A monitoring system for monitoring equipment has first data processing means for executing a primary, critical task and second data processing means for executing a secondary, non-critical task. When used in a two-point transmitter modulation architecture, the mechanism relies on the fact that the noise statistics at the output of the transmitter can be determined by observing the phase error output of the phase detector within the phase locked loop. A first gap is formed between the diaphragm and the backplate.