Sending and receiving signals from one side of Earth's orbit to the other (two astronomical units) presents unique challenges when neither side benefits from the transmitting/collecting power of a ground antenna on Earth, when both transcievers are spacecraft. Here we discuss our calculations on the restrictions placed on the design of the spacecraft to have a high enough signal-to-noise ratio (SNR) for engaging in a novel experiment: Faraday rotation observations of the interplanetary magnetic field upstream of Earth. To do this, the transceivers must be on either side of Earth in Earth's orbit. (The attached image shows the variability in the plane of polarization (PP) for Faraday rotation analysis as a function of SNR through solar plasma flowing in the plane of the sky; the plasma will not impact Earth. The data was obtained when the STEREO A&B spacecraft were transmitting to the Greenbank Telescope on Earth. The time of transmission is shown in the legend.)