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

Il giorno mercoledì 27 maggio 2015 12:45:08 UTC+2, Kevin Neave ha scritto:
Since you ask...

The first hit from Google for "dsx systems t-advisor" is

http://frank.schellenberg.nl/wp-cont...r_07_12_19.pdf

This states..

"The Traffic Advisor, notifies the pilot the presence of all planes that
enter within the radio operating range (that for the T-Advisor is up to 7
km)"

I may be dim but I read that as "T-Advisor tells you 'that there are lots
of gliders flying within 7 km' ".

So I'll rephrase that.

It *would* tell me that there are lots of planes flying within 7km of me if
they were fitted with DSX.

The aircraft I'm interested in are the ones that are that are converging
with me. Flarm warns me of these as long as they are also Flarm equipped
Flarm is intended as an aid to lookout, generally I've seen most contacts
by the time Flarm generates a warning, occasionally I get a wake up call.
Flarm reminds me that my lookout is not as good as it could be.
(Of course I have no idea how many I'm missing and Flarm isn't picking up)

I don't see what T-Advisor would give me

A large number of the gliders flying XC in the UK (possibly a majority by
now) are using Flarm. I don't know of ANY using DSX.

So I repeat the question, how many gliders in Europe are using DSX?
Or more specifically how many in the UK are using DSX?

KN



At 23:44 26 May 2015, Lucas wrote:
Kevin Neave, can you show in which website you read that the T-Advisor
tells you "that there are lots of gliders flying within 7 km" ?

Kevin,
I honestly do not understand why you are so emotional about this topic. No one is trying to convince you that you should trash your device, nor that's the aim of the petition. But you have to take that some other may prefer a T-Advisor. I personally prefer the T-Advisor because I like better its clock and because I agree with the philosophy behind its warning algorithm. If you ask though "how many gliders in Europe are using a DSX", well, I remind you that was it only one, yet makes you Flarm's policy one of the flarm customers that may die in a mid-air collision with a DSX pilot. You have to agree this is a very unusual way of "customer caring".

Il giorno mercoledì 27 maggio 2015 12:45:08 UTC+2, Kevin Neave ha scritto:
Since you ask...

The first hit from Google for "dsx systems t-advisor" is

http://frank.schellenberg.nl/wp-cont...r_07_12_19.pdf

This states..

"The Traffic Advisor, notifies the pilot the presence of all planes that
enter within the radio operating range (that for the T-Advisor is up to 7
km)"

I may be dim but I read that as "T-Advisor tells you 'that there are lots
of gliders flying within 7 km' ".

So I'll rephrase that.

It *would* tell me that there are lots of planes flying within 7km of me if
they were fitted with DSX.

The aircraft I'm interested in are the ones that are that are converging
with me. Flarm warns me of these as long as they are also Flarm equipped
Flarm is intended as an aid to lookout, generally I've seen most contacts
by the time Flarm generates a warning, occasionally I get a wake up call.
Flarm reminds me that my lookout is not as good as it could be.
(Of course I have no idea how many I'm missing and Flarm isn't picking up)

I don't see what T-Advisor would give me

A large number of the gliders flying XC in the UK (possibly a majority by
now) are using Flarm. I don't know of ANY using DSX.

So I repeat the question, how many gliders in Europe are using DSX?
Or more specifically how many in the UK are using DSX?

KN



At 23:44 26 May 2015, Lucas wrote:
Kevin Neave, can you show in which website you read that the T-Advisor
tells you "that there are lots of gliders flying within 7 km" ?

....besides, are you really sure that all the flarms Flying around you are updated to version 6.01 and therefore that you can see them and been seen?
regards

On Tuesday, May 26, 2015 at 4:44:07 PM UTC-7, Lucas wrote:
The T-Advisor AND Flarm are NOT anticollision system.
Anticollision systems are those who tell the pilot what to do (like TCAS), in case of emergency. Neither system does this.
BOTH systems are NOT anticollision systems.

This is a bit of a hair-splitting argument, but to be clear - there a 1) Traffic display systems (show traffic within a detection volume, but provide no alerts), 2) Traffic advisory systems (alert to new traffic entering a detection volume - like PCAS), 3) Collision detection systems (calculate and warn of other aircraft on a probable collision path - like FLARM), 4) Anti-collision systems (advise pilots on action to avoid a collision), 5) Automated anti-collision systems (autonomously take action to avoid collisions - I'm not aware of any of these - outside of military terrain-following autopilots).

Usefulness goes up as you move up the hierarchy. IMO FLARM, being higher that other systems is more useful.


Cleared this, those who talk about the "predictive algorithm", can please explain:

1) how it works, since they must know how it works, to be in the position of saying that it works or it doesn't

2) how they know that such an algorithm has been implemented into a Flarm system: what proof do they have of this ?

Really? That's a serious question? Well, it warns me of converging traffic and when I look, there is in fact converging traffic in the direction indicated. There is no traffic converging on me for which I get no warning and warnings for traffic that is not a series factor is almost nonexistent.


3) if they have ever seen the trace of at least 10 glider flights in different conditions (competition, cross country, around-the-airfield, ridge soaring,....); whoever has seen some, not many, traces of flights, without the need to be a glider pilot, can understand that a prediction of the position of a glider in a future time beyond a fistful of seconds is impossible, exactly IMPOSSIBLE, since not even its pilot knows it, apart from some cases, like straight flying and constant turn rate thermaling. A glider pilot knows that he will be changing the trajectory of the glider to search for the best netto value, which depends on the micro air movements, which are unknown to the pilot in terms of exact location. Is there a machine capable of predicting these locations ? And even if there was, is there a machine capable of predicting what a glider pilot will do in the next 30-60-80 seconds ? Because this is what the rumored (never verified) "prediction algorithm" does. This is spectacular indeed !

Impossible? As a control-systems engineer I can tell you for a fact that a 1 second sample rate is perfectly adequate for this purpose and you only need 2-3 good data points for each aircraft to make a decent prediction. Even with dropped packets this is a reasonable task. Glider flight dynamics are not so abrupt as to make this an impossible task and pilots are not generally making so many aggressive control inputs as to flail the system. FLARM uses a probabilistic approach base on total energy to err on the side of possible control inputs that handles most situations well.


4) even if they found a system to predict the position of the glider with a certain probability, would they trust as optimal a system that has (obviously) a probability to fail the prediction and miss a danger of collision ? Even if the probability was low (all but sure, since never demonstrated with objective tests and calculated data), 2, 3, 10 collisions (and deads) out of XX'XXX flights are too much. In aeronautics, this approach is wrong: this is not the way we work in professional aeronautics, that has taken us where we are in aviation

We don't need optimal, we need better than human perception and FLARM does that very well indeed.


9B

What Flarm calls "prediction" I think that most likely is a simple
projection. It is quite likely calculated worst than how we calculate the
best point to turn in thermal.
I am referring to the "Beep" in Zanders, or in some flight computers .
If you want to see how a "prediction" is working, look at the thermal
Orbiter I have programmed
https://github.com/LK8000/LK8000/blo...lc/Orbiter.cpp
which is quite similar to what Zander and SeeYou Mobile (and possibly other
software, I don't really know) do.
This is a prediction based on turning angle, estimated banking etc. and I
mention it here for a reason:
there is floating point math involved in such kind of predictions.
We use 400mhz or best ARM cpu on PNA-PDAs.
Flarm is tuned to "predict" on a 8mhz CPU by Atmel, a reduced instruction
set microcontroller that has no math coprocessor and cannot do floating
point calculations natively.

A prediction seems like something magic, and I doubt this is the case.
Each device (flarm, dsx) transmits its own position "predicted" with a
simple projection for the next second .
If your own device matches its own "predicted" position with the one
received from another one, it beeps.
That's how it works.
A projection cannot predict when you level and go straight, nevertheless as
you say it works .
It can not work "very well", as you say. But it is better than nothing.

The assumption is that the glider in thermal with you, or arriving in front
of you, has a device with the same protocol.
In the alps this is no more granted. This is what this thread is about.

greets
paolo




"Tango Eight" wrote in message
...

On Tuesday, May 26, 2015 at 7:44:07 PM UTC-4, Lucas wrote:

Tango Eight, your statement is lacking of a scientific base: WHAT
demonstrates that the "prediction algorithm works very well" ?

*Extensive* end user experience.

This might be helpful: http://en.wikipedia.org/wiki/Straw_man

best regards,
Evan Ludeman / T8

On Wednesday, May 27, 2015 at 7:46:25 PM UTC-7, pcool wrote:

The assumption is that the glider in thermal with you, or arriving in front
of you, has a device with the same protocol.
In the alps this is no more granted. This is what this thread is about.

Wow, why would people buy an incompatible device when there are multiple manufacturers of compatible devices in the market?

On Thursday, 28 May 2015 07:05:42 UTC+2, Andy Blackburn wrote:
Wow, why would people buy an incompatible device when there are multiple manufacturers of compatible devices in the market?

What would happen if the relationship soured between FLARM and the manufacturer of your chosen FLARM device?
Flarm could easily issue another upgrade to the protocol and you are left with a $1000+ system which is now totally worthless and useless.

Who is incompatible with who? You have the freedom to choose a device
manufacturer.
The TAdvisor, and probably the OGN devices soon, are not worst than flarm to
do this job.
Anyway, as a wise guy ("Buddy Bob") here stated, shortly we may have OGN
devices acting as collision avoidance systems.
At that point Flarm will change its protocol and adopt the open one.

I fully agree with Bob, it is pointless to ask Flarm to open the protocol.
What we need is several other manufacturers selling their own devices, based
on the OGN open software for example. I have not signed the petition for
this reason.


"Andy Blackburn" wrote in message
...

On Wednesday, May 27, 2015 at 7:46:25 PM UTC-7, pcool wrote:

The assumption is that the glider in thermal with you, or arriving in
front
of you, has a device with the same protocol.
In the alps this is no more granted. This is what this thread is about.

Wow, why would people buy an incompatible device when there are multiple
manufacturers of compatible devices in the market?

On Thu, 28 May 2015 14:22:41 +0200, pcool wrote:

I fully agree with Bob, it is pointless to ask Flarm to open the
protocol. What we need is several other manufacturers selling their own
devices, based on the OGN open software for example. I have not signed
the petition for this reason.

IIRC the reason that FLARM encrypted the protocol was that the OGN crew
were refusing to honour the 'do not track' bit thus exposing the
whereabouts of people who didn't want to be tracked.

In view of that record, why should we trust OGN to do the right thing?

I won't sign the petition either. If DSX want to sell anti-collision kit,
let them drop their NIH attitude and join LX etc in using the de-facto
standard protocol. As long as FLARM sell licences to allow third parties
to use it they are no better or worse than, e.g. Oracle with their
proprietary attitude to Java or the companies who hold patents that
widely used wireless comms standards depend on: think WiFi.

BTW, has the DSX protocol been published? On a Creative Commons or GPL
license?


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

At 12:22 28 May 2015, pcool wrote:
Who is incompatible with who? You have the freedom to choose a device
manufacturer.
The TAdvisor, and probably the OGN devices soon, are not worst than flarm
to
do this job.
Anyway, as a wise guy ("Buddy Bob") here stated, shortly we may have OGN
devices acting as collision avoidance systems.

OGN Trackers work on a different frequency, so will not interface to Flarm
or DSX.

At that point Flarm will change its protocol and adopt the open one.

Oh?

Even if Flarm did open their encoding, DSX is still not Flarm-compatible.
The do not have the predictive algorithm that Flarm does.

The differances are too great.

I fully agree with Bob, it is pointless to ask Flarm to open the protocol.

What we need is several other manufacturers selling their own devices,
based
on the OGN open software for example. I have not signed the petition for

this reason.

Are there any DSX devices in US? One might supose so judging by the number
of responses from US pilots, but I doubt it.

On Thursday, May 28, 2015 at 9:00:06 AM UTC-4, Tim Newport-Peace wrote:


Even if Flarm did open their encoding, DSX is still not Flarm-compatible.
The do not have the predictive algorithm that Flarm does.


That's not true (logically). One need only have open transmission of 3D location, velocity, turn rate. The predictive element of things is done on the receiving end and need not be symmetric. Better predictive capability yields fewer nuisance alarms.

Most US guys, I think, never heard of DSX until this thread. Did DSX and Flarm have an agreement or did they just hack the protocol?


regards,
Evan Ludeman / T8