The article describes the methodology for the determination of ambient temperature for thermovision measurements. The adopted methodology consists in the use of the technical blackbody model. Determining the value of the ambient temperature parameter makes it possible to enhance the accuracy of temperature measurement of objects exposed to strong irradiation using a thermovision camera.
This article presents a linear strain measurement method insensitive to temperature variations and using fibre Bragg gratings. Two Bragg gratings were applied with periods selected to obtain partial coverage of their spectrum characteristics. One of the gratings was subjected to a tension strength. Placing both gratings in one thermal chamber allowed - through ensuring the same thermal conditions - to obtain insensitivity of the entire scheme to temperature variations. The gratings were recorded on the same optical fibre and reacted to temperature variations in the same degree. Value of strain was indicated based on the transmission spectrum characteristic of two grating schemes. The use of transmission, not reflectance, characteristics of the gratings allowed for a direct measurement of the spectrum, without having to use a coupler or optical circulators, and at the same time, this allowed to simplify the strain detection scheme. We proposed applying the continuous wavelet transform with characteristics of the spectrum scheme of two gratings for improvement of static properties. Especially, the thermal linearity and stability of the sensor was improved. For a strain range up to 750 μe, the non-linearity error of processing characteristic obtained was 0.45%. Thermal stability of the scheme proposed was defined as relative sensitivity of the power to temperature variations. The mean value of such relative sensitivity of the scheme proposed in the temperature scope of 21ºC-95ºC, amounted to 0.195.
The paper presents a method for wireless measurement of car wheel air pressure and temperature using the Tire Pressure Monitoring System, or TPMS module - one of the latest safety systems introduced by the automotive industry - with readings taken on a specifically designed test bench. The paper describes the structure and operating principle of the test bench key elements and how they work with the sensors, the TPMS module, and reference instruments, as well as the data format and accuracy of data transmission between TPMS and the host computer. The software designed for an embedded system emulating the real on-board computer allows for observing raw sensor readings and the effect of calibration in two points of the characteristics.
Outdoor remote temperature measurements in the infrared range can be very inaccurate because of the influence of solar radiation reflected from a measured object. In case of strong directional reflection towards a measuring device, the error rate can easily reach hundreds per cent as the reflected signal adds to the thermal emission of an object. As a result, the measured temperature is much higher than the real one. Error rate depends mainly on the emissivity of an object and intensity of solar radiation. The position of the measuring device with reference to an object and the Sun is also important. The method of compensation of such undesirable influence of solar radiation will be presented. It is based on simultaneous measurements in two different spectral bands, shor-twavelength and long-wavelength ones. The temperature of an object is derived from long-wavelength data only, whereas the short-wavelength band, the corrective one, is used to estimate the solar radiation level. Both bands were selected to achieve proportional changes of the output signal due to solar radiation. Knowing the relation between emissivity and solar radiation levels in both spectral bands, it is possible to reduce the measurement error several times.