A pair of VHF antennae side by side on aft fuselage of the "Twangs" tuned 1/4 wavelength apart and whichever would collect the signal
first....and suppress the other receiver (the last B-29 was sending) would transmit a Morse code letter R (turn right) = "U" dit-dit-dah, and L (turn left) = "D" dah-dit-dit. D=Dog, U=Uncle.
When the 51(s) were on course to the transmitting bomber, either towards the target or home, a Hummmm would be heard/
Uncle Dog.
