Stacking Grabs
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The Grabber takes a screen shot every 10 minutes exactly. Each 10 minute Period starts on the integral 10 minutes past the (UTC) hour.

Your callsign should be transmitted at the same interval exactly, after the start of any Period. (the callsign length should < 9 minutes), The callsign will appear in exactly the same place in every Screen grab from then on. Your keying clock must be synchronised to UTC!

Frame contents are added in software then averaged to produce the stacked image. See photography concepts here.

A raw single frame image, 1 of 20 used to make the stack.

The Stacked image. The difference is remarkable! Click either image to enlarge.

The stacking technique has it's origins in Astro-photography, and the software used for Stacking is unashamedly 'borrowed' from Astronomy.