Reliable soil moisture measurements over large areas are much needed for both hydrologic modelling and remote sensing applications. For collecting such data, portable electronic sensors offer a practical alternative to gravimetric measurements. The conversion of the measured electrical output to soil moisture is nonetheless a non trivial task as it depends on soil type and temperature. In this ...

Over the past five years, Distributed Temperature Sensing (DTS) along fiber optic cables using Raman backscattering has become an important tool in the environmental sciences. Many environmental applications of DTS demand very accurate temperature measurements, with typical RMSE < 0.1 K. The aim of this paper is to describe and clarify the advantages and disadvantages of double-ended calibratio...

We describe the overall performance of the STIS CCD after HST Servicing Mission #4 and the associated updates to calibration reference files. Most aspects of CCD performance are found to be fairly consistent with extrapolations of the trends seen prior to the failure of STIS in August 2004. The CCD gain value for the CCDGAIN = 4 setting has been redetermined using net count ratios of standard s...

Future sea surface salinity missions will require Lband radiometers to have calibration stabilities of ≤ 0.05 K over 2 days. This research program has focused on determining the optimum radiometer requirements and configuration to achieve this objective. System configuration and component performance have been evaluated with radiometer test beds at both JPL and GSFC. The GSFC testbed uses a cry...

We present an overview of the National Institute of Standards and Technology high temperature blackbodies, both in operation and in development, suitable for heat-flux sensor calibration. Typical results of calibrations using the transfer technique in the 25 mm Variable-Temperature Blackbody are presented to demonstrate the long-term repeatability of the calibration technique. A comparative stu...

Imaging fiber bundles can map the curved image surface formed by some high-performance lenses onto flat focal plane detectors. The relative alignment between the focal plane array pixels and the quasi-periodic fiber-bundle cores can impose an undesirable space variant moiré pattern, but this effect may be greatly reduced by flat-field calibration, provided that the local responsivity is known. ...

Tolerances in the fabrication of metal oxide (MOX) gas sensors lead to inter-device variability baseline and sensitivity, even for same batch. This has traditionally forced use individual calibration models (ICMs) built specifically each sensor unit, which requires an expensive time-consuming process hinders replacement. We propose Global (GCMs) using responses multiple units, then applied a ne...

In this paper we present a 2μW temperature compensated on-chip digitally controlled oscillator and a 70nW uncompensated, ultra low power oscillator. The temperature compensated oscillator has a temperature stability of 8ppm/C while uncompensated oscillator has a stability of 4%/C. The uncompensated oscillator is calibrated using stable oscillator often to achieve high effective temperature stab...

Solar radiation data are an important input for estimating evapotranspiration and modelling crop growth. Direct measurement of solar radiation is now carried out in most European countries, but the network of measuring stations is too sparse for reliable interpolation of measured values. Instead of direct measurements, solar radiation may be estimated from empirical solar radiation models that ...