I couldn’t find any heading data in the MSG records from a dump1090 feed. The specs indicate that the Field 14 is for Track which is derived from the horizontal and vertical velocities. Is there any data field for heading? I’m not seeing any MSG4 records (perhaps these are sent at intervals that I did not trap).
The original source code does not have comments on heading data (only on Track that I noted above). Any guidance on estimating heading (other than using intermediate computation using successive coordinates) would be appreciated.
Also, is there an Easter Egg with JSON output on port 8080 under certain conditions?
Yessir, I do understand the difference between ground track and heading (both types of the latter, too) but I have negligible experience in aviation matters compared to average members in this forum.
Given you’re talking about “MSG4 records” I guess that you’re looking at the Basestation output?
This is a legacy format that is very limited in terms of what it can tell you. You are better off decoding the raw messages directly, or looking at aircraft.json for decoded aircraft state.
aircraft.json can distinguish track, mag_heading, and true_heading.
Whether you actually get those fields depends a lot on what the aircraft is sending. In a pure ADS-B environment usually you will only get ground track/speed - the transponder prefers to send these and only sends heading/TAS if the ground track/speed information is available.
In an environment where there are Mode S EHS interrogations happening (this is common everywhere except in the US) dump1090 may be able to decode heading / TAS / IAS from the EHS responses in addition to what ADS-B is providing.
You are absolutely correct! (Experience counts time and time again!!).
Yes, aircraft.json has everything usable and there is no need for me to reinvent the wheel especially since Basestation has limited support. I should simply get on with extending the data for custom uses. I had done this a few years ago (as noted in my initial inquiry) but lost all documentation/files and at my age gray matter is in short supply.
Quick question: Is there a table for “aircraft” type (in json schema) corresponding to A1, A2, A3,… I understand these values but is there an A4 (yet to receive this value), for example?
Man, I thought here was my chance to work on async Python (& MQTT) but the cold water was definitely well deserved! Appreciate it truly because of the rugby scrum paradigm - having so much fun, never mind the ball!
Your (and @wiedehopf) kind of advice is always reassuring to stay focused.
Thanks again, @obj. This information is very useful. My original pursuit (that I am resuming) was to be alerted when my dongle receives data from an Airbus 380 (of course, this will get rarer over time). The other idea (when I was in Houston) was to get an alert if AN-225 data was detected (but these too have stopped coming to KIAH, I believe).
(Experience counts time and time again!!).
