In a ratio detector

Solution (By Examveda Team)

In a ratio detector, the main function is to demodulate an AM (Amplitude Modulation) signal. It is used to convert the AM signal's varying amplitude into an audio signal that can be processed by a radio receiver. The ratio detector is commonly used in AM radio receivers and is similar to the diode detector but with an additional stage for improved linearity and better demodulation performance.

Here’s the detailed explanation for each option:

Option A: the linearity is worse than in phase discriminator
This statement is correct. A ratio detector provides less linearity compared to a phase discriminator. In phase discriminators, the output is a linear function of the phase difference of the incoming signal. In contrast, the ratio detector is non-linear, and the output is more sensitive to variations in signal amplitude. Therefore, the ratio detector's performance is less predictable and less accurate when compared to phase discriminators.

Option B: stabilization against signal strength variations is provided
This statement is partially true but misleading. A ratio detector does attempt to stabilize the output to some degree by responding to the relative strength of the signal. However, it is not as effective in stabilizing the output against large variations in signal strength as more advanced techniques, such as automatic gain control (AGC) or phase discriminators. The ratio detector will still experience some level of distortion or degradation when the signal strength fluctuates significantly.

Option C: the output is twice that obtainable from a similar phase discriminator
This statement is incorrect. The output of a ratio detector is not simply twice that of a similar phase discriminator. The ratio detector operates by comparing the outputs from two diodes, and its output depends on the ratio of the signals from each. The relationship between the output and the input signal is not directly a factor of "twice" the output of a phase discriminator.

Option D: the circuit is the same as in a discriminator, except that the diodes are reversed
This statement is incorrect. Although the ratio detector and discriminator are both used to demodulate AM signals, their circuits are not the same. The discriminator typically involves a tuned circuit and focuses on phase shifts to detect frequency deviations, while the ratio detector works by comparing the signals from two diodes. The difference in operation and design makes this statement inaccurate.

Therefore, the correct answer is Option A: "the linearity is worse than in phase discriminator."