A Self-Adaptable Method to Optimize the Performance of Frequency-To-Code Conversion Based Measurement Systems

Accuracy, error compensation and simplicity of transducer's communication and interfacing are three important topics in the design and development of any measurement system. Nowadays, there are a substantial number of transducers and actuators that generate or receive, respectively, frequency modulated signals. The main advantages associated with frequency transducers include its high noise immunity, high output signal power, wide dynamic range and simplicity of signal interfacing and coding [1-2]. The frequency-to-digital conversion (FDC) is easily performed by any microcontroller, or circuits based on commercial off-the-shelf (COTS) components, without need of an analog-to-digital converter (ADC), and the same easiness exists when frequency signals are required for actuators. Eliminating the need of ADCs and DACs reduces the cost of instrumentation and measurement systems and eliminates a large number of error sources associated with these conversion devices. This paper is dedicated to FDC based measurement systems, giving particular attention to calibration issues and self-adaptive measurement capabilities that can be used to select a suitable conversion accuracy for a given signal-to-noise ratio. Some simulation and experimental results for a temperature and humidity measurement system will be included as application examples.