This paper presents practical measurements of surface acoustic wave (SAW) velocity using phase technique. The two most important practical properties relating surface wave propagation on piezoelectric substrate are the wave velocity and electromechanical coupling coefficient. The main technique for obtaining precise results of SAW velocity is based on the use of laser probe method, which is expensive and complex. The presented method using phase technique is simple and accurate. The practical measurements are applied across the usable bandwidth of the SAW devices from 30 to 40 MHz, the used SAW filters are chosen due to its operating frequencies, commercial, and have wide bandwidth. This method is applied practically for two available commercial SAW filters F1034, Toshiba product and X101 (E8335) Sanyo product both are used in IF stages in color TV. Moreover, measurements with and without deposited sample of liquid are made for both types of filters. The interpretation of the obtained results indicate that this simple method of measurement along with the preceding programs have the possibility to be used as characterization technique for loading liquid properties, which is best suitable for chemical sensors and biosensors.

A method for characterizing Σ&Delta modulators is described which can be built in large integrated circuits or systems-on-chip. The method can be used to measure gain and phase, as well as, total harmonic distortion and signal to noise and harmonic distortion ratio parameters. It is prone to be built in circuit, when computational resources such as digital signal processors or re-programmable logic are available, but can also be used in computer simulations making it easier to compare expected with measured performances.

A lot of geotechnical engineering problems can be analysed in situ with tests of horizontal and vertical loaded piles. These are required, for instance, to study the behaviour of piles isolated and in groups. Based on the emergent concept of "smart sensor" a unit was developed that converts the deformation of the concrete pile measured by an LVDT on digital information. This unit is integrated on a local area network supervised by a command unit located at the surface. The communication protocol is based on a master-slave structure supported by dedicated developed commands.

This paper describes test procedures to characterize the behavior of logarithmic analog-to-digital converters. Logarithmic A/D converters are usually characterized in terms of signal-to-noise ratio (SNR) or in deviation of the ideal characteristic in dB. There are a lack of test methods definition in the literature, as can be observed in the IEEE standard 1241 for these type of converters. Systematic test procedures have been applied to µ-law converters according to the G.711 standard, and to a new type of high-speed true logarithmic pipeline A/D converter. DNL and INL had been defined in the logarithmic domain to allow correct characterization of this class of converters.

A prototype of humidity sensor, based on a solgel ceramic compound of phosphorous pentoxide P2O5 and silica SiO2, is presented. The sensing principle is based on the high affinity between phosphorous pentoxide and water: the frequency spectrum of the electrical impedance varies according to humidity with remarkable sensitivity. The silica basis allows the sensing element to be deposed on a oxidized silicon chip substrate for microsensor applications. The sol-gel production allows the sensing element to be easily developed as thin-film for fast time response. Design criteria and preparation procedure of the material, metrological characterization of the sensing element, and preliminary response tests of the sensor prototype are reported. Experimental results show the sensing element to be promising for a high-sensitive humidity low-temperature microsensor.