Methods and apparatus for storing data records associated with an extreme value are disclosed. Signal data is stored in a first buffer of a set of buffers. If a local extreme value for the first buffer exceeds a global extreme value, signal data is stored in a second buffer of the set of buffers. This process is repeated, wrapping around and overwriting buffers until the signal data in a current buffer does not have a local extreme value that exceeds the global extreme value. When this happens, signal data may be stored in a subsequent buffer and if a local extreme value of the subsequent buffer does not exceed the global extreme value, further signal data may be stored in the subsequent buffer in a circular manner until either an instantaneous extreme value exceeds the global extreme value or the recording period ends. In an embodiment, the extreme value may be a peak value.
