Satellites accept signals from transmitting earth stations (the uplink), translate the signal to a different frequency band, and retransmit it at suitable power levels to receiving earth stations (the downlink).
The satellite "footprint," defined by the beamwidth of the spacecraft antenna, maybe contoured to the shape of the intended coverage area, but is nevertheless likely to be thousands of miles across. The satellite channel is visible to all points within the coverage area and, therefore, readily interceptable within that area. The signals from many satellites may be received from locations beyond the borders of the contiguous United States. The key to targeted interception, consequently, is determining which satellite and transponder channel frequencies are of interest.
- ↑ 47 C.F.R. §2.1; id. §25.201.