Several techniques have been used to perform the conjugation (references 10-12) and a heterodyning method is illustrated in Figure 3. For simplicity assume a reference plane has been established by using the signal received by one of the orbiting conjugation modules as a phase reference. This signal. Wo, would be distributed to each of the remaining modules where it would be heterodyned with a locally generated signal, W^ (bottom of Figure 3). Two sidetones are produced, Wo - Wjp, which are separated by filters and distributed to two other mixers. The upper sidetone, Wo + Wjp is heterodyned with a local sample of the uplinked reference frequency, Wo. This module is shown displaced with respect to the reference module and it will therefore see the reference frequency as having a different phase, related to the amount of displacement, given by where is the apparent phase of the locally received signal relative to that received by the reference module. is the relative displacement of the local module and is the wavelength of the reference frequency, Wo. The displacement could be the result of a deformed or perturbed antenna surface. After heterodyning with the locally received signal, a lower sidetone, having the same frequency and phase as the locally generated signal Wjp, is separated by a bandpass filter and routed to an output phase identical to the conjugated phase displacement, mixer. Note the phase displacement, is preserved but reversed in sign. A second heterodyning in the output mixer produces a sidetone having the same frequency as the reference, Wo, but having a relative
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