TT21/TN72 power consumption

[jfitch]

For those of you contemplating this, I've made some rough power measurements. Sitting in my shop with a clear view towards the airport, the TT21 is reporting nearly constant interrogations, and drawing between 120 and 150 ma. The TN72 alone draws about 70 ma. When both are powered and broadcasting ADS-B, the power is about 170 - 210 ma. All measurements taken with a clamp on hall effect sensor, +/- 10ma. So roughly, the extra power to transmit ADS-B is lost in the noise. The TN72 takes measurable power, but not much. This is a pretty cheap way to make yourself seen.

[dans]

Test

[Craig Funston[_3_]]

On Saturday, May 19, 2018 at 2:12:04 PM UTC-7, jfitch wrote:
> For those of you contemplating this, I've made some rough power measurements. Sitting in my shop with a clear view towards the airport, the TT21 is reporting nearly constant interrogations, and drawing between 120 and 150 ma. The TN72 alone draws about 70 ma. When both are powered and broadcasting ADS-B, the power is about 170 - 210 ma. All measurements taken with a clamp on hall effect sensor, +/- 10ma. So roughly, the extra power to transmit ADS-B is lost in the noise. The TN72 takes measurable power, but not much. This is a pretty cheap way to make yourself seen.

Thanks Jon. Nice to have real data.

Craig

[[email protected]]

On Saturday, May 19, 2018 at 3:12:04 PM UTC-6, jfitch wrote:
> For those of you contemplating this, I've made some rough power measurements. Sitting in my shop with a clear view towards the airport, the TT21 is reporting nearly constant interrogations, and drawing between 120 and 150 ma. The TN72 alone draws about 70 ma. When both are powered and broadcasting ADS-B, the power is about 170 - 210 ma. All measurements taken with a clamp on hall effect sensor, +/- 10ma. So roughly, the extra power to transmit ADS-B is lost in the noise. The TN72 takes measurable power, but not much. This is a pretty cheap way to make yourself seen.

Not related to power consumption but still of possible interest to those of you trying to make this ADS-B out system work for gliders. I have been in touch with Darryl and Jon via email since I was unable to configure my TT22 and TN72 properly. My settings worked in that the FAA was able to send me a "Performance Report" on ADS-B out after a long flight but it was full of red boxes and con-compliance stuff. I talked to Midcontinent Avionics and they finally came back with a good reason for all this. I had sent the "core" of my Trig TT22 to them for a required firmware upgrade which they performed quickly and at no cost (except for shipping). I now heard from them that the "head" (display and function input) of the TT22 also has to be upgraded so that I can see the new settings options for the various and quite confusing combinations. Darryl had sent me settings that I never found when going through my device. With hindsight, I could have figured it out myself....
Still waiting for the proper settings from Trig and Mid-Continent.
Herb, J7

[Richard Pfiffner[_2_]]

On Friday, May 25, 2018 at 2:42:47 PM UTC-7, wrote:
> On Saturday, May 19, 2018 at 3:12:04 PM UTC-6, jfitch wrote:
> > For those of you contemplating this, I've made some rough power measurements. Sitting in my shop with a clear view towards the airport, the TT21 is reporting nearly constant interrogations, and drawing between 120 and 150 ma. The TN72 alone draws about 70 ma. When both are powered and broadcasting ADS-B, the power is about 170 - 210 ma. All measurements taken with a clamp on hall effect sensor, +/- 10ma. So roughly, the extra power to transmit ADS-B is lost in the noise. The TN72 takes measurable power, but not much.. This is a pretty cheap way to make yourself seen.
>
> Not related to power consumption but still of possible interest to those of you trying to make this ADS-B out system work for gliders. I have been in touch with Darryl and Jon via email since I was unable to configure my TT22 and TN72 properly. My settings worked in that the FAA was able to send me a "Performance Report" on ADS-B out after a long flight but it was full of red boxes and con-compliance stuff. I talked to Midcontinent Avionics and they finally came back with a good reason for all this. I had sent the "core" of my Trig TT22 to them for a required firmware upgrade which they performed quickly and at no cost (except for shipping). I now heard from them that the "head" (display and function input) of the TT22 also has to be upgraded so that I can see the new settings options for the various and quite confusing combinations. Darryl had sent me settings that I never found when going through my device. With hindsight, I could have figured it out myself....
> Still waiting for the proper settings from Trig and Mid-Continent.
> Herb, J7


Here are some setting you can try

http://www.craggyaero.com/tt22_tn72_settings.htm

Richard
www.craggyaero.com

[[email protected]]

I used the settings Richard just provided in my experimental glider and the ADSB report showed no errors. You do need both the core and the display of the TT22 to be updated to the latest versions to see the options listed. Also really nice is the GPS based squat switch option that is now available.

[jfitch]

On Friday, May 25, 2018 at 2:42:47 PM UTC-7, wrote:
> On Saturday, May 19, 2018 at 3:12:04 PM UTC-6, jfitch wrote:
> > For those of you contemplating this, I've made some rough power measurements. Sitting in my shop with a clear view towards the airport, the TT21 is reporting nearly constant interrogations, and drawing between 120 and 150 ma. The TN72 alone draws about 70 ma. When both are powered and broadcasting ADS-B, the power is about 170 - 210 ma. All measurements taken with a clamp on hall effect sensor, +/- 10ma. So roughly, the extra power to transmit ADS-B is lost in the noise. The TN72 takes measurable power, but not much.. This is a pretty cheap way to make yourself seen.
>
> Not related to power consumption but still of possible interest to those of you trying to make this ADS-B out system work for gliders. I have been in touch with Darryl and Jon via email since I was unable to configure my TT22 and TN72 properly. My settings worked in that the FAA was able to send me a "Performance Report" on ADS-B out after a long flight but it was full of red boxes and con-compliance stuff. I talked to Midcontinent Avionics and they finally came back with a good reason for all this. I had sent the "core" of my Trig TT22 to them for a required firmware upgrade which they performed quickly and at no cost (except for shipping). I now heard from them that the "head" (display and function input) of the TT22 also has to be upgraded so that I can see the new settings options for the various and quite confusing combinations. Darryl had sent me settings that I never found when going through my device. With hindsight, I could have figured it out myself....
> Still waiting for the proper settings from Trig and Mid-Continent.
> Herb, J7

AH, yes, both units need a software upgrade. This was covered in several other threads, but I'm not sure I've seen that in the official docs from Trig.. Somewhere they do give the minimum firmware versions, if you are back rev from that you need to upgrade.

[Darryl Ramm]

On Friday, May 25, 2018 at 6:56:15 PM UTC-7, wrote:
> I used the settings Richard just provided in my experimental glider and the ADSB report showed no errors. You do need both the core and the display of the TT22 to be updated to the latest versions to see the options listed.. Also really nice is the GPS based squat switch option that is now available.

Thud. Sound of me beating my head against the wall.

Be careful, those settings Richard/Craggy Aero provided (and I helped write up) never say to set the squat switch to AUTO (to use GPS airspeed based air/ground determination). It may not be clear but the only intent there was you either use NONE (for TABS/SIL=1) or use a real physical pitot switch for SIL=3/2020 compliant installs (in which case you pick the option for a physical "swat" switch). Maybe a warning not to use AUTO needs to be there.

There is not really anything nice about the GPS squat switch and I don't know how many times I need to warn about that. I wish Trig would throw that crap out and provide pitot pressure switches with all their TN72 units sold for gliders. The AUTO (GPS groundspeed) mode in the Trig transponders is very easily fooled by low groundspeed seen in wave flights. Transmitting ADS-B ground messages while airborne is potentially a safety issue, certainly in violation of regulations, and will eventually get the FAA's attention, it will get flagged to FSDO staff who watch aircraft ADS-B issues. They have enough stuff to deal with with other aircraft transmitting bad ADS-B messages that the glider community does not need to add to it.

For SIL=1/TABS you do not need to broadcast ADS-B ground messages so set the squat switch in the menu to NONE (or not connected or whatever it's called). There is just no reason to ever use AUTO for SIL=1/TABS, there is no practical benefit at all for gliders and only bad things might come from that.

For SIL=3/2020 compliant installs, all aircraft are required to broadcast ADS-B ground messages when on the ground. Even though it's of likely no benefit to gliders in any practical scenario, and kinda silly, ... but since 14 CFR 91.227 (indirectly) requires ground messages to be broadcast we can't just disable it like we can do with TABS. I would not trust AUTO (i.e. use GPS groundspeed) at all, even in a glider that might really never be used for serious wave flights. As I've posted here multiple times before... for a SIL=3 install with the TN72 (which can only be done in experimental gliders and only with a TT22) I would use the pitot pressure switch that is provided in the TN70/TN72 STC kit (no you are not using the STC, you are just getting a known correct type of pneumatic switch and some tubing connectors in a kit).

I've worked with the main Trig glider dealers in the USA so they should be aware of this and know about ordering that STC kit (it's ~$150) and pretty trivial to install between the pitot and static lines behind the panel. Trig glider dealers selling pre-made cables to connect the TN72 to the TT22 also tell me they are including the extra wiring in their wiring harnesses for that pitot switch (but even without that it's simple to add, the SPST pneumatic switch shorts one TT22 pin to ground). I really hope that when customers buy a TN72 their dealers are talking with them about this and if they should buy that pitot switch kit or not.

[Darryl Ramm]

On Friday, May 25, 2018 at 8:41:29 PM UTC-7, jfitch wrote:
> On Friday, May 25, 2018 at 2:42:47 PM UTC-7, wrote:
> > On Saturday, May 19, 2018 at 3:12:04 PM UTC-6, jfitch wrote:
> > > For those of you contemplating this, I've made some rough power measurements. Sitting in my shop with a clear view towards the airport, the TT21 is reporting nearly constant interrogations, and drawing between 120 and 150 ma. The TN72 alone draws about 70 ma. When both are powered and broadcasting ADS-B, the power is about 170 - 210 ma. All measurements taken with a clamp on hall effect sensor, +/- 10ma. So roughly, the extra power to transmit ADS-B is lost in the noise. The TN72 takes measurable power, but not much. This is a pretty cheap way to make yourself seen.
> >
> > Not related to power consumption but still of possible interest to those of you trying to make this ADS-B out system work for gliders. I have been in touch with Darryl and Jon via email since I was unable to configure my TT22 and TN72 properly. My settings worked in that the FAA was able to send me a "Performance Report" on ADS-B out after a long flight but it was full of red boxes and con-compliance stuff. I talked to Midcontinent Avionics and they finally came back with a good reason for all this. I had sent the "core" of my Trig TT22 to them for a required firmware upgrade which they performed quickly and at no cost (except for shipping). I now heard from them that the "head" (display and function input) of the TT22 also has to be upgraded so that I can see the new settings options for the various and quite confusing combinations. Darryl had sent me settings that I never found when going through my device. With hindsight, I could have figured it out myself...
> > Still waiting for the proper settings from Trig and Mid-Continent.
> > Herb, J7
>
> AH, yes, both units need a software upgrade. This was covered in several other threads, but I'm not sure I've seen that in the official docs from Trig. Somewhere they do give the minimum firmware versions, if you are back rev from that you need to upgrade.

https://www.trig-avionics.com/support/trig-product-software/

But it's poorly written and confusing.

Control head: version 1.14
TT21/Tt22: version 2.12

You want the latest stuff in both cases. You absolutely cannot do 2020 Compliant ADS-B Out with the TN72 without this this, and I'd not try to do TABS either.

The most common problem *by far* with Trig ADS-B Out installs is simply people not having the software up to date. I've seen three (or four?) people get caught by this.

Both version numbers display on the control head LCD during power up, and then disappear quickly. I wish Trig had a better way of showing those, but I normally use my iPhone to photograph that startup screen.

[Dirk_PW[_2_]]

Question. So if you are doing a SIL=1 install, and you set the squat switch to "none", is the ground-vs-air transmit modes controlled manually? (i..e. via the GND and ALT switches on the head unit? And a secondary question, if you set it to "GND", then will the unit transmit "ADS-B ground" messages?

[Darryl Ramm]

On Wednesday, May 30, 2018 at 10:54:02 AM UTC-7, Dirk_PW wrote:
> Question. So if you are doing a SIL=1 install, and you set the squat switch to "none", is the ground-vs-air transmit modes controlled manually? (i.e. via the GND and ALT switches on the head unit? And a secondary question, if you set it to "GND", then will the unit transmit "ADS-B ground" messages?

There are some deeper questions hidden there, which I wish I had my head fully around. But this is touching on stuff I'm curious about so give me some time and I'll get an email off to Trig and others. But this really does not affect these scenarios in practice. I can't imagine any practical situation where a glider transmitting ADS-B surface messages was actually helpful. If anybody found themselves taxiing a glider at a major airport with say ADSE-X surface surveillance then that is still going to detect your glider location (with transponder in ALT) via SSR interrogations.

My main concern is you never want to transmit ADS-B surface messages when in the air. Which is what the GPS ground speed based determination may do. I would just never use that, it is potentially causing more problems than it's solving.

The RTCA standards for ADS-B Out actually allow light aircraft (and gliders) to never transmit ADS-B surface messages (i.e. OK to transmit airborne only messages when on the surface). That seems a smart RTCA decision because of that potential down side of erroneously transmitting surface messages when actually airborne . But the FAA seems to disagree, It's subtle wording in CFR 14 91.227 (i.e. for 2020 Complaint installs) about needing to transmit aircraft width and length (that are only broadcast in ADS-B surface messages), and clarifications in things like AC 20-165B that says this should be a automatic determination, that vendors and others are interpreting as requiring 2020 Complaint ADS-B Out installs even in light aircraft to transmit ADS-B surface messages if on the ground, and to have that automatically determined.... which is why I'm suggesting using that pitot pressure switch for all 2020 Complaint (SIL=3) installs with the TT22/TN72... even if in practice you would likely be just as safe with no switch and the transponder always in ALT mode. TABS TSO-C199 makes it clear that for TABS/SIL=1 installs surface messages are entirely optional (and therefore keep it simple: just don't ever transmit surface messages).

A general comment on transponder modes: Things changed from the old days where transponders were supposed to be in STBY mode until say entering a runway. Now transponder should almost always be in ALT mode, including when on the ground. The only exceptions I can think of is STBY if you think the encoder really needs to warm up (~minute or so) or ON mode if you know the encoder or ADS-B GPS is producing garbage or ATC requests you put the transponder into ON or STBY if they see it is not working correctly. Being in any mode except ALT when flying is really bad, ATC can't see your altitude, and it prevents TCAS from working and airliners etc. being able to avoid running into you. Since most glider pilots rarely talk to ATC, they may never work out their transponder is in the wrong mode. My way of thinking is if I never put that transponder in anything except OFF or ALT (full clockwise or counterclockwise turns of the mode knob on a TT21/22) I am unlikely to make a mistake.