http://www.channeleco.com/en/Item/Show.asp?m=1&d=1266 Product description: QT-SM100 soil moisture meter is based on TDR (Time domain Reflectometry) technology, it can be used to rapidly measure the moisture of various types of soils. By measuring the dielectric constant of soil or other media, the meter can calculate soil water content, because soil water content is closely related to the dielectric constant. Soil moisture data can be transmitted to a handheld Android terminal by WIFI.FeatureGPS coordination can be recordedRecord data Automatically or manuallyWireless data transmission via Wi-FiRecognize sensors by two-dimensional code。 Automatically recognize connected sensors