[aprssig] -IS to RF Igating (was: APRS on Android)

Eric Lorenz K9LGE k9lge at emlorenz.com
Mon Jan 24 18:23:16 EST 2011

Dear Steve:

I am sorry that I stressed you out so...it seems to have worked fine for 
me when I used it, and no one had any complaints about the amount good 
or bad of characters I might have been injecting into the APRS channel. 
Maybe you missed that last sentence of mine...IT"S WHAT I HAVE RIGHT 
NOW. I have other things to spend the $33 on.

Again, sorry I haven't been doing it 'correctly'.


On 01/24/2011 04:29 PM, Stephen H. Smith wrote:
> On 1/24/2011 2:07 PM, Eric Lorenz K9LGE wrote:
>> Hi Lynn:
>> I run under K9LGE-10 on my Droid X.
>> The only other drawback is since data and phone cannnot run at the 
>> same time, I have to re-enable APRSDroid after I get a call (unless I 
>> have something set incorrectly and it is supposed to do it 
>> automatically). So, when I am on the phone a lot in the car, I won't 
>> run it.
>> (The other was a failed experiment to setup a local fill-in 
>> digi...discovered there *was* another digi in the area so mine didn't 
>> seem to be needed).
>> A little background...I travel over a lot of the midwest, primarily 
>> between IL and WI and MN. I have been told that because of the amount 
>> of APRS traffic on the network in WI, I probably would have next to 
>> no luck in asking ops to reverse Igate...so I guess I will have to 
>> save my nickels for a  APRS channel.better radio-based APRS-solution. 
>> My current setup uses a Kenwood TM-251A fed from a Garmin eTrex via a 
>> KPC-3. 
> Arrrgh!!!    You are transmitting raw NMEA strings with this setup -- 
> a horrible waste of air time in urban areas.   Raw NMEA sentences are 
> 3 times longer than standard APRS-format strings and TEN times longer 
> than compressed Mic-E format posits.  [The KPC3 in tracker mode 
> transmits the 100+ character NMEA string received from the GPS as-is 
> without reformatting it.]
> Not only are you needlessly taking up more air time than required; you 
> are shooting yourself in the foot by absolutely minimizing the chance 
> you will be heard!    Bear in mind that ALL of a packet must be heard  
> PERFECTLY before ANYTHING can be recovered from it.
> The long raw NMEA packets have a far far higher chance of being 
> stepped on by another station transmitting at the same time, or 
> getting corrupted by mobile flutter or a pop of noise.       Consider 
> substituting a  $33 TinyTrak III (which can generate short-form APRS 
> posits or Mic-E format), and then use the KPC3 as a send/receive TNC 
> under software control at home.
> TTIII Info: <http://www.byonics.com/tinytrak/>

Eric Lorenz K9LGE
Communications Trailer Coordinator
Disaster Services Technology
American Red Cross of Greater Chicago
630-430-2421 cell

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