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Modem Expert Lecture
Presented by fred harris, San Diego State University, USA
Our technological society has fielded modems for 50 years. The early modems moved 600 bits per second through shielded 4-kHz bandwidth wire-line channels. Modern modems move 108 bits over sever multipath corrupted 100 MHz bandwidth RF channels. In this 50 year time span the modem has undergone quite striking changes in architecture and hardware as it embraced wider bandwidth in pursuit of higher capacity. The modem permeates our economy, our commerce, our military, our entertainment media, and our research and development activity. The half day modem tutorial will emphasize the signal processing that is performed in the physical layer of the communication link. We will cover the three major processing tasks performed in the modem. These are first tier processing: that of filtering, spectral translating, and signal conversion, second tier processing: synchronization, the alignment of frequency and phase of carrier and symbol timing, and the third tier processing: the suppression of artifacts due to imperfect analog components in the signal conditioning and signal transport path between transmit and receive ports. Reference: fred harris, Wade Lowdermilk, "Software Defined Radio", Tuturial 22, IEEE Instrumentation and Measurement Magazine, February 2010, pp.23-32.
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