubricants. These tests were used to quantify the influence of these parameters on load-dependent (mechanical), load-independent (spin), and total power loss. Trends in mechanical gear mesh efficiency and total gearbox efficiency were discussed in terms of rotational speed and transmitted torque. Finally, recommendations were made for the design of spur gear pairs, surface roughness, and lubricant selection for improved efficiency.

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This paper describes the design and characterization of a lumped-element tunable IF filter using thinfilm barium strontium titanate (BST) varactors. The filter was designed to operate from 30-88MHz in three separate switchselectable bands with a 0-12V DC control voltage. A relatively constant insertion loss of <5dB was obtained over the desired tuning range.The circuit was also characterized over temperature from -40°C to +80°C, showing relatively little change in insertion loss over temperature, but a slight reduction in tuning range at elevated temperatures.

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