In phase-shift keying (PSK) demodulation, a voltage-controlled oscillator (VCO) is often used as part of the demodulation process. The VCO generates an output signal whose frequency is controlled by an input voltage. The specific voltage threshold for triggering a VCO in PSK demodulation can vary depending on the implementation and the modulation scheme used.
In PSK demodulation, the VCO is typically used to track the phase changes in the received signal. The phase changes correspond to the different symbols or phases in the PSK modulation scheme. The voltage input to the VCO is adjusted to keep the VCO's output frequency in sync with the phase changes of the incoming PSK signal.
The voltage threshold for triggering the VCO will depend on factors such as the modulation index of the PSK signal, the desired demodulation sensitivity, and the design of the demodulation circuitry. It's important to note that the threshold voltage might not be a fixed value, but rather a range or a dynamically adjusted value to accommodate varying signal conditions.
In some cases, automatic gain control (AGC) circuits may be used to adjust the input voltage to the VCO, ensuring that the demodulation process is robust to changes in signal strength. Additionally, digital signal processing techniques might be employed to optimize the demodulation performance and dynamically adjust the VCO's input voltage.
To determine the specific voltage threshold for triggering a VCO in PSK demodulation, you would need to refer to the technical specifications of the demodulation circuit or system you are working with, or perform simulations/experiments to find the appropriate threshold for your specific application.