Contents
Which one is true about ratio detector?
Correct Option: D As with the Foster-Seeley discriminator, a ratio detector has a single tuned circuit in the transformer secondary. Therefore, the operation of a ratio detector is similar to that of the Foster-Seeley discrimination. In fact, the diodes D1 and D2 are identical.
How does a demodulation circuit work?
Demodulation is a key process in the reception of any amplitude modulated signals whether used for broadcast or two way radio communication systems. Demodulation is the process by which the original information bearing signal, i.e. the modulation is extracted from the incoming overall received signal.
What is the principle of FM detection?
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.
What are AM and FM in communication?
In AM, a radio wave is known as the “carrier” or “carrier wave” is modulated in amplitude by the signal that is to be transmitted. In FM, a radio wave is known as the “carrier” or “carrier wave” is modulated in frequency by the signal that is to be transmitted. The amplitude and phase remain the same.
What are the advantages of ratio detector?
Advantages of the ratio FM detector Simple to construct using discrete components. Offers good level of performance and reasonable linearity. Provides a good level of immunity to amplitude noise . Ratio detector has wider bandwidth than Foster Seeley discriminator.
What is the use of ratio detector?
The ratio detector is a type of detector circuit, commonly used in radio receivers for demodulating frequency modulated (FM) signal. The ratio detector is a variant of the Foster-Seeley discriminator, but one diode conducts in an opposite direction, and using a tertiary winding in the preceding transformer.
What is the circuit used for producing AM called?
The circuit used for producing AM is called a modulator. Its two inputs, the carrier and the modulating signal, and the resulting outputs are shown in Fig. 3-3. Amplitude modulators compute the product of the carrier and modulating signals.
What are the two actions needed to demodulate an AM carrier?
There are two methods used to demodulate AM signals:
- The envelope detector is a very simple method of demodulation that does not require a coherent demodulator.
- The product detector multiplies the incoming signal by the signal of a local oscillator with the same frequency and phase as the carrier of the incoming signal.
What is the output voltage of a ratio detector?
Ratio detector is another frequency demodulator circuit. The ratio detector output voltage is equal to half of the difference between the output voltages from the individual diodes. Hence similar to the phase discriminator the output voltage is proportional to the difference between the individual output voltages.
How does a ratio detector work in a tuned circuit?
The signal that goes directly to the center tap of the secondary splits equally there, and the diode rectify it to create equal voltages across the two capacitors to ground, in a kind of voltage doubler action. Then, the signal is applied to the tuned circuit.
How does a ratio detector work in a FM receiver?
The re- quired dc voltage in this circuit is developed across two load resistors, and there is an electrolytic capacitor in shunt across the resistors, as in Fig. 4. The sensitivity of the ratio detector is half that of the discriminator.
How does a ratio detector work on a transformer?
The operation of the ratio detector centres around a frequency sensitive phase shift network with a transformer and the diodes that are effectively in series with one another. When a steady carrier is applied to the circuit the diodes act to produce a steady voltage across the resistors R1 and R2, and the capacitor C3 charges up as a result.