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GSM localisation -- for John Henderson



 
 
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  #11  
Old February 14th 16, 07:58 AM posted to alt.cellular.gsm
gm
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Posts: 12
Default GSM localisation -- for John Henderson

Hi !
This is the full result:

+CENG:0,"0713,38,99,219,02,18,263f,00,00,456,3"
+CENG:1,"0730,23,20,219,02,456"
+CENG:2,"0062,39,22,219,01,3f16"
+CENG:3,"0717,20,16,219,02,456"
+CENG:4,"0064,33,56,219,01,3f16"
....

Sometimes it can pick up to 6 towers.
The full list is just in first row...

GM

On 01.02.2016 00:49, John Henderson wrote:
gm wrote:

The module that am using is from company called Tinysine.
http://www.tinyosshop.com/index.php?...product_id=464


It says "Based on SIMCom's SIM900 Module".

So you should be able to read TA using that command.

John


  #12  
Old February 14th 16, 07:59 AM posted to alt.cellular.gsm
gm
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Posts: 12
Default GSM localisation -- for John Henderson

Btw. in this mode, we get this whole list every 3 seconds.


On 14.02.2016 08:58, gm wrote:
Hi !
This is the full result:

+CENG:0,"0713,38,99,219,02,18,263f,00,00,456,3"
+CENG:1,"0730,23,20,219,02,456"
+CENG:2,"0062,39,22,219,01,3f16"
+CENG:3,"0717,20,16,219,02,456"
+CENG:4,"0064,33,56,219,01,3f16"
...

Sometimes it can pick up to 6 towers.
The full list is just in first row...

GM

On 01.02.2016 00:49, John Henderson wrote:
gm wrote:

The module that am using is from company called Tinysine.
http://www.tinyosshop.com/index.php?...product_id=464


It says "Based on SIMCom's SIM900 Module".

So you should be able to read TA using that command.

John



  #13  
Old February 15th 16, 12:17 AM posted to alt.cellular.gsm
John Henderson[_2_]
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Posts: 57
Default GSM localisation -- for John Henderson

gm wrote:

+CENG:0,"0713,38,99,219,02,18,263f,00,00,456,3"


The twelfth (and last) argument is 3.

That's the TA value from the last interaction the device had with the tower.

Each value (range 0 through 63) puts the device a further 553.5 metres away
from the tower. That puts you between 1.7 and 2.2 km away.

TA from to
0 0 0.6
1 0.6 1.1
2 1.1 1.7
3 1.7 2.2
4 2.2 2.8
5 2.8 3.3

and so on.

The limitation of this method is that TA gets calculated by the tower during
any interaction with the device, and the value given to the device to
control its timing.

So you'll be reading the last value used. If the device has moved, or has
camped on a cell on a different tower since then the value will be stale.

You can overcome this limitation by forcing an interaction with the tower,
and checking that the cell ID is the same before and after.

Back when I was chasing cell location information, I used the command:

AT+CLIP?

to force a suitable interaction, and get a fresh TA value.

John


  #14  
Old February 16th 16, 01:34 PM posted to alt.cellular.gsm
gm
external usenet poster
 
Posts: 12
Default GSM localisation -- for John Henderson

Thank you for your input !.
So how should i make the triangulation, if i know the TA value.
Should i send the data to server and make the data processing there, or
should i make some kind of basic calculation directly on the MCU unit.

Am asking this because i dont know how or what should be the best way to
make the triangulation.

I saw some samples on the net but there are many different approaches.
As far as i can understand, each tower is sending data in some
predefined radius. If the mobile device crosses 3 or more "circles" i
should get the data and based on TA i can move it closer to tower.
Is the the general idea ?

GM

On 15.02.2016 01:17, John Henderson wrote:
gm wrote:

+CENG:0,"0713,38,99,219,02,18,263f,00,00,456,3"


The twelfth (and last) argument is 3.

That's the TA value from the last interaction the device had with the tower.

Each value (range 0 through 63) puts the device a further 553.5 metres away
from the tower. That puts you between 1.7 and 2.2 km away.

TA from to
0 0 0.6
1 0.6 1.1
2 1.1 1.7
3 1.7 2.2
4 2.2 2.8
5 2.8 3.3

and so on.

The limitation of this method is that TA gets calculated by the tower during
any interaction with the device, and the value given to the device to
control its timing.

So you'll be reading the last value used. If the device has moved, or has
camped on a cell on a different tower since then the value will be stale.

You can overcome this limitation by forcing an interaction with the tower,
and checking that the cell ID is the same before and after.

Back when I was chasing cell location information, I used the command:

AT+CLIP?

to force a suitable interaction, and get a fresh TA value.

John



  #15  
Old February 16th 16, 08:01 PM posted to alt.cellular.gsm
John Henderson[_2_]
external usenet poster
 
Posts: 57
Default GSM localisation -- for John Henderson

gm wrote:

Thank you for your input !.
So how should i make the triangulation, if i know the TA value.
Should i send the data to server and make the data processing there, or
should i make some kind of basic calculation directly on the MCU unit.


TA will just give you your absolute location in the shape of a a donut.

To locate yourself using only TA values would require you to have TA values
from different towers (and know their locations). In general, you cannot
choose which tower you want to use.

So triangulation will usually mean weighing-up signal strengths from known
towers. as an overlay onto that donut.

John
  #16  
Old February 29th 16, 09:51 AM posted to alt.cellular.gsm
gm
external usenet poster
 
Posts: 12
Default GSM localisation -- for John Henderson

Hi John.
This is the situation after few tests:
- i can not get "exact" position. The closest position is 50 meter away
and that is quite hard to get. In my opinion this is because strength of
the signal varies according the reading. If i run command for data
"catch" more often, i get different signal strength ( module is on fixed
place and not moving). Mostly in the range +- 3 which is range from
around 4 - 9 dbm. So around 50 - 150 meters.

Funny thing, but maybe would be easier to locate this module if it's on
the move :-)



On 16.02.2016 21:01, John Henderson wrote:
gm wrote:

Thank you for your input !.
So how should i make the triangulation, if i know the TA value.
Should i send the data to server and make the data processing there, or
should i make some kind of basic calculation directly on the MCU unit.


TA will just give you your absolute location in the shape of a a donut.

To locate yourself using only TA values would require you to have TA values
from different towers (and know their locations). In general, you cannot
choose which tower you want to use.

So triangulation will usually mean weighing-up signal strengths from known
towers. as an overlay onto that donut.

John


  #17  
Old March 1st 16, 08:49 AM posted to alt.cellular.gsm
John Henderson[_2_]
external usenet poster
 
Posts: 57
Default GSM localisation -- for John Henderson

gm wrote:

This is the situation after few tests:
- i can not get "exact" position. The closest position is 50 meter away
and that is quite hard to get. In my opinion this is because strength of
the signal varies according the reading. If i run command for data
"catch" more often, i get different signal strength ( module is on fixed
place and not moving). Mostly in the range +- 3 which is range from
around 4 - 9 dbm. So around 50 - 150 meters.


When dealing with signal strength, so much depends on the alignment of
antennas on the tower, and on the terrain and topography.

You're never going to get very good accuracy. The exception is TA, which
will give you absolute limits to work with.

Funny thing, but maybe would be easier to locate this module if it's on
the move :-)


Yes, that will sometimes be the case, I'm sure.

John
 




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