Help us with this petition for security on anti-collision systems

On Friday, May 29, 2015 at 7:29:47 PM UTC-4, Lucas wrote:
On Friday, May 29, 2015 at 2:33:02 PM UTC+2, Tango Eight wrote:
On Friday, May 29, 2015 at 8:10:48 AM UTC-4, wrote:
We wish to thank everybody. We have some 900 pilots (and are growing) that think that the protocol should be free and then everybody is free to buy the system he prefers!

No monopoly, especially on security. IGC should agree with this.
THANKS AGAIN

One more time...

Did DSX and Flarm have an agreement, or did DSX reverse engineer Flarm's IP without Flarm's blessing?

I think we know the answer. I know what my response would be to a competitor that reverse engineered *my* IP.

Petitions are for losers, anyway. You want to do business, you behave like businessmen.

-Evan Ludeman / T8

One more time: have you read the previous posts ?
If yes: you know that the T-Advisor works in a different way and the hardware is more performing. What is reverse engineer for ?
If not, you can go up and read them.

Are you connected with Flarm ?
If you mention the IP, you are supposed to know them. Can you write here for everyone what IP Flarm has ?
Again, it's in the previous posts, so it is clear that you have not read them or you ignore them purposely.
To show that you know the subject, write here the IP that Flarm has.
Otherwise you make allegations without any base, which is useless for a discussion and a bad behavior.

No, I am not affiliated with Flarm. I am a retail customer. See how easy that is? You ask a question, I give you a simple straight answer. It's how civilized adults interact.

There's a song I like to whistle at times like this, and it even involves a strawman.

-Evan Ludeman / T8

On Friday, May 29, 2015 at 4:35:14 PM UTC-7, Lucas wrote:

Your note doesn't solve the basic problem: you cannot "predict" where the pilot will go in 10-20-... seconds.
Therefore any "prediction" is not possible.
This is very simple: there is no way of predicting what the pilot will do in most situations.
As already wrote, it's enough to look at a flight trace.
And, pardon me, but I have been working on flight dynamics for 19 years now. I don't know about you, but the background seems quite different at this point.

Experience: NASA Ames Research Center.

It is at best an academic argument and at worst a dangerous one to say that because you can't predict with 100% certainty that the pilot won't make an aggressive control input that it is pointless or ("impossible") to project forward a flight path for 15 seconds.

If the pilot makes aggressive control inputs any prediction of future position will change, and the old prediction will no longer be accurate. However, that does not make any attempt to predict future position useless. Most control inputs over a 15 second time period when thermalling or when cruising do not so alter the trajectory as to make a path estimate irrelevant. Generally the trajectory is pretty predictable. It's actually pretty hard to make a material change in your position in a thermal and it takes a while for it to evolve. Even if there is an aggressive control input the algorithm adjusts to include the change. If you maneuver and become a collision threat FLARM generates a warning, if you don't become a collision threat it doesn't.

Works pretty well for me.

9B

You are the administrator of ClearNav, and you have been working WITH flarm
in the past to integrate their work into yours.
I think it is unfair to call you a simple retail customer.
I think that you are playing with no success the strawman with us.


"Tango Eight" wrote in message
...

No, I am not affiliated with Flarm. I am a retail customer. See how easy
that is? You ask a question, I give you a simple straight answer. It's how
civilized adults interact.

There's a song I like to whistle at times like this, and it even involves a
strawman.

-Evan Ludeman / T8

I'm ill with the 'flu and can't fly or do much else so...

I've been on a conference call with Flarm guys exactly once, mostly concerned with their data port specification and how to use it best with our product (n.b. we're still waiting on dataport spec for v6). I bought all my flarm gear at retail price, through the retail channel. Flarm has never shared with me any information not already in the public domain.

None of that is really your business, but I'll share just for the sake of transparency.

The DSX guys have clearly behaved badly enough in a commercial sense to poison any future possibility of cooperation with Flarm. This was a *completely* predictable outcome to anyone with a shred of business savvy. That their proponents won't even acknowledge this explicitly isn't going to help (bring in "Bones" to deliver a cameo "He's [DSX] dead, Jim"). Am I happy about the Flarm monopoly? No. I would absolutely love to see a very basic, inexpensive device (which is what I understand the original Euro flarm was) made available in USA that I could get my local club guys to buy. Powerflarm is so expensive that the *only* significant US market is going to remain competition pilots. At $500, we (that is: safety advocates) could expand the user base a *lot* and I think that would be a very good thing, but I don't think Flarm will ever do this.

Complete aside (I'm just killing time waiting on this damned bug to expire):

You don't seem to know what a "Straw Man Argument" is. There are several good websites devoted to logical fallacies and we can all do well to study and avoid these common and aggravating rhetorical mistakes.

Example of Straw Man: You insist that Flarm doesn't do "prediction" because it cannot know *exactly* (i.e. to one wingspan let's say) where a glider will be in 30 seconds time. This is an absurdly high standard of "prediction" in this case, because a lower precision estimate of likely future location is in fact very useful, especially because this can be rapidly revised if the pilot changes course. What you've done in a rhetorical sense is construct a towering giant of a foe (the "Straw Man") which you proceed to knock over trivially, claiming victory, but in fact all you have done is distract. It's a favorite technique of the political class: the rubes and ideologues *always* bite. We should all try to be smarter than that.

I'm quite confident I have done no such thing on this thread.

best,
Evan Ludeman / T8


On Saturday, May 30, 2015 at 8:22:31 AM UTC-4, pcool wrote:
You are the administrator of ClearNav, and you have been working WITH flarm
in the past to integrate their work into yours.
I think it is unfair to call you a simple retail customer.
I think that you are playing with no success the strawman with us.


"Tango Eight" wrote in message
...

No, I am not affiliated with Flarm. I am a retail customer. See how easy
that is? You ask a question, I give you a simple straight answer. It's how
civilized adults interact.

There's a song I like to whistle at times like this, and it even involves a
strawman.

-Evan Ludeman / T8

On Saturday, May 30, 2015 at 1:22:31 PM UTC+1, pcool wrote:
You are the administrator of ClearNav, and you have been working WITH flarm
in the past to integrate their work into yours.
I think it is unfair to call you a simple retail customer.
I think that you are playing with no success the strawman with us.


"Tango Eight" wrote in message
...

No, I am not affiliated with Flarm. I am a retail customer. See how easy
that is? You ask a question, I give you a simple straight answer. It's how
civilized adults interact.

There's a song I like to whistle at times like this, and it even involves a
strawman.

-Evan Ludeman / T8

So if a reputable avionic company assesses a technical solution from another company as being worth collaborating with that necessarily invalidates their opinion and/or objectivity? Well I guess that having been involved in systematic trial of Flarm in 2007 I am tainted too. And, of course, all those 25,000 paying customers have an axe to grind as well. I understand now - the less the knowledge or experience of, or investment in, a product that an individual has then the more valid is his opinion

Then we all agree on the fact that we dont want a monopoly.
I am not by any mean pushing one or another technology, I exactly want what
you write, too.
I cant subscribe a petition like the one in this thread, I think it is
worthless, to be gentle.

Concerning the strawman, it is an english term and it is not in use commonly
although the meaning is clear.
In this case it is abused, I think, and let me say it sounds offensive .
The argumentation about "where is a glider in 30 seconds" made by a 8mhz
device with no math computing power, leaves no doubts to me.
This is why I keep calling it projection, and Andy did explain what I think
better than I can do myself.

Whatever, we all agree it works.


"Tango Eight" wrote in message
...

I'm ill with the 'flu and can't fly or do much else so...

I've been on a conference call with Flarm guys exactly once, mostly
concerned with their data port specification and how to use it best with our
product (n.b. we're still waiting on dataport spec for v6). I bought all my
flarm gear at retail price, through the retail channel. Flarm has never
shared with me any information not already in the public domain.

None of that is really your business, but I'll share just for the sake of
transparency.

The DSX guys have clearly behaved badly enough in a commercial sense to
poison any future possibility of cooperation with Flarm. This was a
*completely* predictable outcome to anyone with a shred of business savvy.
That their proponents won't even acknowledge this explicitly isn't going to
help (bring in "Bones" to deliver a cameo "He's [DSX] dead, Jim"). Am I
happy about the Flarm monopoly? No. I would absolutely love to see a very
basic, inexpensive device (which is what I understand the original Euro
flarm was) made available in USA that I could get my local club guys to buy.
Powerflarm is so expensive that the *only* significant US market is going to
remain competition pilots. At $500, we (that is: safety advocates) could
expand the user base a *lot* and I think that would be a very good thing,
but I don't think Flarm will ever do this.

Complete aside (I'm just killing time waiting on this damned bug to expire):

You don't seem to know what a "Straw Man Argument" is. There are several
good websites devoted to logical fallacies and we can all do well to study
and avoid these common and aggravating rhetorical mistakes.

Example of Straw Man: You insist that Flarm doesn't do "prediction" because
it cannot know *exactly* (i.e. to one wingspan let's say) where a glider
will be in 30 seconds time. This is an absurdly high standard of
"prediction" in this case, because a lower precision estimate of likely
future location is in fact very useful, especially because this can be
rapidly revised if the pilot changes course. What you've done in a
rhetorical sense is construct a towering giant of a foe (the "Straw Man")
which you proceed to knock over trivially, claiming victory, but in fact all
you have done is distract. It's a favorite technique of the political
class: the rubes and ideologues *always* bite. We should all try to be
smarter than that.

I'm quite confident I have done no such thing on this thread.

best,
Evan Ludeman / T8


On Saturday, May 30, 2015 at 8:22:31 AM UTC-4, pcool wrote:
You are the administrator of ClearNav, and you have been working WITH
flarm
in the past to integrate their work into yours.
I think it is unfair to call you a simple retail customer.
I think that you are playing with no success the strawman with us.


"Tango Eight" wrote in message
...

No, I am not affiliated with Flarm. I am a retail customer. See how easy
that is? You ask a question, I give you a simple straight answer. It's
how
civilized adults interact.

There's a song I like to whistle at times like this, and it even involves
a
strawman.

-Evan Ludeman / T8

On Saturday, May 30, 2015 at 9:29:15 AM UTC-7, pcool wrote:
Then we all agree on the fact that we dont want a monopoly.
I am not by any mean pushing one or another technology, I exactly want what
you write, too.
I cant subscribe a petition like the one in this thread, I think it is
worthless, to be gentle.

Concerning the strawman, it is an english term and it is not in use commonly
although the meaning is clear.
In this case it is abused, I think, and let me say it sounds offensive .
The argumentation about "where is a glider in 30 seconds" made by a 8mhz
device with no math computing power, leaves no doubts to me.
This is why I keep calling it projection, and Andy did explain what I think
better than I can do myself.

Whatever, we all agree it works.


I don't know exactly how the Flarm guys do their math to project a flight path, but I think of it as a cone with it's point at the glider and it's wide end 15 seconds ahead of the glider. The cone can be straight or curved and the cone's centerline defines the overall curvature, which can be defined by a number of factors, but for simplicity's sake lets say that it is a circle based on the last three datapoints (it could be any kind of mathematical curve). If the glider is flying straight, the circle has an infinite radius (a straight line). If the glider is thermaling the circle has a radius of a few hundred feet.

Now imagine the pilot of the glider has decided that instead of thermalling to the left he wants to thermal to the right because he thinks the core is not at the center of the left hand turn but rather at the center of the new right hand turn he wants to establish.. He puts the stick over to the right and the glider starts to roll. The bank shallows, passes through wings level and eventually settles in a steady right hand turn. From start to finish it takes around 10 seconds. What happens to the projection of his future flight path? As his circle widens the projection widens until it is straight out in front of him and then starts curving to the right until it is a cone curved to the right in a circular arc with a radius of several hundred feet (whatever his turn radius is.

It is true that because no instrument can read the pilot's mind you cannot predict that the point 15 second ahead of the glider will flip from being on a left hand circular arc to a right hand circular arc, but that projected point and any given moment is the BEST ESTIMATE of where the glider is headed and as the wide end of the cone arcs through straight ahead the edge of the cone will intersect any paths on that new circle. It won't be a 15 second warning, more like 7-10 seconds depending on how much the cone widens. There is no algorithm or system that will read the mind of the pilot before he even knows his mind, but the Flarm approach certain warns you of a glider heading your way as soon as it is in fact heading your way - that's what we want it to do.

You can be more conservative and set the warning to alert for any glider that is close enough to hit you based on the maximum possible closure rate - assuming both pilots turn aggressively to go exactly head to head. This would require a warning for any glider within a mile to a mile and a half (assuming 300 knot closure rate). Also assume the other glider is in a 25 knot thermal or 25 knots of sink and you are in the opposite to take a worst case scenario. Anyone plus or minus about 1200 feet and within a mile to a mile and a half distance should generate a warning. That is the warning volume to be 99.9999% sure that no matter what you do or the other pilot does you will be warned at least 15 seconds from possible impact. Oh, except if the higher glider has speed brakes out, then you need more like a +/- 2500 foot warning height band.

Without some assumption on projected path, collision warning turns into a traffic alert system if you want 100% certain that no matter what either pilot does you will be warned at least 15 seconds ahead of time. Getting continuous warnings on dozens of glider all the time defeat the purpose I'd like to see served in a collision warning system - that it only warns you when a collision is a real possibility, not a 0.0001% chance that I would get warned about a few seconds later anyway if the worst case circumstances in terms of pilot maneuvering actually came to pass.

If that's what this has been about, it is kind of silly and academic. You should only give warning on things that are pretty likely to happen - or like the boy who cried wolf, people will stop listening to you.

9B

Very interesting view, Andy!
But, can a Flarm cpu do this? My doubts come from the fact that the
calculation engine in my flight software takes about 25ms every second on a
400mhz ARM cpu. For flight path estimation, some of those calculations would
be necessary too. A very conservative estimation would be 20% of 25ms,
needed by flarm too. So let's say 5ms, but on 8mhz (50 times slower). That
means 250ms.
The available time slot is 1000ms but it cannot be used entirely, because
the data must be transmitted and received within the timeslot itself.
So using the same thumb rule, I would say 250ms out of 750ms are used for
calc, leaving 500ms for the rest.
The "rest" being dealing with the gps, receiving data from the radio,
processing data and compare for each data the collisions. outputting NMEA to
serial port if needed, recording the flight, managing the leds etc.
And we must consider that the ATmel 128 cpu has no floating point, no math,
and even a sin() and cos() function are made from scratch in C language by
the cross compiler.
This is why, although "thumb ruled", I cannot thing that a cone like yours
is in use, but something much more simpler.
Because there is no time to do things like you say, I believe.
What do you think?

"Andy Blackburn" wrote in message
...

I don't know exactly how the Flarm guys do their math to project a flight
path, but I think of it as a cone with it's point at the glider and it's
wide end 15 seconds ahead of the glider. The cone can be straight or curved
and the cone's centerline defines the overall curvature, which can be
defined by a number of factors, but for simplicity's sake lets say that it
is a circle based on the last three datapoints (it could be any kind of
mathematical curve). If the glider is flying straight, the circle has an
infinite radius (a straight line). If the glider is thermaling the circle
has a radius of a few hundred feet.

Now imagine the pilot of the glider has decided that instead of thermalling
to the left he wants to thermal to the right because he thinks the core is
not at the center of the left hand turn but rather at the center of the new
right hand turn he wants to establish.. He puts the stick over to the right
and the glider starts to roll. The bank shallows, passes through wings level
and eventually settles in a steady right hand turn. From start to finish it
takes around 10 seconds. What happens to the projection of his future flight
path? As his circle widens the projection widens until it is straight out in
front of him and then starts curving to the right until it is a cone curved
to the right in a circular arc with a radius of several hundred feet
(whatever his turn radius is.

It is true that because no instrument can read the pilot's mind you cannot
predict that the point 15 second ahead of the glider will flip from being on
a left hand circular arc to a right hand circular arc, but that projected
point and any given moment is the BEST ESTIMATE of where the glider is
headed and as the wide end of the cone arcs through straight ahead the edge
of the cone will intersect any paths on that new circle. It won't be a 15
second warning, more like 7-10 seconds depending on how much the cone
widens. There is no algorithm or system that will read the mind of the pilot
before he even knows his mind, but the Flarm approach certain warns you of a
glider heading your way as soon as it is in fact heading your way - that's
what we want it to do.

You can be more conservative and set the warning to alert for any glider
that is close enough to hit you based on the maximum possible closure rate -
assuming both pilots turn aggressively to go exactly head to head. This
would require a warning for any glider within a mile to a mile and a half
(assuming 300 knot closure rate). Also assume the other glider is in a 25
knot thermal or 25 knots of sink and you are in the opposite to take a worst
case scenario. Anyone plus or minus about 1200 feet and within a mile to a
mile and a half distance should generate a warning. That is the warning
volume to be 99.9999% sure that no matter what you do or the other pilot
does you will be warned at least 15 seconds from possible impact. Oh, except
if the higher glider has speed brakes out, then you need more like a +/-
2500 foot warning height band.

Without some assumption on projected path, collision warning turns into a
traffic alert system if you want 100% certain that no matter what either
pilot does you will be warned at least 15 seconds ahead of time. Getting
continuous warnings on dozens of glider all the time defeat the purpose I'd
like to see served in a collision warning system - that it only warns you
when a collision is a real possibility, not a 0.0001% chance that I would
get warned about a few seconds later anyway if the worst case circumstances
in terms of pilot maneuvering actually came to pass.

If that's what this has been about, it is kind of silly and academic. You
should only give warning on things that are pretty likely to happen - or
like the boy who cried wolf, people will stop listening to you.

9B

On Sun, 31 May 2015 16:18:10 +0200, pcool wrote:

Very interesting view, Andy!
But, can a Flarm cpu do this? My doubts come from the fact that the
calculation engine in my flight software takes about 25ms every second
on a 400mhz ARM cpu. For flight path estimation, some of those
calculations would be necessary too. A very conservative estimation
would be 20% of 25ms, needed by flarm too. So let's say 5ms, but on 8mhz
(50 times slower). That means 250ms.
The available time slot is 1000ms but it cannot be used entirely,
because the data must be transmitted and received within the timeslot
itself.
So using the same thumb rule, I would say 250ms out of 750ms are used
for calc, leaving 500ms for the rest.
The "rest" being dealing with the gps, receiving data from the radio,
processing data and compare for each data the collisions. outputting
NMEA to serial port if needed, recording the flight, managing the leds
etc.
And we must consider that the ATmel 128 cpu has no floating point, no
math, and even a sin() and cos() function are made from scratch in C
language by the cross compiler.
This is why, although "thumb ruled", I cannot thing that a cone like
yours is in use, but something much more simpler.
Because there is no time to do things like you say, I believe.
What do you think?

"Andy Blackburn" wrote in message
...

I don't know exactly how the Flarm guys do their math to project a
flight path, but I think of it as a cone with it's point at the glider
and it's wide end 15 seconds ahead of the glider. The cone can be
straight or curved and the cone's centerline defines the overall
curvature, which can be defined by a number of factors, but for
simplicity's sake lets say that it is a circle based on the last three
datapoints (it could be any kind of mathematical curve). If the glider
is flying straight, the circle has an infinite radius (a straight line).
If the glider is thermaling the circle has a radius of a few hundred
feet.

Now imagine the pilot of the glider has decided that instead of
thermalling to the left he wants to thermal to the right because he
thinks the core is not at the center of the left hand turn but rather at
the center of the new right hand turn he wants to establish.. He puts
the stick over to the right and the glider starts to roll. The bank
shallows, passes through wings level and eventually settles in a steady
right hand turn. From start to finish it takes around 10 seconds. What
happens to the projection of his future flight path? As his circle
widens the projection widens until it is straight out in front of him
and then starts curving to the right until it is a cone curved to the
right in a circular arc with a radius of several hundred feet (whatever
his turn radius is.

It is true that because no instrument can read the pilot's mind you
cannot predict that the point 15 second ahead of the glider will flip
from being on a left hand circular arc to a right hand circular arc, but
that projected point and any given moment is the BEST ESTIMATE of where
the glider is headed and as the wide end of the cone arcs through
straight ahead the edge of the cone will intersect any paths on that new
circle. It won't be a 15 second warning, more like 7-10 seconds
depending on how much the cone widens. There is no algorithm or system
that will read the mind of the pilot before he even knows his mind, but
the Flarm approach certain warns you of a glider heading your way as
soon as it is in fact heading your way - that's what we want it to do.

You can be more conservative and set the warning to alert for any glider
that is close enough to hit you based on the maximum possible closure
rate -
assuming both pilots turn aggressively to go exactly head to head. This
would require a warning for any glider within a mile to a mile and a
half (assuming 300 knot closure rate). Also assume the other glider is
in a 25 knot thermal or 25 knots of sink and you are in the opposite to
take a worst case scenario. Anyone plus or minus about 1200 feet and
within a mile to a mile and a half distance should generate a warning.
That is the warning volume to be 99.9999% sure that no matter what you
do or the other pilot does you will be warned at least 15 seconds from
possible impact. Oh, except if the higher glider has speed brakes out,
then you need more like a +/- 2500 foot warning height band.

Without some assumption on projected path, collision warning turns into
a traffic alert system if you want 100% certain that no matter what
either pilot does you will be warned at least 15 seconds ahead of time.
Getting continuous warnings on dozens of glider all the time defeat the
purpose I'd like to see served in a collision warning system - that it
only warns you when a collision is a real possibility, not a 0.0001%
chance that I would get warned about a few seconds later anyway if the
worst case circumstances in terms of pilot maneuvering actually came to
pass.

If that's what this has been about, it is kind of silly and academic.
You should only give warning on things that are pretty likely to happen
- or like the boy who cried wolf, people will stop listening to you.

I see what you're getting at, but I know what I've done using a Parallax
BS2 STAMP that was running a 'compiled', i.e. probably P-coded, integer
BASIC to do some simple time-critical calculations while driving an RC
servo and scanning a pair of switches.

I also remember just what we managed to get a smallish mainframe to do
back in the early 70s with its 1.5 uS (666 Khz) cycle time.

I don't know the Atmel at all, but if it can use interrupts for i/o
handling rather than dimly waiting for each byte to dribble in from its
serial ports then the position might look a bit better than you seem to
think it is.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

I bet you could do a good enough job without a lot of trig. You need position, velocity vector and some measure of curvature. You could probably do the horizontal and vertical parts separately. The cone part is just relaxing the distance that constitutes a collision conflict progressively with each increase in projection time/distance.

Of course the proof is in how FLARM behaves so they are doing something like what I described.

How the calculations fit in processing time available is a question for the likes of Dave Nadler who understand these issues intimately.

9B