Borys Stoew

A Compact UWB Indoor and Through-Wall Radar with Precise Ranging and Tracking

Ultrawideband (UWB) technology has many advantages compared to its narrowband counterpart in many applications. We present a new compact low-cost UWB radar for indoor and through-wall scenario. The focus of the paper is on the development of the signal processing algorithms for ranging and tracking, taking into account the particular properties of the UWB CMOS transceiver and the radiation characteristics of the antennas. Theoretical analysis for the algorithms and their evaluations by measurements are presented in the paper. The ranging resolution of this UWB radar has achieved 1-2 mm RMS accuracy for a moving target in indoor environment over a short range, and Kalman tracking algorithm functions well for the through-wall detection.

GPS observations of daily variations in the atmospheric water vapor content

Abstract Estimates of the atmospheric Integrated Water Vapor (IWV) for 30 GPS sites in Europe, covering the period from January 1997 until August 1999 are analyzed. For every month the diurnal cycle in the IWV is estimated by averaging the data referred to that particular hour for that month. The average peak-to-peak value of the diurnal cycle during the winter months is between 0.6 mm and 1.5 mm, while during the summer months the peak-to-peak value is between 0.8 mm and 3.2 mm. The GPS results at the Onsala Space Observatory are compared to those obtained from a co-located microwave radiometer and nearby (distance 37 km) radiosonde launches. We find that the estimated diurnal variations are comparable to the uncertainties in the measurements and the models used. However, a clear dependence between the peak-to-peak value and latitude of the observations is seen during the summer months. No such dependence is detected for the winter period.

Real-time processing of GPS data delivered by SWEPOS

Abstract The Swedish geodetic network of GPS receivers, SWEPOS, generates data with a temporal resolution of 1 s. These are used in 3 different GPS processing activities where total atmospheric delay estimates are obtained at 5 minute intervals. We present an additional real-time (RT) processing strategy which allows for the delivery of estimates of atmospheric parameters every 15 s with a typical delay of 3 s, based on the use of broadcast satellite orbits. The total delay data from the RT processing are compared to the results from the final GIPSY solution using the Final orbits as well as to the results from the analysis that routinely delivers 7-day delayed estimates using the Rapid orbits. The rms differences in total delay between the RT solution and the ‘Final’ solution are at the 0.02 m level. The rms differences between the ‘Rapid’ and the ‘Final’ solution are about 0.007 m. For the studied period the dynamic range of the total delay is about 0.1 m.

Spatial error correlation of GPS atmospheres as determined from simulations

Abstract We have made Monte Carlo simulations in order to quantify the influence of several error sources on the atmospheric delay derived in our regular “Precise Point Positioning” analysis of GPS data. Satellite position and clock errors were found to be the greatest sources of error. The RMS size of the atmospheric delay error due to these sources is suggested to be 4–8 mm, and the correlation of the delay error over 1000 km is 0.5-0.7. In our real-time analysis of the atmospheric delay satellite orbits and clock offsets are modelled in the Kalman filter. The modelled errors suggest an uncertainty in the atmospheric delay of 10–13 mm, and a decrease in the correlation coefficients to about 0.65 over a distance of 1000 km. For both the Precise Point Positioning and the real-time analysis the influence from antenna signal scatter will give additional error contributions.