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Which one of the following statement is correct? In a ratio detector:
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- Linearity is worse than that of a phase discriminator
- Stabilization is provided, against signal strength variations.
- The output is twice of that obtainable from a similar phase discriminator.
- The circuit is same as that in a discriminator, except that the diode connections are reversed.
- Linearity is worse than that of a phase discriminator
Correct Option: D
The ratio detector has one major advantage over the slope detector and Foster-Seeley discriminator for FM demodulation is that it is relatively immune to amplitude variations in its input signal.
The schematic diagram for the ratio detector is shown. 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. However, with the ratio detector, one diode is reversed (D2 ) and current ld can flow around the outermost loop of the circuit. Hence alternative (D) is the correct choice.
