Condition monitoring device

A condition monitoring apparatus which monitors a condition of equipment including a rotor, the condition monitoring apparatus comprising:

• a storage configured to store a plurality of results obtained from a plurality of divided data strings, respectively, resulting from division of a data string obtained by sampling at a regular time interval of signals from sensors provided in the equipment, where in the plurality of results includes a plurality of frequency spectra corresponding to the plurality of divided date strings, respectively;
• and
• a calculator configured to 1) estimate a plurality of rotation speeds corresponding to the plurality of divided data strings from the plurality of results accumulated in the storage, respectively, 2) correct the plurality of divided data strings based on the plurality of rotation speeds, respectively, and 3) generate a corrected data string by combining the plurality of corrected divided data strings,
• wherein estimating the plurality of rotation speeds includes sequentially calculating a rate of variation in speed between each pair of divided data strings that are adjacent each other in the plurality of divided data strings.