AMRAD at Hamvention 2009

[Bob Bruninga]

> As I understand it, 
> (a) I've got to set up my VX-7R [DTMF memory]
> (b) I've got to carry a paper grid reference 
> (c) I've got to remember to update my  
> position every 100 feet, so that anyone who 
> happens to be near a display can see where 
> I am, provided they know my callsign.  

Basically, APRS is not a tracking system.  It was never designed to provide the bandwidth for continuous tracks on everyone or even on ANYone.   That is the great missconception about APRS and what burdens the network with unnecessary tracking data when 99% of everyone could care less where 99% of everyone else is.

APRS is a communications system to facility communications between hams needing to communicate without any apriori knowledge.  There is no reason to transmit your position, unless there is a specific reason why you want someone else to know where you are at that instant.  Or to give them in the blind, your operating frequency.

But if  you stop for an hour in a forum, or stop for 30 minutes under the AMRAD tent, or the Bar, then you might want to send out a posit to let your buddy know where you are.  In this case there are only three XY coordinates of interest to you.  The one at the AMRAD space, the one at the bar, and the one at the Forums.

> Alternatively, someone who wants to know 
> where I am can call my callsign on an 
> agreed frequency.  

That works too but requires some inconveniences too. 

1) you must have a pre-arranged freq
2) the freq must be relatively clear of other chatter
3) No opportunity for meeting others without #1,#2
4) the recepient must be listeing FULL time
5) Must have his volume turned up
6) Must be paying attention to ALL voice traffic so that he can possibly hear his own call amongst the othres

So both methods have advantages and disadvantages.

An advantage of APRStt is that it is global.  Once you send out your DTMF callsign memory, anyone in the World of amateur radio that needs to conatact you can not only see you are in dayton (or timbucktu), but can text message you.  Again, not that anyone would, but if you ARE expecting someone at a distance to contact you, this gives you the means to be contacted.

For special evnts like marathons, etc.  The two digit numbers you may use for your position can be the mile-marks.  This lets a VIP shadow, or SAG wagon or any other non-APRS moving asset occasionally report what station it is near (not while moving of couse0, but when he shifs from one station to another.  This eliminates a lot of voice traffic from an already overloaded voice net.

> Please explain what I have failed to understand...

Hope that helps.
Bob, WB4APR
>>
>> "Bob Bruninga " <bruninga at usna.edu> writes:
>>
>>>> We will have chairs and a chance to sit
>>>> down and help us talk to prospective
>>>> new members.
>>>
>>> Remember, this year at Dayton, there will be an APRStt (Touchtone)  
>>> gateway.  Meaning anyone with any old HT with a DTMF keypad can  
>>> report his position anywhere at Hamvention (to nearest 100 feet)  
>>> using only a single X and Y digit (00 to 99) see the map on
>>> www.aprs.org/aprstt.html
>>>
>>> Of course, to know WHO is where, you have to pre-program your  
>>> CALLSIGN into a DTMF memory.  When you want to report where you  
>>> are, you send the callsign memory, then manually key in Bxy#.  The  
>>> B key means a POSIT, the X and Y digits are from the map grid on  
>>> the web page above, and # marks the end of data.
>>>
>>> So if someone would put up an APRS display at the AMRAD space,  
>>> then ALL AMRAD wanderers can report where they are at any time  
>>> with only those 4 key strokes on the APRStt channel (which will be  
>>> 146.58).
>>>
>>> The APRStt gateway inside the arena will convert these DTMF  
>>> strings to an APRS packet over on the APRS channel so everyone can  
>>> see everyone.
>>>
>>>> I have made up a downloadable map from
>>>> Google Maps
>>>
>>> A similar one was loaded on the UIVIEW yahoo groups site, so that  
>>> everyone would be looking at a good map of the buildings and flea  
>>> market area that was using UIview.
>>>
>>> Bob, WB4APR
>>> _______________________________________________
>>> Tacos mailing list
>>> Tacos at amrad.org
>>> http://www.amrad.org/mailman/listinfo/tacos
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