Introducción a las radiocomunicaciones. Modulaciones digitales avanzadas 1 | 55/97 | UPV

Title: Introduction to Radio Communications. Advanced Digital Modulations 1 Auto-description: This video explains the optimization of data transmission through advanced digital modulations. These techniques combine basic modulations with multiple carriers to improve energy efficiency and spectrum utilization, thereby increasing the bit rate. However, they require more complex receivers and are more sensitive to the signal-to-noise ratio, which can increase the probability of errors due to noise. The first advanced modulation mentioned is QPSK, which consists of two binary PSK modulations with carriers 90 degrees out of phase. It allows 2 bits per symbol to be represented with a configuration of four distinguishable phases. The presentation includes graphic and time-based examples of how these symbols are transmitted. Differential Phase Modulations are also described, such as DBPSK and DQPSK, which are differentially coded variants of the basic PSK and QPSK modulations, respectively. This method facilitates correct demodulation even with receiver and transmitter oscillators that are not perfectly synchronized, as it is based on phase changes between successive symbols rather than absolute phases. However, it is susceptible to significant errors in the presence of fluctuating noise. Finally, QAM modulation is introduced, which varies the amplitude in addition to the phase, with the example of 16-QAM allowing the transmission of 4 bits per symbol. While it offers better spectral efficiency, it is less robust to noise than previous modulations. Variants with a larger number of states are mentioned, such as 256-QAM to 4096-QAM, which offer very high spectral efficiency but are more vulnerable to noise. Advanced systems can use adaptive modulation that adjusts the modulation level based on signal-to-noise conditions. Author: Despujol Zabala Ignacio Course: This video is 55/97 of the MOOC course Introduction to Radio Communications.    • MOOC Introducción a las radiocomunicaciones   Register at: https://upvx.es/courses/course-v1:edx... Polytechnic University of Valencia (UPV): https://www.upv.es More videos at:    / valenciaupv   Access our MOOCs: https://upvx.es #radiocommunications #qpsk #dqpsk #qam