Measurement of the Capture Effect of Frequency Modulation
Abstract
Capture Effect is a phenomenon associated with frequency modulation (FM). The capture effect relates the ability of the receiver demodulator to recover the message of the dominant carrier when two or more FM carriers of unequal power level are present. In this research, an experimental system is constructed that generates the sum of two FM signals and demodulates that sum using a phase-locked loop (PLL). The effect on capture by several parameters is measured. These parameters are the frequency deviation of the FM signal, the frequency of the message, and the lowpass filter design of the PLL demodulator. Capture ratios as small as 0.387 dB are observed. Results show that the frequency deviation of the stronger signal affects capture. The frequency deviation of the weaker signal has no effect on capture. Frequencies of the message have small effects on capture.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1989
- Accession Number
- ADA228058
Entities
People
- Dennis G. Bevington
Organizations
- Naval Postgraduate School