AAVSP-05 analogue video standard for aircraft systems

What it is

AAVSP-05 is the NATO Allied Avionics Systems Publication that standardises analogue, composite raster video for aircraft systems. It sets the electrical and timing characteristics a video signal has to meet, and the requirements for the source, distribution and sink equipment that generates, carries and displays it, with a separate annex extending the same scheme to colour (RGB) video. It is a technical interface specification, not a process or quality-assurance document: it obliges nothing of an organisation beyond building equipment that conforms to the parameters it sets out.

The standard defines three named classes of line standard, and any device that generates, distributes or displays this kind of video in an aircraft system has to meet whichever class or classes apply. Its own foreword warns that its sections are not to be read in isolation but together, because a source, a distribution path and a sink each carry their own requirements that only add up to an interoperable system when read as a whole.

Why a common video standard matters

The value of AAVSP-05 shows up wherever more than one nation's or more than one supplier's equipment has to share a video signal on the same aircraft. A sensor, camera or recorder built to one set of electrical and timing values only interoperates with a display or distribution system built by someone else if both sides were designed against the same standard. The publication states its own purpose as promoting interoperability and facilitating "multiple sources and/or multiple sinks to be included in the total video system," including allowance for the noise and signal degradation that switching or mixing devices introduce.

How it binds

AAVSP-05 does not bind by existing. NATO nations' agreement to use it is recorded separately: "the agreement of nations to use this publication is recorded in STANAG 3350." STANAG 3350 carries the nations' commitment; a supplier meets AAVSP-05 itself because a contract, a tender or an aircraft integration programme specifies it, not because the document is in force in the abstract.

What each chapter covers

Chapter 1 sets the scope: the distribution-system characteristics of analogue raster composite video, video line required values, and the source, distribution and sink interfaces, with colour under Annex A. Chapter 2 sets general requirements - specified values have to hold across the full range of environmental operating conditions, and it identifies the three interfaces the standard defines. Chapter 3 defines the three named classes of line standard and requires that any installation for distribution and display be designed to accept Class A, or both Class B and Class C, signals. Chapter 4 allows control, test or display data to be encoded into unused television lines during the field blanking period, at the possible expense of picture lines if that period is exceeded.

Chapter 5 sets what a video source has to meet: output impedance and its tolerance to short-circuit and transient conditions, provision for external synchronisation, and the source's own output-level, rise-time, gamma and propagation-delay characteristics. Chapter 6 covers the receiving side: input impedance and its withstand to transient and common-mode conditions, and the amplitude, signal-to-noise and bandwidth characteristics a sink must accept. Notably, display equipment has to be able to operate on Class A, or on both Class B and Class C together, without needing an external switch to change mode. Chapter 7 defines the distribution network as everything between source outputs and sink inputs, requiring it to withstand a continuous short-circuit at any output without damage, alongside tabulated gain, noise, cross-talk and bandwidth characteristics.

Annex A extends the standard to colour: red, green and blue signals, with the green signal carrying the composite synchronisation and blanking information the main standard defines, and sync on the red and blue signals optional. It adds channel-matching tolerances between the three signals and defines an optional Vertical Interval Reference signal for calibration purposes. Annex B defines the standard's own vocabulary - line datum, gamma, interlace, polarity and the rest - several of which carry a narrower meaning here than in everyday use.

What the document does not cover

AAVSP-05 names no certification, accreditation or surveillance scheme, and describes no audit or inspection process. A device either meets the tabulated electrical and timing parameters for the class it claims, or it does not; the document gives no indication of who checks that or how often. It also does not fix connector types, cable routing or installation practice beyond the electrical characteristics it defines - those are left to the aircraft system design.

Standards it references

STANAG 3350 is the NATO Standardization Agreement covering AAVSP-05: the document by which nations record their agreement to use it. AAVSP-05 carries the technical requirements; STANAG 3350 is how those requirements reach a NATO nation's own programmes and contracts.

The document also lists three related civil and international standards its own line and signal criteria draw on, none of them held in our catalogue: ITU-R Recommendation ITU-R BT.472-3, on the video-frequency characteristics of a television system for international programme exchange between 625-line countries; EIA Standard RS-343A, on electrical performance for high-resolution monochrome closed-circuit television cameras; and EIA Standard RS-170, on electrical performance for monochrome television studio facilities, which the standard also credits as the basis for its own 875-line drawings.