Category: Radar (SAR)
Speckle
Speckle is a grainy noise pattern in SAR imagery caused by coherent interference, typically reduced by filtering or multi-looking.
Also known as: speckle noise
Expanded definition
Speckle is inherent to coherent radar imaging. It appears as salt-and-pepper texture that can obscure subtle signals and inflate variance in pixel-level analysis.
Speckle reduction methods include spatial filtering, temporal averaging, and multi-looking. These methods trade off noise reduction against spatial detail.
In time series, speckle can create false change if you compare single scenes pixel by pixel. Many SAR analytics use aggregation (for example field averages) or robust temporal methods to stabilize measurements.
Related terms
SAR (Synthetic Aperture Radar)
SAR is an active radar sensor that works day or night and can see through clouds, measuring surface scattering rather than reflected sunlight.
Backscatter
Backscatter is the amount of radar signal returned to the sensor, influenced by roughness, moisture, and structure.
Time Series
A time series is a sequence of observations over time for the same location, used for monitoring and change detection.