FM demodulation is a key process in the reception of a frequency modulated signal. Once the signal has been received, filtered and amplified, it is necessary to recover the original modulation from the carrier. It is this process that is called demodulation or detection.

How is FM demodulation?

A simple and effective FM demodulation technique involves a high-pass filter (for FM-to-AM conversion) followed by an AM demodulator. A high-pass-filter-based FM demodulator is preceded by a limiter to prevent amplitude variations from contributing error to the demodulated signal.

What is a radio demodulator?

A demodulator is an electronic circuit (or computer program in a software-defined radio) that is used to recover the information content from the modulated carrier wave. The signal output from a demodulator may represent sound (an analog audio signal), images (an analog video signal) or binary data (a digital signal).

Why LPF is used in demodulator?

The capacitor and resistor form a low-pass filter to filter out the carrier frequency. Such a device is often used to demodulate AM radio signals because the envelope of the modulated signal is equivalent to the baseband signal.

What happens to the AM waveform during the demodulation process?

In the demodulation process the audio or other signal carried by amplitude variations on the carrier is extracted from the overall signal to appear at the output. As the most common use for amplitude modulation is for audio applications, the most common output is the audio.

What are the types of FM demodulation?

There are different types of FM demodulators including:

• Slope Detector.
• Foster-Seeley Discriminator.
• Ratio Detector.
• Pulse-Averaging Discriminators.
• Quadrature Detectors.
• Phase-Locked Loops.

How PLL can be used as an FM demodulator?

To look at the operation of the PLL FM demodulator take the condition where no modulation is applied and the carrier is in the centre position of the pass-band the voltage on the tune line to the VCO is set to the mid position. However if the carrier deviates in frequency, the loop will try to keep the loop in lock.

How do you use PLL as a frequency demodulator?

What is the effect of adding the capacitor in foster Seeley detector?

The capacitors C1 and C2 filter any remaining RF signal which may appear across the resistors. The capacitor C4 and R3 also act as filters ensuring no RF reaches the audio section of the receiver. Like the ratio detector, the Foster-Seeley circuit operates using a phase difference between signals.

What is the function of FM demodulator?

In any radio that is designed to receive frequency modulated signals there is some form of FM demodulator or detector. This circuit takes in frequency modulated RF signals and takes the modulation from the signal to output only the modulation that had been applied at the transmitter.

What is a high-pass filter-based FM demodulator?

A high-pass-filter-based FM demodulator is preceded by a limiter to prevent amplitude variations from contributing error to the demodulated signal. A phase-locked loop can be used to achieve high-performance FM demodulation. The use of integrated-circuit PLLs makes this approach less complex than it might seem.

What is a quadrature FM detector?

The quadrature FM detector or demodulator is used in many FM radios and receivers. Frequency Modulation Tutorial Includes: The FM quadrature demodulator and its relation the coincidence detector or demodulator provide another form of FM detector circuit that is used in many areas, being easily incorporated into integrated circuits.

What is a Foster Seeley FM demodulator?

Foster Seeley FM : In the days when radio used discrete components, this was the other main contender for the FM demodulator in radios. The Foster Seeley FM demodulator was very similar in many respects for the ratio detector. However instead of using a third winding on the transformer, it used a separate choke.