ASTERIX

Surveillance records grouped by ASTERIX category.

Connect the parser

using Asv.Gnss;
using Asv.IO;

var protocol = Protocol.Create(builder =>
{
    builder.Protocols.RegisterAsterixProtocol();
});

The stream parser is AsterixMessageParser and its message model is AsterixMessage. See Quick Start for router, port, and subscription setup. Registration selects decoders; the receiver must already be configured to emit the required data.

Default message coverage

The default categories are 001, 002, 004, 010, 020, 021, 034, 048, and 247. Category IDs use byte; each category model contains its supported data-item implementations.

Message model
`AsterixMessageI002`
`AsterixMessageI004`
`AsterixMessageI034`
`AsterixMessageI001`
`AsterixMessageI010`
`AsterixMessageI020`
`AsterixMessageI021`
`AsterixMessageI048`
`AsterixMessageI247`

Usage and limitations

Category registration is not a claim of complete coverage of every edition, UAP, or optional data item. Match the sender's category edition and field layout against the corresponding Messages/Ixxx source directory. Test recordings and excluded raw-message files do not add runtime category support.

Implementation reference

Coverage above follows Protocols/Asterix/AsterixProtocol.cs under src/Asv.Gnss. Inspect concrete message classes for field names, units, and supported payload revisions.

Specification message catalog

The message-level registration unit is an ASTERIX category. The following table lists all categories registered in AsterixProtocol; the local PDF set provides category specifications only for CAT020 and CAT021. No complete catalog of all EUROCONTROL categories is available in this checkout.

Status: Model present means a concrete payload model exists in the current checkout; it does not certify complete field, revision, encoding, or firmware coverage. Partial identifies a known incomplete decoder. Not implemented means no matching concrete model was found. Default reports whether the standard registration adds that model. Models outside the default set require explicit registration. See the limitations above before transmitting messages.

Page references below are PDF page numbers (1-based), including covers and front matter.

Category	C# model	Status	Default	Local PDF coverage
001	`AsterixMessageI001`	Model present	Yes	No category specification PDF in this checkout
002	`AsterixMessageI002`	Model present	Yes	No category specification PDF in this checkout
004	`AsterixMessageI004`	Model present	Yes	No category specification PDF in this checkout
010	`AsterixMessageI010`	Model present	Yes	No category specification PDF in this checkout
020	`AsterixMessageI020`	Model present	Yes	CAT020 ed. 1.9
021	`AsterixMessageI021`	Model present	Yes	CAT021 ed. 2.1 and 2.7
034	`AsterixMessageI034`	Model present	Yes	No category specification PDF in this checkout
048	`AsterixMessageI048`	Model present	Yes	No category specification PDF in this checkout
247	`AsterixMessageI247`	Model present	Yes	No category specification PDF in this checkout

CAT020 and CAT021 data-item catalogs

The tables below list every standard data item defined by the local category PDFs. They do not expand bit fields inside those items. A matching item number means a model exists, not that all revisions of that item are compatible. In particular, AsterixRecordI021 declares the edition 2.1 mapping; CAT021 edition 2.7 support must not be inferred from a shared item identifier. C# FRN values are reported exactly as implemented, independently of the printed PDF UAP.

CAT020

Sources: Protocols/Asterix/Messages/I020/Docs/cat020-asterix-mlt-messages-part-14.pdf (edition 1.9).

Item	Name	Status	C# model	C# FRN	Record dispatch	PDF reference
I020/010	Data Source Identifier	Model present	`AsterixFieldI020Frn001Type010`	1	Yes	ed. 1.9 p. 20
I020/020	Target Report Descriptor	Model present	`AsterixFieldI020Frn002Type020`	2	Yes	ed. 1.9 p. 21
I020/030	Warning/Error Conditions	Model present	`AsterixFieldI020Frn024Type030`	24	Yes	ed. 1.9 p. 23
I020/041	Position in WGS-84 Coordinates	Model present	`AsterixFieldI020Frn004Type041`	4	Yes	ed. 1.9 p. 24
I020/042	Position in Cartesian Coordinates	Model present	`AsterixFieldI020Frn005Type042`	5	Yes	ed. 1.9 p. 25
I020/050	Mode-2 Code in Octal Representation	Model present	`AsterixFieldI020Frn026Type050`	26	Yes	ed. 1.9 p. 26
I020/055	Mode-1 Code in Octal Representation	Model present	`AsterixFieldI020Frn025Type055`	25	Yes	ed. 1.9 p. 27
I020/070	Mode-3/A Code in Octal Representation	Model present	`AsterixFieldI020Frn008Type070`	8	Yes	ed. 1.9 p. 28
I020/090	Flight Level in Binary Representation	Model present	`AsterixFieldI020Frn010Type090`	10	Yes	ed. 1.9 p. 29
I020/100	Mode-C Code	Model present	`AsterixFieldI020Frn011Type100`	11	Yes	ed. 1.9 p. 30
I020/105	Geometric Height (WGS-84)	Model present	`AsterixFieldI020Frn015Type105`	15	Yes	ed. 1.9 p. 31
I020/110	Measured Height (Local Cartesian Coordinates)	Model present	`AsterixFieldI020Frn014Type110`	14	Yes	ed. 1.9 p. 31
I020/140	Time of Day	Model present	`AsterixFieldI020Frn003Type140`	3	Yes	ed. 1.9 p. 32
I020/161	Track Number	Model present	`AsterixFieldI020Frn006Type161`	6	Yes	ed. 1.9 p. 32
I020/170	Track Status	Model present	`AsterixFieldI020Frn007Type170`	7	Yes	ed. 1.9 p. 33
I020/202	Calculated Track Velocity in Cartesian Coordinates	Model present	`AsterixFieldI020Frn009Type202`	9	Yes	ed. 1.9 p. 34
I020/210	Calculated Acceleration	Model present	`AsterixFieldI020Frn016Type210`	16	Yes	ed. 1.9 p. 35
I020/220	Target Address	Model present	`AsterixFieldI020Frn012Type220`	12	Yes	ed. 1.9 p. 35
I020/230	Communications/ACAS Capability and Flight Status	Model present	`AsterixFieldI020Frn022Type230`	22	Yes	ed. 1.9 p. 36
I020/245	Target Identification	Model present	`AsterixFieldI020Frn013Type245`	13	Yes	ed. 1.9 p. 38
I020/250	Mode S MB Data	Model present	`AsterixFieldI020Frn021Type250`	21	Yes	ed. 1.9 p. 39
I020/260	ACAS Resolution Advisory Report	Model present	`AsterixFieldI020Frn023Type260`	23	Yes	ed. 1.9 p. 41
I020/300	Vehicle Fleet Identification	Model present	`AsterixFieldI020Frn017Type300`	17	Yes	ed. 1.9 p. 42
I020/310	Pre-programmed Message	Model present	`AsterixFieldI020Frn018Type310`	18	Yes	ed. 1.9 p. 43
I020/400	Contributing Devices	Model present	`AsterixFieldI020Frn020Type400`	20	Yes	ed. 1.9 p. 44
I020/500	Position Accuracy	Model present	`AsterixFieldI020Frn019Type500`	19	Yes	ed. 1.9 p. 46
RE	Reserved expansion	Container model	`AsterixFieldI020Frn027TypeRe`	27	Yes	UAP / separate appendix
SP	Special purpose	Not implemented	-	-	No	UAP / separate appendix

CAT021

Sources: Protocols/Asterix/Messages/I021/Docs/part12-cat021-asterix-ads-b-messages-ed2.1.pdf (edition 2.1), Protocols/Asterix/Messages/I021/Docs/asterix-adsbtr-cat021-part12-v2-7.pdf (edition 2.7).

Item	Name	Status	C# model	C# FRN	Record dispatch	PDF reference
I021/008	Aircraft Operational Status	Model present	`AsterixFieldI021Frn041Type008`	41	Yes	ed. 2.1 p. 19; ed. 2.7 p. 20
I021/010	Data Source Identification	Model present	`AsterixFieldI021Frn001Type010`	1	Yes	ed. 2.1 p. 20; ed. 2.7 p. 21
I021/015	Service Identification	Model present	`AsterixFieldI021Frn004Type015`	4	Yes	ed. 2.1 p. 20; ed. 2.7 p. 21
I021/016	Service Management	Model present	`AsterixFieldI021Frn039Type016`	39	Yes	ed. 2.1 p. 21; ed. 2.7 p. 22
I021/020	Emitter Category	Model present	`AsterixFieldI021Frn034Type020`	34	Yes	ed. 2.1 p. 22; ed. 2.7 p. 23
I021/040	Target Report Descriptor	Model present	`AsterixFieldI021Frn002Type040`	2	Yes	ed. 2.1 p. 23; ed. 2.7 p. 24
I021/070	Mode 3/A Code in Octal Representation	Model present	`AsterixFieldI021Frn021Type070`	21	Yes	ed. 2.1 p. 26; ed. 2.7 p. 31
I021/071	Time of Applicability for Position	Model present	`AsterixFieldI021Frn005Type071`	5	Yes	ed. 2.1 p. 26; ed. 2.7 p. 32
I021/072	Time of Applicability for Velocity	Model present	`AsterixFieldI021Frn009Type072`	9	Yes	ed. 2.1 p. 27; ed. 2.7 p. 33
I021/073	Time of Message Reception for Position	Model present	`AsterixFieldI021Frn013Type073`	13	Yes	ed. 2.1 p. 28; ed. 2.7 p. 34
I021/074	Time of Message Reception of Position–High Precision19	Model present	`AsterixFieldI021Frn014Type074`	14	Yes	ed. 2.1 p. 8; ed. 2.1 p. 29; ed. 2.7 p. 35
I021/075	Time of Message Reception for Velocity	Model present	`AsterixFieldI021Frn015Type075`	15	Yes	ed. 2.1 p. 30; ed. 2.7 p. 36
I021/076	Time of Message Reception of Velocity–High Precision 21	Model present	`AsterixFieldI021Frn017Type076`	17	Yes	ed. 2.1 p. 8; ed. 2.1 p. 31; ed. 2.7 p. 37
I021/077	Time of ASTERIX Report Transmission	Model present	`AsterixFieldI021Frn031Type077`	31	Yes	ed. 2.1 p. 32; ed. 2.7 p. 38
I021/080	Target Address	Model present	`AsterixFieldI021Frn012Type080`	12	Yes	ed. 2.1 p. 33; ed. 2.7 p. 39
I021/090	Quality Indicators	Model present	`AsterixFieldI021Frn019Type090`	19	Yes	ed. 2.1 p. 34; ed. 2.7 p. 40
I021/110	Trajectory Intent	Model present	`AsterixFieldI021Frn038Type110`	38	Yes	ed. 2.1 p. 37; ed. 2.7 p. 51
I021/130	Position in WGS-84 Co-ordinates	Model present	`AsterixFieldI021Frn006Type130`	6	Yes	ed. 2.1 p. 41; ed. 2.7 p. 56
I021/131	High-Resolution Position in WGS-84 Co-ordinates	Model present	`AsterixFieldI021Frn007Type131`	7	Yes	ed. 2.1 p. 42; ed. 2.7 p. 57
I021/132	Message Amplitude	Model present	`AsterixFieldI021Frn043Type132`	43	Yes	ed. 2.1 p. 43; ed. 2.7 p. 58
I021/140	Geometric Height	Model present	`AsterixFieldI021Frn018Type140`	18	Yes	ed. 2.1 p. 43; ed. 2.7 p. 59
I021/145	Flight Level	Model present	`AsterixFieldI021Frn023Type145`	23	Yes	ed. 2.1 p. 44; ed. 2.7 p. 60
I021/146	Selected Altitude	Model present	`AsterixFieldI021Frn036Type146`	36	Yes	ed. 2.1 p. 45; ed. 2.7 p. 61
I021/148	Final State Selected Altitude	Model present	`AsterixFieldI021Frn037Type148`	37	Yes	ed. 2.1 p. 46; ed. 2.7 p. 62
I021/150	Air Speed	Model present	`AsterixFieldI021Frn010Type150`	10	Yes	ed. 2.1 p. 47; ed. 2.7 p. 63
I021/151	True Airspeed	Model present	`AsterixFieldI021Frn011Type151`	11	Yes	ed. 2.1 p. 47; ed. 2.7 p. 64
I021/152	Magnetic Heading	Model present	`AsterixFieldI021Frn025Type152`	25	Yes	ed. 2.1 p. 48; ed. 2.7 p. 64
I021/155	Barometric Vertical Rate	Model present	`AsterixFieldI021Frn027Type155`	27	Yes	ed. 2.1 p. 48; ed. 2.7 p. 65
I021/157	Geometric Vertical Rate	Model present	`AsterixFieldI021Frn028Type157`	28	Yes	ed. 2.1 p. 49; ed. 2.7 p. 66
I021/160	Airborne Ground Vector	Model present	`AsterixFieldI021Frn029Type160`	29	Yes	ed. 2.1 p. 50; ed. 2.7 p. 67
I021/161	Track Number	Model present	`AsterixFieldI021Frn003Type161`	3	Yes	ed. 2.1 p. 51; ed. 2.7 p. 68
I021/165	Track Angle Rate	Model present	`AsterixFieldI021Frn030Type165`	30	Yes	ed. 2.1 p. 51; ed. 2.7 p. 68
I021/170	Target Identification	Model present	`AsterixFieldI021Frn033Type170`	33	Yes	ed. 2.1 p. 52; ed. 2.7 p. 69
I021/200	Target Status	Model present	`AsterixFieldI021Frn026Type200`	26	Yes	ed. 2.1 p. 53; ed. 2.7 p. 70
I021/210	MOPS Version	Model present	`AsterixFieldI021Frn020Type210`	20	Yes	ed. 2.1 p. 54; ed. 2.7 p. 72
I021/220	Met Information	Model present	`AsterixFieldI021Frn035Type220`	35	Yes	ed. 2.1 p. 55; ed. 2.7 p. 74
I021/230	Roll Angle	Model present	`AsterixFieldI021Frn022Type230`	22	Yes	ed. 2.1 p. 57; ed. 2.7 p. 76
I021/250	Mode S MB Data	Model present	`AsterixFieldI021Frn044Type250`	44	Yes	ed. 2.1 p. 58; ed. 2.7 p. 77
I021/260	ACAS Resolution Advisory Report	Model present	`AsterixFieldI021Frn045Type260`	45	Yes	ed. 2.1 p. 59; ed. 2.7 p. 79
I021/271	Surface Capabilities and Characteristics	Model present	`AsterixFieldI021Frn042Type271`	42	Yes	ed. 2.1 p. 60; ed. 2.7 p. 81
I021/295	Data Ages	Model present	`AsterixFieldI021Frn047Type295`	47	Yes	ed. 2.1 p. 62; ed. 2.7 p. 83
I021/400	Receiver ID	Model present	`AsterixFieldI021Frn046Type400`	46	Yes	ed. 2.1 p. 72; ed. 2.7 p. 93
RE	Reserved expansion	Container model	`AsterixFieldI021Frn054TypeRe`	54	Yes	UAP / separate appendix
SP	Special purpose	Container model	`AsterixFieldI021Frn055TypeSp`	55	Yes	UAP / separate appendix

The local reserved-expansion appendices (appendixcat020pt14aed12.pdf and appendixcat021pt12aed11.pdf) describe subfields rather than additional message categories. A container model in the table is not a claim that those appendices are fully decoded. The ASTERIX Part 1 PDF defines common framing, not another category catalog.

All protocols

22 October 2026