Angle Modulation and Demodulation
Innovative Technologies in Education (ITE)
The angle modulation & demodulation module will deal with
the angle modulation techniques currently used in modern analog
and digital communications systems. An analog or digital information
signal will be conveyed on to a carrier signal whose instantaneous
angle or frequency varies according to the variation of the original
information signal. The module will offer the advantage of increased
signal to noise ratio without increases in transmitter power. Specifically,
Phase Modulation (PM) and conventional Frequency (FM) will be studied
as well as modulation and demodulation techniques.
RECOMMENDED EXPERIMENTS
1. Phase Modulation - Time & spectrum displays of 400 Hz sine
wave - Bessel lines - Time & spectrum displays for NRZ, PAM,
PSK, QPSK and M-array PSK 2. Correlation of PM and FM - Generate
PM with an FM modulator - Generate FM with a PM modulator 3. Analog
FM - Spectrum, Bessel lines - Narrow & wide band FM 4. Digital
FM - spectrum displays for NRZ, PAM and M-FSK - CPFSK and non-CPFSK
5. FM Detectors - ratio & zero crossing - frequency discriminator
6. FM Demodulation For Strong Signal & Noise - SNR0 dependence
on SNR1 - Pre-emphasis, de-emphasis 7. FM Demodulation For Weak
Signal & Noise - FM threshold effect - performance at the threshold
- click noise 8. PLL as an FM Detector - Effect of loop parameters
on performance - Effect of noise on PLL
TECHNICAL SPECIFICATIONS
The angle modulation & demodulation module will consist of
the following main blocks:
- Phase Modulator - Vco - Rf Switch - Ratio Detector - Frequency
Discriminator - Zero Crossing Detectors - Pre-Emphasis - De-Emphasis
- Integrator - Differentiator - Limiter -Pll
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