Patent ID: 8130948

Claim:
A method of addressing groups of broadcast satellite receivers within a physical geographic portion of a total footprint within which broadcast signals from a common broadcast source can be received, the method comprising: at each of two or more satellite transmitters having a common transmission frequency band, transmitting two or more respective signals at each of a plurality of frequencies within the common transmission frequency band; at each of selected ones of the receivers, comparing a relative phase of the signals received from the two or more satellite transmitters at each of the frequencies and generating an indicator representative of a characteristic of the relative phase at each of the frequencies; generating from the indicator a common key for the receivers in a certain location to access location-based services for those receivers that are in possession of the common key; conveying the common key to a broadcast source; encoding services for the receivers that are in possession of the common key with reference to the common key; and wherein: there are a plurality of transmission rounds and in each of the transmission rounds the signals are transmitted at the plurality of frequencies, the frequencies being different for the different transmission rounds; and the received signals are subjected to a Fourier transform, and a resultant of the transform for the different transmission rounds are combined to produce a multibit codeword.