Pekka Ahola

A helicopter-borne eight-channel ranging scatterometer for remote sensing. I. System description

For pt.II see ibid., vol.31, no.1, p.170-9 (1993). HUTSCAT, a helicopter-borne dual-frequency FM-CW scatterometer, is described. The HUTSCAT measures the backscattering properties of a target with a range resolution of 65 cm. The real-time ranging capability is obtained by performing the fast Fourier transform (FFT) to the received time-domain signal. The measurement is made simultaneously at eight channels (VV, HH, HV, and VH modes of polarization at 5.4 GHz and 9.8 GHz). The scatterometer measures the radar return spectrum for eight channels in 16.6 ms, which corresponds to an along-track distance of 0.33 m for the helicopter speed of 20 m/s. The radar system has been designed for remote sensing of forests, sea ice, and snow. >

Helicopter-borne measurements of radar backscatter from forests.

Abstract Helicopter-borne scatterometer measurements of various forest and surface types were conducted in spring 1988 in Espoo, near Helsinki. The scatterometer operates at 5-4 and 98 GHz and employs four linear polarizations (VV, HH, VH and HV). At each of the eight channels the radar can measure the backscattering properties of a target with a range resolution of 1 metre. The experimental results indicate that the location of backscattering sources within the forest canopy varies substantially with tree species. By applying principal-component analysis to the radar return versus range spectrum, identification of tree species is shown to be possible.

Backscatter Behaviour Of Low-salinity Sea Ice At C- And X-band

A helicopter-borne dual-frequency scatterometer was used to investigate the backscattering behavior of low-salinity sea ice at 5.4 GHz and 9.8 GHz. The measurements were conducted in the BEPERS-88 Sea Ice Campaign in the Gulf of Bothnia, March 6-12, 1988. The backscattering properties of several sea ice types were examined at the two frequencies, using HH, VV, HV, and VH polarization modes.

Microwave Radiometer And Radar Measurements In The SAAMEX Campaign

The Surface and Atmospheric Airborne Microwave Experiment (SAAMEX) was held in Finland on 14-21 March 1990. The institutes providing airborne microwave sensors for the campaign were the British Meteorological Office (BMO) and the Helsinki University of Technology (HUT). The three main targets were sea ice, snow, and forest canopies. Ground truth measurements were made by several Finnish research institutes.

Overview of EMAC-95 snow and ice airborne campaign in Finland

The 1995 European Multisensor Airborne Campaign (EMAC-95) on snow and ice was funded by European Space Agency (ESA) and national authorities. The main test sites were in Finland (sea ice, snow in boreal areas) and Norway (land ice, snow in mountainous areas). The airborne instruments included two microwave radiometer systems (Helsinki University of Technology HUTRAD and UK Meteorological Office system) and two SAR sensors (ESAR from DLR (Germany) and EMISAR from Technical University of Denmark). This paper summarizes the activities in the Finnish test sites. Results from the HUT microwave radiometer measurements in the Campaign are given.

Development Of Airborne Dual-frequency Scatterometer

A he1 icopter-borne dual -frequency FM-CW scatterometer for remote sensing is described. The scatterometer can measure the radar b ackscatter from a target w ith a range resolution of one meter. The measurement is made simultaneously at eight channels (VV, HH, HV, and VH modes of polarization at 5.4 GHz and 9.8 GHz). 1. SUMMARY

A New Radar System for Remote Sensing

A helicopter-borne dual-frequency FM-CW scatterometer for remote sensing is described. The scatterometer can measure the radar backscatter from a target with a range resolution of one meter. This is accomplished by preforming the Fast Fourier Transform to the received time-domain signal. The measurement is made simultaneously at eight channels (VV, HH, HV, and VH modes of polarization at 5.4 GHz and 9.8 GHz).

X-band Side-looking Airborne Radar For Remote Sensing

A side-looking airborne radar (SLAR) has been designed and constructed in the Laboratory of Space Technology, Helsinki University of Technology. The SLAR provides a microwave backscattering image of the target. The maximum measurement distance is 19 km. The spatial resolution of the radar is presently about 75 m by 75 m. The radar has been tested using a helicopter but it is possible to use the equipment in an airplane as well. The applications of the SLAR are mapping of sea ice, forests and oil spills. which is 0.5 degrees. With this antenna, the across-track resolution is 156 m at distance of 19 km. Digital signal processing ( averaging ) improves the across-track resolution and the S/N ratio. The parameters of the radar are presented in Table 1.