# DEMODFM

## Purpose:

Demodulates an FM series using the Hilbert Transform.

## Syntax:

DEMODFM(series, fmin,
fmax)

series |
- |
A series or table. |

fmin |
- |
Optional. A real, the minimum
modulation frequency used to
scale the result. If not specified, no output scaling is performed. |

fmax |
- |
Optional. A real, the maximum
modulation frequency used to
scale the result. If not specified, no output scaling is performed. |

## Returns:

A series or array.

## Example:

W1: gtriwave(1000,.001, 4)

W2: W1 * 100 + 20

W3: cos(integ(2*pi*W2))

W4: demodfm(W3)

W2 represents the scaled information signal and W3 is the resulting
frequency modulated signal. The amplitude of W2 determines the instantaneous
frequency of W3. The instantaneous frequency of W3 ranges from:

min(w3) == 20 Hz

to

max(w3) == 120 Hz

W4 is the unscaled demodulated result.

## Example:

W1: gtriwave(1000, .001, 4)

W2: modfm(w1, 20, 100)

W3: demodfm(w2)

W4: demodfm(w2, 20, 100)

Same as above except the minimum and maximum modulation frequencies
are specified in W4 to scale the result.

## Remarks:

DEMODFM uses HILB to calculate the Hilbert Transform.

See MODFM to frequency modulate
a series.

See GSWEEP to generate a linearly swept sinewave.

See DEMODAM to demodulate an amplitude modulated
series.

## See Also:

DEMODAM

GSWEEP

HILB

MODAM

MODFM