3-33
PEAK DETECTION uses the amplitude, or duration, of a pulse to charge a holding capacitor and
restore the modulating waveform.
A LOW-PASS FILTER is used to demodulate pdm by averaging the pulse amplitude over the
entire period between pulses.
PULSE CONVERSION is used to convert ppm, pdm, or pcm to pdm or pam for demodulation.
ANSWERS TO QUESTIONS Q1. THROUGH Q40.
A-1. Re-creating original modulating frequencies (intelligence) from radio frequencies.
A-2. Circuit in which intelligence restoration is achieved.
A-3. A circuit that can detect the presence or absence of rf energy.
A-4. An antenna, tank circuit for tuning, rectifier for detection, filter to give constant output, and an
indicator device.
A-5. Heterodyning.
A-6. By giving a different beat frequency for each signal.
A-7. Regenerative detector.
A-8. Oscillator, mixer, and detector.
A-9. (1) Sensitive to the type of modulation applied, (2) nonlinear, and (3) provide filtering.
A-10. The modulation envelope.
A-11. Rectifies the rf pulses in the received signal.
