Coded modulation is a technique used in digital communications to improve the transmission of information over a noisy channel. It involves the combination of error control coding and modulation schemes to encode the data at the transmitter and decode it at the receiver. This results in a more reliable and efficient communication system, as the coding helps to correct errors that occur during transmission. In coded modulation, different modulation schemes can be used, such as amplitude, phase, and frequency modulation, combined with various error control coding techniques like convolutional coding or turbo coding. The choice of modulation and coding schemes depends on the specific requirements of the communication system in terms of data rate, bandwidth, and error rate performance. Overall, coded modulation is a powerful technique that can significantly improve the performance of digital communication systems in terms of reliability, efficiency, and spectral efficiency. It is widely used in various applications, including satellite communications, digital broadcasting, wireless communication, and optical communication systems.