Here's an interesting project thought.

A remote base/repeater site, on a very remote hilltop. No internet or cell service available. I'd like to put a couple cameras up there monitoring a couple different things. What I'd like to do is the ability to send a DTMF code to get a snapshot from a camera, then transmit that via SSTV over the repeater.

I suppose a lot of custom code would be required to handle this, but there should be some suitable packages for the Raspberry Pi that can be incorporated.

Thoughts and ideas appreciated.

--
73,
Michael WA7SKG

"Any day you do not learn one new thing is a wasted day."

This project will strictly utilize existing analog FM channels at the site. However, the question is not really the transmission medium, but the nuts and bolts of taking the picture and transmitting it on command.

Thanks for your input.

Michael WA7SKG


Don Poaps wrote on 12/11/21 8:59 AM:

I suppose a lot of custom code would be required to handle this, but there should be some suitable packages for the Raspberry Pi that can be incorporated.

Hmmm.. ok, I can give you some ideas of some LInux projects that have components of this functionality:

I'd like to put a couple cameras up there monitoring a couple different things.

Any data over a repeater's audio path is going to be slow so you're going to have to de-res the pictures pretty heavily.  For example, a 320Kbyte picture will take about 1.3min via a digital SSTV mode. 

   - GraphicsMagick to do scripted image modifications

What I'd like to do is the ability to send a DTMF code to get a snapshot from a camera

   - SvxLink has some nice scripting abilities which you can probably use to trigger various functions from DTMF.

then transmit that via SSTV over the repeater

Qsstv has some very powerful analog and digital SSTV modes though I don't know strong it's automation support might be.  What kind of repeater controller is running at your site?  It will clearly need another "port" to connect to the computer sending the function.  If it's a digital repeater, some versions have bulk file modes that can possibly make things faster than using SSTV.  Good luck!

--David
KI6ZHD

Here is an application that sends images over AX.25:  Packet Compressed Sensing Imaging (PCSI)

If part of the transmission gets lost there is just an overall degradation in image quality, not a missing piece.

The direwolf software TNC has a builtin DTMF decoder which sends a specially encoded packet to all connected applications.

You would need a script to look for that message, tell the camera to capture an image, then command PSCI to transmit it.

PSCI sends packets to direwolf which sends them over the radio.

5-6 years ago a colleague at Associated Press used a Raspberry PI and it's camera. They focused it on the Volcano  just outside of MEXICO City. It was however on the internet. It took a picture every minute.. If the last minute picture was vastly different than the current picture it would kick into live stream mode, and start uploading to AP's servers back in New Jersey and Kansas City.. There were 2 duplicate units.

Remember the train that derailed in Philadelphia, with the engineer asleep at the switch. It took a 25mph curve at over 55... My colleague was killed in that derailment.

We had talked about how cool Raspberry PI's were and he was not a ham but interested in the applications hams were developing. I'm sure the community would of benefited from his tinkering..

Here's to my Colleague- RIP - Merry Christmas,

Now back to the topic....

If it's line of site..Why not use. Broadband Hamnet (previously known as HSMM-Mesh)? Simply, it's hams using our radio privileges to operate a private wi-fi computer network. I have heard of 45km hops... (33.5 miles) with pringle can antenna's
You use reprogrammed routers, that can be had used, and sent even 1080i HDTV.. You can even stick a PC at the site and VNC into everything that has a USB or RS-232.. like battery chargers, solar panel management etc..and use Tilt-pan-zoom off the shelf HDTV cameras..

FINAL THOUGHT-
T-mobile- Verizon ans AT&T have internet hot spot plans. On a mountain top there must be connectivity... AT&T has a plan for Apple tablets, unlimited internet access for $20 per month. IT must be an Apple Tablet.. They check IMEI-MEID frequently a lot of guys found out during the covid scare. if it's not apple tablet, they suspend the account.  Apple tablets can operate as a hot spot.

Merry Christmas,

Larry W8LM