Comparison of modulation methods
- 1. Advantages/disadvantages/applications of various modulation schemes Advantages Disadvantages Applications 1. DSB-SC Lower power consumption The modulation system is simple Complex detection Analog TV systems: to transmit color information 2. SSB-SC Better management of the frequency spectrum Low power consumption The generation of exact SSB is rather difficult. Complex detection Two way radio Frequency division multiplexing 3. VSB-SC It is a compromise between DSB and SSB. Therefore it is easier to generate than SSB-SC Demodulation system is still complex. Its bandwidth is about 25% greater than SSB-SC. Analog TV broadcast systems 4.items 1~3 with carrier Envelope detection is possible Low power efficiency Wireless broadcasting systems 5. 8,16 level VSB-SC ATSC digital television standard＋ 6. FM Increased immunity to noise Require a larger bandwidth Radio broadcasting; direct-satellite broadcasting 7.PM Increased immunity to noise more complex receiving hardware data-communications systems 8.PSK Power efficiency. System is the simplest Low bandwidth efficiency Low speed communication 9. ASK Bandwidth efficiency Low power efficiency 10. M-ary PSK Require more bandwidth Transmitted power is lower V-32 Telephone data/fax modems Satellite transmission of DTVB programs. 11. QAM An attractive alternative to SSB-SC. Sharp cutoff band-pass filters are not required. Compared with SSB, QAM is more exacting in terms of the carrier frequency and phase or the requirement for a distortion-less transmission medium Used in cable communication for the transmission of DTV and internet traffic between cable modem and modem termination systems. 12. SHD AM/FM RECEIVERS Increased selectivity against adjacent channels Interference from signal frequencies close to the intermediate frequency Radio broadcasting 13. LINE CODES Power efficiency, Error detection and correction capability. Zero PSD at f=0 Transmit only one bit of information over the interval of Tb second Optical communications 14. M-ary PAM Transmits more bits in a symbol time. Require more power (M2 ) less system complexity High rate data links + M.S. Richer et al,” The ATSC digital television system”, proc. IEEE, vol.94, pp.37-43, Jan, 2006. www.atsc.org
- 2. AM Amplitude modulation ASK Amplitude shift keying ATSC Advanced Television Systems Committee DSB Double sideband DTV Digital television FM Frequency modulation PAM Pulse amplitude modulation PM Phase modulation PSK Phase shift keying QAM Quadrature amplitude modulation SC Suppressed carrier SHD Superheterodyne SSB Single sideband VSB Vestigial sideband