Gillham code: Difference between revisions

Revision as of 20:17, 8 December 2010

Revision as of 20:33, 4 February 2011

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{{Infobox aviation

|name=Gillham Codecode

|image=Image:CessnaARC-RT-359ATransponder04.jpg

|caption=A Cessna ARC RT-359A [[Transponder (aviation)|transponder]] (the beige box) in the instrument panel of a [[Grumman American AA-1|American Aviation AA-1 Yankee]] light aircraft. The transponder gets its altitude information from an encoding altimeter mounted behind the instrument panel that communicates via the Gillham Codecode.

}}

A'''Gillham code''' is a [[digital]] [[code]] using an eleven-wire interface that is used to transmit uncorrected [[Barometer|barometric]] [[altitude]] between an encoding altimeter or analog [[air data computer]] and a [[Transponder (aviation)|transponder]]. It is a modified form of a [[Gray Codecode]] and is sometimes referred to as a "Gray Codecode" in avionics literature.<ref name="Code List"> [http://www.airsport-corp.com/modecascii.txt List of altitudes and Gillham codes]</ref>

The code was named in memory of the late Ronald Lionel Gillham, the UK's representative to the IATA committee developing the specification for the second generation of Air Traffic Control System, known in the UK as "Plan Ahead", who died suddenly in March 1968. Mr Gillham was said to have had the idea of using a modified Gray Codecode while at a family dinner.{{Citation needed|date=December 2010}}

The Gillham code seems unique in that its's only application is in the transmission of height information from an altitude encoder to an secondary surveillance radar (SSR) transponder as used in aircraft.{{Citation needed|date=December 2010}}

== Altitude Encoder ==