aviconv-asterix

Bidirectional EUROCONTROL ASTERIX codec — part of the aviconv converter family.

Supported categories (pinned editions):

Scope

Bidirectional. ASTERIX is a binary sensor/tracker wire format; aviconv both decodes it into typed, JSON-serialisable records and encodes records back to binary. As of 0.2.0, encode(decode(b)) == b holds byte-exact for every record carried through iter_records (see docs/packages/asterix.md for the raw vs. typed encode paths and the decode-subset LSB-quantisation table).

A decode subset of each category is mapped to typed fields (data source, times, WGS-84 positions, flight levels, velocities, identity); every other present data item is still measured via its UAP layout and preserved hex-encoded in raw_items, so nothing on the wire is silently dropped. If a record sets an FSPEC bit with no UAP entry (edition mismatch), that data block is undecodable — the block LEN is used to resynchronise at the next block (--skip-errors).

CAT048 position is polar, not WGS-84. I048/040 carries slant range

• azimuth relative to the reporting radar, not a lat/lon — ASTERIX does not carry the radar site's own position, so no georeferencing is possible from a CAT048 record alone. Cat048Record exposes rho_nm and theta_deg and deliberately has no lat/lon field.

Position honesty extends to CAT010/CAT020, each in its own way. Cat020Record carries WGS-84 (lat/lon) and local Cartesian (x_m/y_m) as two independent wire items — both may be present on the same record, and neither is ever derived from the other. Cat010Record instead carries exactly one of three position kinds depending on sensor type — polar (rho_m/theta_deg, sensor-relative, in metres, not the NM Cat048Record uses), WGS-84 (lat/lon), or local Cartesian (x_m/y_m) — and the other two stay None rather than being synthesised across kinds. Cat011Record (A-SMGCS fused system tracks) mirrors Cat020Record's two-kind shape rather than Cat010Record's three-kind one — WGS-84 (lat/lon) and local Cartesian (x_m/y_m) are two independent wire items, both exposed when present, neither ever derived from the other; there is no polar flavour, since fused tracks are not sensor-relative.

Usage

from aviconv_asterix import encode_records, iter_records

records = list(iter_records(open("radar.ast", "rb").read()))
print(records[0].callsign, records[0].lat, records[0].lon)

encode_records(records) == open("radar.ast", "rb").read()  # True

Every record decoded via iter_records carries its original octets in raw_items; re-encoding it (unmodified or not) re-emits those octets verbatim, byte-exact, regardless of any typed-field edits made via model_copy. Records built from scratch (no raw_items) encode from their typed fields instead, via each item's build callable — see docs/packages/asterix.md for which items have one wired.

CLI (NDJSON, one record per line):

aviconv asterix decode radar.ast
aviconv asterix decode - < radar.ast          # binary stdin
aviconv asterix decode radar.ast --skip-errors -o out.ndjson

aviconv asterix encode records.ndjson -o radar.ast
aviconv asterix decode radar.ast | aviconv asterix encode -   # round-trip

Licence

MIT. The ASTERIX category specifications are published by EUROCONTROL; this package is not endorsed by or affiliated with EUROCONTROL.