Page 99 - Digital Analysis of Remotely Sensed Imagery

70 Cha pte r T w o

No. of
Nominal Positions/ Swath Width, Incident
Mode Resolution, m Beams km Angles, deg
Fine 8 15 45 37–47
Standard 30 7 100 20–49
Wide 30 3 150 20–45
ScanSAR 50 2 300 20–49
narrow
ScanSAR wide 100 2 500 20–49
Extended high 18–27 3 75 52–58
Extended low 30 1 170 10–22

Source: CSA, 2005.
TABLE 2.29 Characteristics of Radsarsat-1 Imagery in Seven Modes of Scanning

Radarsat data are rather expensive. An archived image acquired
2
in the standard mode (100 100 km ) costs US$2750 at level 0 (i.e.,
raw data). The price goes as high as US$3750 for more processed
path-oriented and map-oriented data. An additional programming
fee is chargeable for data recorded upon user request. The exact
amount of the programming fee varies with the urgency of request.
Data recorded prior to January 1, 1999, are sold at a heavily discounted
price. In spite of this, they are still much more expensive than other
optical satellite data, such as ASTER. Radarsat-1 data may be delivered
in a stored media via courier or electronically via the Internet in a
wide range of spatial resolutions and swath widths.
Succeeding Radarsat-1, Radarsat-2 was successfully launched
into the same orbit as Radarsat-1 on December 14, 2007, safeguarding
the continuity of data supply. Radarsat-2 makes a few improvements
over its predecessor, such as enhanced spatial resolution to as low as
3 m, looking directions (both left- and right-looking imaging is
possible), reduced revisit period to 2 to 3 days (based on 500-km
swath width) at the equator, and onboard geolocation via GPS to an
accuracy of ±60 m in real time. It is possible to acquire multichannel
images at bandwidths of 11.6, 17.3, 30, 50, and 100 MHz. The sensor
is fully flexible in selecting polarization that includes HH, HV, VH,
and VV (Table 2.30). Together with different beam modes, the image
resolution ranges from 3 to 100 m, and the swath width varies from
20 to 500 km. These improvements are made possible owing to the
deployment of a state-of-the-art phased array antenna. It comprises
hundreds of miniature transit-receive modules. Controlled by a
computer, the antenna is able to steer at the full range of swath and
alternate operation modes nearly instantaneously.