What is the lower threshold of 256-QAM?

The lower threshold of 256-QAM (Quadrature Amplitude Modulation) is indeed between 28-30 dB. This modulation technique is commonly used in digital television and cable modems due to its ability to transmit high data rates. The range mentioned reflects the minimum signal-to-noise ratio (SNR) required for reliable performance in this modulation scheme.

In practical terms, achieving a lower threshold below this range would result in an increased error rate and decreased performance in data transmission. Higher thresholds are generally associated with improved signal integrity and data throughput. Understanding the SNR requirements for various modulation levels is critical for any technician working in the field to ensure optimal service quality and reliability in communications systems.