Based on a submission by VK1ET, but I've tweaked it a bit to use the
bFlags.
Basically, only print out values in --interactive that have been
received from the aircraft. Previous versions would display 0.000 for
lat and long for any positionless aircraft. This version prints blanks
instead for any/all fields that are not yet known.
Remove dependency of the SBS output code on the historic (a) aircraft
structure. The only items that were required were the decoded aircraft
Lat/Lon and these are now included in the mm structure.
Rewrite the SBS output code to use mm->bFlags when populating the output
fields. This ensures that all available data is output, and also that no
stale data is sent.
Using the mm->bFlags variable for SBS output means there is no further
requirement for the sbsFlags member in the aircraft structure, so remove
it.
Cross your fingers and hope this hasn't introduced too many bugs !
Implement additional bFlags to validate AircraftOnGround, and FS.
Decode Aircraft On Ground from DF0, DF4, DF5, DF16, DF20, and DF21 where
possible.
Flag FS as valid for DF4, DF5, DF20, DF21,
Remove dr and um from the mm structure. They're only used in console
list output mode, so decode them there if required.
Additional flags in the bFlags variables for even and odd CPR lat/lon
updates.
Change the interactiveReceiveData function to use the bFlags when
updating the aircraft (a) structure from the newly received (mm) message
structure. This should hopefully be faster than basically re-decoding
the DF, type and subtypes all over again.
If we decode the lat/lon into the aircraft (a) structure, back populate
it into the message (mm) structure. This allows us to print a decoded
Lat/Lon in the decoded message list output.
If --modeac is specified, then the program will be building an aircraft
list. Calculate the altitude when we create the aircraft structure (a) ,
and then back copy it into the mm structure. This avoids us having to do
a second ModeAtoModeC conversion in the list output display.
Also - bug fix in the ns_vel calculation.
Changes to 'dump1090.c'-file made accordingly.
modified: .gitignore
modified: dump1090.c
deleted: gmap.html
new file: public_html/gmap.html
new file: public_html/script.js
new file: public_html/style.css
Update the bFlags structure member to indicate which other structure
members contain decoded values.
Also, trim out mm structure members that are simple bitwise ands from
the raw data, unless the results are used in lots of places whereby
decoding them once is more efficient.
Extend the DF-17 CPR decoding to use User Lat/Lon for ground positions.
Also start implementing a bFlags structure variable to indicate which
fields in the mm and a data structures contain valid values.
Based on initial code supplied by VK1ET
Allow the user to specify their receivers (technically their aerials)
physical location. This is required for decoding ground positions, and
also for uploading aircraft data to various sharer sites.
The position can be hardwired by setting the MODES_USER_LATITUDE_DFLT
and MODES_USER_LONGITUDE_DFLT constants before compilation, or entered
at runtime via the new command line switches --lat and --lon. Either
way, the values are checked for validity before use.
Only clear mm after we are sure we have got a Mode A/C. This reduces
processor load.
Also tidy up some Linux compiler warnings that result from the last
change.
Based on a submission by VK1ET. Fully decode DF-17, metype 19. Take care
to only update fields that are valid in the data.
Also, initialise (to zero) the mm structures before use
1) Implement additional timestamps to remember when a new Lat/Lon value
is generated.
2) Increase callsign[] character array to 16 chars to make it long word
aligned.
3) Change some more comments from /* to //
Use memset to clear entire structures at initial creation to zero, and
then populate values that should not be zero. Do this rather than
individually clear each structure member to zero.
This should be faster, plus it's safer when new structure members are
added because you don't have to remember to initialise them.
Use 32 bit registers to hold multiple characters and shift them. This
removes the need for multiple memory reads.
Also tidy up the DF-17 extraction routine to make it more readable.
ICAO documents refer to AC13 for altitude encoding and ID13 for squawk
wncoding. Rename decodeGillhamField to decodeID13Field to better
represent this.
There is a quite complex if/else construct for gathering statistics
inside the main decodeModeS loop. To speed the loop up when not
gathering statistics, make the whole construct conditional on Modes.stat
being set.
Also tidy up a few comments
Allow the decodeModeMessage function to re-calculate msgtype and
msgbits. This makes the code a bit more portable by not requiring the
calling function to fill in these fields before the call.
Changes supplied by John VK1ET.
This tidies up the thread termination, which then allows for use of [a
trapped] Ctrl/C to cleanly terminate the program and dump stats if flag
set.
Lots of changes to the decodeModesMessages() function, and associated
helper functions, with the aim of speeding the code up by reducing the
number of calls to the CRC functions. Also, only update the mm variables
which are part of the message we're decoding.
Change the way CRC's are generated and checked.
Change the way single and double bit error is implemented.
General tidy up of the function to make it more readable.
Modify all the Mode=S Gillham altitude decoding to use a new function
decodeGillhamField()
Change the Mode-S signal strength so that it rounds to the nearest
integer
Assume that DF0-DF15 are all short 56 bit messages
Assume that DF16-DF31 are all long 112 bit messages
This helps us error detect and error recover for bits in the first byte
The DF's for altitude include a Q bit to distinguish either 100ft or
25ft altitude encoding. This version implements the 100ft increments
used by older aircraft. These codes are basically ModeC altitudes
transmitted over ModeS.
Reformat the --interactive display to show more information
Add a "Mode" column. This displays the The primary message type "S" or
"A" plus any matching modes "a" and/or "c". Requires --modeac switch.
Add a "Sig" column to show the signal strength.
Add a --fix command line switch to enable error correction using CRC.
Change the default to OFF/Disabled.
Error correction can very occasionally result in an incorrect solution
to the crc equation. It also takes significant CPU work for very few
corrected results. Therefore, the default has been changed to OFF, but
you can re-enable it if you wish by using the --fix command line switch.
Implement changes suggested by John/VK1ET
Changes to cprNFunction to ensure fflag {was 'isodd'} is used as a flag.
Fix to decodeCPRrelative to pass 'surface' flag.
The original code stores the squawk as a decimal (base 10) value. Change
this to a hex value to reduce the amount of maths required to convert
the input binary value..
Rename all the variables used to store the squawk to "modeA", rather
than variously identity, squawk and modeA.
Several variables within structures contain the same information in
different forms.
The aircraft structure contains addr and hexaddr. Hexaddr is a printable
string version of addr. However, hexaddr is only ever used in printf
statments, so we can use printf(%06x) to print addr. This saves a printf
for every received command.
The modesMessage structure contains addr, and aa1,aa2,aa3 as separate
bytes. aa1,aa2 and aa3 are only ever used to construct addr, and to
print out. Therefore, we can use addr instead of them..
The original code made an attempt to reconcile a newly arrived ModeA/C
message with every known Mode-S report at the time of detection.
However, the results of matching up Modes A/C and S are only used in the
interactive display routine, and that is only called periodically from
within the BackgroundTasks loop.
Doing the matching on every ModeA/C arrival incurs quite a large CPU
processing load. Moving the matching up routine to the backgroundTasks
loop means that the task is performed muck less frequently and therefore
uses less CPU time.
