Under indoor environments, a beacon’s received-signal strength is very unstable. Utilizing the signal strength indication for estimating the distance between Access Points(APs) and beacons is very hard as the received signal frequently contains noise signals. Therefore, the noise signals need to be eliminated from the signal. Traditional research methods remove the noise signals by extracting and removing the peak signals. However, these methods consider only the upper side peak signals. This paper proposes a signal processing method that eliminates impulse noises in the beacon-AP signal in real time. By applying a noise filter to the two directional signals of impulse noises, the impulse noises can be eliminated. In the experiments, the proposed method was compared with traditional research methods. Compared to the traditional method, the proposed method reduced the difference between the calculated and estimated signal strength to 64%.