PPT-Chapter 4. Amplitude Modulation

Husheng Li The University of Tennessee AM Signals and Spectra An AM signal can be written as Power of AM The total transmit power is given by We can prove that at least 50 often close to 23 of the total transmitted power resides in a carrier term that is independent of the signal and thus conveys no message information what a waste. Husheng Li. The University of Tennessee. Chopper Sampling . We introduce a switching function such that . x_s. (t)=x(t)s(t), where. Nyquist. Criterion. The sampling rate should be at least twice the bandwidth of the signal, in order to fully reconstruct the signal.. . Group B. Ali . Qasim. Haris. . Suhail. Imaan. Tariq. Mohsin. . Zafar. Arsalan. . Hameed. Abdul . Rahman. . Rida. . Zainab. Ehsanullah. . Zafar. Hassan . Iqbal. Amna. Aziz. Manal. Fatima. Qambar. 1. st. . semster. 1436-1437. King Saud University . College of Applied studies and Community . Service. 1302CT. DSB-SC. Double Side Band Suppress Carrier (DSB-SC) is one type of Amplitude Modulation. 1. Introduction. A digital signal is superior to an analog signal because it is more robust to noise and can easily be recovered, corrected and amplified. For this reason, the tendency today is to change an analog signal to digital data. In this section we describe two techniques, . Husheng Li. The University of Tennessee. Chopper Sampling . We introduce a switching function such that . x_s. (t)=x(t)s(t), where. Nyquist. Criterion. The sampling rate should be at least twice the bandwidth of the signal, in order to fully reconstruct the signal.. Analog data to analog signal. (AM, FM, PM). Digital data to analog signal. (ASK, FSK, BPSK, QAM). Analog data to digital signal. (PCM, DM). Digital data to digital signal. (line codes). Signal Encoding Techniques (modulation and encoding). Exchange of information from point A to point B. 100001101010001011101. 100001101010001011101. Transmit. Receive. Wireless Communication. Exchange of information from point A to point B. 100001101010001011101. Amplitude Modulation (AM). Time domain equation. y. AM. (t. ) = . Information or message x carrier. . = . m(t) . x A cos(w. c. t. ). . Frequency domain equation. Double . sideband . Tenenbaum, . Wetherall. (uploaded on Canvas). Communication. Exchange of information from point A to point B. 100001101010001011101. 100001101010001011101. Transmit. Receive. Wireless Communication. Code division multiple access Steps in CDMA Modulation. CDMA is a spread spectrum multiple access technique. https://store.theartofservice.com/the-modulation-toolkit.html. Code division multiple access Steps in CDMA Modulation. . Normal Amplitude Modulation. Lecture . 1-3. University of . Mustansiriyah. College of Engineering. Department of Computer Engineering . Binary modulation schemes . ASK. , FSK, . PSK. n. = . 1, . M = 2 (Only Two . output conditions are . possible). Baud . is equal to . the bit . rate. M-. ary. Modulation Techniques. QPSK, 8-PSK, 18-PSK, QAM, 16-QAM. Example: ASK, FSK, PSK, QAM. Binary digital modulation. Multilevel digital modulation. Amplitude Shift Keying. Binary-ASK --- BASK. Or On-Off Keying OOK. Uses two amplitude levels for the modulated carrier . 1. http://www.gaussianwaves.com/2012/05/performance-comparison-of-digital-modulation-techniques/. Note: M=2^m.