Modulation Calculator
Calculate modulation index for amplitude, frequency, and phase modulation
Calculate Modulation Index
Amplitude of the modulating signal
Amplitude of the carrier signal
Modulation Index Results
Formula used: μa = Am / Ac
Optimal range: 0.5 ≤ μa ≤ 1.0 for efficient AM without distortion
Modulation Analysis
Example Calculation
FM Radio Station Example
Scenario: FM broadcast station
Maximum frequency deviation (Δf): 75 kHz
Highest message signal frequency (fm): 15 kHz
Modulation type: Frequency Modulation
Calculation
μf = Δf / fm
μf = 75,000 Hz / 15,000 Hz
μf = 5
This is wideband FM with good signal quality
Modulation Types
Amplitude Modulation
μa = Am / Ac
Range: 0 to 1 (ideal)
Frequency Modulation
μf = Δf / fm
No upper limit
Phase Modulation
μp = Δθ
Radians (0 to π typical)
Modulation Tips
AM: Keep modulation index ≤ 1 to avoid distortion
FM: Higher index provides better noise immunity
PM: Often used in digital communication systems
Higher modulation index = wider bandwidth requirement
Understanding Modulation
What is Modulation?
Modulation is the process of converting data into radio waves by adding information from a low-frequency signal to a high-frequency carrier signal. The carrier signal can travel long distances but doesn't carry useful information until modulated.
Types of Modulation
- •Amplitude Modulation (AM): Varies carrier amplitude
- •Frequency Modulation (FM): Varies carrier frequency
- •Phase Modulation (PM): Varies carrier phase
Modulation Index
The modulation index quantifies the degree of modulation. It represents the ratio of the message signal variation to the carrier signal characteristics.
AM: μa = Am / Ac
FM: μf = Δf / fm
PM: μp = Δθ
Applications
- • AM: AM radio broadcasting, aviation communication
- • FM: FM radio, two-way radio, television audio
- • PM: Digital communication, satellite systems