A recording unit includes one or more signal sensors and a recording controller. The recording controller is configured to execute a first recording instruction to record first data received from the one or more signal sensors. The first data is recorded according to first recording rules that specify a first value of a parameter. The recording controller is also configured to, in response to an irregularity detected in the first data, execute a second recording instruction to record second data received from the one or more signal sensors. The second data is recorded according to second recording rules that specify a second value of the parameter, where the second value differs from the first value.