Hi,

I'm looking for a tool with a GUI that indicates all
reachable W-LAN access points and their distance to
my machine. Do you know such an application?

Regards,
Tim

On 2008-07-02, Tim Frink <plfriko@yahoo.de> wrote:

> I'm looking for a tool with a GUI that indicates all reachable
> W-LAN access points and their distance to my machine.

How would an application know the distance to a WAP?

> Do you know such an application?

No, and I don't think it's possible (even in theory).

-- 
Grant Edwards                   grante             Yow! This PORCUPINE knows
                                  at               his ZIPCODE ... And he has
                               visi.com            "VISA"!!

Grant Edwards <grante@visi.com> wrote:
> On 2008-07-02, Tim Frink <plfriko@yahoo.de> wrote:
> 
>> I'm looking for a tool with a GUI that indicates all reachable
>> W-LAN access points and their distance to my machine.
> 
> How would an application know the distance to a WAP?

The probably is no way of knowing the actual linear distance.  If, however, 
you assumed all access points had the same transmit power, you could sort
of infer how far away they are based on the recieved signal strength.  This
would also flawed, however, as it doesn't take into consideration 
interferance from obstructions.

> 
>> Do you know such an application?
> 
> No, and I don't think it's possible (even in theory).

Toshiba laptops that come installed with Windows have a utility called 
'radar' that is part of the Toshiba ConfigFree tools.  It doesn't really do 
what the OP really wants, but the interface could mislead a un-informed
user into thinking it does.

-- 
Frank Stutzman

I believe that Kismet actually does this.

i

On 2008-07-02, Frank Stutzman <stutzman@skywagon.kjsl.com> wrote:
> Grant Edwards <grante@visi.com> wrote:
>> On 2008-07-02, Tim Frink <plfriko@yahoo.de> wrote:
>> 
>>> I'm looking for a tool with a GUI that indicates all reachable
>>> W-LAN access points and their distance to my machine.
>> 
>> How would an application know the distance to a WAP?
>
> The probably is no way of knowing the actual linear distance.  If, however, 
> you assumed all access points had the same transmit power, you could sort
> of infer how far away they are based on the recieved signal strength.  This
> would also flawed, however, as it doesn't take into consideration 
> interferance from obstructions.
>
>> 
>>> Do you know such an application?
>> 
>> No, and I don't think it's possible (even in theory).
>
> Toshiba laptops that come installed with Windows have a utility called 
> 'radar' that is part of the Toshiba ConfigFree tools.  It doesn't really do 
> what the OP really wants, but the interface could mislead a un-informed
> user into thinking it does.
>

-- 
   Due to extreme spam originating from Google Groups, and their inattention 
      to spammers, I and many others block all articles originating 
       from Google Groups. If you want your postings to be seen by 
         more readers you will need to find a different means of 
                       posting on Usenet.
                   http://improve-usenet.org/

On 2008-07-02, Frank Stutzman <stutzman@skywagon.kjsl.com> wrote:
> Grant Edwards <grante@visi.com> wrote:
>> On 2008-07-02, Tim Frink <plfriko@yahoo.de> wrote:
>> 
>>> I'm looking for a tool with a GUI that indicates all reachable
>>> W-LAN access points and their distance to my machine.
>> 
>> How would an application know the distance to a WAP?
>
> The probably is no way of knowing the actual linear distance.
> If, however, you assumed all access points had the same
> transmit power,

and isotropic radiating patterns (at least in the horizontal
plane), and an isotropic receive antenna, and a calibrated
receive signal strength indicator, and no in-band interference,
and so on.

My assertion of not possible "even in theory" was a bit
hyperbolic -- under very controlled conditions it is
theoretically possible.  It's just not possible in the real
world using real WAPs and personal computers.

> you could sort of infer how far away they are based on the
> recieved signal strength.  This would also flawed, however, as
> it doesn't take into consideration interferance from
> obstructions.

In an electrically quiet open field with non-directional
antennas where all the WAPs are on widely separated channels
and are using identical transmit power, you could get a pretty
decent idea of relative distances.

> Toshiba laptops that come installed with Windows have a
> utility called 'radar' that is part of the Toshiba ConfigFree
> tools.  It doesn't really do what the OP really wants, but the
> interface could mislead a un-informed user into thinking it
> does.

Yea, now that I think about it, the OLPC XO laptop has a
display that implies it knows both distance and direction to
other wireless nodes.

-- 
Grant Edwards                   grante             Yow! BARBARA STANWYCK makes
                                  at               me nervous!!
                               visi.com            

On Wed, 02 Jul 2008 10:52:12 -0500, Ignoramus14593 wrote:

A: Because it destroys the logical flow of a thread of comments,
   and makes it difficult to keep up with a conversation.

Q: Why do so many people object to top posting?

A: Writing your reply to a message above what you are referring to
   rather than below it.

Q: What is "top posting"?



> I believe that Kismet actually does this.


-- 
"Bother!" said Pooh, as Lorena Bobbitt tied him to the bed.

On Wed, 02 Jul 2008 14:54:27 +0000, Tim Frink wrote:

> Hi,
> 
> I'm looking for a tool with a GUI that indicates all reachable W-LAN
> access points and their distance to my machine. Do you know such an
> application?
> 
> Regards,
> Tim

Several utilities, including wifi-radar, will give you relative signal 
strengths - that's as good as you're going to get.

On 2008-07-02, Dan C <youmustbejoking@lan.invalid> wrote:
> On Wed, 02 Jul 2008 10:52:12 -0500, Ignoramus14593 wrote:
>
> A: Because it destroys the logical flow of a thread of comments,
>    and makes it difficult to keep up with a conversation.
>
> Q: Why do so many people object to top posting?
>
> A: Writing your reply to a message above what you are referring to
>    rather than below it.
>
> Q: What is "top posting"?
>
>
>
>> I believe that Kismet actually does this.
>
>

I disagree
-- 
   Due to extreme spam originating from Google Groups, and their inattention 
      to spammers, I and many others block all articles originating 
       from Google Groups. If you want your postings to be seen by 
         more readers you will need to find a different means of 
                       posting on Usenet.
                   http://improve-usenet.org/

Ignoramus14593 <ignoramus14593@NOSPAM.14593.invalid> writes:

> On 2008-07-02, Dan C <youmustbejoking@lan.invalid> wrote:
>> On Wed, 02 Jul 2008 10:52:12 -0500, Ignoramus14593 wrote:
>>
>> A: Because it destroys the logical flow of a thread of comments,
>>    and makes it difficult to keep up with a conversation.
>>
>> Q: Why do so many people object to top posting?
>>
>> A: Writing your reply to a message above what you are referring to
>>    rather than below it.
>>
>> Q: What is "top posting"?
>>
>>
>>
>>> I believe that Kismet actually does this.
>>
>>
>
> I disagree

You disagree that Kismet actually does this?

On 2008-07-03, Maxwell Lol <nospam@com.invalid> wrote:

>>>> I believe that Kismet actually does this.
>>>
>>
>> I disagree
>
> You disagree that Kismet actually does this?

I don't know about anybody else, but I certainly disagree that
Kismet does it.

-- 
Grant Edwards                   grante             Yow! You should all JUMP
                                  at               UP AND DOWN for TWO HOURS
                               visi.com            while I decide on a NEW
                                                   CAREER!!

On Thu, 03 Jul 2008 08:59:57 -0500, Grant Edwards wrote:

> On 2008-07-03, Maxwell Lol <nospam@com.invalid> wrote:
> 
>>>>> I believe that Kismet actually does this.
>>>>
>>>
>>> I disagree
>>
>> You disagree that Kismet actually does this?
> 
> I don't know about anybody else, but I certainly disagree that
> Kismet does it.

I think we'll have to agree to disagree.

To Ignoramus:  See what fucking top-posting does?  Confusion all around. 
Wise up, doofus.


-- 
"Bother!" said Pooh, as he wondered why he bothered to answer.

Grant Edwards wrote:
> On 2008-07-02, Tim Frink <plfriko@yahoo.de> wrote:
> 
>> I'm looking for a tool with a GUI that indicates all reachable
>> W-LAN access points and their distance to my machine.
> 
> How would an application know the distance to a WAP?

round trip ping delay?

> 
>> Do you know such an application?
> 
> No, and I don't think it's possible (even in theory).
> 

Just about is.

On Wed, 02 Jul 2008, in the Usenet newsgroup comp.os.linux.misc, in article
<iLCdneHMKpBdOPbVnZ2dnUVZ_uLinZ2d@posted.visi>, Grant Edwards wrote:

>Frank Stutzman <stutzman@skywagon.kjsl.com> wrote:

>> Grant Edwards <grante@visi.com> wrote:

>>> Tim Frink <plfriko@yahoo.de> wrote:

>>>> I'm looking for a tool with a GUI that indicates all reachable
>>>> W-LAN access points and their distance to my machine.

For what reason?  Distance _usually_ is not a critical factor in
selecting a station - signal strength is (assuming comparable access
or authorization, BER, routing, etc.).

>>> How would an application know the distance to a WAP?

Well, you take this string...

>> The probably is no way of knowing the actual linear distance.
>> If, however, you assumed all access points had the same
>> transmit power,
>
>and isotropic radiating patterns (at least in the horizontal
>plane), and an isotropic receive antenna, and a calibrated
>receive signal strength indicator, and no in-band interference,
>and so on.

The last point _may_ be possible - the rest are fantasies true only
in the world of advertising.

>My assertion of not possible "even in theory" was a bit
>hyperbolic -- under very controlled conditions it is
>theoretically possible.  It's just not possible in the real
>world using real WAPs and personal computers.

Agreed. One need only experiment to demonstrate that "it ain't gonna
work".

>> you could sort of infer how far away they are based on the
>> recieved signal strength.  This would also flawed, however, as
>> it doesn't take into consideration interferance from
>> obstructions.

"interference" meaning absorption, reflections and refractions, as
opposed to the result of two (or more) transmitters being received at
the same time.

>In an electrically quiet open field with non-directional
>antennas where all the WAPs are on widely separated channels
>and are using identical transmit power, you could get a pretty
>decent idea of relative distances.

assuming the "signal strength" indication is linear (or logarithmic)
and has sufficient granularity.  Most wireless lan cards have (at
best) an approximation of signal strength and this may not even be
consistent (in some cases, an increase in actual received signal level
may result in a _decrease_ in the indication i.e. the curve is not
monotonic). A display with eight bars indicating signal levels from "I
think I can hear it" up to "it's blasting my ears off" is useless.
Signal strength IN FREE SPACE (which means away from ground, trees,
buildings and _everything_ else) is given by a long series of variables
(transmitter power, transmitter cable loss, transmitter antenna gain,
propagation loss, receiver antenna gain, receiver cable loss), and
that propagation loss term is complex (involving frequency, distance,
and polarization). Down here on earth, there is also atmospheric
absorption and precipitation involved, but over the relatively short
distances can be assumed to be constant.  The distance term of the loss
is based on a squares law function, which means doubling the distance
results in a four times the loss (or a quarter of the signal at the
original distance).

        Old guy

Ignoramus14593 wrote:

> On 2008-07-02, Dan C <youmustbejoking@lan.invalid> wrote:
>> On Wed, 02 Jul 2008 10:52:12 -0500, Ignoramus14593 wrote:
>>
>> A: Because it destroys the logical flow of a thread of comments,
>>    and makes it difficult to keep up with a conversation.
>>
>> Q: Why do so many people object to top posting?
>>
>> A: Writing your reply to a message above what you are referring to
>>    rather than below it.
>>
>> Q: What is "top posting"?
>>
>>
>>
>>> I believe that Kismet actually does this.
>>
>>
> 
> I disagree
I disagree too !

You need a minimum of two points of reference and bearings to estimate
range/distance.

The best that "Kismet" whatever that is, can do, is to give an
indication of relative signal strengths. 

-- 
Best Regards:
                     Baron.

The Natural Philosopher <a@b.c> wrote:
> Grant Edwards wrote:
>> On 2008-07-02, Tim Frink <plfriko@yahoo.de> wrote:
>> 
>>> I'm looking for a tool with a GUI that indicates all reachable
>>> W-LAN access points and their distance to my machine.
>> 
>> How would an application know the distance to a WAP?
> 
> round trip ping delay?
> 
>> No, and I don't think it's possible (even in theory).
>> 
> 
> Just about is.

Hate to burst your bubble but let's throw out some
basic physics and see how this holds up.

Let's say you're 100 feet from a WAP. That's about
100ns in air. Ask yourself if ANYTHING you can do 
in software on a general purpose PC can accurately
measure 100 ns.

Then consider the antenna on your WiFi card.
It is designed to be more-or-less omnidirectional.
With a single antenna is there any information at
all that indicates the _direction_ of the incoming
signal?

In _theory_ this could work but you would need
some specialized hardware at both your end
and at the WAP's end.

If you really want to know where a WAP is you need
two directional antennas so that you can triangulate.

Stan
-- 
Stan Bischof ("stan" at the below domain)
www.worldbadminton.com 

On 2008-07-03, Dan C <youmustbejoking@lan.invalid> wrote:
> On Thu, 03 Jul 2008 08:59:57 -0500, Grant Edwards wrote:
>
>> On 2008-07-03, Maxwell Lol <nospam@com.invalid> wrote:
>> 
>>>>>> I believe that Kismet actually does this.
>>>>>
>>>>
>>>> I disagree
>>>
>>> You disagree that Kismet actually does this?
>> 
>> I don't know about anybody else, but I certainly disagree that
>> Kismet does it.
>
> I think we'll have to agree to disagree.

If "it" is measure distance to WAPs, there's simply no way an
application running on a PC with a normal WiFi interface can do
it.  All you can measure is signal strength.

-- 
Grant Edwards                   grante             Yow!  How do I get HOME?
                                  at               
                               visi.com            

On 2008-07-03, The Natural Philosopher <a@b.c> wrote:
> Grant Edwards wrote:
>> On 2008-07-02, Tim Frink <plfriko@yahoo.de> wrote:
>> 
>>> I'm looking for a tool with a GUI that indicates all reachable
>>> W-LAN access points and their distance to my machine.
>> 
>> How would an application know the distance to a WAP?
>
> round trip ping delay?

You've got to be kidding.

-- 
Grant Edwards                   grante             Yow!  .. the HIGHWAY is
                                  at               made out of LIME JELLO and
                               visi.com            my HONDA is a barbequed
                                                   OYSTER! Yum!

On 2008-07-03, Baron <baron.nospam@linuxmaniac.nospam.net> wrote:

>>>> I believe that Kismet actually does this.
>>>
>>>
>> 
>> I disagree
> I disagree too !
>
> You need a minimum of two points of reference and bearings to
> estimate range/distance.

Even if you had a ridiculously directional antenna, it's not at
all certain that the strongest receive signal comes from the
same direction as the location of the transmitter.  A nice
sharp null in an antenna pattern is probably better for use as
a direction indicator than the main lobe, but it's still going
to point the wrong way a certain amount of the time due to
obstacles, reflections and multi-path.

> The best that "Kismet" whatever that is, can do, is to give an
> indication of relative signal strengths. 

Exactly.

-- 
Grant Edwards                   grante             Yow!  I wish I was a
                                  at               sex-starved manicurist
                               visi.com            found dead in the Bronx!!

stan@worldbadminton.com <stan@worldbadminton.com> wrote:

> The Natural Philosopher <a@b.c> wrote:
>> Grant Edwards wrote:
>>> On 2008-07-02, Tim Frink <plfriko@yahoo.de> wrote:
>>> 
>>>> I'm looking for a tool with a GUI that indicates all reachable
>>>> W-LAN access points and their distance to my machine.
>>> 
>>> How would an application know the distance to a WAP?
>> 
>> round trip ping delay?
>> 
>>> No, and I don't think it's possible (even in theory).
>>> 
>> 
>> Just about is.
>
> Hate to burst your bubble but let's throw out some
> basic physics and see how this holds up.
>
> Let's say you're 100 feet from a WAP. That's about
> 100ns in air. Ask yourself if ANYTHING you can do 
> in software on a general purpose PC can accurately
> measure 100 ns.
>
> Then consider the antenna on your WiFi card.
> It is designed to be more-or-less omnidirectional.
> With a single antenna is there any information at
> all that indicates the _direction_ of the incoming
> signal?
>
> In _theory_ this could work but you would need
> some specialized hardware at both your end
> and at the WAP's end.
>
> If you really want to know where a WAP is you need
> two directional antennas so that you can triangulate.

I think you've got it, Stan. This isn't a computer problem, it
is a radio problem. This fellow needs to locate a local radio
amateur (ham) club and ask for help there.


Tome 

stan@worldbadminton.com wrote:
> The Natural Philosopher <a@b.c> wrote:
>> Grant Edwards wrote:
>>> On 2008-07-02, Tim Frink <plfriko@yahoo.de> wrote:
>>>
>>>> I'm looking for a tool with a GUI that indicates all reachable
>>>> W-LAN access points and their distance to my machine.
>>> How would an application know the distance to a WAP?
>> round trip ping delay?
>>
>>> No, and I don't think it's possible (even in theory).
>>>
>> Just about is.
> 
> Hate to burst your bubble but let's throw out some
> basic physics and see how this holds up.
> 
> Let's say you're 100 feet from a WAP. That's about
> 100ns in air. Ask yourself if ANYTHING you can do 
> in software on a general purpose PC can accurately
> measure 100 ns.
> 

should be possible. Its hard I grant you. Probably do a series of packet 
echoes from various targets and do statistical analyis on the returns.

That plus consideration of signal strength should give more than a crude 
estimate.


> Then consider the antenna on your WiFi card.
> It is designed to be more-or-less omnidirectional.
> With a single antenna is there any information at
> all that indicates the _direction_ of the incoming
> signal?
> 

Who mentioned direction? Nothing in the OP mentioned direction.

Why raise a straw man?

> In _theory_ this could work but you would need
> some specialized hardware at both your end
> and at the WAP's end.
> 
> If you really want to know where a WAP is you need
> two directional antennas so that you can triangulate.
> 

He doesn't. He wants to know how far it is.


> Stan

Sidney Lambe wrote:
> stan@worldbadminton.com <stan@worldbadminton.com> wrote:
> 
>> The Natural Philosopher <a@b.c> wrote:
>>> Grant Edwards wrote:
>>>> On 2008-07-02, Tim Frink <plfriko@yahoo.de> wrote:
>>>>
>>>>> I'm looking for a tool with a GUI that indicates all reachable
>>>>> W-LAN access points and their distance to my machine.
>>>> How would an application know the distance to a WAP?
>>> round trip ping delay?
>>>
>>>> No, and I don't think it's possible (even in theory).
>>>>
>>> Just about is.
>> Hate to burst your bubble but let's throw out some
>> basic physics and see how this holds up.
>>
>> Let's say you're 100 feet from a WAP. That's about
>> 100ns in air. Ask yourself if ANYTHING you can do 
>> in software on a general purpose PC can accurately
>> measure 100 ns.
>>
>> Then consider the antenna on your WiFi card.
>> It is designed to be more-or-less omnidirectional.
>> With a single antenna is there any information at
>> all that indicates the _direction_ of the incoming
>> signal?
>>
>> In _theory_ this could work but you would need
>> some specialized hardware at both your end
>> and at the WAP's end.
>>
>> If you really want to know where a WAP is you need
>> two directional antennas so that you can triangulate.
> 
> I think you've got it, Stan. This isn't a computer problem, it
> is a radio problem. This fellow needs to locate a local radio
> amateur (ham) club and ask for help there.
> 
> 
I think it is actually a problem of literacy when someone takes a post 
that IN ITS TITLE says 'distance' and then goes on to talk about 
bearings....;-)


> Tome 
> 

On 2008-07-04, The Natural Philosopher <a@b.c> wrote:

> I think it is actually a problem of literacy when someone takes a post 
> that IN ITS TITLE says 'distance' and then goes on to talk about 
> bearings....;-)

Taking bearings from two known positions is probably the only
feasible way to measure distance.

-- 
Grant Edwards                   grante             Yow!  Are the STEWED PRUNES
                                  at               still in the HAIR DRYER?
                               visi.com            

On 2008-07-04, The Natural Philosopher <a@b.c> wrote:

> should be possible.

It isn't.

> Its hard I grant you. Probably do a series of packet echoes
> from various targets and do statistical analyis on the
> returns.

Analyze _what_?

> That plus consideration of signal strength should give more
> than a crude estimate.

I don't see how.  Signal strength depends on too many things
other than distance.  How do you know whether a signal is
stronger because it's closer or because, or from a higher
power transmitter, or using a directional antenna.

> Who mentioned direction? Nothing in the OP mentioned direction.

No, but some programs that pretend to display direction were
mentioned.

>> If you really want to know where a WAP is you need
>> two directional antennas so that you can triangulate.
>
> He doesn't. He wants to know how far it is.

And the only way to do that is to know _where_ it is.

-- 
Grant Edwards                   grante             Yow!  Now, I think it would
                                  at               be GOOD to buy FIVE or SIX
                               visi.com            STUDEBAKERS and CRUISE for
                                                   ARTIFICIAL FLAVORING!!

The Natural Philosopher <a@b.c> wrote:

> Sidney Lambe wrote:
>
>> stan@worldbadminton.com <stan@worldbadminton.com> wrote:
>>
>>> The Natural Philosopher <a@b.c> wrote:
>>>
>>>> Grant Edwards wrote:
>>>>
>>>>> On 2008-07-02, Tim Frink <plfriko@yahoo.de> wrote:
>>>>>
>>>>>> I'm looking for a tool with a GUI that indicates all
>>>>>> reachable W-LAN access points and their distance to my
>>>>>> machine.
>>>>>
>>>>> How would an application know the distance to a WAP?
>>>>
>>>> round trip ping delay?
>>>>
>>>>> No, and I don't think it's possible (even in theory).
>>>>
>>>> Just about is.
>>>
>>> Hate to burst your bubble but let's throw out some basic
>>> physics and see how this holds up.
>>>
>>> Let's say you're 100 feet from a WAP. That's about 100ns in
>>> air. Ask yourself if ANYTHING you can do in software on a
>>> general purpose PC can accurately measure 100 ns.
>>>
>>> Then consider the antenna on your WiFi card. It is designed
>>> to be more-or-less omnidirectional. With a single antenna is
>>> there any information at all that indicates the _direction_
>>> of the incoming signal?
>>>
>>> In _theory_ this could work but you would need some
>>> specialized hardware at both your end and at the WAP's end.
>>>
>>> If you really want to know where a WAP is you need two
>>> directional antennas so that you can triangulate.
>>
>> I think you've got it, Stan. This isn't a computer problem, it
>> is a radio problem. This fellow needs to locate a local radio
>> amateur (ham) club and ask for help there.
>>
>
> I think it is actually a problem of literacy when someone takes
> a post that IN ITS TITLE says 'distance' and then goes on to
> talk about bearings....;-)

My first reaction was to chuckle and agree with you, but Grant
has a good point. 

However, you could just use a signal-strength meter and travel in
the direction that gave the strongest reading until you arrived
at the transceiver...

You might not be able to see it, or its antenna, but you'd
know you were there when moving in any direction caused the
reading to diminish.


Tome

Grant Edwards wrote:
> On 2008-07-04, The Natural Philosopher <a@b.c> wrote:
> 
>> I think it is actually a problem of literacy when someone takes a post 
>> that IN ITS TITLE says 'distance' and then goes on to talk about 
>> bearings....;-)
> 
> Taking bearings from two known positions is probably the only
> feasible way to measure distance.
> 
? I'll throw my tape measure away then.

Oh..how do I now know how far aprt those two known positions are...?

Grant Edwards wrote:
> On 2008-07-04, The Natural Philosopher <a@b.c> wrote:
> 
>> should be possible.
> 
> It isn't.
> 
>> Its hard I grant you. Probably do a series of packet echoes
>> from various targets and do statistical analyis on the
>> returns.
> 
> Analyze _what_?
> 
>> That plus consideration of signal strength should give more
>> than a crude estimate.
> 
> I don't see how.  Signal strength depends on too many things
> other than distance.  How do you know whether a signal is
> stronger because it's closer or because, or from a higher
> power transmitter, or using a directional antenna.
> 
>> Who mentioned direction? Nothing in the OP mentioned direction.
> 
> No, but some programs that pretend to display direction were
> mentioned.
> 
>>> If you really want to know where a WAP is you need
>>> two directional antennas so that you can triangulate.
>> He doesn't. He wants to know how far it is.
> 
> And the only way to do that is to know _where_ it is.
> 
No, its not.

On 2008-07-04, The Natural Philosopher <a@b.c> wrote:

>>>> If you really want to know where a WAP is you need
>>>> two directional antennas so that you can triangulate.
>>> He doesn't. He wants to know how far it is.
>> 
>> And the only way to do that is to know _where_ it is.
>> 
> No, its not.

Then please show us another way to do it.

-- 
Grant Edwards                   grante             Yow!  Yow! I want my nose
                                  at               in lights!
                               visi.com            

Grant Edwards wrote:
> On 2008-07-04, The Natural Philosopher <a@b.c> wrote:
> 
>>>>> If you really want to know where a WAP is you need
>>>>> two directional antennas so that you can triangulate.
>>>> He doesn't. He wants to know how far it is.
>>> And the only way to do that is to know _where_ it is.
>>>
>> No, its not.
> 
> Then please show us another way to do it.
> 
Well  radar would work, or measuring round trip echo delays, or you 
could swing a cat on a bit of string, and listen to when it hit the 
target..there are so many ways of measuring distance without knowing 
where something is.

I mean, you could walk blindfold with a pedometer, and home in on it and 
never know where you were at all.

If you put a light on it, you could measure recieved illumination, which 
would tell you how far it was..


Best of all, if yo swung it round your hed ona precisely long bit of 
string at the precise angle and let go. you could tell how far away it 
landed. Not where mind you, just how far. I call this the 'lost golf 
ball' principle,.

Grant Edwards wrote:

> On 2008-07-03, Baron <baron.nospam@linuxmaniac.nospam.net> wrote:
> 
>>>>> I believe that Kismet actually does this.
>>>>
>>>>
>>> 
>>> I disagree
>> I disagree too !
>>
>> You need a minimum of two points of reference and bearings to
>> estimate range/distance.
> 
> Even if you had a ridiculously directional antenna, it's not at
> all certain that the strongest receive signal comes from the
> same direction as the location of the transmitter.  A nice
> sharp null in an antenna pattern is probably better for use as
> a direction indicator than the main lobe, but it's still going
> to point the wrong way a certain amount of the time due to
> obstacles, reflections and multi-path.

I agree !  A shielded loop with a deep null is very effective
particularly if the signal is quite good. 

>> The best that "Kismet" whatever that is, can do, is to give an
>> indication of relative signal strengths.
> 
> Exactly.

Hi Grant,
They have obviously never been on a radio fox hunt. 

-- 
Best Regards:
                     Baron.

On 2008-07-04, The Natural Philosopher <a@b.c> wrote:
> Grant Edwards wrote:
>> On 2008-07-04, The Natural Philosopher <a@b.c> wrote:
>> 
>>>>>> If you really want to know where a WAP is you need
>>>>>> two directional antennas so that you can triangulate.
>>>>> He doesn't. He wants to know how far it is.
>>>> And the only way to do that is to know _where_ it is.
>>>>
>>> No, its not.
>> 
>> Then please show us another way to do it.
>
> Well  radar would work, or measuring round trip echo delays,

No, it _won't_ work.  The delay caused by the IP stack are
orders of magnitude larger than those caused by propogation
delay.  If you ping two WAPs and one has half the ping times,
it's probably because it has a faster processor.

-- 
Grant Edwards                   grante             Yow!  YOW!! I am having
                                  at               FUN!!
                               visi.com            

On 2008-07-04, Baron <baron.nospam@linuxmaniac.nospam.net> wrote:
> Grant Edwards wrote:
>
>> On 2008-07-03, Baron <baron.nospam@linuxmaniac.nospam.net> wrote:
>> 
>>>>>> I believe that Kismet actually does this.
>>>> 
>>>> I disagree
>>> I disagree too !
>>>
>>> You need a minimum of two points of reference and bearings to
>>> estimate range/distance.
>> 
>> Even if you had a ridiculously directional antenna, it's not at
>> all certain that the strongest receive signal comes from the
>> same direction as the location of the transmitter.  A nice
>> sharp null in an antenna pattern is probably better for use as
>> a direction indicator than the main lobe, but it's still going
>> to point the wrong way a certain amount of the time due to
>> obstacles, reflections and multi-path.
>
> I agree !  A shielded loop with a deep null is very effective
> particularly if the signal is quite good. 
>
>>> The best that "Kismet" whatever that is, can do, is to give an
>>> indication of relative signal strengths.
>> 
>> Exactly.
>
> Hi Grant,
> They have obviously never been on a radio fox hunt. 

I've never actually been _on_ one, but I am familiar with the
methods used (I haven't forgotten everything from my ham radio
days).  I've also spent a little time building and testing
2.4GHz WiFi antennas.  Enought time to know that you don't have
the slightest chance of measuring distance to WAPs using
off-the-shelf consumer gear.

-- 
Grant Edwards                   grante             Yow!  Sorry, wrong ZIP
                                  at               CODE!!
                               visi.com            

Grant Edwards wrote:
> On 2008-07-04, The Natural Philosopher <a@b.c> wrote:
>> Grant Edwards wrote:
>>> On 2008-07-04, The Natural Philosopher <a@b.c> wrote:
>>>
>>>>>>> If you really want to know where a WAP is you need
>>>>>>> two directional antennas so that you can triangulate.
>>>>>> He doesn't. He wants to know how far it is.
>>>>> And the only way to do that is to know _where_ it is.
>>>>>
>>>> No, its not.
>>> Then please show us another way to do it.
>> Well  radar would work, or measuring round trip echo delays,
> 
> No, it _won't_ work.  The delay caused by the IP stack are
> orders of magnitude larger than those caused by propogation
> delay.  

But constant.
Anyway, we are talking theoretical not practical.


If you ping two WAPs and one has half the ping times,
> it's probably because it has a faster processor.
> 
I can concieve other techniques relying on statistial analysis of 
collision detection..

Grant Edwards wrote:
> On 2008-07-04, Baron <baron.nospam@linuxmaniac.nospam.net> wrote:
>> Grant Edwards wrote:
>>
>>> On 2008-07-03, Baron <baron.nospam@linuxmaniac.nospam.net> wrote:
>>>
>>>>>>> I believe that Kismet actually does this.
>>>>> I disagree
>>>> I disagree too !
>>>>
>>>> You need a minimum of two points of reference and bearings to
>>>> estimate range/distance.
>>> Even if you had a ridiculously directional antenna, it's not at
>>> all certain that the strongest receive signal comes from the
>>> same direction as the location of the transmitter.  A nice
>>> sharp null in an antenna pattern is probably better for use as
>>> a direction indicator than the main lobe, but it's still going
>>> to point the wrong way a certain amount of the time due to
>>> obstacles, reflections and multi-path.
>> I agree !  A shielded loop with a deep null is very effective
>> particularly if the signal is quite good. 
>>
>>>> The best that "Kismet" whatever that is, can do, is to give an
>>>> indication of relative signal strengths.
>>> Exactly.
>> Hi Grant,
>> They have obviously never been on a radio fox hunt. 
> 
> I've never actually been _on_ one, but I am familiar with the
> methods used (I haven't forgotten everything from my ham radio
> days).  I've also spent a little time building and testing
> 2.4GHz WiFi antennas.  Enought time to know that you don't have
> the slightest chance of measuring distance to WAPs using
> off-the-shelf consumer gear.
> 
That I can certainly agree with ;-)

Google WiFi Tracking it can be done and has been done.

On 2008-07-05, The Natural Philosopher <a@b.c> wrote:

>>>> Then please show us another way to do it.
>>> Well  radar would work, or measuring round trip echo delays,
>> 
>> No, it _won't_ work.  The delay caused by the IP stack are
>> orders of magnitude larger than those caused by propogation
>> delay.  
>
> But constant.

No, they're not.  Not at the nanosecond scale.  More
importantly the average values of the software and hardware
delays are going to varey wildly from one WAP model and versio
of firmware to another.

> Anyway, we are talking theoretical not practical.

Even so, it won't work.

> If you ping two WAPs and one has half the ping times,
>> it's probably because it has a faster processor.
>> 
> I can concieve other techniques relying on statistial analysis
> of collision detection..

More nonsense.

-- 
Grant Edwards                   grante             Yow!  I'm encased in the
                                  at               lining of a pure pork
                               visi.com            sausage!!

Grant Edwards wrote:
> On 2008-07-05, The Natural Philosopher <a@b.c> wrote:
> 
>>>>> Then please show us another way to do it.
>>>> Well  radar would work, or measuring round trip echo delays,
>>> No, it _won't_ work.  The delay caused by the IP stack are
>>> orders of magnitude larger than those caused by propogation
>>> delay.  
>> But constant.
> 
> No, they're not.  Not at the nanosecond scale.  More
> importantly the average values of the software and hardware
> delays are going to varey wildly from one WAP model and versio
> of firmware to another.
> 
>> Anyway, we are talking theoretical not practical.
> 
> Even so, it won't work.
> 
>> If you ping two WAPs and one has half the ping times,
>>> it's probably because it has a faster processor.
>>>
>> I can concieve other techniques relying on statistial analysis
>> of collision detection..
> 
> More nonsense.
> 
I take that to mean you didn't understand what I said.?

Grant Edwards wrote:

> On 2008-07-04, Baron <baron.nospam@linuxmaniac.nospam.net> wrote:
>> Grant Edwards wrote:
>>
>>> On 2008-07-03, Baron <baron.nospam@linuxmaniac.nospam.net> wrote:
>>> 
>>>>>>> I believe that Kismet actually does this.
>>>>> 
>>>>> I disagree
>>>> I disagree too !
>>>>
>>>> You need a minimum of two points of reference and bearings to
>>>> estimate range/distance.
>>> 
>>> Even if you had a ridiculously directional antenna, it's not at
>>> all certain that the strongest receive signal comes from the
>>> same direction as the location of the transmitter.  A nice
>>> sharp null in an antenna pattern is probably better for use as
>>> a direction indicator than the main lobe, but it's still going
>>> to point the wrong way a certain amount of the time due to
>>> obstacles, reflections and multi-path.
>>
>> I agree !  A shielded loop with a deep null is very effective
>> particularly if the signal is quite good.
>>
>>>> The best that "Kismet" whatever that is, can do, is to give an
>>>> indication of relative signal strengths.
>>> 
>>> Exactly.
>>
>> Hi Grant,
>> They have obviously never been on a radio fox hunt.
> 
> I've never actually been _on_ one, but I am familiar with the
> methods used (I haven't forgotten everything from my ham radio
> days).  I've also spent a little time building and testing
> 2.4GHz WiFi antennas.  Enought time to know that you don't have
> the slightest chance of measuring distance to WAPs using
> off-the-shelf consumer gear.

Grant, Are you ok with me mailing you a pdf ? 

-- 
Best Regards:
                     Baron.

Glen wrote:

> Google WiFi Tracking it can be done and has been done.

I agree, but it isn't able to measure distance.
Radar only achieves this because of line of sight and its control over
its transmitted signal.

-- 
Best Regards:
                     Baron.

On 2008-07-05, Baron <baron.nospam@linuxmaniac.nospam.net> wrote:

>> I've never actually been _on_ one, but I am familiar with the
>> methods used (I haven't forgotten everything from my ham radio
>> days).  I've also spent a little time building and testing
>> 2.4GHz WiFi antennas.  Enought time to know that you don't have
>> the slightest chance of measuring distance to WAPs using
>> off-the-shelf consumer gear.
>
> Grant, Are you ok with me mailing you a pdf ? 

Sure.

-- 
Grant

 

On 2008-07-05, The Natural Philosopher <a@b.c> wrote:

>>> I can concieve other techniques relying on statistial analysis
>>> of collision detection..
>> 
>> More nonsense.
>> 
> I take that to mean you didn't understand what I said.?

I understand what you said, but...  1) you don't have access to
collision detection information from an application. 2) Even if
you did, I don't see any way that you can derive distance
information from it.  I think I'm done arguring about this.  

If you're so convinced it can be done, then go do it.

-- 
Grant

Grant Edwards <grante@visi.com> wrote:
> On 2008-07-03, The Natural Philosopher <a@b.c> wrote:
>> Grant Edwards wrote:
>>> On 2008-07-02, Tim Frink <plfriko@yahoo.de> wrote:
>>> 
>>>> I'm looking for a tool with a GUI that indicates all reachable
>>>> W-LAN access points and their distance to my machine.
>>> 
>>> How would an application know the distance to a WAP?
>>
>> round trip ping delay?
> 
> You've got to be kidding.
> 

This discussion is what happens when folks step outside
the realm of their knowledge. Software folks might like
to gloss over the real world of RF/uW and assume everything
can be done in software, but that doesn't make it
true.

If the data you need ( as in this case ) doesn't
exist in the real world, no magic software/OS
is going to supply it. 

Anyone here who really thinks that they can measure
distance to a WAP given off-the-shelf WiFi receiver
is mistaken. Sorry- that's just the way it is.

Stan

-- 
Stan Bischof ("stan" at the below domain)
www.worldbadminton.com 

Grant Edwards wrote:

> On 2008-07-05, Baron <baron.nospam@linuxmaniac.nospam.net> wrote:
> 
>>> I've never actually been _on_ one, but I am familiar with the
>>> methods used (I haven't forgotten everything from my ham radio
>>> days).  I've also spent a little time building and testing
>>> 2.4GHz WiFi antennas.  Enought time to know that you don't have
>>> the slightest chance of measuring distance to WAPs using
>>> off-the-shelf consumer gear.
>>
>> Grant, Are you ok with me mailing you a pdf ?
> 
> Sure.
> 
Sent 10:51

-- 
Best Regards:
                     Baron.

Grant Edwards wrote:
> On 2008-07-05, The Natural Philosopher <a@b.c> wrote:
> 
>>>> I can concieve other techniques relying on statistial analysis
>>>> of collision detection..
>>> More nonsense.
>>>
>> I take that to mean you didn't understand what I said.?
> 
> I understand what you said, but...  1) you don't have access to
> collision detection information from an application. 2) Even if
> you did, I don't see any way that you can derive distance
> information from it.  I think I'm done arguring about this.  
> 
> If you're so convinced it can be done, then go do it.
> 
Oh it can be, but its a lot of hardware and software..

stan@worldbadminton.com wrote:
> Grant Edwards <grante@visi.com> wrote:
>> On 2008-07-03, The Natural Philosopher <a@b.c> wrote:
>>> Grant Edwards wrote:
>>>> On 2008-07-02, Tim Frink <plfriko@yahoo.de> wrote:
>>>>
>>>>> I'm looking for a tool with a GUI that indicates all reachable
>>>>> W-LAN access points and their distance to my machine.
>>>> How would an application know the distance to a WAP?
>>> round trip ping delay?
>> You've got to be kidding.
>>
> 
> This discussion is what happens when folks step outside
> the realm of their knowledge. Software folks might like
> to gloss over the real world of RF/uW and assume everything
> can be done in software, but that doesn't make it
> true.
> 
> If the data you need ( as in this case ) doesn't
> exist in the real world, no magic software/OS
> is going to supply it. 
> 
> Anyone here who really thinks that they can measure
> distance to a WAP given off-the-shelf WiFi receiver
> is mistaken. Sorry- that's just the way it is.
> 

No one specified an off the shelf wifi receiver ;-)


> Stan
> 

The Natural Philosopher wrote:

> Grant Edwards wrote:
>> On 2008-07-05, The Natural Philosopher <a@b.c> wrote:
>> 
>>>>> I can concieve other techniques relying on statistial analysis
>>>>> of collision detection..
>>>> More nonsense.
>>>>
>>> I take that to mean you didn't understand what I said.?
>> 
>> I understand what you said, but...  1) you don't have access to
>> collision detection information from an application. 2) Even if
>> you did, I don't see any way that you can derive distance
>> information from it.  I think I'm done arguring about this.
>> 
>> If you're so convinced it can be done, then go do it.
>> 
> Oh it can be, but its a lot of hardware and software..

Come back when you have made a fortune doing it !
Remember you have no control over the transmitter.  At the receiver you
can do what you like, since you only have one of them !

-- 
Best Regards:
                     Baron.

The Natural Philosopher <a@b.c> wrote:
>> 
>> Anyone here who really thinks that they can measure
>> distance to a WAP given off-the-shelf WiFi receiver
>> is mistaken. Sorry- that's just the way it is.
>> 
> 
> No one specified an off the shelf wifi receiver ;-)

OP asked:

"I'm looking for a tool with a GUI that indicates all
reachable W-LAN access points and their distance to
my machine. Do you know such an application?
"

Quite clearly he's looking for a piece of software
to run on a std PC to determine distances to WAP's.

He didn't state the words "off the shelf wifi receiver"
but the meaning is implicit.

Stan

PS- hopefully this one is dead and we can get back to Linux!
> 
>> Stan
>> 

-- 
Stan Bischof ("stan" at the below domain)
www.worldbadminton.com 

Baron wrote:
> The Natural Philosopher wrote:
> 
>> Grant Edwards wrote:
>>> On 2008-07-05, The Natural Philosopher <a@b.c> wrote:
>>>
>>>>>> I can concieve other techniques relying on statistial analysis
>>>>>> of collision detection..
>>>>> More nonsense.
>>>>>
>>>> I take that to mean you didn't understand what I said.?
>>> I understand what you said, but...  1) you don't have access to
>>> collision detection information from an application. 2) Even if
>>> you did, I don't see any way that you can derive distance
>>> information from it.  I think I'm done arguring about this.
>>>
>>> If you're so convinced it can be done, then go do it.
>>>
>> Oh it can be, but its a lot of hardware and software..
> 
> Come back when you have made a fortune doing it !
> Remember you have no control over the transmitter.  At the receiver you
> can do what you like, since you only have one of them !
> 
Why on earth would I want to develop a pointless piece of kit, when 
generally you can spot the things littering the house and street.

stan@worldbadminton.com writes:

> OP asked:
>
> "I'm looking for a tool with a GUI that indicates all
> reachable W-LAN access points and their distance to
> my machine. Do you know such an application?
> "
>
> Quite clearly he's looking for a piece of software
> to run on a std PC to determine distances to WAP's.
>
> He didn't state the words "off the shelf wifi receiver"
> but the meaning is implicit.

When I saw that, I thought of the web sites that had Wifi sites listed
by geographical region, like Wigle.net, or something like Skyhook's
database.

Gents

I wrote a white paper on this, and during my research I ran across a
company that can do this( http://www.ekahau.com/?id=4500)

and it can be done with off the shelf equiment, but your looking at
25-50K in setup and software cost.
if you spend some time "AND OPEN YOU MIND" their are white paper out
that detail how to do this.

I bet you could write the software and buy a compatable unit for under
2k

G

Glen <Glen_Ossman@ossman-cg.net> wrote:
> Gents
> 
> I wrote a white paper on this, and during my research I ran across a
> company that can do this( http://www.ekahau.com/?id=4500)
> 
> and it can be done with off the shelf equiment, but your looking at
> 25-50K in setup and software cost.
> if you spend some time "AND OPEN YOU MIND" their are white paper out
> that detail how to do this.
> 
> I bet you could write the software and buy a compatable unit for under
> 2k

OK- last word from me. I know that nobody can change
True Believers but I can't let something this blatant
go without a minimal comment.

The above system shows how with a bunch of WAP's at known
positions along with a good site map,  one can appoximate the 
location of a given receiveri based on relative signal
strengths. This is the opposite of what the OP is looking
for and in no way is extendable to locating a WAP
from a given receiver ( OP's PC).

You can "OPEN YOUR MIND" all you like but you can't change physics
( unless I suppose you are Ludwig Plutonium...)

Stan

-- 
Stan Bischof ("stan" at the below domain)
www.worldbadminton.com 

On 2008-07-08, stan@worldbadminton.com <stan@worldbadminton.com> wrote:

> You can "OPEN YOUR MIND" all you like but you can't change
> physics ( unless I suppose you are Ludwig Plutonium...)

Good old Ludwig.  I wonder what he's doing these days...

-- 
Grant Edwards                   grante             Yow! Nipples, dimples,
                                  at               knuckles, NICKLES,
                               visi.com            wrinkles, pimples!!

stan@worldbadminton.com wrote:
> Glen <Glen_Ossman@ossman-cg.net> wrote:
>> Gents
>>
>> I wrote a white paper on this, and during my research I ran across a
>> company that can do this( http://www.ekahau.com/?id=4500)
>>
>> and it can be done with off the shelf equiment, but your looking at
>> 25-50K in setup and software cost.
>> if you spend some time "AND OPEN YOU MIND" their are white paper out
>> that detail how to do this.
>>
>> I bet you could write the software and buy a compatable unit for under
>> 2k
> 
> OK- last word from me. I know that nobody can change
> True Believers but I can't let something this blatant
> go without a minimal comment.
> 
> The above system shows how with a bunch of WAP's at known
> positions along with a good site map,  one can appoximate the 
> location of a given receiveri based on relative signal
> strengths. This is the opposite of what the OP is looking
> for and in no way is extendable to locating a WAP
> from a given receiver ( OP's PC).
> 
> You can "OPEN YOUR MIND" all you like but you can't change physics
> ( unless I suppose you are Ludwig Plutonium...)
> 

However since the position is determined by knowing the relative 
distances from the wfi points, its actually a simple inverse calculation 
to do the reverse.

But go on; close your mind...as I said, it probably COULD be done, but 
oh, what a complicated way...where's my tape measure?

> Stan
> 

Stan


let play a game, you look up  how GPS works ( good place to start on
how time can be used to caculate distance)
and then for fun look up enhanced E911 location works.

then make a leap in logic that you only need 2 points to caculate
distance, you have 1 point and the "time" it take to get data from
point 2 so guess what you have distance

No RF was used

Now grap a physic books and hit yourself in the head.