## Bit error rate (BER) performance for baseband data systems

#### In order to determine the likelihood of a data detector decoding symbols correctly in the presence of noise, we have to operate with probabilities and statistics. Noise is non-deterministic, that is, its amplitude and phase vary randomly with time so that during some symbols the instantaneous levels of noise will be greater than for others. We thus must resign ourselves to working out the probability of decoding symbols in error, rather than the certainty of decoding symbols in error. |

#### Often in fact we wish to be informed of the probability of bit error rather than symbol error as this directly impinges on the integrity of data sent to the user. For the binary case, symbol error probability and bit error probability are of course identical.