[aprssig] Packet Compressed Sensing Imaging (PCSI)

[Mobilinkd LLC]

Would love to see iOS and Android versions of this -- send/receive photos
directly from a smart device.  If there's anything I can do to help make
this happen please let me know.

I've linked to your work here:
https://www.reddit.com/r/hamdevs/comments/hisp7h/packet_compressed_sensing_imaging_pcsi/


Kind Regards,

Rob Riggs WX9O
Mobilinkd LLC


On Sun, Jun 28, 2020 at 6:20 PM Scott Howard <showard at nd.edu> wrote:

> Dear APRS SIG,
>
> I'm happy to share a new image transfer method called PCSI that a team of
> students and I have been developing during quarantine. PCSI is digital
> (packet based), unconnected multicast (UI frames), compatible with APRS
> (basically turbo-charged APRS Vision
> https://www.tapr.org/pdf/DCC1997-APRSvision-WB4APR.pdf), resilient to
> packet loss (every receiving station can receive a different random set of
> packets and still reconstruct the entire image), and computationally
> trivial for the transmitter (8-bit microcontroller can easily construct
> packets). The goal is to be used with low-power microcontrollers and weak
> signals (even HF modes) transmitting images when packets will likely be
> lost. In SSTV and other unconnected digital image modes like SSDV, if the
> signal is weak or packets are lost, entire sections of the image are
> distorted or missing. In PCSI, if packets are lost, you still receive the
> entire image. Every additional packet received (in any order) simply
> increases image quality. Images take between 1-4 minutes to come in using
> 1200 baud, which is on par with SSTV. It's all controlled with an easy GUI
> where you just set your call sign, load your file, then click send.
>
> I've used it to transmit images locally between a hamshield KISS system
> and a kenwood TH-D72a, and between two direwolf systems acoustically
> through speakers and microphones. Now it's ready for testing in the wild.
> *Details and usage videos are here:*
> https://maqifrnswa.github.io/PCSI/
> *Windows and Linux binaries* (for TCP or serial port KISS devices) are
> available here:
> https://github.com/maqifrnswa/PCSI/releases/tag/v0.0.0 (It should work on
> Macs too, I just don't have one to build binaries. If you're comfortable
> with python on Mac, you can also just use the source code.)
> *Python Source code (everything is open source)*:
> https://github.com/maqifrnswa/PCSI
>
> The method isn't necessarily tied to APRS and can be used over any band or
> mode, but if you'd like to explore its use for tactical and timely image
> transmission over APRS (basically the goal of APRS Vision), you can set it
> to use base91 encoding, use the "{{V" info prefix, and use an appropriate
> altnet. For now, I've been using the destination address PCSI to indicate
> that these are PCSI packets.
>
> Since this is a specialized group of experts, I'd appreciate any testing
> and feedback you can give. It's kind of a fun mode - you start watching the
> entire image come in over time, and as packets arrive, the image comes in
> to focus. To transmit and receive, you just need any KISS
> TNC/soundmodem/direwolf/etc. It might be a cool way to send low-res images
> over lossy and weak HF channels when you don't want to spend bits on FEC
> (although you could also put FEC on top of this method). Any feature
> requests, advice, or tips are welcome as well.
>
> Backstory: When CoVid-19 shut down universities, students weren't able to
> continue lab based work. I came up with this project so that undergraduate
> lab assistants could work remotely while supporting a new educational
> initiative that my university is pursuing around students developing
> technology for high altitude balloons. The results are like magic - even
> receiving 20%-30% of the total bytes of the original image (i.e., 70-80%
> packet loss) gives high quality images. And it's a good introduction for
> students to the math behind compressed sensing imaging. There are also
> other tricks under the hood, like the optional use of chroma compression to
> increase speed.
>
> Cheers and thanks!
> Scott
>
> --
>
>
> *Scott Howard, PhD*
> *Associate Professor*
> Department of Electrical Engineering
> University of Notre Dame
> http://ee.nd.edu
>
> 574-631-2570 (direct)
> 574-631-4393 (fax)
>
> h <http://www.nd.edu/~showard>ttps://howardphotonics.nd.edu
> Follow me on Twitter @HowardPhotonics
> <https://twitter.com/HowardPhotonics>
>
> 262 Fitzpatrick Hall
> Notre Dame, IN 46556
>
>
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