In this thesis work, an FSK demodulator using digital quadricorrelator was designed. This FSK demodulator operates based on the digital form of quadricorrelator which is known as an ideal frequency detector. Digital quadricorrelator was designed using standard digital logic devices, and used no analog devices and circuits at all. Therefore, the circuit designed will have good reliability against aging effect and drift of devices, and easy to implement with integrated circuit. And, linear range of frequency discrimination can be adjusted from ±20% to ±100% with simple modification. A non-coherent demodulation can be done by detecting a direction of frequency drift. And a effect of increasing number of the mixing axes in quadricorrelator was investigated.
Computer simulation shows that a performance of receiver with digital demodulator converges to that of analog quadricorrelator receiver as the number of mixing axes increased. And the best combination of modulation index and filter bandwidth is obtained also from the simulation. Finally, a example circuit design of practical receiver was shown.
