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[aprssig] APRS as a Situational Awareness tool

Robert Bruninga bruninga at usna.edu
Mon Jan 14 23:44:25 UTC 2008


>> And the key to getting APRS used, is to not 
>> try to change those volunteer operators, but 
>> instead, to place a PC APRS display in front 
>> of them, not to make him an APRS opeator, 
>> but so that he has a MAP display that he can 
>> zoom around on the map as needed to see what
>> is going on.... [objects placed there by others]
> 
> And what program do you propose be used for 
> this... something that already exists, or is 
> this an invitation for someone to write a new 
> one?

I think ANY APRS program or clone can pretty well be used as the
map display.  And just about anyone in the club can use those
functions. That has rarely been a problem since that seems to be
the focus of most clones.  

You will notice that almost all of my complaining over these
years rarely has to do with displays, but instead is the lack of
any care for the the optimal -transmission- of data keeping in
mind the limitations of the network and human nature which can
not be relied on for real-time settings in each changing
situation.

Too many clones simply focused on the maps, and just figured
transmit at afixed rate and they were done.  Extremely simple,
but not at-all what APRS transmission was all about as a SYSTEM
and a network.

Many of the following parts of the TRANSMIT algorithms were left
out of many clones making APRS hard to use in real time:

- High initial rate (8 seconds) for any new data
- Continuous decay  (doubling of time to next pkt)
- 10m final rate if path is direct or one hop
- 30m final rate if path is 2 or more hops
- Decay applies to GPS input too (parked cars)
- Decay also applies to OBJECTS, WX and own station
- Smart (redundant and delayed) acks for messages
- embedded reply-acks to greatly improve message throughput
- proportional pathing (lower rate for higher hops)
- Message delivery time out -and- RETRY-ON HEARD
- ALOHA circle automatically computed & displayed
- Aloha circle determines max hop count
- Warnings against improper settings
- Transmitting PHG data so we can SEE the RF network
- Transmitting the user-activity bit if present

Well, I guess I also complain about displays too..., I may as
well list the DISPLAY processes that were left out of many
clones:

- the 8 or so Symbol color attributes
  - Moving or dead reckoned versus fixed.
  - message or non message capable (trackers vs users)
  - Fresh, stale or Old versus new
  - Objects versus stations
  - own objects versus other station's objects
  - Special, priority and emergency stations
- Display of stations activity bits (user present)
- Vicinity plotting for packets without position info
- Position ambiguity for things with less precision
- A consistent and easy to see map RANGE scale
- Display of PHG data for network visualization
- Display of the stations individual ALOHA circle

Oh well, I run on...

Bob, WB4APR





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