An Analysis of the Response of Digital Demodulators to Frequency Shift Keyed Signals.
Abstract
The theory and operational characteristics of a digital pulse counting frequency demodulator are presented. The demodulator, called the pulse width demodulator (PWD) in this report, is realized with solid state components and uses pulse circuitry to perform demodulation. The output of the demodulator may be applied to a low pass filter (LPF) to recover the modulating voltage. The PWD possesses the following properties: (1) wideband operation, (2) no tuning requirement, (3) simple resistor adjustment for selecting the operating frequency range and (4) ability to operate at frequencies beyond the design range due to the circuit's ability to automatically frequency divide. The demodulator performance for analog and digital (FSK) modulating voltages is obtained at both commercial intermediate frequencies of 455 kHz and 10.7 MHz. Its performance in the presence of noise is investigated and compared to theoretical results for non-coherent FSK systems.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1975
- Accession Number
- ADA021822
Entities
People
- Myron Wasiuta
Organizations
- Naval Postgraduate School