Has this been done? Please provide link to solution or discussion of why attempted solutions have failed.
My thought was: use 2 identical laptops stacked up, the bottom one showing the jamming pattern and the top one showing the cleartext. Since the laptops are so close physically, their respective scan oscillators should phase lock spontaneously like Huygen's clocks, making the remote separation of the jamming signal from the cleartext impossible.
A more aggressive approach would be: find that phreak and report him/her. Put together something as close to a Van Eck rig as the law allows, connect the output to your possibly eavesdropped computer (by a summing point), then scan your log periodic antenna across the countryside. If you get a feedback oscillation at some heading, you've found your phreak. Now you just need the range. Triangulation? Speed-of-light calculation? The latter might be just the speed of light divided by the feedback oscillation frequency divided by a constant = 2 or larger.ask