View Full Version : Gillham Code
Hello everybody!
I`m looking for your advice.
Who can explain me what is it - Gillham Code ? Where I can obtain some theoretical info about this. I read about this a lot in Transponders (Mode `S`) but what is it exactly I don`t know.
I`m looking forward for sombody help.
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STAS
forget
24th Mar 2000, 01:21
STAS,
See http://travel.wsj.com/n/SB940364329366490363-air-travel.html
Thank you Forget it was very helpful .
I have read this topic but anyway I don`t understand why Gillham circuits uses 11 wires for transmission of altitude data ?
And as I understood from topic it`s quite old fashioned system and in new equipment it`s not used ? Am I right ?
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STAS
Blacksheep
24th Mar 2000, 18:15
Aaaargh not the dreaded Gillham Code again!!!! The most overworked Airworthiness Directive in recorded history.
The incident quoted on the web-site above resulted in a veritable snowstorm of unnecessary paperwork with two each ADs from the FAA, UKCAA, Netherlands RLD and Australian CASA across my desk in the past couple of months. Not to mention baffled inquiries from a number of airline customers of ours.
Gillham Code inputs into transponders are used in aircraft that do not produce a "digital" output from the altitude encoding device. In aircraft that have ARINC 429 databus transmission between the Transponders and the Digital Air Data Computers (ie. the majority of the current airline fleets) Gillham Code isn't an issue. Doesn't stop the Airworthiness Authorities panicking and swamping everyone with BUMPH though! I suppose their motto is "If you don't know what they are talking about, issue an AD" :) :)
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Through difficulties to the cinema
Blacksheep,
Actually I have asked because I found in Mode `S` transponder Installation Manual(Allied Signal) that both mode `S` trpdr`s are connected to ADC`s by Arinc 429 and also connected to encoding altimeters by Gillham connection ?
I already asked Allied Signal (Honeyweel) representative about this but steel don`t have answer. That`s a question.
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STAS
JET SET SPARKY
24th Mar 2000, 18:37
didn't this used to be called 'gray code' or am i getting confused again?
Jet Set Sparky,
I`m not sure that I understand what you mean.
I understand that Gillham Code related to C format `gray code` .But what`s the point exactly I don`t understand .
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STAS