Mode S behaviour - normal?

[Smaragd]

I have a TRT800 transponder and Dittel KRT2 radio. Have today at last managed to get PAW audio warnings working correctly with the KRT2 (the KRT2 manual isn't totally clear). I was surprised to find that I was receiving warnings about my own aircraft - though when I got home I realised that the wrong Hex code was set. However what also surprised me was that the warnings, and the aircraft entry on the traffic page, were there even when the transponder was in STBY. Is this to be expected?

[exfirepro]

Smaragd,

If you had the wrong hex code, PilotAware would naturally consider your transponder (and any associated ADSB transmissions) to be a threat. Regards the warnings you were getting for your own aircraft, is your transponder rigged for ADSB out? If so, it might transmit ADSB even when the transponder side is set to Standby. You would need to check the manual and/or consult your supplier.

Under normal circumstances, your transponder/ADSB signal will appear on the traffic screen as this holds all received signals - like a collection box, before sending only those selected by the software to the audio alerts and your Nav System.

A screen grab of your traffic screen would help by indicating the 'mode' for the signal, e.g. CSA-P = Mode C, Mode S, ADSB and P3i or whatever combination is being received from that contact.

Regards

Peter

[Smaragd]

Thanks Peter. Wrong hex code understood; I reset registration after the last upload; I just forgot to do the hex code.

The traffic line showed CS... ; the transponder is not set up for ADSB out (which the traffic line confirms). The signal strength was oscillating between Traffic Alert (most of the time) and Traffic Warning - irrespective of whether I was in STBY or ACS modes.

It should all be irrelevant now that I have corrected the hex code; I was just surprised at and curious about reception of a signal in STBY. As far as I know the STBY function of the transponder is working normally - ATC have pointed that out when I've selected a squawk but forgotten to select ACS!

[exfirepro]

Smaragd,

Strange one. I definitely wouldn't expect to see a signal from a transponder on standby and can't think why this should occur.

The hex code alone by the way will ONLY filter out your transponder if you have selected to receive 'Mode S' ONLY in the 'Mode C/S Select' part of your PAW Configure Screen and obviously if the correct hex adress is in both PAW and your transponder (worth re-checking). If you have selected to receive Modes C and S, you need to select 'Mode CS + Filter (Beta), or you will still get false alerts from the altitude transmissions from your transponder because of the way PilotAware has to 'learn' which is your own transponder without the benefit of Hex codes in case you were running pure Mode C.

If you still experience problems next time out try to get some screen grabs - especially the traffic screen - and get back to us so we can have another look.

Regards

Peter

[Smaragd]

Thanks again Peter. I had CS + Beta (Filtered) selected.

[Ray McKeown]

Check the software release level on your TRT800.  I believe older versions (i.e 3.*) produced "squitter" transmissions every  1 or 2 seconds even when on standby. This would include broadcasting your registration (if entered in your XPDR) and your  pressure altitude. The PAW would detect that. On  software levels > 4.0 the squitter is inactive on standby.

Regards, Ray   

[Smaragd]

Interesting, Ray.! My software standard is 4.8, though. Not directly a PAW matter, but I'd be interested in any information you have on the TRT800 (it's a reworked TRT600, not one of the later TRT800Hs). I had hoped to be able to use it for ADS-B Out as it claimed to be ADS-B Out ready, but I've connected it and it doesn't. I have been in touch with Funke following their Dec 2015 information letter on ADS-B for the 800H, to ask what the position is on the 800, but I have had conflicting answers and no clear position.

[Ray McKeown]

Hmmm.....ok. This is more complicated than I thought . Maybe  there is a hardware and firmware  issue  and I'm not clear on the difference between TRT800 and TRT800H.

First, the empirical evidence. One of my friends has  TRT800  with s/w  3.4  and I receive  ES transmissions from him when he is in STBY. My other friend  (and myself) have TRT800H  (HW 5.0 SW 5.6)  and we don't  pick each other up  when in STBY. 

Second, an old TRT800  FUNKE manual  says this:-

TRT800 / P/N 800ATC-(200)-(200)
Operation and Installation
Document-No: 03.2102.010.71e / Revision: 2.02 13
2.5 Transponder Mode selection
Press (repeatedly) to select from following Modes:
• STBY  „Standby“
Transponder only responds to directly addressed Mode S
interrogations, squitter remains active.
If a ground switch is connected, actuation of this switch will cause
the transponder switch to standby mode.

The manual for my  TRT800H  in the same section states that ES is inactive when in STBY.

On ADS-B OUT, I have connected a GPS source to the TRT800H  and am successfully  broadcasting my position and altitude on ES.  However I am not broadcasting my track which results in the position being shown on a receiving navigation  tool (e.g. SKYDEMON)  but with the aircraft icon always shown as NORTH up regardless of my track.  I reported this to FUNKE who advise me that I need a software upgrade to resolve this bug  and want to charge me a lot of money to do so .     Needless to say all my PAW P3I transmissions pass all of the information.


Regards, Ray

[exfirepro]

Ray,

I personally run a Trig TT21 with ADSB Out via a 'Byonics' GPS Unit - installed before I got involved with PilotAware, so I'm not really able to help with the Funke units, but finding your information very interesting nonetheless.

The difference between the companies is amazing though. Trig are happy to update units to the latest firmware free of charge. Might there be a way to use this fact to influence/persuade Funke, or do they just not care about their customers?

Always worth a bit of arm twisting in my experience. What have you got to lose.

Regards

Peter

[Smaragd]

Hmmm.....ok. This is more complicated than I thought . Maybe  there is a hardware and firmware  issue  and I'm not clear on the difference between TRT800 and TRT800H.

First, the empirical evidence. One of my friends has  TRT800  with s/w  3.4  and I receive  ES transmissions from him when he is in STBY. My other friend  (and myself) have TRT800H  (HW 5.0 SW 5.6)  and we don't  pick each other up  when in STBY. 

Second, an old TRT800  FUNKE manual  says this:-

TRT800 / P/N 800ATC-(200)-(200)
Operation and Installation
Document-No: 03.2102.010.71e / Revision: 2.02 13
2.5 Transponder Mode selection
Press (repeatedly) to select from following Modes:
• STBY  „Standby“
Transponder only responds to directly addressed Mode S
interrogations, squitter remains active.
If a ground switch is connected, actuation of this switch will cause
the transponder switch to standby mode.

The manual for my  TRT800H  in the same section states that ES is inactive when in STBY.

OK, here's my limited understanding. For the plain TRT800, in STBY squitter remains active, ie unsolicited transmissions (unsolicited by an interrogator) are still occurring. PAW is just listening (not interrogating) so sees them (as presumably will TCAS?). The transmissions will not be detected by ground radar interrogations as they are not appropriate responses to an interrogation. They will also be outputted in response to a specific interrogation of that aircraft's ID by a Mode S ground radar.
For the TRT800H, extended squitter (ie a fuller data set) is inactive in STBY, nor does the unit respond to directed Mode S interrogations. As nothing is seen on PAW, I imagine that the whole squitter message is being suppressed, not just the extended part.
Does this make any sense?

[Ray McKeown]

Hmmm.....ok. This is more complicated than I thought . Maybe  there is a hardware and firmware  issue  and I'm not clear on the difference between TRT800 and TRT800H.

First, the empirical evidence. One of my friends has  TRT800  with s/w  3.4  and I receive  ES transmissions from him when he is in STBY. My other friend  (and myself) have TRT800H  (HW 5.0 SW 5.6)  and we don't  pick each other up  when in STBY. 

Second, an old TRT800  FUNKE manual  says this:-

TRT800 / P/N 800ATC-(200)-(200)
Operation and Installation
Document-No: 03.2102.010.71e / Revision: 2.02 13
2.5 Transponder Mode selection
Press (repeatedly) to select from following Modes:
• STBY  „Standby“
Transponder only responds to directly addressed Mode S
interrogations, squitter remains active.
If a ground switch is connected, actuation of this switch will cause
the transponder switch to standby mode.

The manual for my  TRT800H  in the same section states that ES is inactive when in STBY.

OK, here's my limited understanding. For the plain TRT800, in STBY squitter remains active, ie unsolicited transmissions (unsolicited by an interrogator) are still occurring. PAW is just listening (not interrogating) so sees them (as presumably will TCAS?). The transmissions will not be detected by ground radar interrogations as they are not appropriate responses to an interrogation. They will also be outputted in response to a specific interrogation of that aircraft's ID by a Mode S ground radar.
For the TRT800H, extended squitter (ie a fuller data set) is inactive in STBY, nor does the unit respond to directed Mode S interrogations. As nothing is seen on PAW, I imagine that the whole squitter message is being suppressed, not just the extended part.
Does this make any sense?

Well it certainly makes sense but I have no idea whether your assumptions are correct. I've only ever had email exchanges with FUNKE and whilst courteous, any queries on specifics are simply answered by referral to existing user documentation which is less than helpful.

Peter..... TRIG do seem to be much more customer friendly. I've tried with FUNKE but they seem to be pretty adamant  that any upgrades /bug fixes outside guarantee period are chargeable.

[exfirepro]

Hi Ray,

My commiserations. Certainly glad I bought a Trig!

Peter

[Chris7777]

Hi Smaragd

I have a plain vanilla TRT800.You may be interested in my upgrade experience. I had three instances of differnt ATCs saying they could not see me, so after changing everything else. I sent my TRT800 (originally purchased 24th May 2005 software v3.7?) to funke in October 2016. It was updated to Mod 10/11, software version 5.2, Firmware 102 and they added a new Rec board. Cost about £300, but v5.2 is still flawed. See this thread http://forum.pilotaware.com/index.php/topic,286.msg3971.html#msg3971

I understand that for ADS-B out to work correctly I need software version 5.3.
 
I asked funke if it was possible to update this transponder to v 5.3? I got this reply.

Dear Chris,
 
our new SW will be available approximately at the End of March/Beginning of April.
 
Regards ...

Funke are always very polite but no mention of an apology or a free update. I guess that will cost another £300!

[Admin]

There is no way that you should pay a further £300, that would be outrageous considering that the upgrade you had was not fit for purpose, assuming you are still within the warranty period (Oct 16)
I am sure they would not bill you again, would they ?

Thx
Lee

[exfirepro]

Not if they want to avoid lots of adverse publicity and loss of transponder sales!!

Peter