... DCS, PHS & 3G. 2.detector range: 20M EST-101A cellphone signal detector +alarming systemTechnical parametersEach frequency band has a corresponding antenna ... .When the detector is working, the TTL signal and RS-485 communication signal are output by the system.Sentivity of the ... plug into the socket, then switch on. When the power indicator is lit, it means that the device starts working. (Different ...