Generic embedded sensor development: high-speed analogue preconditioning and data acquisition systems

摘要

The design of a high-speed, low-cost, generic analogue preconditioning system, which is capable of interfacing with a wide variety of transducers, is described. A multi-purpose, configurable data acquisition module, which is also capable of data generation, is presented. Software support is provided by advanced signal analysis and innovative presentation algorithms that are implemented on a powerful embedded digital signal processor.ududPrecision voltage-feedback and high-speed current-feedback operational amplifiers are combined to form adaptable, front-end multi-stage composite amplifiers. These distinctive composite amplifiers retain the individual qualities of their incorporated parts. The amplifier’s output voltage range is designed to match a standard ADC input voltage range. Easy to implement data converter circuitry and front-end signal amplification components were implemented on a detachable printed circuit daughterboard. A resourceful method of interfacing allows a series of Texas Instruments DSP mother-boards to be accessible. The PCB features single and dual input channel operation, adjustable input voltage ranges and sampling rates under software control. Bi-directional capability adds diagnostic functionality to the already versatile highperformance data acquisition system.ududThe high-speed preconditioning and data converter element’s vulnerability to inconsistent and non-ideal real world effects such as noise, signal interference, parasitics, proximity effects and other layout problems is discussed.ududReal-time digital filtering, spectrum and phase analysis sub-routines form codeintensive multi-functional programmes that simultaneously display visually and record numerically the input signal properties in a comprehensive fashion. A user directed, automated, calibration software programme was developed to correct for precision-based errors caused by the signal conditioning instrumentation.