|One of my APRS transmitters|
using the Mic-E packet format.
Fresh photo for the blog.
Mangling packets in transit is wrong, and by default it would make these position packets, which are completely valid according the protocol specification, fail to decode, and fail to plot on aprs.fi. To get around this aprs.fi and many other decoders try to detect these broken packets and extract whatever information is left in them after the broken igate.
Yesterday evening I fixed a few bugs in the Mic-E packet decoder used by aprs.fi. This improves the handling of mangled packets a bit further.
- The correct symbol table identifier (primary or secondary) is now successfully decoded from mangled Mic-E packets. The table identifier byte was incorrectly extracted before the demangling trick - from the wrong offset due to the mangling. Thanks to KD0KZE for the bug report.
- Speed and course information is no longer decoded from Mic-E packet if demangling was applied. That information has been lost in transit when the packet got mangled by the igate.
- Mangled Mic-E packets are now indicated with a mice_mangled flag in the decoded raw packets. Switch from Normal to Decoded mode in the raw packets list to see it in action. Expect to see broken igates highlighted on aprs.fi later on.