Dwell

 

In Dwell mode the satellite is manoeuvred during the data take, extending the sensor exposition time by a configurable factor.

The manoeuvre is basically a pitch operation in which the satellite is pitched forward at the start of the data take, and gradually changes the pitch until the end of the data take, ending with an aft pitch position.

The pitch is symmetrical around the centre of the data take, with zero-pitch right at the centre.

Optionally it is possible to add a gradual roll correction to compensate for the Earth's lateral displacement during the data take.

The swath duration will be longer than the equivalent Nadir-only operation, according to the dwell factor.

As a result of the dwell operation the footprints will show a certain level of distortion due to the variable slant range.

The Sensor Wizard allows to define additional parameters:

• Dwell time factor: Multiplication factor of the swath duration, implementing the extended dwell time. The actual multiplication factor will be tuned down if necessary to comply with the Pitch range constraint.

• Pitch range: Maximum pitch span around pitch zero. A range of 60 degrees will lead to pitch values within the +- 30 degree range, symmetrically around zero.

• Roll correction: Apply roll correction to compensate the lateral displacement of the Earth during the data take.

• Roll correction ON	Roll correction OFF

• Outer border: Display an external swath boundary for special acquisitions, showing equivalent nadir times. More information here.

IMPORTANT: the satellite needs to be agile, to allow both along-track and cross-track steering. This requires setting the satellite attitude: