Various forms of "spread spectrum" communications can overcome the relative power problem through "spreading codes". Briefly, spreading codes are a generalization of traditional sine & cosine encoding. By using more complex spreading codes, a receiver can accumulate a signal which is far below the "noise", but is still recognizable (and receivable) due to its spreading code. Thus, the receiver "tunes" to the appropriate "channel" by choosing the appropriate "spreading code". In a traditional/"narrow band" radio, this tuning is merely the choice of frequency -- i.e., the "spreading code" in this instance is a simple sine wave of the appropriate frequency. In a spread-spectrum radio, the local beat frequency oscillator (BFO) is replaced with a pseudo-noise PRNG (pseudo random number generator). It takes more work to establish synchronization than with a narrow band radio, but with the appropriate generalization, the overall block diagram of the radio is the same. https://en.wikipedia.org/wiki/Code_division_multiple_access At 05:02 PM 4/16/2016, rcs@xmission.com wrote:

One reason planets are hard to see is the nearby star swamping the signal. If you choose a particular wavelength and signal encoding, you might get something detectable against this background.