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NUCp tracking and CPR position sanity checks.

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Track NUCp when we compute positions.

Do speed checks when we have an updated position with the same or worse NUCp
before accepting the new position. Don't do speed checks on new postions if
they improve NUCp - assume that the new position is better.

Include NUCp in aircraft.json

Gather stats on reasons for rejecting CPR data due to range/speed check failures.

Expire old positions if we have had no updates for 60 seconds.

Closes #16, closes #17.
This commit is contained in:
Oliver Jowett 2015-02-18 00:12:35 +00:00
parent 38845c2447
commit bfe2cb0336
6 changed files with 164 additions and 42 deletions
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9
README-json.md
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@ -41,6 +41,7 @@ This file contains dump1090's list of recently seen aircraft. The keys are:
* squawk: the 4-digit squawk (octal representation)
* flight: the flight name / callsign
* lat, lon: the aircraft position in decimal degrees
* nucp: the NUCp (navigational uncertainty category) reported for the position
* seen_pos: how long ago (in seconds before "now") the position was last updated
* altitude: the aircraft altitude in feet, or "ground" if it is reporting it is on the ground
* vert_rate: vertical rate in feet/minute
@ -104,10 +105,14 @@ Each period has the following subkeys:
* background: milliseconds spent doing network I/O, processing received network messages, and periodic tasks.
* cpr: statistics about Compact Position Report message decoding. Has subkeys:
* global_ok: global positions successfuly derived
* global_bad: global positions that were rejected because they were out of range
* global_bad: global positions that were rejected because they were inconsistent
* global_range: global positions that were rejected because they exceeded the receiver max range
* global_speed: global positions that were rejected because they failed the inter-position speed check
* global_skipped: global position attempts skipped because we did not have the right data (e.g. even/odd messages crossed a zone boundary)
* local_ok: local (relative) positions successfully found
* local_skipped: local (relative) positions not used because we did not have the right data (e.g. position was ambiguous given the receiver range)
* local_skipped: local (relative) positions not used because we did not have the right data
* local_range: local positions not used because they exceeded the receiver max range or fell into the ambiguous part of the receiver range
* local_speed: local positions not used because they failed the inter-position speed check
* filtered: number of CPR messages ignored because they matched one of the heuristics for faulty transponder output
* tracks: statistics on aircraft tracks. Each track represents a unique aircraft and persists for up to 5 minutes after the last message
from the aircraft is heard. If messages from the same aircraft are subsequently heard after the 5 minute period, this will be counted