FM Detector

Introduction to FM Detector

Fm detector is termed as discriminator. Fm detector is a balanced double diode demodulator. Fm detector splits audio signal from frequency modulated IF signal.

 The FM detector circuits are categorized like this:

TYPES OF FM DETECTOR

1. Travis discriminator

2. Foster-Seeley discriminator

3. Radio detector.

253_FM Detector Homework Help.jpg

It is a 3 stages tuned (or) stagger tuned discriminator. In this type, three tuned circuits are employed that are tuned to three dissimilar frequencies. In the final IF transformer the first tuned circuit that is tuned to the intermediate frequency. It contains two secondary coils.

Two Signal diodes are employed. They are associated to the secondary coils. Two filter networks are connected in the output section. These filter networks are R.C filters. Output audio signal is taken beyond the filter condensers.

While the input signal rises from the center frequency first diode conducts and second it doesn't conduct. Therefore half cycle of audio signal is charged in output. At the output, Half cycle the two half cycles are joint and taken like audio signal. The R.F signals are bypassed through the condensers. This audio signal is applied on to the audio amplifier for amplification.

FOSTER SEELEY DISCRIMINATOR

Foster Seeley discriminator is also termed as phase shift discriminator or center tuned discriminator. Only two tuned circuits are employed that are tuned to center frequency in this circuit. From the final IF amplifier (limiter) input signal is applied to it. The primary and secondary coils have been got by the final IFT.

Two signal diodes are used. Among the primary and center tap of the secondary a coupling capacitor is connected. Thus by this coupling condenser and mutual induction the input signal is applied to the secondary.

The diodes are balanced while equal signal voltage is applied. Therefore the output is similar and net audio signal output is 0. At another levels (apart from centre frequency) the output of one diode is larger than another. The output is positive, if the total output is larger than centre frequency, and on the other hand while output is smaller, the output is negative. Carrier signals are filtered and AF signal is split and provided to the output stage.

 

RATIO DETECTOR

This circuit looks like the discriminator circuit. The major variation is that the signal diodes are connected in reverse direction. It is not essential to make use of a limiter stage. The two tunrf circuits are contained by final IF transformer. By coupling capacitor and output section, the input signal is applied two filter condensers are connected and one load resistor is employed. While, the unmodulated signal is applied, the output signal voltage is similar. And while the input signal changes the output voltage also changes. While input signal frequency is raised, more output voltage is generated. If input signal frequency is get decreased, less output voltage is generated. If input signal is raised more than centre frequency, the output of first tuned circuit is gets high, and while the output of second tuned circuit is low. Therefore the output is +ive. If input signal is low, the output becomes -ive. So the two signal voltages are combined and so audio signal is acquired.

DOUBLE CONVERSION

If two different IF's are employed in a receiver, it is termed as Double conversion. It is employed in communication receivers.

Latest technology based Electrical Engineering Online Tutoring Assistance

Tutors, at the www.tutorsglobe.com, take pledge to provide full satisfaction and assurance in FM Detector homework help via online tutoring. Students are getting 100% satisfaction by online tutors across the globe. Here you can get homework help for FM Detector, project ideas and tutorials. We provide email based FM Detector homework help. You can join us to ask queries 24x7 with live, experienced and qualified online tutors specialized in FM Detector. Through Online Tutoring, you would be able to complete your homework or assignments at your home. Tutors at the TutorsGlobe are committed to provide the best quality online tutoring assistance for Electrical Engineering homework help and assignment help services. They use their experience, as they have solved thousands of the Electrical Engineering assignments, which may help you to solve your complex issues of FM Detector. TutorsGlobe assure for the best quality compliance to your homework. Compromise with quality is not in our dictionary. If we feel that we are not able to provide the homework help as per the deadline or given instruction by the student, we refund the money of the student without any delay.

©TutorsGlobe All rights reserved 2022-2023.