The voltage threshold for triggering a Voltage-Controlled Oscillator (VCO) in Frequency Modulation (FM) demodulation can vary depending on the specific circuitry and design of the FM demodulator. There isn't a single fixed voltage threshold that universally applies to all VCOs in FM demodulation. However, I can provide you with some general information about how VCOs are used in FM demodulation and the factors that can influence the voltage threshold.
In FM demodulation using a VCO, the incoming FM signal is used to directly control the frequency of the VCO. As the frequency of the incoming signal changes, it causes the frequency of the VCO to change accordingly. The output of the VCO is then typically passed through a frequency-to-voltage converter to obtain the demodulated signal.
The voltage threshold for triggering the VCO would depend on the design of the demodulation circuit and the characteristics of the VCO itself. It's often determined by factors such as the desired sensitivity of the demodulator, the frequency deviation of the FM signal, and the overall signal-to-noise ratio of the system.
In some cases, the VCO might be designed to start oscillating at a certain input voltage level, effectively acting as a threshold. This voltage level can be set during the design phase of the circuit and might depend on the specific application and requirements.
To determine the voltage threshold for a VCO in an FM demodulation circuit, you would need to consider the specifications of the VCO, the demodulator circuitry, and the characteristics of the FM signal you are trying to demodulate. Simulation or experimentation might also be necessary to fine-tune the threshold to achieve optimal demodulation performance.