Abstract: A digital radar receiver generates the input signal which is a stream of complex numbers. The input signal is rearranged and sorted by measurement volumes, resulting in Doppler data vectors. Doppler data vectors are filtered using a number of different digital filters. The output Doppler data vectors of the filters together with the original Doppler data vector are the candidate signals. Each candidate signal is analyzed using several criteria in order to find the one signal which is most likely to be caused by precipitation and has the ground clutter removed by the filtering. The selected signal is then used to calculate the meteorological products. The selected signal is also used to derive a velocity value or velocity distribution while taking into account the effects of the filtering performed earlier.

Abstract: An image is produced of a target region from tomographic measurements through statistical inversion. The target region is mapped with a grid of voxels. Unknowns in the voxels are the components of a vector-valued variable. A next version of the vector-valued variable is repeatedly generated by drawing for each component a value from a conditional distribution. Elements of a theory matrix indicate, what is the contribution of each voxel in the grid to a detection result. The non-zero elements of the theory matrix are stored in a compressed form. A proper subset of the elements of the theory matrix is decompressed for either updating the quantity Ax and/or calculating the quantity AjT(Ax), where A is the theory matrix, x is the vector-valued variable and AjT is the transpose of the j:th column of the theory matrix.

Abstract: A method is provided for constructing a tomographic reconstruction through the application of statistical inversion. Unknowns associated with points of a reconstruction grid are represented with components of a vector-valued variable. A next version of the vector-valued variable is repeatedly created by drawing for each component a value from a conditional distribution. The components of a so generated version of the vector-valued variable are used as the tomographic reconstruction. The components are divided into sets, so that components in a set represent unknowns associated with mutually independent points of the reconstruction grid, or into independent collections. For at least two components of a set or at least two collections, the drawing of values from a conditional distribution is performed in parallel in a computer-implemented process.

Abstract: A method and an arrangement are provided for producing a computed distribution of speeds of scatterers in a target volume (1701). An estimate distribution of speeds at which scatterers would move in the target volume is provided (1201). It is converted (1202) to a candidate autocorrelation function that represent autocorrelation data points that a pulse radar would measure from the current estimate distribution. The fit of a candidate ACF to a measured ACF is measured (1203). The estimate distribution is accepted if a measured fit fulfills a predefined acceptance criterion, or modified (1205) in which case processing returns to the conversion of the modified estimate distribution to an ACF. An accepted estimate distribution is output (1206) as a computed distribution of speeds that describes the actual distribution of speeds.

Abstract: A method and an arrangement are provided for producing a computed distribution of speeds of scatterers in a target volume (1701). An estimate distribution of speeds at which scatterers would move in the target volume is provided (1201). It is converted (1202) to a candidate autocorrelation function that represent autocorrelation data points that a pulse radar would measure from the current estimate distribution. The fit of a candidate ACF to a measured ACF is measured (1203). The estimate distribution is accepted if a measured fit fulfils a predefined acceptance criterion, or modified (1205) in which case processing returns to the conversion of the modified estimate distribution to an ACF. An accepted estimate distribution is output (1206) as a computed distribution of speeds that describes the actual distribution of speeds.

Abstract: A method and apparatus are disclosed for performing tomographic reconstruction. An object to be examined is represented with a tomographic model that includes grid points. A set of measurement data represents attenuation experienced by radiation that propagated through parts of the object to be examined. Statistical inversion is applied to convert the set of measurement data into a calculated distribution of attenuation values associated with at least a number of the grid points. Applying statistical inversion includes associating values of a prior with the grid points, which prior includes at least one regularization parameter. The values of the prior for different grid points come from using different values of the regularization parameter. The method includes producing an image representation of the calculated distribution of attenuation values.

Abstract: Moving objects are detected with a radar by collecting samples of a received signal over an integration period. The terms of a match function contain a product of a sample of said received signal and a delayed-in-time, Doppler-shifted replica of a transmission and depend on parameters that describe an object that caused a reflection of the transmission. The most probable values of the parameters are found by maximizing the match function through Fourier transforming a vector consisting of terms of the match function. Those of said products that contain a non-zero contribution of said delayed-in-time, Doppler-shifted replica of a transmission are actually computed while the others of said products are zero Only non-zero blocks of the products count as final terms to the vector to be Fourier transformed that have nonzero value while intermittent blocks that have zero value are left out.