[aprssig] Packet Compressed Sensing Imaging (PCSI)

Wed Jul 1 10:42:27 EDT 2020

This is fantastic.  Its what I have always thought would be useful adjunct
to APRS> See http://aprs.org/aprn.html
Although that (Auto Picture Relay Network) was based on SSTV, this new
digital method should work fine.

But NOT on the APRS channel.
What we need is an OBJECT that gets posted on the APRS local channel that
announces a PCSI image and that points to the FREQUENCY to download.
Two methods I guess?  The image runs continuously for a set period, or
someone who wants the image QSY's and requests it.
THat way it starts when they are ready.

If the FREQ object format is followed, then the Kennwoods and Yaesu's can
auto QSY with the press of the TUNE or QSY button.
THough they will QSY the other band, and not the data band

bob, WB4APR

On Tue, Jun 30, 2020 at 2:58 PM Mobilinkd LLC <mobilinkd at gmail.com> wrote:

> 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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