In frequency modulation (FM) demodulation using a voltage-controlled oscillator (VCO), the voltage threshold for triggering the VCO isn't a fixed value that can be universally stated. It can vary based on the specific design of the FM demodulation circuit, the characteristics of the VCO, and the modulation index of the incoming FM signal.
The basic principle of FM demodulation using a VCO involves converting the frequency variations of the FM signal into voltage variations. As the frequency of the FM signal changes, the output voltage of the VCO changes accordingly. This voltage can then be processed to extract the original modulating signal.
The voltage threshold for triggering the VCO typically relates to the point at which the demodulated voltage change is significant enough to ensure reliable demodulation. This threshold might be set based on the sensitivity and linearity of the VCO, as well as the noise characteristics of the system.
To determine the voltage threshold for triggering the VCO in your specific application, you would need to consider factors such as the modulation index of the incoming FM signal, the frequency range of the VCO, the desired output signal quality, and the characteristics of the demodulation circuitry.
It's important to note that FM demodulation using a VCO is often a part of more complex systems, and the specific threshold and related parameters would need to be determined through practical experimentation or detailed circuit analysis.