a single, 100 kW FM radio station at 300 km from the observing site could produce up to a 100 K effective temperature in a 1 MHz channel due to troposcatter, or 100 mK due to meteor reflections. Fortunately, these mechanisms of atmospheric propagation exhibit diurnal or transient behavior (as is the case for sporadic E propagation, tropospheric ducting, and meteor reflections) or require specific geometries for peak efficiency (as is the case for troposcatter), making sensitive measurements possible at remote sites at least some of the time.

Another concern is that local objects in the environment will scatter both external noise and receiver noise, which will then be picked up by the system and correlate with the original noise, causing sinusoidal ripples in the measured spectrum. We have estimated the magnitude of the reflections of the Galactic foreground from objects like trees and mountains on the horizon where the antenna gain is reduced by a factor of 20 dB or more. As long as objects subtend solid angles under about 100 deg$^2$, the spectrum will only be affected by a few parts per million (*ppm*). We have also considered the magnitude of noise originating from the receiver that will 