The frequency detected by an optical power meter typically refers to the frequency of a modulated test tone used for fiber identification and continuity testing, not a property of the meter itself. These test tones are commonly 270 Hz, 1 kHz, or 2 kHz. Some specialized units can identify a wider range, such as 12 different tones, specifically used for ribbon fiber testing.
Understanding Optical Power Meter Functionality
An optical power meter measures the power of a light source. It doesn't inherently "have" a frequency in the same way a signal generator does. However, in fiber optic testing, modulated light sources are often used in conjunction with optical power meters. These modulated light sources emit light with a specific tone or frequency.
Test Tone Frequencies
- Common Frequencies: As mentioned, 270 Hz, 1 kHz, and 2 kHz are standard.
- Ribbon Fiber Testing: Some advanced power meters can detect a wider range of tones (up to 12 different tones) to identify individual fibers within a ribbon cable. Each fiber in the ribbon might be assigned a unique tone, allowing for easy identification at the far end.
Why Use Test Tones?
- Fiber Identification: Test tones allow technicians to easily identify the correct fiber among many others.
- Continuity Testing: Confirming that a signal can be transmitted through a fiber optic cable from one end to the other.
- Fault Isolation: Using tones can help pinpoint breaks or issues within the fiber optic link.
Example Scenario
Imagine a technician needs to identify a specific fiber in a bundle of hundreds. The technician uses a light source to inject a 1 kHz tone into one end of the fiber. At the other end, the technician uses an optical power meter that is configured to detect the 1 kHz tone. When the meter detects the 1 kHz signal, the technician knows they have located the correct fiber.
