[aprssig] APRN (Automatic Picture Relay Network) revival?
bruninga at usna.edu
Sat Aug 8 16:06:33 CDT 2015
Thanks. I think you answered most of what I was after. That is, there are
presently no tiny cameras with direct to digital transmission over RF, but
you did remind me that the existing APRN concepts are probably still valid.
That is, the transmission from the mobile robot camera may be SSTV
(Greatest availabililty of cameras) , but as soon as it is received, then
it is converted to a file and networked onward as needed in digital form.
So I guess then, my call is for a revitalization of a global APRN network
that can receive these images from mobile robots (on RF) and seamlessly
make them available to viewers (and robot drivers).
We're talking about the kind of driving that Mars rovers do. THey get a
fixed image, layout the path to be taken within that field of view, then
execute the maneuvre and take anotehr picture.
Of course if you heard the news, dont drive your robot near Philly where
vandals might bash it to pieces...
I envision a mobile robot mission across America driven by (and protected
by) Ham Radio Clubs across the county. Driven completely by remote
control and handed off from club to club with vision going to the APRM and
position to APRS.
On Sat, Aug 8, 2015 at 12:34 PM, Stephen H. Smith <wa8lmf2 at aol.com> wrote:
> On 8/8/2015 6:53 AM, Robert Bruninga via aprssig wrote:
>> Can we go back and look at the APRN again to see if it is time to upgrade
>> it to digital, so that images can be sent end-to-end instead of posted to
>> web pages?
>> Given the same resolution of a simple SSTV (120 by 120 pixels?) how small
>> of a JPEG file can result? Shouldnt take long at 9600 baud.
> 120x120 is from a bygone era of 5FP7 radar CRTs being used as display
> The standard minimum SSTV resolution today is a 320x240 pixel (quarter
> VGA) 3:4 aspect image that will yield about a 50-90K image when saved as a
> JPG. Over 99% of all SSTV today is generated and received with
> PC-based soundcard software, rather than dedicated hardware devices, and is
> sent with modem-like multiple audio tones, not as serial data that would be
> compatible with a packet-like transmission system.
> What is "upgrade to digital" supposed to mean? Classic SSTV is totally
> analog. It's almost literally NTSC in (very) slow motion.
> "Digital SSTV" as it exists today, (and is embodied in the recently
> orphaned EasyPal program whose author died of cancer around the beginning
> of the year) is essentially just a general-purpose error-corrected file
> transfer program.
> You shove an existing image file (.JPG, .TIF, .GIF, etc) into the transmit
> routine that encapsulates it in several layers of error correction before
> transmission. The actual over-the-air transmission uses multiple (4, 8 or
> 16) QAM audio subcarriers in the voice passband. At the RX end, EasyPal
> unpacks the original file from it's layers of FEC and reconstitutes it as
> the original image file. The typical transmission time is a minute or so
> and consists of the roaring grinding noise typical of multi-subcarrier data
> transmisions; i.e. like "56K modems" or digital voice.
> The issue is the easiest way to capture the original live image. N1VG's
> (Argent Data) single-board SSTV cam will capture 320x240 color images and
> encode them into your choice of several of the most popular <ANALOG> SSTV
> formats. However, the output is FMed audio tones, not logic level data.
> At the receive end, you would use one of the common soundcard SSTV
> programs such as mmSSTV (Windows freeware) to decode and display.
> I am not aware of ANY standalone hardware that will do EasyPal-style
> "digital" SSTV. The closest I have come is running EasyPal on one of
> these dirt-cheap Windows tablets that has built-in cams.
Can we go back and look at the APRN again to see if it is time to upgrade
it to digital, so that images can be sent end-to-end instead of posted to
Given the same resolution of a simple SSTV (120 by 120 pixels?) how small
of a JPEG file can result? Shouldnt take long at 9600 baud.
The application is remote controlled ROBOTS for the ARRL's STEM outreach.
Students build "mars rovers" and then each school lets the kids then try to
control the other school's robot over APRS.
Mark Spencer at the ARRL has developed the MAREA concepts for the remote
control, and I want to revive the APRN concept to give the robots vision.
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