Topband: drift net buoy?

[Charles Yahrling]

Based on your audio of recurring beep and stated azimuth, my guess is a
fish gear beacon or Woods Hole research buoy. Georges Bank is WSW of
eastern mass and not far offshore.

If you want to see a good depiction of comb generator signal, check out
W2AEW's vid of the same name.  I've seen and heard true comb with NaP3 on
40M and 80M last fall and it looks very much like high duty cycle PWM;
sounds like a coarse grinding wheel on the edge of a big sheet metal
plate.  Unmistakable.