>Where can I find any info about the grey code that the encoder sends
>to the transponder
Tim - sorry for slow response, only just back from the Charney Manor
weekend. Here are a couple of relevant postings from the Matronics
Avionics list:
>Date: Mon, 07 Jul 2003 09:46:02 -0400
>From: Finn Lassen <finnlassen@netzero.net>
>To: avionics-list@matronics.com
>Subject: Re: Avionics-List: Grey code for altitude encoders
>Here's a link to get you started:
>http://www.nist.gov/dads/HTML/graycode.html
>
>Gray-to-Bin:
>B(i) Binary (bit i)
>G(i) Gray (bit i)
>MSBit just copied to output. ( B(n) = G(n) )
>Subsequent bits: B(i) = B(i+1) XOR G(i) (i = n -1 to 0)
>
>Altitude encoder output to Binary:
>1) Invert all 9 bits
>2) Get checksum of upper 6 bits
>3) Convert upper 6 bits to gray and multiply by 10
>4) Lower 3 bits:
>5) Change 100 to 111
>6) Convert to bin to Gray
>7) If checksum was 0 then add to previous result (upper * 10) and subtract 1
> else subtract from previous result
>9) Subtract 12 from result and display, appending 2 zeroes or just
>display in x100's feet
>
>Only have a hard copy of table.
>Search for:
>MODE A AND MODE C CODES
>The Full List
>by
>Darryl Phillips
>THE AIRSPORT CORPORATION
>Affordable Avionics.
>
>I assume he still has this posted somewhere.
>
>Finn
>Here the table:
>
>http://www.airsport-corp.com/modecascii.txt
>
>http://www.airsport-corp.com/modec.htm
>
>
>Finn
Hope this helps - and apologies for repetition if someone else has
already posted all this!
regards
Rowland
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