Frequency Domain Sensors and Frequency Measurement Techniques

Abstract

Getting fast and accurate information is of paramount importance for most monitoring, data acquisition, and monitoring systems; there are sensors that transform their input into a frequency domain output, this kind of sensors are known as Frequency Domain Sensors (FDS); when the value of the output frequency is measured in a FDS, the value of the sensor’s input (measurand) can be calculated, that is why the frequency measurement in the output of FDS is critical for using such sensors. In this work different kinds of resonant sensors (FDS) are reviewed; also frequency measurement techniques are explored; finally a novel frequency measurement method is proposed and analyzed for resolution improvement in frequency domain sensors.

Effect of phase in fast frequency measurements for sensors embedded in robotic systems

“…The analysis, as shown in Figure 1, shows the functioning of the principle of rational approximations, which has been reported and analyzed in previous publications. 10,[13][14][15][16]18 An important characteristic is that the mentioned reports lack realism. For this reason, the aim of this work is to evaluate the effect of phase from input signals, which is closer to reality than previous reports.…”

“…[7][8][9] These improvements include not a fixed sampling time, insensitivity to jitter, and accuracy limited by the reference stability. [10][11][12][13][14][15] The application of such a technique has been proposed for several tasks, like sensors for chemical compounds 16,17 or automotive industry. 12 The aim of this work is to provide an analysis of how the phase of signals, during measurement, affects the approximation of an unknown frequency.…”

Surface acoustic wave humidity sensors based on uniform and thickness controllable graphene oxide thin films formed by surface tension

“…As one of the acoustic resonators, the surface acoustic wave sensor (SAW) has advantages of small size, high sensitivity 11,12 , simple processing, and high test accuracy due to its quasi-digital output signal 13 . Combined with aluminum nitride (AlN) as the piezoelectric material, the fabrication of SAW devices is compatible with the Complementary Metal Oxide Semiconductor (CMOS) process 14 .…”