Doc.: TX-GS-DD-3302
Issue: 1.7
Date: 15.10.2010
Page: 20 of 109
Cluster Applied Remote Sensing
TerraSAR-X Ground Segment
Basic Product Specification Document
Public
2.2 Full Performance and Data Access Range
The TerraSAR-X instrument performance is specified by the manufacturer for incidence angles within the so-
called full performance range in right-looking mode. The spacecraft may also be operated in left-looking mode
or with a wider range of incidence angles defining the data access range. These operations improve the access
time to a scene. However, due to reduced performance these products are not open for general access.
Imaging Mode Polarization
Mode
Full Performance
Beam Configurations
Incidence Angle
(Look Angle) Range
Stripmap single strip_003- strip_014 19.7° - 45.5°
(18.2° - 41.3°)
Stripmap dual stripNear_003 - stripFar_014 19.9° - 45.4°
(18.3° - 41.3°)
Spotlight &
High-Resolution
Spotlight
single & dual spot_010 – spot_100 19.7° - 55.2°
(18.2° - 49.5°)
ScanSAR single scan_003 – scan_011 19.7° - 45.5°
(18.2° - 41.3°)
Table 2-6: Full performance beams and incidence angle ranges
All elevation beams covering the data access range in single polarization stripmap and ScanSAR mode are listed
in the Annex C. They are called strip_01 to strip_27 and the 122 spotlight beams are called spot_001 to
spot_122, respectively. The ScanSAR beam configurations scan_xy are composed of 4 consecutive stripmap
beams beginning with the corresponding near range one. The performance specifications in this document refer
only to the full performance range, i.e. Strip_3 to Strip_14 in stripmap/ScanSAR modes and Spot_010 to
Spot_100 in spotlight modes. The smaller dual polarization swathes in stripmap are adjusted to the single polari-
zation beams with the same numbering.
Basic products with incidence angles outside the full performance range can not be ordered nominally since they
may have a degraded performance. The left-looking mode has no guaranteed performance as well and addi-
tionally an impact on mission operations (the solar array is turned away from the sun, the SAR antenna is turned
into the sun). Thus the ordering of left-looking acquisitions for users is restricted while products from the corre-
sponding left-looking “full performance range” of already acquired data takes may be retrieved from the cata-
logue.
2.3 Recommended Performance Range
Generally, for TerraSAR-X the ambiguity control and evaluation is a challenge due to the short antenna. Conse-
quence of the antenna dimension is a quite high PRF with minimum values of about 3000 Hz. The initially speci-
fied ambiguity ratios are generally meet but in some imaging geometries and instrument settings the ambiguities
may dominate the visual impression of images of high contrast scenes (e.g. harbors). In the commissioning
phase, the image analysis w.r.t. range and azimuth ambiguities concluded that there should be an indication for
the user on the ambiguity quality dependent on the scene context. This resulted in the introduction of an addi-
tional performance range, the Recommended Performance Range which indicates the range of incidence
angles considered preferable for scenes with very high contrast, e.g. land see transitions.
It was also found that a total ambiguity ratio is not significant. Therefore, the ambiguity requirement is applied
separately to azimuth and range ambiguities. Based on the results of the performance estimation, the recom-