What is the name of the hardware device, which converts data from a digital format into a format suitable for an analog transmission medium, such as telephone or radio? The data is being transmitted by first modulating carrier wave signals to encode digital information. The receiver thereafter is capable of demodulating the signal and recreating the original digital information.

Such devices can use various ways of modulating and demodulating, but the best-known usage utilizes telephone lines.

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Answer to yesterday's question: Letter "P" stands for "portable". The idea, as described in the question, was to allow document sharing, where documents could include text formatting and inline images. Being a proprietary format until release as an open standard in 2008, PDF has evolved to be a universally used file format, setting the standard for cross-platform usability.