Propagation of electrical and optical signals in networks

Electrical signals (that is, the full-TV signal we need to modulate) it is a fixed frequency that is set by the state, that is, the total source of the signal we want to modulate. From electrical signals to light signals: the popular understanding is to be modulated by the signal loaded into the light-emitting diode, with its strong and weak changes to control the luminous intensity of the light-emitting diode changes, and then by the same module of the photosensitive transistor received by some conversion circuit modulation to the laser and other components to achieve light transmission. This is what my personal understanding may be wrong in general this means. Of course, reception is a reverse process. You send the end of what, the receiving side of course also need the same equipment, such as you on the 250MHZ and 576MHZ to the corresponding with the two frequency point of the field test, to use the words need to be able to produce resonance equipment.

Because all the data is converted to electrical signals in the physical layer, through the network cable to spread. When the other end is reached, the data link layer is converted to a data frame represented by a 0, 12 binary code according to the electrical signal of the physical layer , which is transformed into a packet at the Network layer and converted to data Segment , in the application layer becomes the user's data, the receiving process is a reverse process.

Optical fiber Transmission process:

The light signal is transmitted along the optical medium by the LED or injected laser diode ild, and at the other end there is a pin or APD photodiode as the detector to receive the signal. The modulation of the optical carrier is the shift-amplitude keying method, also called the Luminance Modulation (intensitymodulation). A typical practice is to represent two binary digits at a given frequency, with the appearance and disappearance of light. Both led and injected laser diode ILD signals can be modulated in this way, and the pin and ILD detectors respond directly to brightness modulation.

Power amplification-the optical amplifier is placed before the light transmitting end to increase the optical power of the fiber. The optical power of the whole line system is improved. Online Relay Amplification-the larger buildings or the distance between buildings, can play the role of relay amplification, improve the optical power. Pre-amplification-the number is amplified after the photoelectric detector on the receiving end to improve the reception capacity.

The role of the cat

A cat is a modem that is responsible for converting the electrical signals from the computer side to the optical signal of the network layer.

Propagation of electrical and optical signals in networks