AEDP-4607 NATO ground moving target indicator format

What it is

AEDP-4607 is the NATO Allied Engineering Documentation Publication that defines the Ground Moving Target Indicator Format, GMTIF: a binary, message-oriented data format for transmitting Ground Moving Target Indicator (GMTI) radar detection data. It lets a radar sensor on an aircraft, a UAV, a satellite or a ground-based platform, and the systems that request, receive and exploit its data, exchange dwell-by-dwell target detections, high-range-resolution radar data, mission and platform information, and a record of how the data has been processed, in a common binary layout. The current edition is Edition A, Version 1, promulgated February 2024.

AEDP-4607 and STANAG 4607

AEDP-4607 has no force by itself. NATO's Letter of Promulgation states: "The agreement of nations to use this publication is recorded in STANAG 4607." The STANAG is the ratified commitment among nations, and AEDP-4607 is the technical content it points to. This is a relatively new split: earlier editions of the format were published directly inside the STANAG 4607 document itself, and today "the STANAG document simply describes the agreement to use the standard now captured in AEDP-4607" (clause 1.3). A system needs to implement GMTIF because a NATO or national programme, tender or contract requires interoperable GMTI dissemination, traced back to a nation's ratification of STANAG 4607, not because the format exists in a catalogue.

Who builds to it

The document speaks in engineering terms, not compliance terms. It refers to "the sensor manufacturer" who "needs to stipulate how its sensor system is best used" (Annex C-1.6), and to "the radar management operator (or the automated equivalent)" who schedules and tasks radar dwells (Annex C-1.6). Its optional Job Request and Job Acknowledge Segments similarly name a Requestor tasking sensor service and a platform approving, modifying or denying that request.

Packets, segments and the Dwell Segment

Every transmission is a packet: a Packet Header followed by one or more Message Segments, each preceded by its own Segment Header naming the segment type and byte length. Every data field is typed Mandatory, Conditional or Optional, and an "Existence Mask" lets a segment omit fields it is not sending, so a field cannot be assumed present just because the segment type is.

The Packet Header carries a version code, packet size, a nationality digraph (NATO platforms use "XN"), a security classification, an exercise indicator distinguishing real, simulated and synthesized data, and platform, mission and job identifiers. The Mission Segment, sent at least every two minutes, carries the mission and flight plan and the reference date against which every dwell time in the packet is measured.

The Dwell Segment is the core of the format: it is sent for every logical grouping of target reports, "even if no targets are detected", and carries sensor position, the dwell area scanned, and, for each detection, a Target Report with location, radial velocity, classification and measurement uncertainty. The HRR Segment carries High Range Resolution and Range-Doppler data referenced back to a Target Report, useful for target-length and recognition work beyond a basic detection. The Job Definition Segment defines the sensor job itself, including the four-corner area tasked and the radar mode, and "shall be sent before the first visit of a job" and re-sent "at least once every 30 seconds thereafter". A Processing History Segment, sent every three minutes, records every processing or modification operation a downstream system has applied to the data, so a receiving exploitation system can see what has already been done to what it is looking at.

What AEDP-4607 leaves to other layers

The format is narrowly scoped to the data content itself. As the document states: "The format does not specify error detection/correction, encryption, or the physical transmission of the data. The format requires these functions to be accomplished by the lower layers of the communications media that transmit the data" (clause 2.2). GMTIF assumes the packets it describes arrive error-free; how they get there, and how they are protected in transit, is left entirely to the communications system carrying them.

Positions throughout the format are geodetic, referenced to the WGS-84 earth model; data is transmitted big-endian with two's-complement signed integers and a binary-angle encoding for latitude, longitude, heading, pitch and roll; and the character set is the Basic Character Set defined by STANAG 4545, the NATO Secondary Imagery Format.

Extending the format

New platform or sensor types, and segments beyond those Edition A defines, are registered with the standard's Custodian and published in a Registry of Controlled Extensions, rather than invented locally by an implementer. AEDP-4607 "shall be used in conjunction with" a companion NATO Ground Moving Target Indicator Format Implementation Guide, published separately as "a Standards Related Document (AEDP-7)" (clause 1.3), which carries the fuller implementation guidance, test and validation procedures, and configuration management plan that this document itself does not include. AEDP-7 is due to be replaced by AEDP-4607.1 once revised; until then, the document says to treat AEDP-7 as current.

How conformance is checked

AEDP-4607 names no certification scheme and no accredited or notified body, and nothing in the document describes a third party assessing a system's conformance to award a certificate. What it names instead is a test and validation process, carried in the companion Implementation Guide, which "provides implementation guidance, test and validation procedures, a configuration management plan, and amplifying information for this standard" (clause 1.3). In practice, conformance is something an implementing organisation demonstrates and holds evidence for using that guide's procedures, closer to self-declaration than to any audited scheme.

Standards it references

• STANAG 4607 - the ratified agreement giving AEDP-4607 its force; the STANAG now records the nations' commitment while this document carries the technical content.
• STANAG 7023 - Air Reconnaissance Primary Imagery Data Standard. GMTIF data may be embedded in a STANAG 7023 imagery stream, and the two documents share the same platform-orientation reference geometry.
• AAP-03 - NATO's terminology directive, followed for the naming and abbreviation conventions used throughout this document.
• STANAG 4545 - NATO Secondary Imagery Format. GMTIF may be embedded within an NSIF stream, and its Basic Character Set defines the alphanumeric character set AEDP-4607 uses.

Standards it references

• STANAG 4545Background
• STANAG 7023Background
• AAP-03Background