[aprssig] Dayton meltdown.

Wes Johnston aprs at kd4rdb.com
Mon May 23 11:57:57 EDT 2005

I see what you are saying.... all signals are repeated from the location
of the external antenna... but there will be timing differences between
two people at different locations inside the building since they are
different distances from the indoor GPS antenna.... but since this
antenna is the only emitter of all GPS signals there would be no
difference in time delay from one GPS signal to the next, so although
two different users may be two different distances from the repeater, it
would really be no different than two GPS users using two different
lengths of coax on thier antennas.  So the more I think about it, the
more I think you are right, everyone would just read the location of the
external antenna.

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.

Back to the drawing board.  That was my _one_ idea for the day, and I
blew it!  ;-)


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 getting
>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 was
>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
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.tapr.org/pipermail/aprssig_lists.tapr.org/attachments/20050523/2e106702/attachment.html>

More information about the aprssig mailing list