The voltage threshold for triggering a Voltage-Controlled Oscillator (VCO) in Frequency Modulation (FM) demodulation can vary depending on the specific design of the circuit and the characteristics of the signals involved. However, I can provide you with a general understanding of how this process works.
In FM demodulation, the goal is to recover the modulating signal (baseband signal) from a frequency-modulated carrier signal. This is typically achieved using a circuit called a Frequency Discriminator or a Phase-Locked Loop (PLL), which incorporates a VCO.
The VCO in this context generates an output frequency that is directly proportional to the input voltage applied to it. In FM demodulation, the frequency deviation of the carrier signal is directly related to the amplitude of the modulating signal. The demodulation process involves converting the frequency variations of the carrier signal back into amplitude variations, allowing the original modulating signal to be recovered.
The voltage threshold for triggering the VCO depends on the modulation index (the ratio of the peak frequency deviation to the frequency of the modulating signal) and the sensitivity of the VCO. A higher modulation index would typically require a larger voltage swing to achieve the same amount of frequency deviation, which affects the threshold voltage.
It's important to note that specific values for the voltage threshold can't be given without knowing the specific parameters of the circuit and the signals involved. Designers often consider the modulation index, VCO characteristics, and the dynamic range of the modulating signal when setting up the voltage threshold for proper demodulation.
If you're working with a specific circuit or application, you might need to consult the datasheets or technical documentation for the components you're using to determine the appropriate voltage threshold for your FM demodulation setup.