An ADS-B In Question

On Wednesday, January 13, 2016 at 3:21:40 PM UTC-8, wrote:
Well that got technical right away. In general terms, would I be able to know about small aircraft with transponders, ie C172 etc, flying into the airport I fly? It's a class E airport, but near a class B airport so, most aircraft are transponder equipped. The device I am looking at is an ADS B - in, receiver, and I would send the information to my iPhone 6+ via wifi. It seems like most major areas now have ADS -B coverage and since I don't have to install an ADS-B out signal, yet. It seems like a solution to what I am looking for, which is some indication of another aircraft near me when my eyes did not pick him up.
Since I am not sending the "out" signal, would I not receive the transponder only traffic? Also since the "out" signal is not present, would the set up just report useless information to me and maybe even show my own glider as traffic?
The device I'm looking at is a TRX1000 from Air Avionics, used with iGlide software.
Thank you.

You are in the USA? Which local airport?

This really has been flogged to death in the past. have you tried looking up those past threads?

And any answer is going to be "technical". this stuff, especially in the USA, is a complex ball of string.

But the simple answer is if you are not outputting a *compliant* ADS-B Out signal, correctly configured to describe the aircraft's ADS-B In capability, the FAA ground infrastructure will not broadcast TIS-B data for your client aircraft. TIS-B is what lets you "see" transponder equipped traffic. So no ADS-B Out worrying about TIS-B is a non-starter.

Then even if you have all that, where exactly are you worrying about seeing such traffic? is that within both ADS-B ground coverage and SSR coverage? Don't assume, check - ask other local pilots who have ADS-B Out & In today.

TIS-B is a transitionary thing, and a bit of a mess. Over time as many aircraft equip with 1090ES our UAT Out then the ideal ADS-B receiver becomes a dual-link (1090ES and UAT In) device. That is the only thing that makes sense for stand-alone receivers in the USA GA market. And maybe there is some hope somebody will integrate a UAT receiver with PowerFLARM's internal 1090ES receiver. It's possible but would take somebody willing to d a lot for no chance of making money on it. of course if most aircraft just equip with 1090ES Out, they you just see them direct on a PowerFLARM. Totally whtotu reliance on ADS-B ground infrastructure.

I suspect the TRX1000 was never something intended for the USA market. Does it even support ADS-R and TIS-B as used in the USA? I'd be very careful assuming it was suitable for use here. Check with the manufacturer -- but unfortunately that same manufacturer has been giving some clueless answers about ADS-B questions to folks from the USA, which makes me think they don't understand much about the operation of ADS-B here.

I'm lost as to why anybody in the USA would look at an Air Avionic TRX1000 when the PowerFLARM is widely used and already has FLARM and 1090ES In (but (apparently) does not support TIS-B).

I guess my real answer to this is kind of unfortunately if you are having to ask questions like this,it is not the time for you really be playing with ADS-B. ADS-B right now is something for the geekier folks to play with. Everybody else in glider land in the USA either gets basic 1090ES In with their powerFLARM or should wait and see what happens with mandatory carriage and TABS regulations and new future products. But don't put off adopting a transponder if flying near busy airspace --and pick a good Mode S transponder (e.g. Trig TT-22) that will allow future 1090ES Out upgrades.

Just to make it clear: PowerFLARM will not only show Flarm and 1090ES ADS-B traffic, but also all transponder- equipped aircraft (move C and S) as non-directional "threats" with altitude and approximate range (if being interrogated by SSR/ATC. So the short answer is: get a PowerFLARM, and back it up with a mode S transponder is you can.

Kirk
66

On Wednesday, January 13, 2016 at 6:21:40 PM UTC-5, wrote:
Well that got technical right away. In general terms, would I be able to know about small aircraft with transponders, ie C172 etc, flying into the airport I fly? It's a class E airport, but near a class B airport so, most aircraft are transponder equipped. The device I am looking at is an ADS B - in, receiver, and I would send the information to my iPhone 6+ via wifi. It seems like most major areas now have ADS -B coverage and since I don't have to install an ADS-B out signal, yet. It seems like a solution to what I am looking for, which is some indication of another aircraft near me when my eyes did not pick him up.
Since I am not sending the "out" signal, would I not receive the transponder only traffic? Also since the "out" signal is not present, would the set up just report useless information to me and maybe even show my own glider as traffic?
The device I'm looking at is a TRX1000 from Air Avionics, used with iGlide software.
Thank you.
The TRX1000 is a completely useless piece of equipment for the US market. It's a 1090ES only receiver that doesn't support ADS-R or TIS-B, so you will never see any ADS-B UAT OUT equipped aircraft nor any transponder equipped aircraft, regardless of whether or not your own aircraft is ADS-B OUT equipped.

There are a number of reputable ADS-B receivers that are specifically designed for the US market that fully support ADS-R and TIS-B. A number of these are dual frequency, so they will directly see both UAT and 1090ES targets when you are not within range of an ADS-B ground station and/or are not ADS-B OUT equipped. That is the way to go.

The big question is whether iGlide will support any of these receivers. For the time being, you may have to use GA focused solutions like Foreflight for an ADS-B based collision avoidance system for use with these receivers.

In defense of Air Avionics, I just received an email from them today saying the TRX1000 would not do what I was looking for. I'll call a local avionics shop (recommended by my FSDO), and ask about a transponder/flarm solution.

On Thursday, January 14, 2016 at 6:46:52 AM UTC-6, Mike Schumann wrote:

There are a number of reputable ADS-B receivers that are specifically designed for the US market that fully support ADS-R and TIS-B. A number of these are dual frequency, so they will directly see both UAT and 1090ES targets when you are not within range of an ADS-B ground station and/or are not ADS-B OUT equipped. That is the way to go.


Mike, you are leaving out the critical fact that without ADS-B OUT in YOUR plane, you do NOT "directly see both UAT and 1090ES targets...". Just having a cheap dual freq (UAT and 1090) ADS-B receiver will NOT show you UAT traffic around you unless there is an ADS_B OUT equipped plane nearby, and will NOT show you current transponder-only equipped traffic. IT IS NOT "THE WAY TO GO" UNLESS YOU HAVE ADS-B OUT!!!! (yes I'm shouting ;^)!

Without ADS-B out the ONLY complete traffic awareness solution at present is PowerFLARM + Mode S xponder. Period.

The big question is whether iGlide will support any of these receivers. For the time being, you may have to use GA focused solutions like Foreflight for an ADS-B based collision avoidance system for use with these receivers.

ARRRGGHH.... In a glider? Really?

Kirk
66

Especially if your glider is certified I would be finding/calling a glider A&P who has done FLARM and a Transponder installs before. And look over any Transponder install documentation that may exist from your glider manufacturer. That is usually much better than trying to deal with an avionics shop.. Very few of those folks would know what a PowerFLARM is if it bit them on the ass.

Yesterday I took my home assembled (by someone else) ADS-B In thingy for
a ride in my Pipistrel Sinus within a 10-mile radius of Moriarty, NM.
Using Avare as my display software and my Android phone as the display
device (temporarily), I was very pleased with the traffic displayed.

I currently have the system set to display all traffic out to 100,000' -
I don't know if that's vertical, horizontal, or both, but I did see a
lot of airliners coming and going from ABQ or simply passing overhead in
the high 30s and low 40s. I also saw quite a bit of traffic down low in
the traffic patterns of airports along the Rio Grande (Mid Valley (E98),
Albuquerque (ABQ), Double Eagle II (AEG), and Santa Fe (SAF)). All of
the airports except for SAF were below my radio horizon so I surmise I
received their position, altitude, and direction via a ground station.
I also saw one aircraft southeast of Moriarty at 11,850' PA. I was
about 10 miles horizontally and 1,350' lower than him.

Arriving at the airport yesterday, I could not find my two rolls of Dual
Lock fasteners so I had to make do with duct taping everything to the
top of the glare shield (it's an experimental aircraft and the
components are light weight). I had heard that the system would create
a lot of electrical noise which could interfere with the comm radio, but
I found it to be completely "quiet".

Now, if it would only display targets on XCSoar so I wouldn't have to
switch screens... Note: This is currently simply an experiment and,
this time of year, there is little to no traffic where I'm flying.

I haven't yet figured out how to capture the data stream from the
receiver to see what I can learn from it.

On 1/10/2016 1:59 PM, Dan Marotta wrote:
Very helpful, thanks!

So far I've only looked at the data stream being sent to the Avare
application. It's a text stream which includes aircraft call sign (if
avaliable, e.g., UAL178), the ICAO address, lat, lon, and altitude.
I'd look at the source code, but my eyes get bleary pretty quickly.

I don't intend for this to me much more than a toy, though I do plan
to try it in flight just to see how it works. When the time comes,
I'll get proper equipment.

Thanks again.

On 1/10/2016 1:43 PM, Darryl Ramm wrote:
Dan

The ADS-B ground station will be broadcasting ADS-R and TIS-B data for client aircraft that are near (i.e. within the ADS-B service "jockey puck" of +/- 3.500' and 15nm radius around the client aircraft). So it may not be, and does not need to be, client aircraft near *you*. Say a suitable equipped ADS-B Out aircraft was 1,000' directly overhead some other transponder only equipped traffic (within SSR coverage) on the other side of a mountain range, where all those aircraft are out of sight to you. The ADS-B ground you had line of site to the ADS-B ground tower covering that airspace you would still see those ground broadcasts intended really for he client aircraft on the other side of the range.

That's again points to the basic irony looking at TIS-B and ADS-R transmissions, they are made for client aircraft near the target, not necessarily near you. As the other target aircraft moves away from the client aircraft, maybe towards you. You stop seeing it on ADS-B. Oops. And in your case it is more likely than not won't be a ADS-B client aircraft near you that is causing what you see for a remote aircraft on the other side of a mountain, the client aircraft will be over on the other side, closer to the target.

What you see at distances will depend on the signal strength and distance to the aircraft or ground station and you antenna setup. These small software defined radio modules are fun to play with but built at low cost and don't have the worlds best analog RF front ends. It would be fun to compare them to what is used in commercial portable devices. Part of the reason I'm not too excited about folks using these in their aircraft for more than experimenting/playing around. The antenna used and it's location/sky visibility will affect coverage as well. It could well be that you will see lots of distant aircraft via ADS-R and TIS-B but not ADS-B direct, because you can receive transmissions from the ground tower well but not those more distant aircraft even if you have line of site to them.

I've mentioned in the past it is hard to try to reverse engineer overall what is going on, especially you cannot easily tell what is being broadcast for what client aircraft. However it should be relatively easy to technically tell if you are receiving data for a TIS-B target. That information is included in the air broadcast messages and fully exposed in the de-facto standard GDL-90 serial communications these portable (hobby and commercial) ADS-B receivers are using.

The GDL9-90 communication protocol is documented and publicly available. e.g. herehttps://www.faa.gov/nextgen/programs/adsb/wsa/media/GDL90_Public_ICD_RevA.PDF. (that one is old, I'd imagine there may be more recent updates even of he GDL90 has long ago stopped being interesting).

The first question I would have is how much of the GDL-90 protocol does and receiver software really implement and does it software correctly send out the target type field data. I've not played with it so I don't know, hopefully it does. Reading the source code should also make that clear.

So even if most commercial traffic display software won't show on the display what type an ADS-B target is it is possible for somebody a little technical to look at this stuff and tell. Easy for example to just grab the GDL-90 serial steam and process it with a text utility. The software Dan is using does logging and I suspect this is all in those log files or can be turned on, but I've not looked.

it is also clear over the air what a ADS-R or ADS-B direct messages are. If that is simply exposed in the traffic stream form any of these devices should be easy to work out for technical folks.. again just by reading the source code.

Hope that helps.









On Sunday, January 10, 2016 at 11:09:02 AM UTC-8, Dan Marotta wrote:
Hopefully Darryl will respond to this but anyone with the knowledge
will be appreciated.



I have a home-grown ADS-B system consisting of a Raspberry Pi 2 and
a couple of software defined radios feeding Avare on my smart
phone. I have line of sight to the ADS-B tower on top of Sandia
Peak, on the east side of Albuquerque. I see a number of 1090ES
targets around the ABQ area, one at 10,400PA', one at 8,200PA' over
SAF, several in the high 30s to low 40s pressure altitude. But I
don't see any targets very far away from Albuquerque.



Is it that only targets within some volume are being transmitted
through the tower within view or am I simply receiving the 1090ES
transmissions directly from the aircraft? I think this may be the
case as I don't see and aircraft on my display that I couldn't see
with binoculars from my house.



When I first turned on the system I saw some aircraft that appeared
to be in the traffic pattern at ABQ and, from where I live on the
east side of the mountains, their transmissions would be blocked by
the mountains. I speculate that there was an ADS-B Out aircraft
flying relatively low near my house and I was receiving TIS-B
transmissions meant for him. I also saw ADS-B weather that day and
there were a lot of snow storms up and down the Rockies.


--

Dan, 5J

--
Dan, 5J

--
Dan, 5J

I have to disagree with you, Kirk since you said "ONLY" and "Period".
That leaves no room for discussion.

"Without ADS-B out the ONLY complete traffic awareness solution at
present is PowerFLARM + Mode S xponder. Period."

Those are ONLY your OPINIONS, and those of a lot of others, but not
those of everyone. I have a Mode S transponder (TT-22) and an MRX PCAS
and I look outside. My electronics "see" the same aircraft as you do
assuming installed transponders and radar coverage which is pretty
complete where I fly. So what if I don't have 360 degree display of the
aircraft around me. It's not a difficult matter to make note of mileage
and delta altitude upon receiving an alert and taking another glance
several seconds later and deciding if the aircraft is closing or
separating from me. There are no worries about "pop up" alerts since I
receive the alerts continuously. It can get pretty annoying while
thermalling!

The only aircraft that has concerned me is that one which had PowerFlarm
installed but no transponder! Now why would anyone do that when he was
possibly invisible to ATC and definitely invisible to non Flarm equipped
aircraft (which includes a lot of airliners overflying Moriarty at 12-14
thousand feet) unless I saw him by looking outside?

As you and I are equipped, we have an equal chance of "seeing" each
other electronically out to the configured ranges of our respective
systems. The price of ADS-B (Out and In) is coming down (especially for
Experimental aircraft). I think I will be able to survive without Flarm
until I decide on which ADS-B system I will install.

On 1/14/2016 9:05 AM, kirk.stant wrote:
On Thursday, January 14, 2016 at 6:46:52 AM UTC-6, Mike Schumann wrote:

There are a number of reputable ADS-B receivers that are specifically designed for the US market that fully support ADS-R and TIS-B. A number of these are dual frequency, so they will directly see both UAT and 1090ES targets when you are not within range of an ADS-B ground station and/or are not ADS-B OUT equipped. That is the way to go.

Mike, you are leaving out the critical fact that without ADS-B OUT in YOUR plane, you do NOT "directly see both UAT and 1090ES targets...". Just having a cheap dual freq (UAT and 1090) ADS-B receiver will NOT show you UAT traffic around you unless there is an ADS_B OUT equipped plane nearby, and will NOT show you current transponder-only equipped traffic. IT IS NOT "THE WAY TO GO" UNLESS YOU HAVE ADS-B OUT!!!! (yes I'm shouting ;^)!

Without ADS-B out the ONLY complete traffic awareness solution at present is PowerFLARM + Mode S xponder. Period.

The big question is whether iGlide will support any of these receivers. For the time being, you may have to use GA focused solutions like Foreflight for an ADS-B based collision avoidance system for use with these receivers.
ARRRGGHH.... In a glider? Really?

Kirk
66


--
Dan, 5J

On Thursday, January 14, 2016 at 6:23:28 AM UTC-8, wrote:
In defense of Air Avionics, I just received an email from them today saying the TRX1000 would not do what I was looking for. I'll call a local avionics shop (recommended by my FSDO), and ask about a transponder/flarm solution.

Well, I have gotten a mixed bag of information from Air-avionics. They had told me to connect the power flarm GPS to the VT-01 Mode S transponder and I would have a a working ADS-B out solution. This is not correct.

On Thursday, January 14, 2016 at 8:50:31 AM UTC-8, Dan Marotta wrote:

Now, if it would only display targets on XCSoar so I wouldn't have
to switch screens...*

My first day with xcsoar. I am on page 16 of the manual and at the bottom is a reference to ADB input and I thought of your post. Post if you figure it out and I will too.