SSTV, Slowly

Following up on last week's SSTV post, we're just about there.  Picked up a refurb MacBook Air for pocket change (more on this below).  Sideloaded Black Cat SSTV along with fldigi, and chirp-next onto it via dipstick drive, and again tested all on the FT-817nd & dummy load.  Went live with fldigi (a digital texting program) and made a few contacts to the usual easy places like TN, NC, & TX.  Then... started pulling a few images off the air.  Here's about the best of the bunch:

Live!  From New York!  (state)

The ionosphere is a noisy place, and it shows in this image.  Not bad at all for less than 100 watts and 3 kHz bandwidth.  You can look at lots of other images people have received and auto-posted at HF Underground.

Great, so that's all working now.  The question arises though, how good can the image quality be, ultimately?  That is to say, what does the scanning process do to the resolution?  Here are two images from my practicing on the image editor, then sending as audio from computer speaker to phone microphone:

input

output

Not terrible, maybe just a tad worse than the old 110 film cameras.  (I used that stuff extensively in an Astrocam rocket; no great surprise.)  A little more practice with the image editor and I'll do some actual transmissions later today.

Now a few notes on that MacBook Air and how it all interfaces with the radios.  It's an early 2020 Intel i3 processor from mac of all trades for 1/3rd the cost of new.  That's plenty of compute power for intended use.  The important thing is that the SSTV software requires OSX v13 or higher, and this is about the minimum machine that checks that particular box.  After that, this laptop only has USB-C ports.  The SignaLink radio interface box I'm using has a USB-A cable, but a $10 adapter sidestepped the problem seamlessly.  In fact, everything worked out about as well as I'd hoped.  The only downside so far is that the i3 is a power hog, and can chew through half its battery in about an hours' use (and that's after applying the full-on daemon killin' cron incantation to matters).  All the more reason to bring a solar panel into the field.

Now on to a few Linux notes.  One of the above-mentioned fldigi texting contacts reported that he'd just upgraded from an old Debian Linux distro to a new Mac M4, just because he couldn't get the Linux machine to talk to his Icom IC-7300 radio.  Linux man, it's a whole 'nother hobby unto itself.

Finally, I may have mentioned that my old Linux laptop's battery charging control system had died, which finally spurred me on to this upgrade.  In the midst of all the goings-on documented above, it mysteriously began working again.  Because how do you get a broken laptop to work?  You buy another one of course.  Eh, I'll keep it around for muddy days in the field.