Fenix Hyperspectral Sensor

The Fenix sensor is a visible to short-wave infra-red hyperspectral instrument manufactured by ​Specim. It has a similar spectral coverage to the Eagle and Hawk instruments but combined in one instrument which uses the same fore optics.

Raw data format

The Fenix data is captured as ENVI format BIL files (a pair of .hdr and .raw), with an associated nav file (usually one nav file per flight line). The .hdr files are ASCII text files where as the .raw and .nav are binary data files.

The Fenix .raw data files contain 12-bit data (values of 0-4095) stored as 16-bit integer for the VNIR data, and 16-bit data (values 0-65535) for the SWIR data. The first pixel of the first band of each raw file is the frame counter pixel, which is essentially a frame id tag that increments by 1 through out the file. At the end of the raw file, after data capture for this flight line, a number of lines of data are captured with the shutter closed. These lines are referred to as "dark lines" and give sensor ccd values for when no light is present.

The .nav files are a collection of different 'messages'. These contain the real-time position and attitude of the aircraft as well as periodic time stamps marking the start of the flight line capture.

Timing

The Fenix is connected to a navsyncer that sends PPS pulse every second. This is recorded into the .nav files.

Specifications for FENIX SN350005 (details from SPECIM data sheet)

Note that the sensor is constructed from two CCD like devices, with the VNIR and SWIR on each CCD respectively.

Detector size	384*622 (with VNIR binned @ 2x2)
Bit depth (of sensor analog to digital converter)	12 bit VNIR, 16 bit SWIR
Spatial pixels	384
Spectral pixels	622
Spectral resolution	3.5nm (VNIR), 12nm (SWIR)
Nominal spectral range (prior to calibration)	400-2500nm
Central pixel number	194.7
Focal length	16.8mm
Field of View (FOV)	31.94 degrees (16.12 <-> -15.82)
Pixel size (on CCD)
IFOV	0.083 degrees