8-VSB Modulation Explained

This page describes 8 level VSB modulation.

VSB is the short form of Vestigial Sideband Amplitude Modulation. It’s a modulation scheme commonly used in Digital TV. In this modulation technique, the carrier signal is suppressed, and only the upper sideband is transmitted.

The serial data is fed into a Digital-to-Analog Converter (DAC). The DAC converts the serial data, processing it in groups of 3 bits at a time, into a discrete voltage level.

The system encodes 3 bits per symbol, which effectively increases the data rate within the channel.

The example is depicted in the figure above. As shown, each 3-bit group is converted into a relative voltage level: -7, -5, -3, -1, +1, +3, +5, or +7.

This resulting signal is then used to modulate the RF carrier. This process results in a symbol rate of approximately 10800 symbols per second.

This translates into a data rate of 3 bits/symbol * 10800 symbols/second = 32.4 Mbps.