1. What do these abbreviations stand for? PWM PPM PAM PCM ASK FSK PSK AM FM IF AF RF TRF amp Pulse width modulation Pulse position modulation Pulse amplitude modulation Pulse code modulation Amplitude switch keying Frequency switch keying Phase switch keying Amplitude modulation Frequency modulation Intermediate frequency Audio frequency Radio frequency Tuned radio frequency amplifier

3. Change in Logic Level So change in phase No Change in Logic Level So no change in phase Change in Logic Level So change in phase

4. Low-pass filterSample / sample and hold ADC Flash converter PISO shift register Analogue signal input Astable 1 (oscillator) Astable 2 (oscillator) PCM signal output

5. Schmitt trigger regenerator SIPO shift register DAC Digital to analogue converter Low pass filter PCM input Astable (oscillator) Analogue signal output