FM Modulator Passband (Communications Blockset)

Modulate using frequency modulation

Library

Analog Passband Modulation, in Modulation

Description

The FM Modulator Passband block modulates using frequency modulation. The output is a passband representation of the modulated signal. The output signal's frequency varies with the input signal's amplitude. Both the input and output signals are real sample-based scalar signals.

If the input is u(t) as a function of time t, then the output is

where:

f_c is the Carrier frequency parameter.
is the Initial phase parameter.
K_c is the Modulation constant parameter.

Typically, an appropriate Carrier frequency value is much higher than the highest frequency of the input signal. To avoid having to use a high carrier frequency and consequently a high sampling rate, you can use baseband simulation (FM Modulator Baseband block) instead of passband simulation.

By the Nyquist sampling theorem, the reciprocal of the Sample time parameter must exceed twice the Carrier frequency parameter.

Dialog Box

Carrier frequency (Hz): The frequency of the carrier.
Initial phase (rad): The initial phase of the carrier in radians.
Modulation constant (Hertz per volt): The modulation constant K_c.
Sample time: The sample time of the output signal. It must be a positive number.
Symbol interval: Inf by default. To use this block to model FSK, set this parameter to the length of time required to transmit a single information bit.

Pair Block

FM Demodulator Passband

See Also

FM Modulator Baseband

Free Space Path Loss Gaussian Noise Generator