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UKUEHN : Various Improvements

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Sorry Ulrich - I can't get Github to resolve the merge errors and
preserve your commit notes, so I'll add them here.
Improvements on bit error correction, doc update, preparation for
program installation/package build

Hi,
I committed some further improvements on the bit error correction code,
updated the readme, and implemented a way to install the program in the
linux file system hierarchy (allows for package building).

Regards,
Ulrich
This commit is contained in:
Malcolm Robb 2013-05-24 21:24:16 +01:00
parent ee742cf8db
commit 9edba9332a
3 changed files with 107 additions and 58 deletions
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25
README.md
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@ -86,9 +86,13 @@ it without arguments at all is the best thing to do.
Reliability
---
By default Dump1090 tries to fix single bit errors using the checksum.
Basically the program will try to flip every bit of the message and check if
the checksum of the resulting message matches.
By default Dump1090 checks for decoding errors using the 24-bit CRC checksum,
where available. Messages with errors are discarded.
The --fix command line switch enables fixing single bit error correction
based on the CRC checksum. Technically, it uses a table of precomputed
checksum differences resulting from single bit errors to look up the
wrong bit position.
This is indeed able to fix errors and works reliably in my experience,
however if you are interested in very reliable data I suggest to use
@ -190,18 +194,19 @@ Aggressive mode
With --aggressive it is possible to activate the *aggressive mode* that is a
modified version of the Mode S packet detection and decoding.
THe aggresive mode uses more CPU usually (especially if there are many planes
The aggresive mode uses more CPU usually (especially if there are many planes
sending DF17 packets), but can detect a few more messages.
The algorithm in aggressive mode is modified in the following ways:
* Up to two demodulation errors are tolerated (adjacent entires in the magnitude
vector with the same eight). Normally only messages without errors are
checked.
* It tries to fix DF17 messages trying every two bits combination.
* Up to two demodulation errors are tolerated (adjacent entires in the
magnitude vector with the same eight). Normally only messages without
errors are checked.
* It tries to fix DF17 messages with CRC errors resulting from any two bit
errors.
The use of aggressive mdoe is only advised in places where there is low traffic
in order to have a chance to capture some more messages.
The use of aggressive mdoe is only advised in places where there is
low traffic in order to have a chance to capture some more messages.
Debug mode
---