Bessel Functions & Graphs
Using a filter greatly reduces the efficiency of the system since the power amplifier is outputting the carrier signal only to have it shorted to ground via the filter. Adjusting the modulation index to the proper value causes all of the output power to be concentrated in the usable signal, thus increasing efficiency. See FM. The 1st sideband disappears when the Jn(1,β) plot equals zero, the 2nd sideband disappears when the Jn(2,β) equals zero, etc., etc.
Bessel filter pole values can be found here. Bessel filter prototype values can be found here.
Note: Graph generated using Mathcad 4.0.
Related Pages on RF Cafe | - Amplitude Modulation
- Frequency Modulation
- Quadrature (I/Q) Modulator Sideband Suppression
- Bessel Functions & Graphs
- Modulation Principles, AM Modulation, NEETS
- Modulation Principles, FM Modulation, NEETS
- Modulation Principles, Demodulation, NEETS
- Frequency Mixer, Converter, Multiplier, Modulator Vendors
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