Title :
A new modulation-index measuring instrument for square-wave FM signal
Author :
Ikeda, Hiroaki ; Li, Jinzhu ; Wakai, Kazuaki ; Fukuma, Kohshi
Author_Institution :
Shizuoka Univ., Hamamatsu, Japan
Abstract :
A method measuring the modulation indexes of square wave frequency modulation (SWFM) signals have been proposed and experimentally verified. The measurement circuit consists of a series of bandpass filters, DC rectifiers, analog-to-digital converters, and a processor for calculating the frequency deviation. In accordance with the modulation index of the SWFM signal at the fundamental and third-harmonic frequency of the IF carrier, the frequency deviation of the SWFM signal has been found to be precisely determined when the modulation signal is input to the SWFM signal modulator. This method is useful for determining suitable modulation signal levels for sideband spreading in the SWFM signal, and can be applied to the measurement of the modulation index at the transmitter in FM voice communication systems
Keywords :
computerised instrumentation; electric variables measurement; frequency modulation; harmonics; optical communication equipment; signal processing equipment; transmitters; voice communication; wave analysers; DC rectifiers; IF carrier; analog-to-digital converters; bandpass filters; frequency deviation; modulation-index measuring instrument; optical communications; sideband spreading; square wave frequency modulation; square-wave FM signal; third-harmonic frequency; transmitter; voice communication; Circuits; Frequency conversion; Frequency measurement; Frequency modulation; Instruments; Light emitting diodes; Optical modulation; Optical receivers; Optical transmitters; Signal processing;
Conference_Titel :
Instrumentation and Measurement Technology Conference, 1992. IMTC '92., 9th IEEE
Conference_Location :
Metropolitan, NY
Print_ISBN :
0-7803-0640-6
DOI :
10.1109/IMTC.1992.245178
