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"Do It Yourself" airborne proximity warning device



 
 
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  #1  
Old December 9th 13, 02:22 PM posted to rec.aviation.soaring
Linar Yusupov
external usenet poster
 
Posts: 11
Default "Do It Yourself" airborne proximity warning device

Dear rec.aviation.soaring subscribers!

I would like to present you PDF slides of one DIY R&D project.
The slides are about open platform airborne proximity warning device.
It operates at ISM band radio but also capable to receive ADS-B reports at aviation frequency.
It is mainly targeted for our local soaring club use but can also attract pilots worldwide.

The presentation is downloadable at: https://github.com/lyusupov/Argus/ra...g_Dev ice.pdf

If upon reading you'll find it worthwhile, feel yourself free to share this news with someone
upon your discretion.

Don't hesitate to ask any questions here. FAQ document is yet to be created.

Best regards!
Linar Yusupov.
Ads
  #2  
Old December 9th 13, 03:49 PM posted to rec.aviation.soaring
[email protected]
external usenet poster
 
Posts: 14
Default "Do It Yourself" airborne proximity warning device

On Monday, December 9, 2013 4:22:31 PM UTC+2, Linar Yusupov wrote:
Dear rec.aviation.soaring subscribers!



I would like to present you PDF slides of one DIY R&D project.

The slides are about open platform airborne proximity warning device.

It operates at ISM band radio but also capable to receive ADS-B reports at aviation frequency.

It is mainly targeted for our local soaring club use but can also attract pilots worldwide.



The presentation is downloadable at: https://github.com/lyusupov/Argus/ra...g_Dev ice.pdf



If upon reading you'll find it worthwhile, feel yourself free to share this news with someone

upon your discretion.



Don't hesitate to ask any questions here. FAQ document is yet to be created.



Best regards!

Linar Yusupov.


Beautiful!
  #3  
Old December 9th 13, 05:49 PM posted to rec.aviation.soaring
Dan Marotta
external usenet poster
 
Posts: 3,263
Default "Do It Yourself" airborne proximity warning device

Very well done!

I will be watching your progress with interest.

"Linar Yusupov" wrote in message
...
Dear rec.aviation.soaring subscribers!

I would like to present you PDF slides of one DIY R&D project.
The slides are about open platform airborne proximity warning device.
It operates at ISM band radio but also capable to receive ADS-B reports at
aviation frequency.
It is mainly targeted for our local soaring club use but can also attract
pilots worldwide.

The presentation is downloadable at:
https://github.com/lyusupov/Argus/ra...g_Dev ice.pdf

If upon reading you'll find it worthwhile, feel yourself free to share
this news with someone
upon your discretion.

Don't hesitate to ask any questions here. FAQ document is yet to be
created.

Best regards!
Linar Yusupov.


  #4  
Old December 9th 13, 11:09 PM posted to rec.aviation.soaring
Steve Koerner
external usenet poster
 
Posts: 384
Default "Do It Yourself" airborne proximity warning device

This is interesting and clever.

But it does not work with Flarm! Flarm/PowerFlarm is seeing rapid adoption.. A system that competes with Flarm has only the possibility of reducing safety during the time frame that I expect to remain an active glider pilot. Though competition is usually good, it is not a good thing to have competition in this case. What makes it worse is the possibility that any pilot might consider waiting for this instead of installing Flarm/PowerFlarm right now.

Just like Flarm, this system requires that both gliders be like equipped. Having a contingent of Flarm users and a contingent of WiFi users at a contest means that we cannot get to the significant level of safety improvement that would be otherwise achievable with fully adopted Flarm or PowerFlarm.

As I read through the material I couldn't find a single element of technical superiority over PowerFlarm. It seems to me that for one technical standard to replace another established standard it needs to be distinctly better than the first. Being equivalent (if it were) is not near good enough, even if the cost is lower. Soaring is not so strongly cost driven as consumer products for example and in general having an avionic component supported by a manufacturer is a very important benefit.

Starting from where the developers are now, they are very far behind PowerFlarm. Part of the goodness of PowerFlarm is the years of evolution in the algorithms for the collision risk analysis. In a fast changing environment of side by side cruising and close thermalling, PowerFlarm makes good determinations. Even the most brilliant programmer on earth cannot just sit down and write that code. It takes years of observation and feedback to make it work really well in the real world. The electrical components are not the major part of the problem; the magic is really in the software.

And for close proximate flight, I'm led to wonder how the designers might have come to the conclusion that 2-3 second latency would be acceptable for good warnings? Having flown with PowerFlarm, I have to believe that the latency is lower than that.

On the hardware side, I think there are things the developers are not considering well. The use of a high gain (5 dBi) antenna is not advisable. It's important to use a low gain dipole pattern antenna in order to couple well with turning gliders. With a low gain antenna at both TX and RX, the link analysis will be significantly impacted and you will not have the range that has been speculated. PowerFlarm uses a simple dipole for this reason and yet has greater range than is contemplated with the high gain antennas suggested here.

Also related to the coupling matter is the choice of frequency. 2.4 GHz will be significantly more impacted by the nearby human body and other items of near wavelength dimension in the environs of the antenna. This can be overcome to a certain extent with power margin but there isn't power margin. PowerFlarm provides an auxillary receive channel to partially address this issue. An auxillary channel is needed in spades at 2.4 GHz.

There is no mention in the article as to the level of degradation that might be expected in a contest environment with say 50 gliders all within radio range. What is the duty cycle of the waveform? How much would 50 gliders be expected to further reduce functional range?

In this self assembly scenario, who does the testing? One of the things about electronics in general and avionics in particular is the need for sophisticated testing. Having a manufacturer behind an avionics product means that the items have been tested. There is the production testing of each article as it leaves the assembly area. Even more important is that all of the components that go into the design have been technically qualified as suitable. That means that they are tested for operation over a wide temperature range as well as shock and vibration and humidity and pressure. They are tested for having a suitably small degree of parameter variance over the environmental range. All of the USB consumer items that are identify for this project are items that are generally made in China and are intended only for use at room temperature in benign environments. It would be almost remarkably if they all happen to also work over aviation temperature range. I'd be particularly suspicious about the radio module power output and the radio sensitivity over temperature; especially for a device that was never actually intended for operation over temperature.

In fairness the original poster, he did not describe the system as intended to be a replacement for Flarm/PowerFlarm. Yet as described, that would be the obvious thing that many readers might be considering here. For that reason it is worthwhile to point up these considerations and limitations.

Even as I hope that it eventually works well for OP's club, I'm also hoping that no US pilots in particular might be looking at this as a suitable substitute for PowerFlarm.
  #5  
Old December 10th 13, 03:13 AM posted to rec.aviation.soaring
[email protected]
external usenet poster
 
Posts: 5
Default "Do It Yourself" airborne proximity warning device

Interesting read, it has glider pilot creation written all over it. My first impression was that it looks wirey (just invented a new word). I then spent 15 minutes on the net to price the components (identical in most cases but a few exceptions). I got a total of just under $100 on Amazon and Ebay 'buy it now'. I did not include for battery or PDA.
You have 2 types of pilots, the competition guy and the week-end warrior. In most cases, the comp guy is going to have a high end ship and therefore the $1700 powerflarm is an acceptable cost, the week end warriors on the other hand can have a system for approx. 200 bucks (estimating background, take the cost and double it).
I sounds like Linar has started something and based on the above still has some bugs to sort out but Hey! Is is a start.
I will definitely keeps tabs on this thread.

mas
  #6  
Old December 10th 13, 06:19 PM posted to rec.aviation.soaring
Dan Marotta
external usenet poster
 
Posts: 3,263
Default "Do It Yourself" airborne proximity warning device

Maybe someone should develop a device like the MRX PCAS which detects
transponders and includes azimuth in addition to range and elevation. Most
of the algorithms have already been developed. There are well established
methods for very accurately locating a transponder. Look up ASDE-X, for
example (LAT/LON/ALT derived from transponder replies). Alas, I suspect
development cost would far outweigh expected return on investment.

Steve makes excellent points, especially the environmental issues with using
consumer electronics in an aviation envrionment. Having said that, I must
ask if Flarm and PowerFlarm have FAA certification, as does a certified
transponder. Steve's post implies that it is but, according to the FAC
posted at gliderpilot.org, it is not, and does not require certification.
As to Steve's question of the veracity of the system under discussion in an
environment including 50 gliders in close formation, consider that this
display has only 64 pixels and 3 of them display the own ship! That would
be a pretty busy display...

According to the NTSB accident database, since 1994 in the USA there have
been exactly 6 midair collisions involving a glider as listed below (9 if
you consider two gliders running into each other):

1999 - Gllider hit tug which was towing another glider
2003 - Piper Cub flew into aerobatic box and collided with glider using the
box
2006 - Glider and corporate jet collided at 16,000' MSL near Reno, NV
2008 - 2 gliders collide while thermalling
2012 - 2 gliders collide head on
2012 - 2 gliders collide while thermalling at the Worlds Championships

I'm going to guess that neither Flarm nor PowerFlarm were available in 2008
or earlier and, if that is the case, then this technology might have
prevented exactly two accidents in the US. I'll bet that both gliders in
the World's were so equipped and the technology failed, so I'm still waiting
for difinitive proof that it's worthwhile. In most cases, a good outside
scan would also have prevented an accident. In response to the anticipated
statement that we'll never know how many accidents were actually averted by
Flarm, I can only say that a good traffic scan is usually all that's
required, or rejecting or leaving a crowded thermal (competition excepted).

I used the keywords "midair" and "glider" in my search but there may well be
others which I missed. My point is that, considering the number of glider
flights conducted in the US, the risk of a midair is extremely low and, in
my opinion, does not warrant the expense, complexity, or distraction of a
collision warning device for most of the glider flying done in the US.
Competition flying is different, of course, as it concentrates so many
gliders in the same airspace. Europe is much more congested and has far
more glider flights than we do and I can see more of a benefit for them.

And, finally, for a good many of us glider pilots, we cannot simply lay down
for an ASG-29, full panel, and Cobra trailer. For us, the sport is somewhat
cost driven.

"Steve Koerner" wrote in message
...
This is interesting and clever.

But it does not work with Flarm! Flarm/PowerFlarm is seeing rapid adoption.
A system that competes with Flarm has only the possibility of reducing
safety during the time frame that I expect to remain an active glider pilot.
Though competition is usually good, it is not a good thing to have
competition in this case. What makes it worse is the possibility that any
pilot might consider waiting for this instead of installing Flarm/PowerFlarm
right now.

Just like Flarm, this system requires that both gliders be like equipped.
Having a contingent of Flarm users and a contingent of WiFi users at a
contest means that we cannot get to the significant level of safety
improvement that would be otherwise achievable with fully adopted Flarm or
PowerFlarm.

As I read through the material I couldn't find a single element of technical
superiority over PowerFlarm. It seems to me that for one technical standard
to replace another established standard it needs to be distinctly better
than the first. Being equivalent (if it were) is not near good enough, even
if the cost is lower. Soaring is not so strongly cost driven as consumer
products for example and in general having an avionic component supported by
a manufacturer is a very important benefit.

Starting from where the developers are now, they are very far behind
PowerFlarm. Part of the goodness of PowerFlarm is the years of evolution in
the algorithms for the collision risk analysis. In a fast changing
environment of side by side cruising and close thermalling, PowerFlarm makes
good determinations. Even the most brilliant programmer on earth cannot
just sit down and write that code. It takes years of observation and
feedback to make it work really well in the real world. The electrical
components are not the major part of the problem; the magic is really in the
software.

And for close proximate flight, I'm led to wonder how the designers might
have come to the conclusion that 2-3 second latency would be acceptable for
good warnings? Having flown with PowerFlarm, I have to believe that the
latency is lower than that.

On the hardware side, I think there are things the developers are not
considering well. The use of a high gain (5 dBi) antenna is not advisable.
It's important to use a low gain dipole pattern antenna in order to couple
well with turning gliders. With a low gain antenna at both TX and RX, the
link analysis will be significantly impacted and you will not have the range
that has been speculated. PowerFlarm uses a simple dipole for this reason
and yet has greater range than is contemplated with the high gain antennas
suggested here.

Also related to the coupling matter is the choice of frequency. 2.4 GHz
will be significantly more impacted by the nearby human body and other items
of near wavelength dimension in the environs of the antenna. This can be
overcome to a certain extent with power margin but there isn't power margin.
PowerFlarm provides an auxillary receive channel to partially address this
issue. An auxillary channel is needed in spades at 2.4 GHz.

There is no mention in the article as to the level of degradation that might
be expected in a contest environment with say 50 gliders all within radio
range. What is the duty cycle of the waveform? How much would 50 gliders
be expected to further reduce functional range?

In this self assembly scenario, who does the testing? One of the things
about electronics in general and avionics in particular is the need for
sophisticated testing. Having a manufacturer behind an avionics product
means that the items have been tested. There is the production testing of
each article as it leaves the assembly area. Even more important is that
all of the components that go into the design have been technically
qualified as suitable. That means that they are tested for operation over a
wide temperature range as well as shock and vibration and humidity and
pressure. They are tested for having a suitably small degree of parameter
variance over the environmental range. All of the USB consumer items that
are identify for this project are items that are generally made in China and
are intended only for use at room temperature in benign environments. It
would be almost remarkably if they all happen to also work over aviation
temperature range. I'd be particularly suspicious about the radio module
power output and the radio sensitivity over temperature; especially for a
device that was never actually intended for operation over temperature.

In fairness the original poster, he did not describe the system as intended
to be a replacement for Flarm/PowerFlarm. Yet as described, that would be
the obvious thing that many readers might be considering here. For that
reason it is worthwhile to point up these considerations and limitations.

Even as I hope that it eventually works well for OP's club, I'm also hoping
that no US pilots in particular might be looking at this as a suitable
substitute for PowerFlarm.

  #7  
Old December 10th 13, 07:07 PM posted to rec.aviation.soaring
Linar Yusupov
external usenet poster
 
Posts: 11
Default "Do It Yourself" airborne proximity warning device

Thank you for your responses!

I've exhaused my spare time slot today for answering on e-mails.
So I'll leave my comments on this thread later on.
But for now I would like to remind you that:

- it is up to a human being to build an item himself(herself) or buy a product from reseller;
- it is responsibility of Pilot-in-Command and nobody else to carry onboard anything he(she) wants that is within w&b limitations and allowed by law;
- it is responsibility of Pilot-in-Command and nobody else to operate while in flight an electronic device or keep it switched off.
  #8  
Old December 10th 13, 07:14 PM posted to rec.aviation.soaring
[email protected]
external usenet poster
 
Posts: 10
Default "Do It Yourself" airborne proximity warning device

On Tuesday, December 10, 2013 10:19:07 AM UTC-8, Dan Marotta wrote:

I used the keywords "midair" and "glider" in my search but there may well be
others which I missed. My point is that, considering the number of glider
flights conducted in the US, the risk of a midair is extremely low and, in
my opinion, does not warrant the expense, complexity, or distraction of a
collision warning device for most of the glider flying done in the US.
Competition flying is different, of course, as it concentrates so many
gliders in the same airspace. Europe is much more congested and has far
more glider flights than we do and I can see more of a benefit for them.


And, finally, for a good many of us glider pilots, we cannot simply lay down
for an ASG-29, full panel, and Cobra trailer. For us, the sport is somewhat
cost driven.



For some reason it is hard to get the NTSB database to cough up all the incidents. You missed several midairs I know of in the past 5 years or so including one requiring a bailout and one where one pilot tried to bailout but was unable to and thankfully was able to land without injury. That doesn't include a number of scary near misses.

I believe the data shows that midair is the second leading cause of fatality next to stall-spin/collision with terrain. Glider-glider collision is at least ten times likely as glider-GA collision and (by the data) infinitely more likely than glider-air transport collision. If we ever got one of those it would be ugly and bring the stats up to making glider-glider 100 times more likely than glider-air transport.

Yes, contests gather gliders and concentrate traffic but if you look at the some of the work that has been done to accumulate OLC traces into glider flight path "heat maps" you discover that the combination of topography, airports, airspace and (especially) lift sources puts gliders in much closer proximity to each other than you might otherwise think. Gliders tend to occupy a small, common proportion of the available airspace, even though we think we are flying just anywhere. This explains why we see more glider-to-glider collisions than any other kind of glider involved collision. It raises the question as to whether if forced to trade off transponder vs Flarm for cost reasons the most bang for the buck really might be Flarm, even for non-contest flying near terminal areas. The midair collision data suggests this might well be true since the penetration of Flarm and transponders in gliders are both low. The equation would only flip for very small numbers of gliders (5) flying right up against a busy international airport - though there aren't many of these. I carry both Flarm and a Mode S, but I realize others feel they can't afford both, just the way some feel a parachute isn't worth the cost (I believe there also are fewer successful bailouts than glider-glider midairs - so selling one's parachute to buy a Flarm may also be a statistically superior solution - though emotionally I can't imagine anyone making the switch).

In any case, having two, incompatible, Flarm-like technologies is a terrible idea for the reasons already articulated.

9B

  #9  
Old December 10th 13, 08:25 PM posted to rec.aviation.soaring
Steve Koerner
external usenet poster
 
Posts: 384
Default "Do It Yourself" airborne proximity warning device

Hey Dan,

There is actually nothing in my posts that implies that PowerFlarm is FAA certified. I know that it's not and I have no concern that it's not.

Moreover, though your collision statistics are incomplete, your data would in itself drive me to an entirely different conclusion than the one that you prefer.

GW
  #10  
Old December 10th 13, 08:34 PM posted to rec.aviation.soaring
[email protected]
external usenet poster
 
Posts: 10
Default "Do It Yourself" airborne proximity warning device

On Tuesday, December 10, 2013 10:19:07 AM UTC-8, Dan Marotta wrote:

Maybe someone should develop a device like the MRX PCAS which detects
transponders and includes azimuth in addition to range and elevation. Most
of the algorithms have already been developed. There are well established
methods for very accurately locating a transponder. Look up ASDE-X, for
example (LAT/LON/ALT derived from transponder replies). Alas, I suspect
development cost would far outweigh expected return on investment.


I looked it up - ADSE-X is an active radar system that uses either a rotating or phased array antenna (apparently normally mounted on top of the control tower). It's not the sort of thing you'd find you could fit in a glider - even if it were legal. Here's a long to a schematic of the Raytheon version:

http://avstop.com/stories/asde.html

I am not aware of any system you could even adapt to put in a glider that would allow you to get accurate azimuth information off of transponder returns - even in theory.

9B



 




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