?How does a 56k dial-up modem work?

What will be an ideal response?

The new 56k modems are a hybrid design, combining analog signaling and digital signaling. The upstream connection from modem to remote end still uses conventional analog signaling and modulation techniques, and thus is limited to a maximum transmission speed of 33,600 bps. The downstream link, however, is where the 56k modem really stands out. Instead of using analog signaling, the 56k modem employs digital signaling. The telephone system has actually been using digital signaling over telephone lines for many years. In fact, the telephone system can send an 8-bit sample 8000 times per second, which corresponds to 64,000 bits per second, or 64 kbps. If the telephone company can transmit 64 kbps, does this mean that we users can receive a 64-kbps downstream signal? Unfortunately, the answer is "No." When the telephone company transmits a digital 64-kbps telephone signal, the signal is transmitted digitally from one switching center to another. But when a telephone signal is transmitted into our homes and small businesses, it must be adjusted so that it can traverse the local loop. The local loop is the stretch of telephone wire that runs between a house (or small business) and the telephone company's central office. This local loop is analog and can support only analog signaling.?Before the telephone signal is transmitted over the local loop, the central office converts the digital signal to an analog signal. When the analog signal enters your house, your computer's 56k modem converts the analog signal back to digital data, because computers manipulate digital data. When an analog signal is converted to digital data, quantizing noise is introduced. The presence of this noise is the reason it is not possible to transmit a 64-kbps data stream into the local loop. But a smaller data stream, of approximately 56 kbps, is possible.