## Orthogonal FSK detection

#### A typical M-ary FSK detector consists of a bank of correlators (mixers with coherent carrier references), followed by a decision circuit at the output determining which correlator has the largest output and hence which symbol was sent. As the number of symbol states employed tends to infinity, the symbol averaging time becomes very large, reducing the effect of noise to almost zero. The Eb/N0 required for error-free transmission will thus approach the Shannon–Hartley limit of -1.6 dB Eb/N0 for which error-free communication can be achieved, regardless of how many symbol states and hence how much signalling bandwidth is used. |

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