[aprssig] 9600 Baud Packet Network?

Thomas Krahn thomas at tkrahn.com
Sun Jun 12 15:01:32 CDT 2016


For what it is worth:

We have launched a balloon yesterday from Berlin (Germany) with our 
Pecan Pico 7b camera tracker. While we still sent out 1k2 AFSK APRS 
telemetry and position packets, we also encapsulated compressed JPEG 
images from the onboard camera. and sent them down in custom 
experimental 9k5 GFSK packets in APRS style, but on a different 2m 
frequency (144.860 MHz). The packets were received with high sensitivity 
with Kenwood THD72 radios and with less success with RTL-SDR dongles. 
9k6 over 100 miles was not a problem. We captured more than 300 pictures 
that can still be seen on http://ssdv.habhub.org/DK0TU (scroll down to 
image 16 for a nice picture of the historical Tempelhof airport). It 
takes about 2 minutes for a VGA sized picture to come down at 9k6 which 
is a great speed for a 50 grams tracker module (including batteries).

A 9k6 network would be definitely very helpful for such experiments and 
I'm sure this would give a new push for experimenting with imaging and 
other data transmissions that require a somewhat higher data rate. BTW 
our Pecan Pico 7b trackers are open hardware and open source. Feel free 
to use it if you want to build 9k6 trackers that can be received with 
Kenwood or Yaesu 9k6 APRS radios.

https://github.com/DL7AD/pecanpico7
https://github.com/DL7AD/pecan-stm32f429
https://github.com/DL7AD/aprs_ssdv_decoder

http://ssdv.habhub.org/DK0TU

At 1k2 AFSK we also tried to transmit low resolution images (one packet 
every 20 seconds) through regular APRS igates without a path (!) that 
were then tunneled through APRS-IS and then re-posted to habhub with a 
perl script. While this worked great (almost every picture without 
packet loss) this is definitely a high burden for the existing APRS 
network and in the future we only want to use this for long duration 
floaters when they're in very remote regions of the planet.

I really hope for a good 9k6 APRS network. It can definitely be done!

73

Thomas
KT5TK / DL4MDW







On 06/12/2016 07:13 PM, Robert Bruninga via aprssig wrote:
> > I once tried... a 320x240 SSTV-like image over packet.
> >... it took over 15 minutes to send one image.
>
> Agreed, but at 9600 baud it might take only 3 minutes.
>



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