A team of scientists have arrived at the Galactic Center Black hole(mass of 7.95e36 kg). Having parked their spaceship in orbit at a safe distance around the back hole (so that time dilation is not and issue), they want to set up a smaller robotically-controlled station that is closer to the black hole in order to conduct some experiments. They need to construct a device that will transmit the results back to the main station. They were thinking of using a "Compton radio" that was like an FM radio where the transmitted frequency could be modulated (by quickly changing angles) to encode the signal. The issue is they don't know how close to the black hole they can put the remote station, which of what kind of light I would need inside the radio in order for them to tune into a radio station center at 21 cm (bandwidth 0.5 cm), what range of angles are needed to optimize the radio.