Wi-Fi signals are typically information carriers between a transmitter and a receiver. The performance of a Wi-Fi network greatly depends on signal strength of the wireless router or wireless access point. In this paper, we will discuss one way to plot the heat map of Wi-Fi signals using a network of Raspberry-Pi. After analyzing this heat map, we can decide a better placement of Access Points. We will also discuss about the basic variation of the signal strength with the distance, in an open field.