got it ;)
I have now nearly finished coding the GPS to ARINC429 (loads of position labels e.g. 110,111,310,311 concurrently generated – quite a learning experience!) converter and am ready to take a look at generating the Garmin RS232 stream.
If anybody has an old GNS (preferably W?) box kicking around, which I could borrow, I will take a look at what comes out of it. The RS232 stream may be encrypted, or it may just have a CRC or similar.
It probably wants to be in the UK, to minimise shipping cost and delays.
No; I didn’t bother. Too much work borrowing a GNS-W or GTN box. And Garmin are sure to have some crypto on it, which could be quite difficult or impossible to decode. The application was the generation of a “WAAS” position data stream for a bit of avionics, which accepts either the secret Garmin RS232 protocol, or an ARINC429 documented protocol. So I generated the latter, as a part of another project which emulates a KI256:
