What are cable TV system splitters and distributors?

The branch splitter is a passive device for high frequency broadband signal power distribution. Its bandwidth has reached 5-1000MHz at present, its structure is simple, the price is low, and the work does not require power supply, and it is widely used in the field of HFC cable TV. The branch distributor is divided into two types: indoor type and outdoor type to meet the needs of different environments. In addition to being waterproof, field-type devices usually have over-current capabilities to accommodate networks that require power over cables.

Definition and function of branch allocator

Splitter: The power level distribution device that takes a small part of the signal from the main road and sends it to the branch port is called a splitter. The output/input ports of the main circuit are represented by OUT and IN respectively, and the branch ports of the branch circuits are represented by BR/TAP.

Function: Part of the signal is separated from the transmission trunk line or distribution line with a small insertion loss, and sent to each user after attenuation.

Distributor: The power level distribution device that divides the input signal equally to the output port is called a Distributor. The output/input ports are represented by OUT and IN respectively.

Function:

1. Distribution function: Divide the power of the input signal into several channels evenly.

2. Isolation: The signal at one output has no effect on the other output.

3. Matching function: The impedance of the output end and the input end are both 75 ohms.

How the branch allocator works and How the dispenser works

Two and three distributors are the most basic distributors, and the rest are composed of them.The working principle of the second distributor

l Matching circuit: ensure impedance matching.

l Distribution circuit: The principle of distributing the input signal to the two input terminals equally, and isolating the two and three distributors is the same as that of the two distributors.

Technical indicators of the distributor

1. Distribution loss (loss): the difference between the level of the output end and the input end.

2. Isolation: adding a signal at one output and measuring the signal at the other output, the difference in signal level is called mutual isolation.

3. Impedance: Input and output impedance is generally 75Ω

4. Voltage standing wave ratio: the difference between the reflected signal power in decibels and the input signal power in decibels

Technical indicators of the splitter

1. Insertion loss: The level difference between the output level of the main circuit and the input level.

2. Branch loss: the level difference between the branch output level and the input level.

3. Reverse isolation: add a signal to the output of this branch, measure this signal at the main circuit output, and the difference between its signal levels is called reverse isolation.

4. Mutual isolation: For a multi-branch output branch, a signal is added to one branch output, and the signal is measured at the other branch output. The difference between the signal levels is called mutual isolation.

Naming rules for branch allocators

The naming of branches/distributors is usually determined by the manufacturer, but there are certain rules to follow. They are generally the main part of the name determined by the number of branches and the amount of attenuation.

Such as: a splitter, the branch attenuation is 8dB, it is called 108; the two splitter with a branch attenuation of 14dB, it can be called 214..., four splitters, the output attenuation is 8dB, called 408.