The video signal in composite video should have a maximum amplitude of 0.7 volts.
Composite video signals carry all the picture information (brightness, color, and synchronization pulses) on a single cable. Understanding the correct signal amplitude is crucial for ensuring a proper display on your television or monitor. The size, or more accurately, the voltage level of the signal, directly corresponds to the brightness of the image being displayed.
Understanding Composite Video Signal Levels
The amplitude of the composite video signal is standardized to ensure compatibility between different video sources and displays. According to the provided reference:
In a composite video, the video signal has a maximum amplitude of 0.7 volts. This means the bright parts of the picture, the white elements, will have a signal strength of 0.7 volts, while the darker, black parts will register a signal of 0 volts.
This describes the voltage range specifically for the video portion of the signal, excluding the synchronization pulses (which typically go into the negative voltage range).
- 0 Volts: Represents the black level of the image.
- 0.7 Volts: Represents the peak white level of the image.
Intermediate voltage levels between 0V and 0.7V represent different shades of gray, from dark gray (close to 0V) to light gray (close to 0.7V).
Key Voltage Levels
Here's a simple breakdown of the video signal amplitude:
| Video Element | Voltage Level |
|---|---|
| Black Level | 0 Volts |
| Peak White | 0.7 Volts |
It's important to note that the full composite video signal, including synchronization pulses, extends below 0 volts, typically down to -0.3 volts, making the total peak-to-peak amplitude around 1 volt (from -0.3V sync tip to +0.7V peak white). However, the question specifically asks about the "video signal," which the reference defines as ranging from 0V (black) to 0.7V (white).
Maintaining the correct signal level is vital. If the signal is too low, the picture will appear dark and lacking contrast. If the signal is too high, the bright areas may appear "clipped" or washed out.
Understanding these standard voltage levels helps troubleshoot potential issues in composite video connections, ensuring optimal picture quality.
