Level-1 SLC Products
Level-1 Single Look Complex (SLC) products are images in the slant range by azimuth imaging plane, in the image plane of satellite data acquisition. Each image pixel is represented by a complex (I and Q) magnitude value and therefore contains both amplitude and phase information. Each I and Q value is 16 bits per pixel. The processing for all SLC products results in a single look in each dimension using the full available signal bandwidth. The imagery is geo-referenced using orbit and attitude data from the satellite. SLC images are produced in a zero Doppler geometry. This convention is common with the standard slant range products available from other SAR sensors.
The SM SLC Products contain one image per polarisation channel (i.e. one or two images) and are sampled at the natural pixel spacing. This means, the pixel spacing is determined, in azimuth by the pulse repetition frequency (PRF), and in range by the radar range sampling frequency.
The IW SLC product contains one image per sub-swath, per polarisation channel, for a total of three or six images. Each sub-swath image consists of a series of bursts, where each burst was processed as a separate SLC image. The individually focused complex burst images are included, in azimuth-time order, into a single sub-swath image, with black-fill demarcation in between. Due to the one natural azimuth look inherent in the data, the imaged ground area of adjacent bursts will only marginally overlap in azimuth - just enough to provide contiguous coverage of the ground. Unlike SM and WV SLC products, which are sampled at the natural pixel spacing, the images for all bursts in all sub-swaths of an IW SLC product are re-sampled to a common pixel spacing grid in range and azimuth. The resampling to a common grid eliminates the need of further interpolation in case, in later processing stages, the bursts are merged to create a contiguous ground range, detected image.
The EW SLC products contain one image per sub-swath, per polarisation channel, for a total of five or ten images. Each TOPSAR EW burst in a sub-swath is processed as a separate SLC image, and included in a sub-swath image exactly as in the IW case. Like the IW mode, EW is a one natural azimuth look mode, and therefore the EW and IW images have similar properties. As for the IW SLC products, the images for all bursts in all sub-swaths of an EW SLC product are re-sampled to a common pixel spacing grid in range and azimuth.
SLC products are generated for all acquisition modes: