[aprssig] APRN Now! (cell phone uploads too)

Stephen H. Smith wa8lmf2 at aol.com
Mon Aug 10 10:06:09 CDT 2015


On 8/9/2015 9:55 PM, Robert Bruninga via aprssig wrote:
> Shucks, while we wait for the SSTV camera to integrate into the APRN network, 
> with an OBJECT identifying HT remember there is also no restriction on using 
> a cell phone camera NOW to upload an image into the APRN site.

Actually, sending pics with a cell cam, without APRN involved, is already fully 
integrated.    Nearly all cell cams already automatically embed data from the 
phone's GPS into the EXIF (EXtended INformation) header of the JPG file.  Send 
the pic to an email address with the normal"MMS" (Multimedia Messaging Service 
- i.e. a text message with attached picture)- a feature present on nearly all 
phones.  (Even my ancient Moto E-815 clamshell "dumb phone" can do this.)  
Since this IS a text message, you can include any comments in the text part 
before sending.

When the received JPG is viewed in apps like the freeware IrfanView,  clicking 
"Image, Information" will reveal the EXIF  data including GPS coordinates.  One 
more click will open Google Maps with the exact location pinpointed, usually 
within 20-30 feet.

> just remember, because it is easy to do with a cellphone, the APRN site 
> structure should be designed from the ground up to be compatible with the 
> APRS radio as the field entry device, and with the APRS object data as the 
> image identifier and cataloging system.


This is inherently going to be much more kludgy, due to the need to deal with 
both the analog SSTV transmission and the digital packet transmissions 
separately.     I DO run mmSSTV (for the analog pic) and the UZ7HO Soundmodem 
(for the packet data) simultaneously on the same sound card at the same time 
for receive.

Transmit, however, will be much more complex (unless you have an APRS radio 
that can do built-in Mic-E burst on unkey such as a D700, TH-D72, D-710, etc), 
   since you will have two separate sound sources that need to go into the mic 
jack or mini-DIN "data" port. I.e. the N1VG SSTV board and something like an 
OpenTracker or TinyTrack to generate the packet burst.  Not to mention the 
sensing of PTT by the SSTV source to trigger the packet burst afterwards.

This is relatively easy to do with a full-sized radio, but will be a hopeless 
mess on a handheld.   Since the mic and ext speaker are normally on the same 
jack, plugging in a cable to send the APRN image cuts off the internal mic AND 
speaker.  This leads to having to constantly plug and unplug the external 
device in order to hear and make voice transmissions.  Realistically, no one is 
going to walk around with a tangle of Y-cables and multiple external boxes 
dangling from their hand-held.

I assume you would be doing this on a channel other than 144.390, since the 
picture transmission will take from 36 seconds (for the low quality Robot 36 
mode) to 110 seconds (for the far sharper Scottie 1 mode),  which would be VERY 
disruptive to the normal 144.39 APRS channel.   This implies, at the receive 
location, a radio and antenna separate from the one doing normal APRS igate 
duty.   I do this, but i doubt that this will gain very much uptake by the ham 
population at large to create a wide-spread network.





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