[aprssig] Indoor Tracking

Robert Bruninga bruninga at usna.edu
Mon May 23 17:23:26 EDT 2005

>...Well, at least we'd know what hall they were in, 
>and viciinity tracking would work just as well for that... 
>except on the kenwood radios.

Ah, but the Kenwoods can enter their position inside
the building by BOOTH number or building bnumber.    
I call that POINTS tracking.  Prior to Dayon, someone 
simply prepares a POINTS file.  Then All APRS clients 
that support POINTS tracking will see the people indoors perfectly.


(Google for APRS points.txt)

The way it works is that the POINTS.TBL file can
define the location of up to 10 tables of up to
99 points each.  And a D7 user can place himself
at any such point (indoors, or out, below ground
or anywhere without a GPS) by simply entering
the 3 digit number.  Done.

THis has been in APRSdos for about a year.
and any D7 or D700 or actually any tracker
can do it as long as the user can manually enter
the 3 digit number.

de Wb4APR, BOb

Robert Bruninga wrote:

>Indoor GPS...
>Yes, but everyone will still only be at the 
>location of the antenna on the roof, because
>that is where all the signals arrive at their
>given phases.  re-transmitting them inside
>the building is an equal delay to all signals,
>so all positions will all still only be the position
>of the antenna.  Bob, WB4APR
>>>>Wes Johnston <aprs at kd4rdb.com> 5/23/2005 10:21:14 AM >>>
>No..... it's like a passive repeater.  You take an active (ie
>antenna on the roof and plug a passive antenna into it.  Bias the
>thing with 5v to run the preamp on the external antenna.  The passive
>antenna becomes a radiating antenna.  All the GPS signals become
>"mirrored" inside the building.  The only problem I can see is
>the coax thru the roof.  Think of it is cutting a hole in the roof so
>that your portable GPS unit inside the building could see the sky.
>I liked the vicinity tracking, but as far as I know, it's only use
>at dayton back in 1998 using those mfj data radios that were mod'ded
>be really really deaf.
>Robert Bruninga wrote:
>>>Also, has anyone in dayton ever considered a 
>>>GPS repeater in each hall? 
>>But then everyone gets the same position, the
>>position of the antenna on the roof.  
>>My proposal for indoor tracking at Dayton is in 
>>"vicinity tracking" where we put nearly deaf low-power 
>>digis in each room.  With no change on the part of
>>the trackers, once indoors, they start getting reported
>>via the room digis and since we have full path
>>tracing, then the individual is located in the room
>>of the first digi that heard him.
>>This was my plan back in 1998 or so.  Its all 
>>written up in my vicinity.txt file.  These digis are
>>called BOX-N digis and whever APRSdos sees
>>a packet that comes in via a "box-N digi" it
>>ignores the actual posit and plots it as a vicinity
>>plot in the vicniity (100 feet) of the box-N digi.
>>de WB4APR, Bob

More information about the aprssig mailing list