How Fast Can You Talk?

How Fast Can You Talk?

To achieve a particular transmission speed, the modems need to send and receive a signal that can change at that rate. For instance, Figure 16-4 implied that the frequency changed every .1 seconds, meaning that the PC could send 10 bits in every second, or for a rate of 10 bps. That's a ridiculously low speed, but showing faster speeds in the figure would have required a much larger piece of paper! Some early modems sent at 9600 bps, so the sending modem would change the signal (as necessary) every 1/9600 of a second. Similarly, the receiving modem would sample the incoming analog signal every 1/9600 of a second, interpreting the signal as a binary 1 or 0. Today, modems approach speeds around 56 Kbps.