Loganair aircraft - Flight ID Missing

[tarbat]

I've noticed that I no longer see callsigns on Loganair aircraft in MyFlights.  I used to always get these, as I reported on this thread - http://www.airnavsystems.com/forum/index.php?topic=461.msg3366#msg3366

I've confirmed that Loganair aircraft are still transmitting callsigns, since I can see them being shared in Planeplotter by SBS-1 users:


So, for some reason Radarbox is not detecting the callsigns on these aircraft, where the SBS-1 does.  Are callsigns transmitted on different message types, and is Radarbox maybe missing callsigns on a particular message type?

Can this bug be investigated and fixed please.  Not being able to see a callsign also means I no longer see the route details, which is a real pain.

EDIT:  Looks like this bug may have been introduced in v2.0.  Looking back at my ANRB2008 MyLog, I've got over 400 Loganair Flight IDs in my Flights table.  I haven't got ANY in my ANRB2009 MyLog.

Here's a specific example on screen NOW:
Radarbox:


SBS-1 (via. Planeplotter):

[AirNav Support]

So, for some reason Radarbox is not detecting the callsigns on these aircraft, where the SBS-1 does.  Are callsigns transmitted on different message types, and is Radarbox maybe missing callsigns on a particular message type?

Can this bug be investigated and fixed please.  Not being able to see a callsign also means I no longer see the route details, which is a real pain.

EDIT:  Looks like this bug may have been introduced in v2.0.  Looking back at my ANRB2008 MyLog, I've got over 400 Loganair Flight IDs in my Flights table.  I haven't got ANY in my ANRB2009 MyLog.

Looking at your logs it is not a ADS-B enabled aircraft. In this case the flightid is received when a Mode-S Radar bounces of the aircraft. So there won't be a special message type that we can get its could either be the reception of the aircraft was not close enough to pick up the FlightID or maybe some interference.

RadarBox 2009 has not affected the decoding algorithm (firmware) so we are not 100% sure of this.

Keep us posted and we will see whether there is an issue or something else.

[DaveReid]

So, for some reason Radarbox is not detecting the callsigns on these aircraft, where the SBS-1 does.  Are callsigns transmitted on different message types, and is Radarbox maybe missing callsigns on a particular message type?

Can this bug be investigated and fixed please.  Not being able to see a callsign also means I no longer see the route details, which is a real pain.

EDIT:  Looks like this bug may have been introduced in v2.0.  Looking back at my ANRB2008 MyLog, I've got over 400 Loganair Flight IDs in my Flights table.  I haven't got ANY in my ANRB2009 MyLog.

Looking at your logs it is not a ADS-B enabled aircraft. In this case the flightid is received when a Mode-S Radar bounces of the aircraft. So there won't be a special message type that we can get its could either be the reception of the aircraft was not close enough to pick up the FlightID or maybe some interference.

RadarBox 2009 has not affected the decoding algorithm (firmware) so we are not 100% sure of this.

Keep us posted and we will see whether there is an issue or something else.

I'm confused.

Isn't flightid/callsign part of the 1090 Extended Squitter, i.e. it's broadcast whether or not there's a Mode S radar interrogating the aircraft ?

[tarbat]

That's what I thought Dave.  Hence my question to Airnav "Are callsigns transmitted on different message types, and is Radarbox maybe missing callsigns on a particular message type?"

Anyway, I'll be doing some testing today with earlier versions to establish when Radarbox lost this capability.  Looking at an old MyLog, appears to be around March, which was around the time we were beta testing v1.4(?) and I was having emails with A about testing port 30003 output.

[tarbat]

Okay, confirmed this stopped working when v1.4 was released.  In v1.3 I was getting callsigns/flightids for these Loganair aircraft.  Last record I had in MyLog was on 7th March 2008, which is exactly when v1.4 was released.

So, something changed in v1.4 that stopped some callsigns for non-ADS/B aircraft being received.  The SBS-1 receives these callsigns okay.

Airnav, I hope this can be fixed.

[AirNav Support]

Tarbat/DaveReid

We assumed this aircraft does not have ADS-B from the log you showed us hence the "1090 Extended Squitter, i.e. it's broadcast whether or not there's a Mode S radar interrogating the aircraft" which is ADS-B messages won't apply here.

v1.4 did not have a firmware upgrade either so this seems intresting.

We will investigate.

[tarbat]

AFAIK, these Loganair aircraft are not ADS-B equiped, just ModeS.  They do display altitude and squawk, which suggests to me that the callsign is being transmitted in response to a Mode-S radar station, either civilian on the ground, or military in the air (E-3D).

[AirNav Support]

Exactly, furthermore normal Mode-S Aircraft should be showing Flight IDs, if they have it set. This is happening as we can see a few militray aircraft so this wipes out it missing a certain message type hence why we are a bit confused by this.

[DaveReid]

We assumed this aircraft does not have ADS-B from the log you showed us hence the "1090 Extended Squitter, i.e. it's broadcast whether or not there's a Mode S radar interrogating the aircraft" which is ADS-B messages won't apply here.

Yes it does apply here.

You are confusing two different things (which AirNav really ought to understand better).

The Extended Squitter (sometimes incorrectly referred to as the "ADS-B squitter") is broadcast by the majority of aircraft. 

The ES has several different message types, some of which relate to ADS-B data (like the ES Airborne Position message) and obviously are only sent by ADS-B-equipped aircraft. 

Other ES messages, such as the ES Identification and Category message containing the callsign, are sent whether or not the aircraft has ADS-B.  In this case, it's broadcast every 5 seconds and as it's a squitter it does not depend on a ground station interrogation.

[tarbat]

Thanks for the explanation Dave.  I remember similar discussions on the SBS-1 forums!!

I've now been in contact with an SBS-1 user on Na h-Eileanan Siar (Lewis) this morning, and he's definately seeing callsigns for Loganair flights on his SBS-1.  The same aircraft on my Radarbox do not show callsigns.

So Airnav, something to be fixed I guess, to get the ES Identification & Category messages handled correctly.  Maybe only certain aircraft transmit this - these Loganair aircraft are Saab 340B.

[AirNav Support]

We will take a deeper look.

[tarbat]

Thanks.  If you need help testing, let me know.

It's just possible that this has never worked in Radarbox.  The 400+ Loganair flights in my 2008 MyLog might be conversions from my SBS-1 logs, and the output I saw on port 7879 as reported in this post may have been in response to ground radar requests.

It's only recently I've started looking at Loganair flights, with my wife now flying them!

I'm guessing the callsign is in the BDS 08h Ext. Squitter A/C Id & Category message?

[tarbat]

FYI, if it helps diagnose the problem, these were all seen on an SBS-1 today  over Inverness (my area):
400721 LOG774 G-LGNE SAAB 340 United Kingdom 12,125 ft 0.000° 0.000° 0 kts 0° 0 5037 13:12:24 02:26:30
405408 LOG833 G-LGNL SAAB 340 United Kingdom 7,250 ft 0.000° 0.000° 0 kts 0° 0 6021+ 11:18:48 02:39:16
400781 G-GNTB SAAB 340 United Kingdom 14,475 ft 0.000° 0.000° 0 kts 0° 0 6473 11:03:26 02:41:48
405409 LOG953F G-LGNM SAAB 340 United Kingdom 12,500 ft 0.000° 0.000° 0 kts 0° 0 5031 13:25:04 02:45:12
400AD1 LOG911A G-LGNH SAAB 340 United Kingdom 9,125 ft 0.000° 0.000° 0 kts 0° 0 7000 10:58:21 03:10:54
400722 LOG912L G-LGNF SAAB 340 United Kingdom 16,200 ft 0.000° 0.000° 0 kts 0° 0 6024 13:05:16 03:17:40
400CB9 LOG916 G-LGNI SAAB 340 United Kingdom 10,950 ft 0.000° 0.000° 0 kts 0° 0 3263 12:23:52 03:17:40
4009C3 LOG896 G-LGNG SAAB 340 United Kingdom 15,875 ft 0.000° 0.000° 0 kts 0° 0 7425 13:28:49 03:17:41

[tarbat]

To DaveReid, or anyone else who understands Mode-S technicalities!!

I understand the format of an Extended Squitter message is:
- 5 bits for the "Format Type Code"
- 51 bits for the data (eg 3 bits for category, 48 bits for callsign).

Is there a list somewhere of the various 5-bit Format Type Codes?  I understand which BDS's are used in the transponder, so are the BDS numbers then used as the 5-bit code on the message?

eg BDS for the "Identification & Category" message is 08h, so is the Format Type Code on the ES message also 01000b ?

And which of the 6 ES messages should Radarbox be processing for non-ADS/B aircraft:
BDS 0,5 ES Airborne Position (no I guess)
BDS 0,6 ES Surface Position (no I guess)
BDS 0,7 ES Status (maybe?)
BDS 0,8 ES Ident & Category (yes)
BDS 0,9 ES Airborne Velocity (maybe?)
BDS 6,1 ES Aircraft Status (maybe?)

EDIT:  Thinking back to v1.4 beta testing, this problem ties in to a problem I was working on for Andre on the port 30003 output.  We identified that Type 1 messages were not being output on port 30003, and Type 1 messages are the "Identification & Category" messages that are also causing this problem.  So fixing this problem will also help resolve the port 30003 problems that prevent addons like Overflight Logger working.

[DaveReid]

I understand the format of an Extended Squitter message is:
- 5 bits for the "Format Type Code"
- 51 bits for the data (eg 3 bits for category, 48 bits for callsign).

Is there a list somewhere of the various 5-bit Format Type Codes?  I understand which BDS's are used in the transponder, so are the BDS numbers then used as the 5-bit code on the message?

The main ones are:

Format types 1-4 (BDS 0,8):   Identification and Category
Format types 5-8 (BDS 0,6):   Surface Position (NUCp 9 to 6)
Format types 9-18 (BDS 0,5):   Airborne Position (plus baro altitude, NUCp 9 to 0)
Format type 19 (BDS 0,9):   Airborne Velocity
Format types 20-22 (BDS 0,5):   Airborne Position (plus GNSS height, NUCp 9 to 7)

HTH
Dave