10-401-08-BandpassTransmissionDetection-1

10-401-08-BandpassTransmissionDetection-1 - Essential...

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
Baseband Transmission 1 Essential Blocks:Digital Communication System Format Pulse Modulation Bandpass Modulation Transmitter Synchronization Format Detection Demodulation Sampling Receiver Channel 010100 0 T 2T 3T 4T 5T 6T 7T 8T 0 T 2T 3T 4T 5T 6T 7T
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Bandpass Modulation and Demodulation 2 Bandpass versus baseband modulation In digital communication system, digital symbols are transformed into waveforms that are compatible with the characteristics of the tranmission channel In baseband modulation , waveforms take the form of shaped pulses. In bandpass modulation , shaped pulses modulates a sinusoid called carrier wave or RF carrier For example, in radio transmission where the transmission medium is air, the shaped pulses should be converted to electromagnetic (EM) field. This is because EM is transmitted only via antennas whose dimensions are proportional to the wavelength (or frequency) of the EM signal Therefore, bandpass modulation is an essential step for radio transmission ! Haykin: Chapter 9 Sklar: Chapter 4
Background image of page 2
Bandpass Modulation and Demodulation 3 RF carrier signal General form of the sinusoid RF carrier s t = A t cos θ t A t : time-varying amplitude θ t : time-varying angle θ t = ω 0 t φ t Three distinguishing parameters of the sinusoid; -amplitude, -frequency and -phase Then, bandpass modulation can be performed by changing simply any of these parameters or their combinations. -1 -0.5 0 0.5 1 1.5 2 2.5 3 3.5 4 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 -1 -0.5 0 0.5 1 1.5 2 2.5 3 3.5 4 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 Bandpass: ASK/On-Off Keying
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Bandpass Modulation and Demodulation 4 Bandpass modulation schemes When the receiver has the knowledge about the phase of the carrier wave to detect signals, the process is called coherent detection Coherent Phase Shift Keying(PSK) Frequency Shift Keying(FSK) Amplitude Shift Keying(ASK) Continuous phase modulation (CPM) Hybrids Noncoherent Differerentially Phase Shift Keying(DPSK) Frequency Shift Keying(FSK) Amplitude Shift Keying(ASK) Continuous phase modulation (CPM) Hybrids
Background image of page 4
Bandpass Modulation and Demodulation 5 Bandpass Signaling: Amplitude and energy Waveform amplitude coefficient s t = A c cos ωt A c : peak value For sinusoidal waveform, A c = 2 A rms s t = 2 A rms cos ωt = 2A rms 2 cos ωt . Average normalized power
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 12/15/2010 for the course EE EE 401 taught by Professor Alikara during the Spring '10 term at Ankara Üniversitesi.

Page1 / 32

10-401-08-BandpassTransmissionDetection-1 - Essential...

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online