Worth A Thousand Words
Pictures over HF Radio
No way around it, in certain circumstances a picture can be worth a thousand words. If you're training to use HF radio in a partisan/grid down/disaster scenario there could be innumerable circumstances where a picture of a checkpoint, insignia, equipment or other items might be vital to convey critical information. As a theoretical example, sending a SALUTE report of foreign military aircraft landing at an air strip is a great start, having a picture accompany it so that the airframe can be identified is obviously superior. And it was for this reason that an exercise was recently called on the west coast in order to keep current on this skill set.
The end state of the exercise was for each participating station to take a picture of their radio, edit the photo to add their call sign, and send that photo over the air to the west coast SIGCEN using relays as necessary. While I have sent and received images before, this was the first time that I had experienced an exercise like this that would allow the opportunity to gauge just how well (or poorly) image transfer fared from varying distances under given propagation conditions. The result, and the surprise, was just how well it performed. Images were very usable even with some corruption from the entire west coast. Transmit time for a 300x300 image (recommended for this exercise) was less than 2 minutes when using black and white, and about double that for color.
For those new to the process of sending pictures using FLDIGI there’s really only 3 steps.
Set your op mode to MFSK 32 (16 also works, and there are faster modes as well, YMMV) and right click in the blue transmit pane, and select “Send Image”:
Then hit “load” and navigate to the image file you wish to send.
Now with the image loaded select XmtClr to send in color, or XmtGry to send in black and white only.
Now that you know how to send images, here are the results of the exercise as received at my location. Note that the images are cropped or otherwise edited to remove the call signs from the exercise pictures as I make it a policy not to use call signs off air. Hope to see YOU on air next time!
