Labels:text | screenshot OCR: USING 56KBPS MODEM TECHNOLOGY Upstream direction (33.6/40Kbps) Digital UUUU DAC JUILEL telephone network Host 56Kbps 56Kbps Client modem Client modem Host Downstream direction (56Kbps) = Digitd waves = Sine waves Figure 2: The dient bost sends a digital bit stream (digital waves) to the 56Kbps client modem, which, in turn, creates an analog signal (sine waves). When the analog signal reaches the digital portion of the network, the network performs a PCM ADC. The restring digital signal is transmitted through the digital phone network to the 56Kbps server modem and host. The ADC is affected by quantization noise, so this upstream path is limited to about 33.6Kbps or 40Kbps, When the server host transinits, the 56Kbps server modem merely forwards the digital data. When the signal reaches the last analog leg of the connection, the network performs a D.AC to create the analog signal to be delivered to the 56Kbps client modem. This signal is then reconverted to digital for the client bost. The dosenstream direction is not affected by quantization noise, so 56Kbps can be achieved.
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