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An impulse radio ultra-wideband (IR-UWB) transmitter (TX) consuming ultra-low power is presented. The lowcomplexity topology features control of the power spectral density (PSD) and central frequency for a broad range of applications. The PSD and frequency adjustment are accomplished by employing a tunable pulse generator and an adjustable driver. The IR-UWB TX suitable for on-off keying coding is fabricated in a low-cost 180 nm UMC CMOS technology and occupies the total die area of 0.63 mm 2. The measurement results show the transmitter output swing of 320 mVpp (peak-topeak amplitude) with the pulse duration of 0.6 ns, and the spectrum covering the frequency range from 3 to 7.5 GHz. The total DC power consumption is 1 mW resulting in energy consumption of 5 pJ/pulse at 200 MHz data rate.

In this paper, we present a system for measuring and monitoring of groundwater level. Level of groundwater is needed to create hydrodynamic models of inland excess water, which causes significant environmental and economic problem worldwide, because large parts of the flat terrain can be covered by inland excess water. On areas of interest, continuous measurement of groundwater level on several measurement points over long periods of time (several years) is needed as input data for hydrodynamic models. Measurements of groundwater level are made by acoustic system, which measure time of travel of sound to and from level of water inside wells. Every measurement point is equipped with GPRS transceiver, which sends data over GSM network to server connected to internet. Software on server collects and saves measured data in databases in adequate data format. Prototype of system is made, and hardware and software realization, communicating network and measurement results are presented.

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