PP Systems UniSpec SC / DC

Status: Experimental · Vendor: PP Systems · Extensions: .SPT (UniSpec SC), .SPU (UniSpec DC)

The PP Systems UniSpec SC (single-channel) and UniSpec DC (dual-channel) are field spectroradiometers. When their .SPT / .SPU exports expose an axis-first ASCII table, nirs4all-formats reads them through the row-spectral-table reader. The current fixtures are synthetic, so the coverage is scoped until a real field acquisition can validate production headers, units and metadata.

Instruments & software

Produced by PP Systems UniSpec SC / DC instruments and their host software. .SPT files come from the single-channel SC; .SPU files from the dual-channel DC (two radiometer channels). A separate pp_systems reader recognises — and deliberately refuses — Arctic LTER UniSpec-DC vegetation-index products, which are derived summaries rather than raw spectra.

File structure

An optional header preamble of key/value lines (e.g. File, Date, Notes), then an axis-first table: an explicit wavelength column followed by numeric signal columns. The reader requires that explicit axis column and does not claim arbitrary PP Systems reports by extension alone.

What nirs4all-formats extracts

  • Signals — DN columns are emitted as raw_counts; Reflectance columns as reflectance. UniSpec SC exposes dn_white, dn_target, reflectance; UniSpec DC exposes channel_a_dn, channel_b_dn, reflectance.

  • Axis — wavelength in nm.

  • Metadata — header key/value lines (File, Date, Notes, …) are preserved under metadata.vendor.

  • Provenance — source file + SHA-256, reader name and version.

Variants & support status

Variant

Status

Notes

UniSpec SC .SPT (axis-first ASCII)

Experimental

Synthetic fixture; real field acquisition wanted.

UniSpec DC .SPU (axis-first ASCII, two channels)

Experimental

Synthetic fixture; real two-channel acquisition wanted.

Arctic LTER UniSpec-DC index products (CSV/XLSX)

Detected / refused

Derived NDVI/EVI/PRI/WBI/Chl/LAI summaries, not raw spectra.

Limitations & known gaps

  • The committed .SPT / .SPU fixtures are synthetic, so production headers, units and instrument metadata are not yet validated against a real field export.

  • The local Arctic LTER UniSpec-DC CSV/XLSX files are vegetation-index products, not raw .SPT/.SPU spectra; the pp_systems reader refuses them with the dedicated pp-systems-unispec-derived-indices diagnostic and points to a separate reflectance data-scan file that is not present in samples_local/pp_systems/.

  • PP Systems acquisition metadata is preserved verbatim but not normalized into typed fields.

Reference readers

The axis-first exports are readable with pandas or R read.table; nirs4all-formats adds axis detection, signal typing and provenance. A comparison against SPECCHIO or another trusted import path is planned if one becomes available.

Samples & validation

Fixtures under samples/pp_systems/ are golden-backed / semantic-tested on the nm axis: synthetic_unispec.SPT (UniSpec SC, 1 record, 200 points, dn_white / dn_target / reflectance) and synthetic_unispec_dc.SPU (UniSpec DC, 1 record, 200 points, channel_a_dn / channel_b_dn / reflectance). The Arctic LTER index products in samples_local/pp_systems/ are expected refusals via pp-systems-unispec-derived-indices and do not change the raw UniSpec coverage status.