Free · Physics models
AM and FM Modulation Indices
Calculate amplitude modulation depth and frequency modulation index with inverse controls.
- Formula & worked example
- Private in your browser
- No signup
Calculator inputs
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How to use this calculator
- Enter the known values in the units shown. Results update as you type.
- Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
- Use the worked example to check the method. Reset restores the starting fields.
Private by default
Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.
Formula and method
Amplitude modulation index (μ==a==) = 0.50000000. The worked example lists its inputs and unit conventions.
mAM = Vm/Vc; βFM = Δf/fm.
Worked example
Enter these known values and leave the other values blank.
- Calculate modulation index of
- 1
- Message signal amplitude (A==m==)
- 1 V
- Carrier signal amplitude (A==c==)
- 2 V
- Amplitude modulation index (μ==a==)
- 0.5
Assumptions and limitations
- Amplitudes use the same voltage convention and frequencies use the same frequency units. AM depth exceeding one is overmodulation; the positive ratio remains a mathematical result. The FM input Δf is peak frequency deviation, not bandwidth.
- Clear the quantity to solve an inverse; keep known quantities fixed with locks. Some inverses are singular or ambiguous and require further known values.
- Unit selectors convert the same physical quantity. Rounded reference constants and presets limit physical accuracy even when arithmetic displays more digits.
Common questions
What does this model assume?
Amplitudes use the same voltage convention and frequencies use the same frequency units. AM depth exceeding one is overmodulation; the positive ratio remains a mathematical result. The FM input Δf is peak frequency deviation, not bandwidth.
Can I solve for an input?
Editable calculated fields support the captured inverse relationships. Clear the unknown and supply enough independent known values; an inverse must remain within the declared physical domain.
References
Amplitudes use the same voltage convention and frequencies use the same frequency units. AM depth exceeding one is overmodulation; the positive ratio remains a mathematical result. The FM input Δf is peak frequency deviation, not bandwidth.