Chapter 9 Communications Circuits 9.4.4 Analog Circuits A modem converts a signal from digital to analog mode for transmission on an analog circuit, and back to digital mode at the receiving end 9.4.5 Digital circuits A DSU/CSU provides the signal timing and shaping interface between a dte and a digital circuit www.gxmu.edu.cn9.4.4 Analog Circuits A modem converts a signal from digital to analog mode for transmission on an analog circuit, and back to digital mode at the receiving end. 9.4.5 Digital Circuits A DSU/CSU provides the signal timing and shaping interface between a DTE and a digital circuit. www.gxmu.edu.cn Chapter 9 Communications Circuits