How can you identify transmitted optical signals when working with fiber optic patch cords?

Identifying transmitted optical signals in fiber optic patch cords can effectively be accomplished by observing bright white spots through a smartphone camera. This method works because the smartphone camera can capture infrared light, which is emitted by the optical signals traveling through the fiber. When you look through the camera, you may notice bright spots or flashes where the light is present, indicating that the fiber is successfully transmitting signals.

Other methods, such as checking signal strength with a multimeter, are not applicable for optical signals since multimeters are typically used for electrical measurements. Similarly, measuring the temperature of the fiber does not provide any information about the transmitted optical signals. While connecting the fiber to a light source and looking for illumination may seem like a viable option, it doesn't effectively confirm the existence of a transmitted signal within the fiber itself, as the light observed may solely be from the external source rather than a signal traveling through the fiber.