【简答题】A ( ) contains circuitry that converts the data-carrying signals from a digital device to signals that can travel over various communications channels
【单选题】The car will be guided by a differential GPS system that corrects errors arising in global positioning satellite signals()they travel through the ionosphere and troposphere.
【单选题】A 56Kbps Modem is a device that translates the ( ) signals from your computer into analog signals that can travel over a standard phone line, and it can sends data at 56,000 bits per second.