Apparatus for convoluting complex functions expressed as fourier series
US4025769A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 7, 1975 |
| Grant date | May 24, 1977 |
| Priority date | — |
| Expiry date | Jul 7, 1995 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F17/156
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
The azimuth beamspread smear effect in a radar image is simulated by convoluting a terrain function with an antenna gain function for each sweep that the target object is within the antenna gain bandwidth. The initial grid map of elevation-reflectance terrain data is combined with aircraft position and antenna orientation data to provide composite terrain data required to compute a terrain function along each range arc. Each radar sweep generates a data raster of composite terrain data for the R range points within that sweep. The antenna bandwidth is a small sector, M sweeps wide, which moves across the scanned sector as the antenna rotates forming R range arcs. A constantly changing block of composite terrain data for the M sweeps and R points must be continuously maintained to generate the beamspread smear by convolution of the terrain function and the antenna function. The MxR block of terrain data is held in the form of a Fourier series for each range arc. Each range arc Fourier series requires a (2N+1) memory capacity (N sine terms, plus N cosine terms, plus one constant term). The total memory requirement for the MxR data block in Fourier series form is (2N+ 1)R. The terrain…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.