a receiver to sequentially receive multiple pieces of detection data sent from a sensor detecting an event during a sampling period, the sampling period being fixed;

a memory to store a minimum system delay time and a minimum-reception-time expected reception time point calculated to be a time point at which target detection data is to be received, the minimum system delay time being predetermined as a minimum value of system delay times each corresponding to a time from a time point at which the sensor detects the event to the corresponding reception time point, the target detection data being one piece of detection data, out of the multiple pieces of detection data, sent with a minimum time of the system delay times before latest detection data is received; and

a processing circuitry

to measure reception time points at which the multiple pieces of detection data are respectively received,

to estimate a minimum-system-delay jitter to be a difference between the minimum-reception-time expected reception time point and the reception time point of the target detection data, and

to estimate an event detection time point from the minimum system delay time, the minimum-reception-time expected reception time point, a time period from detection of the event corresponding to the target detection data to detection of the event corresponding to the latest detection data, and the minimum-system-delay jitter, the event detection time point being a time point at which the event corresponding to the latest detection data is detected.