Distance measurement apparatus and distance measurement method

A distance measurement apparatus that calculates a distance based on carrier phase detection, the distance measurement apparatus comprising:

• a calculation unit configured to calculate, based on phase information acquired by a first device and a second device at least one of which is movable, a distance between the first device and the second device, wherein
• the first device comprises
• a first reference signal source,
• a first transmitter/receiver configured to transmit three first carrier signals respectively having different frequencies and receive three second carrier signals respectively having same frequencies as the frequencies of the three first carrier signals using an output of the first reference signal source, in which a frequency between a lowest frequency and a highest frequency among the three frequencies is a frequency that deviates from an average value of the lowest frequency and the highest frequency,
• a first receiving signal intensity measurement unit configured to measure a receiving signal intensity of each of the three second carrier signals,
• an estimation unit configured to estimate a receiving signal intensity of the frequency having the average value from at least one of respective three receiving signal intensities of the three first carrier signals and the respective three receiving signal intensities of the three second carrier signals, and
• a fading correction value calculation unit configured to calculate a fading correction value for the distance from the receiving signal intensity of the frequency having the average value, the receiving signal intensity of the lowest frequency, and the receiving signal intensity of the highest frequency,
• the second device comprises
• a second reference signal source configured to operate independently of the first reference signal source, and
• a second transmitter/receiver configured to transmit the three second carrier signals and receive the three first carrier signals using an output of the second reference signal source, and
• the calculation unit calculates the distance using a phase detection result obtained by receiving the three first carrier signals and the three second carrier signals while correcting the calculated distance using the fading correction value.