Track File : Post Processor : New Version (0.2)

[Ian Melville]

Hi Dave,
I have found another glitch, sorry 

After a flight I was surprised to see a PAW contact missing from the post processor, yet is in the track log. I can send you the log, or part of it?

[DaveStyles]

Yes, please do !

If it's not too big can you email it to pilotawarehardware@gmail.com please, otherwise can you Dropbox it or something similiar so that we can pick it up.
Many thanks.

[Ian Melville]

https://dl.dropboxusercontent.com/u/57195501/2016-08-29_13-11.trk

G-CIJO is the reg

I only went out to warm the oil for an oil change, honest!!

[Deker]

For info
Checking the log from last weekend, 3 PAW contacts and was pleased to see the very good range that these were detected at:-
#401BF0# Nearest 27 to furthest 29KM
#D5EB66# Nearest 29 to furthest 30KM
#G-BWMB# Nearest 12 to furthest 32KM.

ATB Deker

[exfirepro]

Hi Deker,

Really good range for P3i contacts. Guess you have your antenna setup pretty much perfect. Great feedback and proves the worth of the Post Processor.

Regards

Peter

[Deker]

Hello Peter,

A very useful tool the post processor, excellent for verifying how the setup is working.
I was using the standard dipole antenna supplied with PAW sat on the dash.
Does show how far 0.5w can go.
Deker.

[bnmont]

Hi Ian,

G-CIJO is my plane.
Were you flying last Monday, I routed from Sandy Bedfordshire to Gloucestershire Airport.
I was using my PAW to provide gps into my Funk transponder so would or should have ben ADSB.

Brian

[Ian Melville]

I was Brian, in G-AWKD.
Flew west from Enstone to Gloucester and back without landing at Glos. just to get some heat into the oil before an oil change.

[Kevin W]

Hi

Having just flown around Europe for a few days with 2 other aircraft I thought I would have a play with the logs.  I didn't have much luck with the post processor (sorry Dave) so did some analysis the hardway.  Would be interested to see if I am interpreting the logs correctly:

The general gist of the command is:

Take all tracks for the trip, search for 1 specific ICAO code, only use PFLAA sentences, only use P3i sentences (#G), work out the distance from me for each sentence in KM's, and print out the number of sentences logged for each distance.

Code: [Select]

kevin@quota Tracks$ cat 2016-09-2*.trk | grep 160XXX | grep PFLAA | grep "#G" | awk -F, '{ printf("%3.0f\n", sqrt($3*$3 + $4*$4)/1000) }' | sort -n | uniq -c
   7933   0
   6879   1
   1393   2
    325   3
    122   4
    181   5
     35   6
     84   7
      1   8
      1 392

There are a couple of lines of data that have to be corrupted in the log here - 392km P3i range, I dont think so

Code: [Select]

kevin@quota Tracks$ cat 2016-09-2*.trk | grep 404XXX | grep PFLAA | grep "#G" | awk -F, '{ printf("%3.0f\n", sqrt($3*$3 + $4*$4)/1000) }' | sort -n | uniq -c
   5727   0
  12557   1
   6846   2
   3723   3
   1006   4
    402   5
    225   6
    117   7
     51   8
      2   9

Given that both aircraft were generally following me, and that the second (404XXX) was generally the furthest away from me - clearly 404XXX has a better antenna setup is my first conclusion.

The conclusion that is very hard to make is at point does p3i reception become unreliable - you cant see the data that I *didn't* receive - thoughts on how to show that appreciated

Cheers
Kev

[exfirepro]

Hi Kevin,

Probably being a bit thick here, but my reading of your figures is that you were only receiving PilotAware P3i signals from your colleagues from between 0 - 8, and 0 - 9 Km respectively. Am I interpreting your figures correctly?. If so, this is a much shorter range than I have experienced personally during extended testing and much shorter than the maximum ranges (in excess of 30 Kms), which we noted during operation of our Ground Station at the recent LAA Rally - bearing in mind of course that air to air detection range should in fact be higher than air to ground.

Although we have had several reports of PilotAware P3i signals being received from well over 30Kms - in purely practical terms I usually advise prospective users that P3i is extremely reliable at up to 10 Miles minimum, and often well beyond - which is significantly beyond the range of normal human visual acuity and beyond the range you appear to be reporting.

If I am reading your figures correctly, you might want to re-evaluate your antenna type/location, though to be fair you do say your colleagues were generally behind you - which is the lowest collision risk approach position (lowest closing speed = longest time to receive warning of aircraft approach) and therefore the position from where I would be least concerned at reduced contact range.

Regards

Peter

[Kevin W]

Hi Peter,

Correct, max distance seen (across 10 flights and 13 hours total flying time) is 8km and 9km respectively for all log entries with a #.  The 3 aircraft setups are:

CTSW - with PAW on the coaming in front of me, P3I aerial as supplied directly on the unit, powered by an Anker branded cigarette lighter style adapter.

CT2K (160XXX) - with PAW Tuned Low Profile Antenna mounted just below the engine, behind the front nose wheel leg, but mounted with a piece of aluminium very close to the vertical aerial that might be causing a problem.

Eurostar (404XXX) - with PAW on the parcel shelf, P3I aerial as supplied directly on the unit, powered by a battery pack

Now generally speaking we were flying in close proximity on this trip, but the Eurostar certainly went 30 miles + away from us on his trip back home

Cheers
Kev

[Kevin W]

I have been trying to think about identifying points that we *didn't* receive packets,

I assume that every time I get a GPGGA I move on to a new time period (typically 1 second);

I assume that in a perfect world I should get a P3I log entry for the aircraft I am close to every new time period;

So this give us something like the below:

Code: [Select]

[kevin@quota Tracks]$ cat 2016-09-2*.trk | awk -F, '{ if ($1 == "$GPGGA") printf "."; else if ($1 == "$PFLAA" && $7 ~ "160XXX" && $7 ~ "#G") print; }' | head -3
........................................................$PFLAA,3,4,11,53,1,160XXX!#G-TOXX#,0,,0,,8*2C
.$PFLAA,3,7,8,56,1,160XXX!#G-TOXX#,0,,0,,8*12
.$PFLAA,3,8,6,56,1,160XXX!#G-TOXX#,0,,0,,8*13

We start off with no reception (whilst we wait for both units to get a GPS signal), and then get a PFLAA sentence every GPGGA time period (represented by 1 full stop).

Building from that, acknowledging that we dont need a perfect world to still give us saftey - lets assume that actually we only need a log entry once every 5 seconds;

And then lets count how many times we get a gap of more than 5 seconds in PFLAA packets for that specific aircraft across various distances between units:

Code: [Select]

kevin@quota Tracks$ cat 2016-09-2*.trk | awk -F, '{ if ($1 == "$GPGGA") printf "."; else if ($1 == "$PFLAA" && $7 ~ "160XXX" && $7 ~ "#G") printf(" %3.0f\n", sqrt($3*$3 + $4*$4)/1000 ); }' | grep -F ..... | awk '{ print $2; }' | sort -n | uniq -c
     25 0
     27 1
     11 2
      2 3
      1 4
      1 5
      1 7

Thats about 70 times that P3I has been lost for 5 seconds or more - which includes 10 new flights and a few reboots, etc - lets call it 50 times we lost signal.

and for the other aircraft:

Code: [Select]

[kevin@quota Tracks]$ cat 2016-09-2*.trk | awk -F, '{ if ($1 == "$GPGGA") printf "."; else if ($1 == "$PFLAA" && $7 ~ "404XXX" && $7 ~ "#G") printf(" %3.0f\n", sqrt($3*$3 + $4*$4)/1000 ); }' | grep -F ..... | awk '{ print $2; }' | sort -n | uniq -c
      7 0
      3 1
      2 2
      2 3
      2 4
      1 6

Thats about 17 times that P3I has been lost for 5 seconds or more - which includes 10 new flights and a few reboots, etc - I think that's close to zero.

Do we think the code is accurately interpreting the log data?

Cheers
Kev

[Kevin W]

For completeness, the same analysis on the track logs from the Eurostar, which was generally at the rear of the formation:

Code: [Select]

kevin@quota CCTracks$ cat 2016-09-2*.trk | grep 160XXX | grep PFLAA | grep "#G" | awk -F, '{ printf("%3.0f\n", sqrt($3*$3 + $4*$4)/1000) }' | sort -n | uniq -c
   5706   0
   2938   1
    531   2
    202   3
     30   4
     16   5
      1 111
      1 17129
kevin@quota CCTracks$ cat 2016-09-2*.trk | grep 401XXX | grep PFLAA | grep "#G" | awk -F, '{ printf("%3.0f\n", sqrt($3*$3 + $4*$4)/1000) }' | sort -n | uniq -c
   2610   0
   4578   1
    530   2
    216   3
     97   4
kevin@quota CCTracks$ cat 2016-09-2*.trk | awk -F, '{ if ($1 == "$GPGGA") printf "."; else if ($1 == "$PFLAA" && $7 ~ "160XXX" && $7 ~ "#G") printf(" %3.0f\n", sqrt($3*$3 + $4*$4)/1000 ); }' | grep -F ..... | awk '{ print $2; }' | sort -n | uniq -c
      9 0
      5 1
      1 2
      1 3
      1 4
      1 5
kevin@quota CCTracks$ cat 2016-09-2*.trk | awk -F, '{ if ($1 == "$GPGGA") printf "."; else if ($1 == "$PFLAA" && $7 ~ "401XXX" && $7 ~ "#G") printf(" %3.0f\n", sqrt($3*$3 + $4*$4)/1000 ); }' | grep -F ..... | awk '{ print $2; }' | sort -n | uniq -c
      3 0
     10 1
      3 2
      1 3
      1 4

The main thing I think to note from that, is that the Eurostar lost reception from the CT2K (160XXX) far fewer times that I did, in fact well within the number of times I would expect given the number of flights it was across.

It's all a game of statistics and interpretiation

Cheers
Kev

[Admin]

Hi Kev

I am on a mobile device and so cannot see the command lines too well.

Just wanted to point out that the # char does not appear instantaneous on the reg
This is because the group info is sent over a number of packets.

If a packet is missed/lost, it needs a full refresh cycle again
Could this be affecting your stats ?

Thx
Lee

[Richard W]

Hi Kevin,

My limited experience matches yours. With two Skyrangers, PAWs mounted on the coamings, kit antennae directly attached, contact would be lost at around 2 km or less in a stern chase. There was no problem if the antennae could 'see' each other, but we were no more than 11 km apart.  Both of us got about 70 pings from another PAW equipped aircraft 60 km distant, pretty we'll on the nose, so it's all about antenna location. ISTM that we need two external antennae, one above and one below the airframe.

I have also experienced the spurious > 100 km pings, which hamper track file analysis.

Richard