How PLL can be used as a 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.
What is PLL demodulation?
A phase-locked loop (PLL) is primarily used in tracking the phase and frequency of the carrier component of an incoming FM signal. PLL is also useful for synchronous demodulation of AM-SC (i.e., Amplitude Modulation with Suppressed carrier) signals or signals with few cycles of pilot carrier.
What is slope error in FM demodulation?
Slope detection is the very simplest form of frequency modulation, FM demodulation. An FM slope detector consists of a tuned circuit where the centre frequency is tuned to a frequency slightly offset from the carrier of the signal. This causes the amplitude of the signal to vary in line with the frequency variations.
What is balanced slope detector in FM demodulation?
A balanced slope detector is an improved version of the slope detector. The drawback of harmonic distortion is removed in this detector by using two slope detectors instead of one as in a single-tuned slope detector.
What is the advantage of using PLL for FM demodulation?
PLL FM demodulator performance Linearity: One of the advantages of the PLL FM demodulator is its high degree of linearity. This is governed by the voltage to frequency characteristic of the VCO within the phase locked loop.
When PLL is used as FM demodulator the output is obtained from?
The output or the phase detector is low-pass filtered and amplified by the amplifier stage. The Output or the amplifier is the control voltage that is applied to VCO to force it to track the incoming frequency. The control voltage is also available at pin number 7. This is the output signal.
How is PLL useful in detecting FM signals?
The PLL uses the concept of minimising the difference in phase between two signals: a reference signal and a local oscillator to replicate the reference signal frequency. Using this concept it is possible to use PLLs for many applications from frequency synthesizers to FM demodulators, and signal reconstitution.
What is FM detector?
FM detectors are circuits that instantaneously convert the frequency changes from the carrier signal to its output voltage counterpart. They are also known as frequency demodulators or discriminators.
Why PLL method is popular for FM demodulation?
The PLL technology eliminates the costly RF transformers needed for circuits like the ratio FM detector and the Foster Seeley circuit. Typically a phase locked loop FM demodulator does not require the use of an inductor, let alone a transformer which is even more costly to manufacture.
What is the disadvantage of slope detector?
Drawbacks of Slope Detector (i) It is inefficient. (ii) It is linear only over a limited frequency range. (iii) It is difficult to adjust as the primary and secondary winding of the transformer must be tuned to slightly different frequencies.
What does an FM detector do?
It is a Tuned-circuit frequency demodulator type wherein it converts FM signals to AM using tuned (LC) circuits and extract the information from the AM envelope using a series connection of a diode and a capacitor (conventional peak detector.) It can be used with any radio even if it does not have an FM capability.