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Compensated Phase History Data (CPHD) is the lowest level of processing Umbra offers and is available for an additional fee. The specification for CPHD is maintained by the US National Geospatial Intelligence Agency (NGA) and is available online here.

“Compensated” is short for “motion compensated,” and at this stage the data isn’t projected into a rectangular grid yet, let alone registered to a real place on Earth. It's not quite raw binary, but it's close.

CPHD offers you maximal control over how you choose refine it into complex phase data or detected products. For advanced users with radar science expertise and strong opinions about image formation techniques, CPHD offers a blank slate to start from.

However, there are few open source or commercially available tools for working with CPHD, which is why we also offer SICD and SIDD.

Data Structure

CPHD breaks down into three constituent "blocks" with an optional fourth block:

  • The "XML Block" contains text-based XML that describes the other blocks

  • The "Signal Block" is a binary formatted file that contains signal data

  • The "Per Vector Parameters (PVP) Block" is a binary formatted file containing one or more one-dimensional arrays of parameter sets

  • The optional "Support Block" is a binary formatted file containing one or more two-dimensional arrays describing either the imaged scene surface height or the sampled antenna pattern(s)

We recommend downloading the full specification and familiarizing yourself with it if you are unfamiliar with CPHD.