Recently, UAVS monitors cars in the diverse kinds of environments. For examples, illegal cars on highways and parking cars in indoor parking lot are traced. Global Position System (GPS) is usually utilized for outdoor environments, but there is no core technology for indoor localization. One of approaches for the indoor localization is beacon. However, the measured Received Signal Strength Indicators (RSSIs) of beacons should be revised to improve the accuracy of the localization of UAVs. Tradition RSSI revision approaches utilizes the diverse kinds of algorithms such as a Kalman filter. Those approaches estimate or calculate the current RSSI by analyzing previous measured RSSIs. However, there is a limit to improve the accuracy of the estimated or calculated RSSIs. Therefore, it is request to do research further about utilizing additional information, which can be collected data in advance. This paper proposes a method to revise RSSIs by analyzing collected data. Measured RSSIs are revised based on collected data in advance. First, the part of consecutive RSSIs until currently measured RSSI is deducted. Next, the part of the consecutive RSSIs among collected RSSIs in advance similar to or equal to the deducted part of the consecutive RSSIs is found. Next, the measured RSSIs are revised based on the found part of the consecutive RSSIs in advance.