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2-antenna complex correlation interferometer |
| | A visibility is a complex quantity. |
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| | A single correlator (=multiplier+integrator) samples only the real part of a visibility, i.e. the cos term. Introducing a 90 degree phase shifter and using a second, independent correlator to register this signal, one samples both the real and imaginary part. |
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 | | The big advantage is that, because the noise of the two correlators is independent, one gains a factor of |
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