[aprssig] APRS RFID apps? (Hot Spots design!)

Patrick winston at winston1.net
Wed Feb 10 13:40:50 CST 2010

How do you define the location of the reader?  I'd sorta envisioned a  
counter value so that instead of just incrementing .01 latitude, you  
could do a spiral effect around the reader using a +.01 lat, +.01 lon,  
-.02 lat, -.02 lon, +.03 lat sort of stepping. which would be reset by  
the config every time the reader either hit a step value (ie 20 tags  
read) or a time value (every 30 minutes)


Quoting Bob Bruninga <bruninga at usna.edu>:

> OK, here is a draft concept for APRS RFID:
> -----------------
> The following is a possible design of an innexpensive ham radio APRS  
> RFID system for application in large venues such as the Dayton  
> Hamvention to keep track of walking operators.  Ten Inch round RFID  
> yellow/red hot spots are placed in each doorway or special location.  
>  APRS participants wear a $2 RFID card in their shoe.  When they  
> cross an APRS hot spot, the hot-spot reader sends the RFID to a  
> centralized on-site PC that associates that RFID to a callsign and  
> then generates an APRS packet on the APRS network showing that  
> person at that location.
> APRS RFID READER:  A $25 RFID reader is the only new hardware required.
> http://www.sparkfun.com/commerce/product_info.php?products_id=8709
> The 9600 baud serial output from this device is connected to a PC  
> for one-door applicaitons or, for large multi-door locations to a  
> typical APRS "tracker" which has special parsing code to convert the  
> RFID number into a speical AX.25 short-range packet (preferably on a  
> separate frequency from he national APRS channel).  The RFID packet  
> format is:
> Where the SSID of the hotspot reader (I) can contains 4 bits of  
> additional info such as direction, speed, etc. The initial "RF" will  
> make this an ALTNET (non-APRS) packet, and the DDDDD-D:DDDD is the  
> 10 byte HEX ASCII RFID code.
> The central processor receives the above RIFID from a given SPOTID  
> and then matches the RFID to a callsign and generates the following  
> standard APRS position packet for the local network (and/or APRS-IS):
> Where the SSID is always -7 from any card operated under that  
> callsign. Where a special unique RFID SYMBOL is used, and the RFID  
> number is included in the first 10 bytes of the packet.  The Free  
> text is associated with that hotspot.  Such as "Entering HARA",  
> Leaving HARA, or ARRL Booth, or KENWOOD Booth etc.
> The position is built by incrementing .01 Latitude from an origin on  
> the map associated with that RFID hot spot.  This way, everyone that  
> crosses that hot spot will appear in a neat table on the map.
> This CALL-7 is used for ALL RFID tags that might be owned by that  
> ham CALL so that no mater what shoes he is wearing or how he is  
> reporting his position, they will all overwrite each other so that  
> only the most recent one ever exists in APRS.
> CALLSIGN ASSOCIATION:  The initial RFID number to callsign  
> association is made at the central processor or point-of-sale of the  
> RFID card -OR- anywhere else that a keyboard or keypad is attached.   
> It doesnt matter, since EVERY such association will generate the  
> above APRS packet and from that , ALL systems locally or globally  
> can collect these associations from the APRS-IS.  Also clubs with  
> large numbers of card holders can submit RFID files to pre-load the  
> APRS-IS system.  Or anyone with any APRS system can manually prepare  
> the above packet and send it once from their HT or Mobile.  From  
> then on, the association is made.
> RFID READER SERIAL DATA:  The RAW output from the RFID reader is at  
> 9600 baud and can be read o any serial port.  The format is as  
> follows:
> Where S is STX (02h)
> DDDDDDDDDD are 5 bytes in 10 ASCII HEX characters
> KK is a HEX checksum
> C is CR and L is LF and E is ETX.
> Special code in a "tracker" type pic processor reads this and  
> generates the local RFID Reader packet which is sent on a separate  
> frequency to the central processor.  Or for one-door applications,  
> direct into a local PC connected to the APRS system (RF or Internet).
> RFID Tag (125 KHz): The Credit card sized RFID's are from $2 down to  
> $1.50 depending on quantity.  They are available from:
> http://www.sparkfun.com/commerce/product_info.php?products_id=8310
> Anything I missed?
> Bob, WB4APR
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