The "Polytone" signals discovered yesterday in the 20 meter digital subband are definitely amateur, not Russian intelligence. Considerable speculation had taken place on the ENIGMA2000 mailing list, until an amateur there mentioned that hams had been using JT65A in this frequency range. It's yet another esoteric digital mode, this one more typically used for EME (Earth-Moon-Earth aka "moon bounce") communications on VHF. It doesn't exchange a lot of information, but its short messages are very reliable in extreme fading situations and high noise floors.
I monitored this frequency range for one entire evening. I barely understand JT65A, but I get enough of what's going on to operate the software. Decoded messages were of sufficient quantity and proper signal characteristics for high confidence in their origin.
In the following dumps from WSJT's output screen, the columns are UTC hhmmss, sync, signal/noise in dB, frequency offset in Hz, measured frequency width in Hz, decode confidence, message text, Reed-Solomon success (1 is good), and overall confidence 0-10 if a "deep search" was needed (it wasn't).
Here's one good exchange. Signal levels aren't terrific, but decode seems to be working. Note the 60-second cycles:
014900 6 -13 0.2 -589 3 * CQ JR3MCV PM74 1 0
015000 0 -15 7.6 46 2
015100 7 -8 0.3 -589 3 * CQ JR3MCV PM74 1 0
015200 2 -17 0.5 -592 4 * JR3MCV AF6AS DM13 1 0
015300 4 -9 0.2 -589 3 * CQ JR3MCV PM74 1 0
015400 5 -14 0.0 -592 1 * JR3MCV AF6AS DM13 1 0
015500 3 -11 -0.2 -589 3 * AF6AS JR3MCV -23 1 0
015600 6 -12 0.1 -587 3 * JR3MCV AF6AS R-15 1 0
015700 6 -7 0.2 -589 3 * AF6AS JR3MCV RRR 1 0
015800 3 -11 0.0 -581 4 * JR3MCV AF6AS R-15 1 0
015900 6 -9 0.3 -589 3 * AF6AS JR3MCV RRR 1 0
020000 7 -10 0.1 -581 3 * JR3MCV AF6AS 73 1 0
020100 5 -9 0.3 -589 0 * AF6AS JR3MCV 73 1 0
Here's a later CQ, which was validated by the presence of a Morse ID transmitted after the JT65A CQ call:
031000 2 -6 0.7 65 4 * CQ WB5TUF EL29 1 6
031200 5 -9 0.1 65 4 * CQ WB5TUF EL29 1 5
Similar with this one:
032700 3 -9 -0.4 27 4 * RZ1OM W9RVG EM57 1 0
And this:
033300 8 -7 -0.1 -75 3 * UT5UBB W9RVG EM57 1 0
It's hams, folks.
