Digitaltoanalog modulation Types of digitaltoanalog modulation Amplitude Shift
- Slides: 39
Digital-to-analog modulation Types of digital-to-analog modulation
Amplitude Shift Keying (ASK) On/Off keying • • The amplitude of the carrier signal is varied to represent binary 1 & 0. Frequency and phase remains the same. Highly susceptible to noise interference. Used up to 1200 bps on voice grade lines, and on optical fiber.
Frequency Shift Keying • Frequency of the carrier is varied to represent digital data (binary 0/1) • Peak amplitude and phase remain constant. • Avoid noise interference by looking at frequencies (change of a signal) and ignoring amplitudes. • Limitations of FSK is the physical capabilities of the carrier. • f 1 and f 2 equally offset by equal opposite amounts to the carrier freq. • In MFSK more than 2 freq are used, each signal element represents more than one bit
Phase Shift Keying • • Phase of the carrier is varied to represent digital data (binary 0 or 1) Amplitude and frequency remains constant. If phase 0 deg to represent 0, 180 deg to represent 1. (2 -PSK) PSK is not susceptible to noise degradation that affects ASK or bandwidth limitations of FSK
BPSK TRANSMITTER BPSK RECEIVER
Signal space diagram of BPSK
4 -PSK (QPSK) method
4 -PSK (QPSK)
4 -PSK (QPSK) COS SIN 45 +0. 707 135 -0. 707 +0. 707 225 -0. 707 315 +0. 707 -0. 707
4 -PSK (QPSK) SIGNAL SPACE DIAGRAM
4 -PSK (QPSK)
QPSK TRANSMITTER a 1 (or) a 2=+√(E/2) (or)-√(E/2)
QPSK RECEIVER
DERIVATION-PROBABILITY OF ERROR IN QPSK
DERIVATION-PROBABILITY OF ERROR IN QPSK
DERIVATION-PROBABILITY OF ERROR IN QPSK
DERIVATION-PROBABILITY OF ERROR IN QPSK
Offset QPSK waveforms • Presence of 180 degree phase shift in QPSK makes the signal to loose constant envelope property. Non linear amplification of such signal causes unwanted side lobes and spectral widening. • In OQPSK maximum phase shift is limited to 90 degree. • Even and Odd bit streams are offset in their relative alignment by one bit period.
Offset QPSK waveforms
Offset QPSK Transmitter
Pi/4 QPSK signaling ØMaximum phase angle change is limited to +135 (or) -135 ØCan be noncoherently detected
Pi/4 QPSK phase shifts
Possible values of Øk are +45, -45, +135, -135
Pi/4 QPSK transmitter
Differential detection of pi/4 QPSK
- Amplitude modulation vs frequency modulation
- Wave modulation
- Advantages of angle modulation
- Dscfc
- Principle of amplitude modulation
- Am modulation
- Am vs fm
- Frequency modulation and demodulation theory
- Advantages and disadvantages of pulse code modulation
- Amplitude modulation
- Amplitude period phase shift
- Amplitude phase shift period
- Frequency shift keying modulation
- Homocyclic diene component
- Bathochromic shift and hypsochromic shift
- Cap 221
- Bathochromic shift and hypsochromic shift
- Difference between arithmetic shift and logical shift
- Logical shift and arithmetic shift
- Gabriel hugh elkaim
- Difference between arithmetic shift and logical shift
- Horizontal plane border movement
- Wct+
- Shift register types
- Similarities of mechanical and electromagnetic waves
- Amplitude wavelength and frequency
- Sine function transformations
- Climas quente
- Small amplitude oscillatory shear
- Rarefaction on a wave
- Gmr head amplitude
- Ecological amplitude definition
- Phase invariance
- Difference between pulse doppler radar and mti radar
- Amplitude mode ultrasound
- Dynamics
- Amplitudes articulaires poignet
- Laisvieji svyravimai
- Interference by division of amplitude
- Ecg tachycardia no p waves