Revision as of 16:02, 1 June 2022 edit GreenC bot (talk \| contribs) Bots 3,061,571 edits Reformat 1 archive link. Wayback Medic 2.5 ← Previous edit		Revision as of 04:24, 14 August 2022 edit undo PaulT2022 (talk \| contribs) Extended confirmed users 2,292 edits →Altitude encoder: WP:OR this may not be the reason for using open-collector output, no mention of reasoning in the referenced source Next edit →
Line 32: An altitude encoder takes the form of a small metal box containing a [[pressure sensor]] and signal conditioning electronics.<ref name="Ameriking_2004"/><ref name="ACK Encoder"/> The pressure sensor is often heated, which requires a warm-up time during which height information is either unavailable or inaccurate. Older style units can have a warm-up time of up to 10 minutes; more modern units warm up in less than 2 minutes. Some of the very latest encoders incorporate unheated 'instant on' type sensors. During the warm-up of older style units the height information may gradually increase until it settles at its final value. This is not normally a problem as the power would typically be applied before the aircraft enters the runway and so it would be transmitting correct height information soon after take-off.<ref name="Shadin_2016"/> ~~Light~~The ~~aircraft~~encoder ~~electrical~~has ~~systems~~an ~~are~~[[open-collector]] ~~typically~~output, compatible with 14 V or 28 V. Toelectrical ~~allow seamless integration with either, the encoder uses a number of [[open-collector]] ([[open-drain]]) [[transistor]]s to interface to the transponder~~systems. The height information is represented as 11 binary digits in a parallel form using 11 separate lines designated D2 D4 A1 A2 A4 B1 B2 B4 C1 C2 C4.<ref name="Phillips_1998_MODEC"/> As a twelfth bit, the Gillham code contains a D1 bit but this is unused and consequently set to zero in practical applications. Different classes of altitude encoder do not use all of the available bits. All use the A, B and C bits; increasing altitude limits require more of the D bits. Up to and including 30700 ft does not require any of the D bits (9-wire interface<ref name="Honeywell_2002"/>). This is suitable for most light general aviation aircraft. Up to and including 62700 ft requires D4 (10-wire interface<ref name="Tooley-Wyatt_2009"/>). Up to and including 126700 ft requires D4 and D2 (11-wire interface<ref name="Tooley-Wyatt_2009"/>). D1 is never used.<ref name="Phillips_1998_ASCII"/><ref name="DFS_2000"/>

Gillham code: Difference between revisions