Radio Receivers
To prevent overloading of the IF amplifier in a receiver, one should use

Double conversion
Variable selectivity
Variable sensitivity
Squelch

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Radio Receivers
In a ratio detector

the circuit is the same as in a discriminator, except that the diodes are reversed
stabilization against signal strength variations is provided
the linearity is worse than in phase discriminator
the output is twice that obtainable from a similar phase discriminator

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