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ADS-B Update



 
 
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  #11  
Old December 13th 17, 05:42 AM posted to rec.aviation.soaring
Darryl Ramm
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Posts: 2,403
Default ADS-B Update

On Tuesday, December 12, 2017 at 8:16:41 PM UTC-8, 2G wrote:
On Tuesday, December 12, 2017 at 2:16:03 PM UTC-8, Darryl Ramm wrote:
...and more than that, I have the Mode C veil stuff wrong as well, thanks for David Anisman for reminding me of past FAA interpretation letters, clearly I made a mistake trying offer a quick hit at airspace stuff while talking about ADS-B. I've updated that post again :-(

I'll write up a separate post trying to get all the airspace stuff properly explained. It deserves some careful writing all in in one place. And I may get a letter off to the FAA to reconfirm again for ADS-B. But the big thing is previous FAA legal interpretation support you can be above any airspace (including within a Mode C veil) at 10,000' in a glider without a transponder and that interpretation should carry over to ADS-B Out after 2020. You can't be below 10,000' and above Class C airspace, that is one that catches some into needing full 2020 ADS-B Out requirements, another is obviously the big dogs who want to fly in Class A airspace after 2020.

No of course I'd hope pilots flying anywhere in or near a Mode C veil would voluntarily equip with transponders and increasingly with ADS-B out. The nice thing is TABS allows you to do that voluntarily at lower cost that full 2020 ADS-B compliance, including using a Trig TT21 transponder (without upgrading it to a TT22) and a TN72 $350 GPS.

My headache is back.


So, now I can have an ADS-B compliant system using my TT21? When did that change?

Tom


I can't follow what you are replying to, a comment about voluntarily equipping with TABS... TABS is *not* a 2020 Complaint ADS-B Out solution.

Did you read the post I linked to at the top of this thread? I explain the options, not one of those mentioned involves a TT21 that gives you a 2020 Complaint ADS-B out solution.

  #12  
Old December 14th 17, 12:47 AM posted to rec.aviation.soaring
2G
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Posts: 1,439
Default ADS-B Update

On Tuesday, December 12, 2017 at 8:42:37 PM UTC-8, Darryl Ramm wrote:
On Tuesday, December 12, 2017 at 8:16:41 PM UTC-8, 2G wrote:
On Tuesday, December 12, 2017 at 2:16:03 PM UTC-8, Darryl Ramm wrote:
...and more than that, I have the Mode C veil stuff wrong as well, thanks for David Anisman for reminding me of past FAA interpretation letters, clearly I made a mistake trying offer a quick hit at airspace stuff while talking about ADS-B. I've updated that post again :-(

I'll write up a separate post trying to get all the airspace stuff properly explained. It deserves some careful writing all in in one place. And I may get a letter off to the FAA to reconfirm again for ADS-B. But the big thing is previous FAA legal interpretation support you can be above any airspace (including within a Mode C veil) at 10,000' in a glider without a transponder and that interpretation should carry over to ADS-B Out after 2020. You can't be below 10,000' and above Class C airspace, that is one that catches some into needing full 2020 ADS-B Out requirements, another is obviously the big dogs who want to fly in Class A airspace after 2020.

No of course I'd hope pilots flying anywhere in or near a Mode C veil would voluntarily equip with transponders and increasingly with ADS-B out. The nice thing is TABS allows you to do that voluntarily at lower cost that full 2020 ADS-B compliance, including using a Trig TT21 transponder (without upgrading it to a TT22) and a TN72 $350 GPS.

My headache is back.


So, now I can have an ADS-B compliant system using my TT21? When did that change?

Tom


I can't follow what you are replying to, a comment about voluntarily equipping with TABS... TABS is *not* a 2020 Complaint ADS-B Out solution.

Did you read the post I linked to at the top of this thread? I explain the options, not one of those mentioned involves a TT21 that gives you a 2020 Complaint ADS-B out solution.


I was replying to your last comment:

"No of course I'd hope pilots flying anywhere in or near a Mode C veil would voluntarily equip with transponders and increasingly with ADS-B out. The nice thing is TABS allows you to do that voluntarily at lower cost that full 2020 ADS-B compliance, including using a Trig TT21 transponder (without upgrading it to a TT22) and a TN72 $350 GPS."

You have previously posted that they TT21 would not satisfy the ADS-B out mandate.

Yes, I read all of your posts.

Tom
  #13  
Old December 14th 17, 01:56 AM posted to rec.aviation.soaring
Darryl Ramm
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Posts: 2,403
Default ADS-B Update

On Wednesday, December 13, 2017 at 3:47:13 PM UTC-8, 2G wrote:
On Tuesday, December 12, 2017 at 8:42:37 PM UTC-8, Darryl Ramm wrote:
On Tuesday, December 12, 2017 at 8:16:41 PM UTC-8, 2G wrote:
On Tuesday, December 12, 2017 at 2:16:03 PM UTC-8, Darryl Ramm wrote:
...and more than that, I have the Mode C veil stuff wrong as well, thanks for David Anisman for reminding me of past FAA interpretation letters, clearly I made a mistake trying offer a quick hit at airspace stuff while talking about ADS-B. I've updated that post again :-(

I'll write up a separate post trying to get all the airspace stuff properly explained. It deserves some careful writing all in in one place. And I may get a letter off to the FAA to reconfirm again for ADS-B. But the big thing is previous FAA legal interpretation support you can be above any airspace (including within a Mode C veil) at 10,000' in a glider without a transponder and that interpretation should carry over to ADS-B Out after 2020. You can't be below 10,000' and above Class C airspace, that is one that catches some into needing full 2020 ADS-B Out requirements, another is obviously the big dogs who want to fly in Class A airspace after 2020.

No of course I'd hope pilots flying anywhere in or near a Mode C veil would voluntarily equip with transponders and increasingly with ADS-B out. The nice thing is TABS allows you to do that voluntarily at lower cost that full 2020 ADS-B compliance, including using a Trig TT21 transponder (without upgrading it to a TT22) and a TN72 $350 GPS.

My headache is back.

So, now I can have an ADS-B compliant system using my TT21? When did that change?

Tom


I can't follow what you are replying to, a comment about voluntarily equipping with TABS... TABS is *not* a 2020 Complaint ADS-B Out solution.

Did you read the post I linked to at the top of this thread? I explain the options, not one of those mentioned involves a TT21 that gives you a 2020 Complaint ADS-B out solution.


I was replying to your last comment:

"No of course I'd hope pilots flying anywhere in or near a Mode C veil would voluntarily equip with transponders and increasingly with ADS-B out. The nice thing is TABS allows you to do that voluntarily at lower cost that full 2020 ADS-B compliance, including using a Trig TT21 transponder (without upgrading it to a TT22) and a TN72 $350 GPS."

You have previously posted that they TT21 would not satisfy the ADS-B out mandate.

Yes, I read all of your posts.

Tom


Tom

The TT21 will not meet the ADS-B out mandate requirements.

The TT21 *can* be used to do ADS-B Out TABS.

They are not conflicting statements.

How we arrived here is painful, at one time I thought it was likely the transponder and ADS-B Out exemptions would be removed. And hoping that _if_ that was going to happen that there would be regulations to allow use of TABS devices for gliders and others to use as a alternate means of complying, or partially complying with ADS-B Out regulations. With the exemption remaining in place TABS regulations really don't become important (OK I'd like if glider could use say use TABS to comply with some remaining ADS-B Out restrictions, say to fly above Class C airspace up to 10,000'). So TABS, besides the TABS device TSO definitions is really all unregulated stuff, you just voluntarily install it, but doing so does not grant you any 2020 ADS-B Out (akk 14 CFR 91.226) compliant privileges.

Drop me a private email if you want to discuss something deeper or specific..

Popping up to a general comment:

With the TN72 GPS we should be covered for folk that worry about TSO or not install issues in certified gliders. The TN72 *is* TSO'ed, but to TSO-C199 (TABS) not say TSO-C145c (for 2020 Compliant ADS-B Out... even if it does meets the performance level of TSO-C145c and can be used to do that in experimental aircraft). For 2020 Complaint ADS-B Out the need for an actual TSO GPS source in any certified aircraft seems well established, regardless of other arguments about that... but I have some faint hope that folks there might establish STCs that get around that (not for gliders but in general for GA).

Jumping ahead to preventing possible issues: one thing people might run into is confusion when discussion with A&P IA folks or FSDO staff... who may assume that any discussion about ADS-B is to meet 14 CFR 91.225 and on the FAA folks will naturally want to follow standard policy there, specifically https://www.faa.gov/regulations_poli...mentID/1029526 My interpretation is simply that does *not* apply to TABS installs, since the install is not being done to comply with 14 CFR 91.226 and 92.227. As always discuss stuff with you A&P IA and let them worry about any questions to FSDO staff if needed.

Now the TN72 is here, $350 + antenna + install costs to add in TABS ADS-B Out to any glider with a TT21 or TT22 already installed seems a great deal, and something folks want to think about over this winter... which was what started my post linked to up top.

  #14  
Old December 14th 17, 02:43 AM posted to rec.aviation.soaring
Andrzej Kobus
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Posts: 585
Default ADS-B Update

On Wednesday, December 13, 2017 at 7:56:41 PM UTC-5, Darryl Ramm wrote:
On Wednesday, December 13, 2017 at 3:47:13 PM UTC-8, 2G wrote:
On Tuesday, December 12, 2017 at 8:42:37 PM UTC-8, Darryl Ramm wrote:
On Tuesday, December 12, 2017 at 8:16:41 PM UTC-8, 2G wrote:
On Tuesday, December 12, 2017 at 2:16:03 PM UTC-8, Darryl Ramm wrote:
...and more than that, I have the Mode C veil stuff wrong as well, thanks for David Anisman for reminding me of past FAA interpretation letters, clearly I made a mistake trying offer a quick hit at airspace stuff while talking about ADS-B. I've updated that post again :-(

I'll write up a separate post trying to get all the airspace stuff properly explained. It deserves some careful writing all in in one place. And I may get a letter off to the FAA to reconfirm again for ADS-B. But the big thing is previous FAA legal interpretation support you can be above any airspace (including within a Mode C veil) at 10,000' in a glider without a transponder and that interpretation should carry over to ADS-B Out after 2020. You can't be below 10,000' and above Class C airspace, that is one that catches some into needing full 2020 ADS-B Out requirements, another is obviously the big dogs who want to fly in Class A airspace after 2020.

No of course I'd hope pilots flying anywhere in or near a Mode C veil would voluntarily equip with transponders and increasingly with ADS-B out. The nice thing is TABS allows you to do that voluntarily at lower cost that full 2020 ADS-B compliance, including using a Trig TT21 transponder (without upgrading it to a TT22) and a TN72 $350 GPS.

My headache is back.

So, now I can have an ADS-B compliant system using my TT21? When did that change?

Tom

I can't follow what you are replying to, a comment about voluntarily equipping with TABS... TABS is *not* a 2020 Complaint ADS-B Out solution.

Did you read the post I linked to at the top of this thread? I explain the options, not one of those mentioned involves a TT21 that gives you a 2020 Complaint ADS-B out solution.


I was replying to your last comment:

"No of course I'd hope pilots flying anywhere in or near a Mode C veil would voluntarily equip with transponders and increasingly with ADS-B out. The nice thing is TABS allows you to do that voluntarily at lower cost that full 2020 ADS-B compliance, including using a Trig TT21 transponder (without upgrading it to a TT22) and a TN72 $350 GPS."

You have previously posted that they TT21 would not satisfy the ADS-B out mandate.

Yes, I read all of your posts.

Tom


Tom

The TT21 will not meet the ADS-B out mandate requirements.

The TT21 *can* be used to do ADS-B Out TABS.

They are not conflicting statements.

How we arrived here is painful, at one time I thought it was likely the transponder and ADS-B Out exemptions would be removed. And hoping that _if_ that was going to happen that there would be regulations to allow use of TABS devices for gliders and others to use as a alternate means of complying, or partially complying with ADS-B Out regulations. With the exemption remaining in place TABS regulations really don't become important (OK I'd like if glider could use say use TABS to comply with some remaining ADS-B Out restrictions, say to fly above Class C airspace up to 10,000'). So TABS, besides the TABS device TSO definitions is really all unregulated stuff, you just voluntarily install it, but doing so does not grant you any 2020 ADS-B Out (akk 14 CFR 91.226) compliant privileges.

Drop me a private email if you want to discuss something deeper or specific.

Popping up to a general comment:

With the TN72 GPS we should be covered for folk that worry about TSO or not install issues in certified gliders. The TN72 *is* TSO'ed, but to TSO-C199 (TABS) not say TSO-C145c (for 2020 Compliant ADS-B Out... even if it does meets the performance level of TSO-C145c and can be used to do that in experimental aircraft). For 2020 Complaint ADS-B Out the need for an actual TSO GPS source in any certified aircraft seems well established, regardless of other arguments about that... but I have some faint hope that folks there might establish STCs that get around that (not for gliders but in general for GA).

Jumping ahead to preventing possible issues: one thing people might run into is confusion when discussion with A&P IA folks or FSDO staff... who may assume that any discussion about ADS-B is to meet 14 CFR 91.225 and on the FAA folks will naturally want to follow standard policy there, specifically https://www.faa.gov/regulations_poli...mentID/1029526 My interpretation is simply that does *not* apply to TABS installs, since the install is not being done to comply with 14 CFR 91.226 and 92.227. As always discuss stuff with you A&P IA and let them worry about any questions to FSDO staff if needed.

Now the TN72 is here, $350 + antenna + install costs to add in TABS ADS-B Out to any glider with a TT21 or TT22 already installed seems a great deal, and something folks want to think about over this winter... which was what started my post linked to up top.


Darryl, the one thing you are not talking about is power supply. Gliders with only battery power present considerable challenges to meet the performance requirement of the FAA regulations. I suggest everyone who wants to install ADS-B out in a glider considers seriously this aspect.

Andrzej
  #15  
Old December 14th 17, 03:00 AM posted to rec.aviation.soaring
[email protected]
external usenet poster
 
Posts: 281
Default ADS-B Update


Darryl, the one thing you are not talking about is power supply.


A K2 pack seems to be working for simple mode C. Is there a reason to expect things to be significantly worse for ADS-B. (Maybe due to higher power out, more GPS power, a higher interrogation rate, and/or longer output transmissions?)
  #16  
Old December 14th 17, 03:15 AM posted to rec.aviation.soaring
JS[_5_]
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Posts: 624
Default ADS-B Update

On Wednesday, December 13, 2017 at 6:00:09 PM UTC-8, wrote:
Darryl, the one thing you are not talking about is power supply.


A K2 pack seems to be working for simple mode C. Is there a reason to expect things to be significantly worse for ADS-B. (Maybe due to higher power out, more GPS power, a higher interrogation rate, and/or longer output transmissions?)


My current panel does well with the 3x 10Ah LiFePO4 batteries on task. I doubt adding the TN72 will change things much. I'm more concerned about where to put another GPS antenna.
Believe the TN72's power supply for the antenna runs a higher voltage than typical GPS antennas will take, so you may find failures if using an off-the-shelf unit. Richard can probably confirm or deny this assumption.
Jim
  #17  
Old December 14th 17, 03:34 AM posted to rec.aviation.soaring
Darryl Ramm
external usenet poster
 
Posts: 2,403
Default ADS-B Update

On Wednesday, December 13, 2017 at 5:43:20 PM UTC-8, Andrzej Kobus wrote:
On Wednesday, December 13, 2017 at 7:56:41 PM UTC-5, Darryl Ramm wrote:
On Wednesday, December 13, 2017 at 3:47:13 PM UTC-8, 2G wrote:
On Tuesday, December 12, 2017 at 8:42:37 PM UTC-8, Darryl Ramm wrote:
On Tuesday, December 12, 2017 at 8:16:41 PM UTC-8, 2G wrote:
On Tuesday, December 12, 2017 at 2:16:03 PM UTC-8, Darryl Ramm wrote:
...and more than that, I have the Mode C veil stuff wrong as well, thanks for David Anisman for reminding me of past FAA interpretation letters, clearly I made a mistake trying offer a quick hit at airspace stuff while talking about ADS-B. I've updated that post again :-(

I'll write up a separate post trying to get all the airspace stuff properly explained. It deserves some careful writing all in in one place. And I may get a letter off to the FAA to reconfirm again for ADS-B. But the big thing is previous FAA legal interpretation support you can be above any airspace (including within a Mode C veil) at 10,000' in a glider without a transponder and that interpretation should carry over to ADS-B Out after 2020. You can't be below 10,000' and above Class C airspace, that is one that catches some into needing full 2020 ADS-B Out requirements, another is obviously the big dogs who want to fly in Class A airspace after 2020.

No of course I'd hope pilots flying anywhere in or near a Mode C veil would voluntarily equip with transponders and increasingly with ADS-B out. The nice thing is TABS allows you to do that voluntarily at lower cost that full 2020 ADS-B compliance, including using a Trig TT21 transponder (without upgrading it to a TT22) and a TN72 $350 GPS.

My headache is back.

So, now I can have an ADS-B compliant system using my TT21? When did that change?

Tom

I can't follow what you are replying to, a comment about voluntarily equipping with TABS... TABS is *not* a 2020 Complaint ADS-B Out solution.

Did you read the post I linked to at the top of this thread? I explain the options, not one of those mentioned involves a TT21 that gives you a 2020 Complaint ADS-B out solution.

I was replying to your last comment:

"No of course I'd hope pilots flying anywhere in or near a Mode C veil would voluntarily equip with transponders and increasingly with ADS-B out.. The nice thing is TABS allows you to do that voluntarily at lower cost that full 2020 ADS-B compliance, including using a Trig TT21 transponder (without upgrading it to a TT22) and a TN72 $350 GPS."

You have previously posted that they TT21 would not satisfy the ADS-B out mandate.

Yes, I read all of your posts.

Tom


Tom

The TT21 will not meet the ADS-B out mandate requirements.

The TT21 *can* be used to do ADS-B Out TABS.

They are not conflicting statements.

How we arrived here is painful, at one time I thought it was likely the transponder and ADS-B Out exemptions would be removed. And hoping that _if_ that was going to happen that there would be regulations to allow use of TABS devices for gliders and others to use as a alternate means of complying, or partially complying with ADS-B Out regulations. With the exemption remaining in place TABS regulations really don't become important (OK I'd like if glider could use say use TABS to comply with some remaining ADS-B Out restrictions, say to fly above Class C airspace up to 10,000'). So TABS, besides the TABS device TSO definitions is really all unregulated stuff, you just voluntarily install it, but doing so does not grant you any 2020 ADS-B Out (akk 14 CFR 91.226) compliant privileges.

Drop me a private email if you want to discuss something deeper or specific.

Popping up to a general comment:

With the TN72 GPS we should be covered for folk that worry about TSO or not install issues in certified gliders. The TN72 *is* TSO'ed, but to TSO-C199 (TABS) not say TSO-C145c (for 2020 Compliant ADS-B Out... even if it does meets the performance level of TSO-C145c and can be used to do that in experimental aircraft). For 2020 Complaint ADS-B Out the need for an actual TSO GPS source in any certified aircraft seems well established, regardless of other arguments about that... but I have some faint hope that folks there might establish STCs that get around that (not for gliders but in general for GA).

Jumping ahead to preventing possible issues: one thing people might run into is confusion when discussion with A&P IA folks or FSDO staff... who may assume that any discussion about ADS-B is to meet 14 CFR 91.225 and on the FAA folks will naturally want to follow standard policy there, specifically https://www.faa.gov/regulations_poli...mentID/1029526 My interpretation is simply that does *not* apply to TABS installs, since the install is not being done to comply with 14 CFR 91.226 and 92.227. As always discuss stuff with you A&P IA and let them worry about any questions to FSDO staff if needed.

Now the TN72 is here, $350 + antenna + install costs to add in TABS ADS-B Out to any glider with a TT21 or TT22 already installed seems a great deal, and something folks want to think about over this winter... which was what started my post linked to up top.


Darryl, the one thing you are not talking about is power supply. Gliders with only battery power present considerable challenges to meet the performance requirement of the FAA regulations. I suggest everyone who wants to install ADS-B out in a glider considers seriously this aspect.

Andrzej


I spent year talking about batteries in gliders and I hope that has been discussed enough, and is mostly well solved today. For those folks who care some old content is here http://www.pacificsoaring.org/articl...PASCO-2006.pdf I'm not sure how helpful that is by itself, and it predates LiFePO4 batteries, but the main things there I hope people do is:

o Calculate a usable accurate (e.g. measure current draw of devices) ships power budget
o Properly charge their batteries and replace old tired batteries
o Undersatnd surface change effects and not to be confused by them.
o Understand that a 10Ah battery, especially a lead-acid chemistry (including VRLA) battery, will *not* deliver 10 Amp for 1 hour, i.e. how batteries are measured/spec'ed.
o Understand what the discharge curve looks like and how to estimate state of charge, if you can... if you can't then counting the power drawn is an option.

The TN72 adds an additional ~100mA load. For many gliders that won't break a power budget. I see folks rolling up to the glider port with multiple PDAs, iPhones, electric heated booties and God know what else. And again, my point here was mostly if you already have a Trig Transponder I want owners to be aware of options to to add ADS-B Out, especially via TABS and the low cost TN72 GPS.

  #18  
Old December 14th 17, 03:56 AM posted to rec.aviation.soaring
Darryl Ramm
external usenet poster
 
Posts: 2,403
Default ADS-B Update

On Wednesday, December 13, 2017 at 6:00:09 PM UTC-8, wrote:
Darryl, the one thing you are not talking about is power supply.


A K2 pack seems to be working for simple mode C. Is there a reason to expect things to be significantly worse for ADS-B. (Maybe due to higher power out, more GPS power, a higher interrogation rate, and/or longer output transmissions?)


Impossible to say for sure.. you could calculate power budgets and tell us :-)

But... I expect them to be generally better at least with a TN72 GPS. Other GPS sources like what Andrzej has used in his ADS-B Out install in his glider (or gliders --done that in two glider now?) may have significantly higher current draw. Huge credit to Andrzej for being a really early adopter of fully 2020 Complaint ADS-B out in his glider(s).

The Trig TT21/TT22 are lower power draw than most old Mode C transponders and their separate encoders. The book numbers for an active interrogated TT22 (with built in encoder) and a TN72 is about 440mA @14V. A little less, but close, to the popular old combination of a Becker ATC 4401 Mode C transponder and ACK A-30 Encoder at 490 mA, and that is an old 175W not 250W output transponder.

The factor in power consumption when adding ADS-B out to a an existing transponder is just adding the power draw of the GPS receiver. There is no "interrogation" involved in ADS-B. There is a ~1 per second extended squitter broadcast, that one little broadcast is irrelevant in terms of power consumption. When you transponder is is a very active environment it is being interrogated many hundreds to around a thousand times per second. The little blinking indicator showing interrogations in a transponder is a big 'ol lie, it's just slowed down so dumb humans can see it blink.



  #19  
Old December 14th 17, 05:07 AM posted to rec.aviation.soaring
Mike C
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Posts: 337
Default ADS-B Update

On Tuesday, December 12, 2017 at 4:52:16 PM UTC-7, jfitch wrote:
On Tuesday, December 12, 2017 at 2:55:00 PM UTC-8, Andrzej Kobus wrote:
On Tuesday, December 12, 2017 at 12:54:46 PM UTC-5, jfitch wrote:
On Tuesday, December 12, 2017 at 1:48:05 AM UTC-8, Darryl Ramm wrote:
It must be time for some more ADS-B posts, either that or we can talk about PW5 :-)

With the ~$350 street price Trig TN72 GPS source now available in the USA I wanted to revisit my understanding of the situation with ADS-B Out in gliders. I wrote a forum post for local Northern California pilots but it probably helps lots of other folks in the USA. See https://www.williamssoaring.com/news...er-this-Winter

---

And specifically I want to correct some doubt/misinformation I've helped spread here before about the Trig TN72 GPS source when it was first announced. The TN72 is either (depending on how it is configured in the paired transponder) a:

1. TABS/TSO-C199 GPS source (with SIL=1)

*or*

2. A "meets performance requirement of TSO-C145c" GPS source (language I prefer, although Trig may say it differently) (with SIL=3)

(OK the TN72 can also do plain NMEA (with SIL=0), but that's not intersting here).

A little more details and the implications of this is described in post linked to above.

It would be great for folks doing 1090ES Out installs to share their experiences. Here, or contact me directly,

I am happy to try to answer questions.

I'm also planning to give a few talks on ADS-B (and FLARM and Transponders) over the next few months, certainly on the West Coast, details later.

Darryl

Regarding the Reno Class B airspace: It was my understanding that a glider can overfly it above 10,000 ft, and a transponder is only required below 10,000 (and ATC clearance below 8400). I can't see where the regulations have changed that for ADS-B?

It's too bad the FAA saw fit to screw certified gliders - limiting the compliance they sought.

Another detail: all the antennas I have seen thus far are suitable for bolting to the side of a DC-3. Do you know of any option that does not involve a loss of 5 points L/D? (I guess the huge one could be mounted indoors under a transparent area.)


I think, the only issue is that Reno is not a class B airspace.


B, C, what's in a letter? . Now personally, I think the PW5 is a fine little glider other than it doesn't penetrate well and its easy to confuse the canopy release with the tow release.


LOL!
  #20  
Old December 14th 17, 07:54 AM posted to rec.aviation.soaring
jfitch
external usenet poster
 
Posts: 1,134
Default ADS-B Update

On Wednesday, December 13, 2017 at 6:56:32 PM UTC-8, Darryl Ramm wrote:
On Wednesday, December 13, 2017 at 6:00:09 PM UTC-8, wrote:
Darryl, the one thing you are not talking about is power supply.


A K2 pack seems to be working for simple mode C. Is there a reason to expect things to be significantly worse for ADS-B. (Maybe due to higher power out, more GPS power, a higher interrogation rate, and/or longer output transmissions?)


Impossible to say for sure.. you could calculate power budgets and tell us :-)

But... I expect them to be generally better at least with a TN72 GPS. Other GPS sources like what Andrzej has used in his ADS-B Out install in his glider (or gliders --done that in two glider now?) may have significantly higher current draw. Huge credit to Andrzej for being a really early adopter of fully 2020 Complaint ADS-B out in his glider(s).

The Trig TT21/TT22 are lower power draw than most old Mode C transponders and their separate encoders. The book numbers for an active interrogated TT22 (with built in encoder) and a TN72 is about 440mA @14V. A little less, but close, to the popular old combination of a Becker ATC 4401 Mode C transponder and ACK A-30 Encoder at 490 mA, and that is an old 175W not 250W output transponder.

The factor in power consumption when adding ADS-B out to a an existing transponder is just adding the power draw of the GPS receiver. There is no "interrogation" involved in ADS-B. There is a ~1 per second extended squitter broadcast, that one little broadcast is irrelevant in terms of power consumption. When you transponder is is a very active environment it is being interrogated many hundreds to around a thousand times per second. The little blinking indicator showing interrogations in a transponder is a big 'ol lie, it's just slowed down so dumb humans can see it blink.


The specs on a TN70/TA70 are 360mA/240mA max/typ @ 14V. That's in addition to the transponder. At 12V that is likely to be 420mA/280mA. Not a killer but a significant extra load. Another 3AH out of the battery on a typical day. If you are ballasted with batteries like Jim, not too big a problem, but if you have the more typical 10 or 12 AH lead acid, it could be a problem.

If you are lucky enough to be flying an experimental glider, the TN72 and a suitable patch antenna looks a lot better for power consumption, perhaps only 150 mA.
 




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