Low Cost Dual Band ADS-B Receiver

On Saturday, February 4, 2017 at 4:07:14 AM UTC-7, Andrzej Kobus wrote:
On Friday, February 3, 2017 at 10:04:36 PM UTC-5, Tom BravoMike wrote:
If ADS-B/In provides the 3D information, which is next used in a variety of softwa ForeFlight, iFlyGPS, XCSoar (pending, hopefully), what can stop the programmers to calculate potential collisions and give similar alerts to those of FLARM? Isn't it all about universality of the system and availability of reliable data between ALL users of the airspace: powerplanes, gliders, trikes AND drones?

Tom BravoMike

BraveMike, compute power is the only thing that might stop this , but I doubt it will since hardware performance is accelerating at high rate (maybe with the exception of WGC gaggles). PowerFlarm has very low compute power, probably to keep power consumption low and to keep hardware cost low (although that has not been passed onto a consumer). When PowerFlarm was invented hardware computing power was low so they made the best algorithm possible and it worked for many years.

The drones will probably drive this market. They will have to have technology to avoid collisions. I would also think that lower cost and energy efficient transponders are going to show up as well.

Just my opinion, I can't predict the future.

http://www.uavionix.com/products/ping2020/ UAV ADS-B transceiver. As it's available now, before the manned version, perhaps it validates what is driving this market. No particularly cheap.

Frank Whiteley

On Friday, February 3, 2017 at 6:23:50 PM UTC-8, Tom BravoMike wrote:
If, theoretically, all those '10 or less in a gaggle' are equipped with ADS-B Out and In, and 'a good tactical display', will the information/warnings provided be still inferior to that of FLARM? Just curious...

Tom BravoMike

Yes, ADS-B will be inferior for a variety of reasons:

1) ADS-B doesn't do path prediction on the transmit side (straight, turning, climbing, descending, etc.). FLARM does.

2) ADS-B doesn't provide collision warning. For glider scenarios, this is almost impossible to do without some form of #1. At best a computer using ADS-B could give traffic alerts based on proximity, which for glider scenarios would generate a lot of false alarms if you tried to use it for anything beyond simple proximity alerts.

3) Most of the collision warning processing is done by FLARM, not the display. Imagine the challenges and confusion potential if each display used its own collision warning algorithm. Since there is no provision in the ADS-B specification for anything other than absolute position display based on GPS location. FLARM sends RELATIVE position and collision warnings to all displays so there is no ambiguity. In addition, there is no plan to provide this functionality that I am aware of across display manufacturers.

4) FLARM de-duplicates FLARM and ADS-B 1090ES and Mode-S transponder traffic based on ICAO ID. If you go a la carte, you would need to do this within each display. There are no plans that I am aware of to do this.

I'm sure there are other challenges. I do think it would be useful to MUX UAT (and possibly TIS-B) traffic into a FLARM NMEA stream, but it has challenges. I'd take whatever FLARM provides natively first, add a transponder second and then see if I need anything else, like ADS-B Out, TIS-B, UAT, or FIS-B (for weather radar, TFRs, etc - but that's a whole new set of display challenges).

9B

Since there is no provision in the ADS-B specification for anything other than absolute position display based on GPS location.

The ADS-B specification requires transmitting 3D velocity vector along with absolute position.

Marc

Andy, regarding doing a MUX of UAT data into a FLARM stream. While it would be nice to see UAT targets on my FlarmView, the question is: would an effort to accomplish this be worthwhile?

I spent a little time seeing if I could find the relative number of UAT boxes vs 1090 boxes. I found a 2014 estimate that said 33% of transponders were UAT, but I don't believe that. The RPi hobbyists using Dump1090 and Dump978 say they are getting maybe seeing 5 planes a day on 978.

-John, Q3

On Saturday, February 4, 2017 at 2:21:30 PM UTC-5, wrote:
I'm sure there are other challenges. I do think it would be useful to MUX UAT (and possibly TIS-B) traffic into a FLARM NMEA stream, but it has challenges. I'd take whatever FLARM provides natively first, add a transponder second and then see if I need anything else, like ADS-B Out, TIS-B, UAT, or FIS-B (for weather radar, TFRs, etc - but that's a whole new set of display challenges).

9B

On Saturday, February 4, 2017 at 2:21:30 PM UTC-5, wrote:
On Friday, February 3, 2017 at 6:23:50 PM UTC-8, Tom BravoMike wrote:
If, theoretically, all those '10 or less in a gaggle' are equipped with ADS-B Out and In, and 'a good tactical display', will the information/warnings provided be still inferior to that of FLARM? Just curious...

Tom BravoMike

Yes, ADS-B will be inferior for a variety of reasons:

1) ADS-B doesn't do path prediction on the transmit side (straight, turning, climbing, descending, etc.). FLARM does.

2) ADS-B doesn't provide collision warning. For glider scenarios, this is almost impossible to do without some form of #1. At best a computer using ADS-B could give traffic alerts based on proximity, which for glider scenarios would generate a lot of false alarms if you tried to use it for anything beyond simple proximity alerts.

3) Most of the collision warning processing is done by FLARM, not the display. Imagine the challenges and confusion potential if each display used its own collision warning algorithm. Since there is no provision in the ADS-B specification for anything other than absolute position display based on GPS location. FLARM sends RELATIVE position and collision warnings to all displays so there is no ambiguity. In addition, there is no plan to provide this functionality that I am aware of across display manufacturers.

4) FLARM de-duplicates FLARM and ADS-B 1090ES and Mode-S transponder traffic based on ICAO ID. If you go a la carte, you would need to do this within each display. There are no plans that I am aware of to do this.

I'm sure there are other challenges. I do think it would be useful to MUX UAT (and possibly TIS-B) traffic into a FLARM NMEA stream, but it has challenges. I'd take whatever FLARM provides natively first, add a transponder second and then see if I need anything else, like ADS-B Out, TIS-B, UAT, or FIS-B (for weather radar, TFRs, etc - but that's a whole new set of display challenges).

9B

There is inherently no technical reason that an ADS-B based system can't provide just as sophisticated collision warnings as FLARM. Both systems rely on GPS position data transmitted once per second. I'm not an expert on this, but FLARM may transmit more predictive data that makes threat analysis in the receiver easier, but there is no inherent technical reason that an app connected to an ADS-B receiver can't track multiple threat targets and compute exactly the same trajectories that FLARM provides.

The BIG advantage of these ADS-B receivers is that they provide accurate position data for non ADS-B OUT, but transponder aircraft, received from ADS-B ground stations via TIS-B. Due to the half baked ADS-B IN implementation of PowerFlarm, which does not support TIS-B, transponder equipped aircraft can only be identified with an approximate range and altitude, so you have no idea if the target is in front of you, to the side, or behind you, nor which direction it is headed, etc...

Then of course PowerFlarm doesnt' provide weather radar, METARS, TAFs, and TFRs which are also standard with most ADS-B IN receivers.

On Saturday, February 4, 2017 at 2:14:17 PM UTC-8, Mike Schumann wrote:
On Saturday, February 4, 2017 at 2:21:30 PM UTC-5, wrote:
On Friday, February 3, 2017 at 6:23:50 PM UTC-8, Tom BravoMike wrote:
If, theoretically, all those '10 or less in a gaggle' are equipped with ADS-B Out and In, and 'a good tactical display', will the information/warnings provided be still inferior to that of FLARM? Just curious...

Tom BravoMike

Yes, ADS-B will be inferior for a variety of reasons:

1) ADS-B doesn't do path prediction on the transmit side (straight, turning, climbing, descending, etc.). FLARM does.

2) ADS-B doesn't provide collision warning. For glider scenarios, this is almost impossible to do without some form of #1. At best a computer using ADS-B could give traffic alerts based on proximity, which for glider scenarios would generate a lot of false alarms if you tried to use it for anything beyond simple proximity alerts.

3) Most of the collision warning processing is done by FLARM, not the display. Imagine the challenges and confusion potential if each display used its own collision warning algorithm. Since there is no provision in the ADS-B specification for anything other than absolute position display based on GPS location. FLARM sends RELATIVE position and collision warnings to all displays so there is no ambiguity. In addition, there is no plan to provide this functionality that I am aware of across display manufacturers.

4) FLARM de-duplicates FLARM and ADS-B 1090ES and Mode-S transponder traffic based on ICAO ID. If you go a la carte, you would need to do this within each display. There are no plans that I am aware of to do this.

I'm sure there are other challenges. I do think it would be useful to MUX UAT (and possibly TIS-B) traffic into a FLARM NMEA stream, but it has challenges. I'd take whatever FLARM provides natively first, add a transponder second and then see if I need anything else, like ADS-B Out, TIS-B, UAT, or FIS-B (for weather radar, TFRs, etc - but that's a whole new set of display challenges).

9B

There is inherently no technical reason that an ADS-B based system can't provide just as sophisticated collision warnings as FLARM. Both systems rely on GPS position data transmitted once per second. I'm not an expert on this, but FLARM may transmit more predictive data that makes threat analysis in the receiver easier, but there is no inherent technical reason that an app connected to an ADS-B receiver can't track multiple threat targets and compute exactly the same trajectories that FLARM provides.

The BIG advantage of these ADS-B receivers is that they provide accurate position data for non ADS-B OUT, but transponder aircraft, received from ADS-B ground stations via TIS-B. Due to the half baked ADS-B IN implementation of PowerFlarm, which does not support TIS-B, transponder equipped aircraft can only be identified with an approximate range and altitude, so you have no idea if the target is in front of you, to the side, or behind you, nor which direction it is headed, etc...

Then of course PowerFlarm doesnt' provide weather radar, METARS, TAFs, and TFRs which are also standard with most ADS-B IN receivers.

I guess you didn't read Andy's post above, which explained several technical reasons why ADS-B is unlikely to provide such warnings? ADS-B operates off of the same GPS data, but does not operate in anything like the same way. Perhaps the standard could be changed to operate in a similar way, but that is not likely to happen in our lifetimes.

On Saturday, February 4, 2017 at 4:14:17 PM UTC-6, Mike Schumann wrote:

There is inherently no technical reason that an ADS-B based system can't provide just as sophisticated collision warnings as FLARM. Both systems rely on GPS position data transmitted once per second. I'm not an expert on this, but FLARM may transmit more predictive data that makes threat analysis in the receiver easier, but there is no inherent technical reason that an app connected to an ADS-B receiver can't track multiple threat targets and compute exactly the same trajectories that FLARM provides.


Ah, but does it do it NOW? Or for the past 5 years? PF has and does. Come back when you can show me an equivalent ADS-b system for experimental GLIDERS. Until then - you are peddling vaporware and snake oil.


The BIG advantage of these ADS-B receivers is that they provide accurate position data for non ADS-B OUT, but transponder aircraft, received from ADS-B ground stations via TIS-B. Due to the half baked ADS-B IN implementation of PowerFlarm, which does not support TIS-B, transponder equipped aircraft can only be identified with an approximate range and altitude, so you have no idea if the target is in front of you, to the side, or behind you, nor which direction it is headed, etc...

Wait - will a non-TSOd or certified setup in an EXPERIMENTAL GLIDER get ANY of those TIS-B ADS-B traffic reports? I thought ONLY CERTIFIED AIRCRAFT WITH CERTIFIED ADS-B OUT SYSTEMS would? If I am wrong, please correct me!

Then of course PowerFlarm doesnt' provide weather radar, METARS, TAFs, and TFRs which are also standard with most ADS-B IN receivers.

So? I'm not flying IFR for cristsakes! I haven't looked at a METAF, TAF, or TFR in over 2500 hours of glider flying! WHOGAS!

Listen, I understand how great ADS-B IN/OUT is for power flying, I can't wait for our towplanes to be equipped, but for gliders (and this is still rec..aviation.soaring, I think) ADS-B is at this time pure smoke and mirrors for most. And by discouraging adoption of a proven system (FLARM) in the US you are doing a great disservice.

Kirk
66
(happily PF'ing since 2013)