What is cable tv splitter?
The cable tv splitter extracts a small part of the energy of the input signal and sends it to one or more branch outputs, and most of the remaining energy reaches the main output port and continues to be transmitted backwards.
The branches of common catv splitters can be single, two, four, six or more, respectively called one way catv splitter, two way catv splitter, 4 way catv splitter, 6 way catv splitter, etc.
Parameters describing the characteristics of the catv cable splitter include:
(1) The so-called “insertion loss” representing the attenuation of the signal from the main input port to the main output port,
(2) The “branch loss” of signal attenuation from the main input port to the branch output port,
(3) The “port isolation” of the isolation performance between each output port (including the main output port and branch port),
(4) and indicators such as “reflection loss” of the matching performance of each port.
Whether it is a catv amplifier splitter or a CATV TAP, they are high frequency multiport devices.
catv taps and splitters is an electronic circuit that can separate a part of one or several equal signals lower than the main output signal level when a main output signal passes smoothly, and it also has good isolation.
As long as a standard impedance coaxial cable or terminal matching resistor is connected to the main output port, the open circuit or short circuit of the branch port has little effect on the input port impedance and network transmission. Cable television networks use this feature to connect the main input ports of each user terminal.
However, it is required that the main output port of each line terminal must be connected to a 75Ω standard load, neither open circuit nor short circuit, nor allowed to be used.
The role and type of catv cable splitter
There are many types of cable tv splitter. According to the number of branch ends, there are one way cable tv splitter, two way cable tv splitter and four way cable tv splitter;
According to the external structure, it can be divided into two categories: cable tv splitter and series unit.
In the same type, they are distinguished by different branch coupling losses.
Signal Amplifiers symbol series unit is also known as series catv amplifier splitter, it has two forms, one is series one unit, which itself is a one tolmnnts coaxial cable splitter, which is installed in a standard plastic user terminal box. The output end is the user’s shared antenna socket, and the input cable and output cable use Ω-type wiring cards;
The other is a two-unit series connection, which itself is a two-way catv splitter, which is also installed in a standard plastic user terminal box. One branch end is the user’s shared antenna socket, and the other branch output end is also Ω type The wiring card is connected to another user socket (often called 0dB user box) with a cable, and the input and output ports also use Ω-type wiring cards.
Tandem units are used extensively in shared antenna systems with recessed mounting.
Most of the cable tv splitters are installed in metal boxes. The input end, output end and branch end use F-type connector seats. The function of each port is represented by text or graphics on the shell. Some cable tv splitters also use line cards.
Cable tv splitters with better sealing properties allow outdoor use. Cable tv splitter is often used in a shared antenna system or a relatively scattered distribution network that adopts an exposed method.
Test method of catv amplifier splitter
The test method of catv amplifier splitter is similar to that of CATV TAP. The instruments used are still field strength meters and TV signal generators. The signal generator can also be replaced by a common antenna socket.
2. Its cabled Signal Tap not only has the task of distributing power signals; however, in addition to transmitting signals, it serves as an impedance matcher for the equipment connected to this port.
This is vital when it comes to high-frequency broadband networks.
Test of coupling loss and access loss
First, connect the input end of Signal Amplifiers to the signal generator, connect the output end of the tolmnnts coaxial cable splitter to a 75Ω resistor, adjust the signal generator to the frequency to be tested, and use a field strength meter to measure the level of the branch end, which is recorded as UB .
Then connect a 75 Ω resistor to the catv cable splitter, disconnect the 75 Ω resistor originally connected to the output end, and use a field strength meter to measure the level of the output end, which is recorded as UO.
Finally, disconnect the catv taps and splitters from the signal generator, and measure the no-load output level of the signal generator, that is, the input level of the cable tv splitter, which is recorded as UI.
So by definition:
Branch coupling loss:
Test of reverse isolation
Connect a 75Ω resistor to the input end of the catv amplifier splitter, connect the branch end to the signal generator, and use a field strength meter to measure the level of the output end, denoted as U’O. Disconnect the catv splitter from the signal generator, measure the output level of the signal generator, record it as U’I, so the reverse isolation is:
The other index characteristics of catv cable splitter, such as mutual isolation, standing wave ratio, operating frequency range, etc., are the same as those of CATV TAP.
The branch coupling loss has a certain relationship with the access loss, the smaller the branch coupling loss, the greater the access loss, and vice versa.
From the perspective of energy conservation, the input power is constant, the more power consumed by the branch end, the less power output by the output end.
For the same tolmnnts coaxial cable splitter, the access loss in the U segment is more than 1dB higher than the access loss in the V segment;
Under the same conditions of coupling loss, the access loss of the two-way cable tv splitter is larger than that of the one-way cable tv splitter, and the access loss of the four-way catv splitter is larger than that of the two-way catv splitter.
Features of catv taps and splitter
The directional coupler of a way catv amplifier splitter has 3 ports, which are called main input, main output and branch output, which are represented by A, B and C respectively in Figure 1. The branch output is taken out from the main input. A small part of the signal power, this feature is called branching feature, if the components in the tolmnnts coaxial cable splitter are lossless, then most of the power input at end A will be output from port B, if represented by PA, PB and PC respectively The input power of terminal A, the output power of terminal B and the output power of terminal C, without loss inside the catv cable splitter, should have:
There is isolation between the branch output end C of the cable tv splitter and the main output end B, that is, when each port has a matching load, if a signal is sent to the cable tv splitter from the C end, the signal will only appear in the cable tv splitter. A side but not B side.
Similarly, if a signal is sent to the cable tv splitter from the B end, the signal will only appear at the A end and not at the C end.
This isolation characteristic is similar to the isolation characteristic between the output ports of CATV TAP, but the levels of the two ports A and B are quite close (the difference between the CATV TAP is at least 3dB).
The isolation characteristic of tolmnnts coaxial cable splitter is directional: when the branch output port takes only a small part of the signal from the main signal, the level of A and B is not much different, but the A port and the B port both have signals at the same time. When the signal is connected to terminal A, the signal from terminal A will be coupled out by terminal C, while the signal transmitted from terminal B to terminal A will not be picked up by terminal C, that is, the coupling effect of terminal C is directional. The signal from B to A is set as the reflected signal, and only the incident signal or the reflected signal can be taken out by using the directional characteristics of Signal Amplifiers. This is the reason why a cable tv splitter is called a directional coupler.
For the cable TV system, the main parameters of Signal Amplifiers are branch loss, insertion loss, characteristic impedance, frequency bandwidth, isolation loss, power passing capability and so on.
Branch loss and insertion loss
The branch loss is the difference between the level of the input port A and the level of the branch output port. If the branch loss is represented by LT, the input level of the A terminal is represented by CA, and the output level of the branch terminal C is represented by Cc, then:
The larger the branch loss LT, the smaller the signal taken out from the branch port. The size of the branch loss should be selected according to the level of the cable tv splitter access point and the level required by the user (or branch line). The LT of the cable tv splitter produced by the manufacturer is generally There are from 7 to 35dB.
Insertion loss is the difference between the signal level of the main input port A and the output signal level of the main output port B. If the insertion loss is represented by LT and the signal level of port B is represented by CB, then: LT=CA-CB
Insertion loss LT represents the drop of the signal level after the line is connected to the directional coupler. Obviously, the size of the insertion loss is related to the amount of energy taken out by the branch. The smaller the branch loss and the larger the ratio of the energy taken out by the branch, the larger the insertion loss.
Isolation loss and branch isolation loss
The ideal cable tv splitter should have complete isolation between the main output port B and the branch output port C, but the actual directional coupler will be affected by the loss of components and various distribution parameters, so that the ideal isolation cannot be obtained.
When there is a reflected signal at the B end, there is still a small amount of inductive signal at the branch end C. The difference between the levels of these two ports is called the isolation loss. The isolation loss has a great influence on suppressing the local oscillator leakage interference between users. At least 25dB.
In the case of multiple branch outputs, in addition to the above indicators, an index of branch isolation loss is added, which represents the isolation degree between each branch output. Multiple branch outputs are realized by CATV TAP, so branch isolation Loss depends on the CATV TAP used.
What is the difference between cable tv splitter and CATV TAP?
1. The identification port of CATV TAP is IN Out, IN It is a two-part CATV TAP. The port identification for cable TV splitter is IN, OUT It is Signal Amplifiers split into two.
2. The signals of CATV TAP are the same. For instance, 306CATV TAP means that there is one input (IN) with three outlets (OUT). It is the number of DBs reduced through each outlet equals 6DB. Signal Amplifiers are able to be cascaded however CATV TAP can’t be used as a cascade due to the high attenuation that comes with CATV TAP connection. Connect to a CATV TAP cable to your TV immediately after the amplifier. If you have more than 2 connections to the TV, make use of a cable TV splitter to connect them all together.
3. The main difference between the catv cable splitter as well as the CATV TAP is the port for output that connects to TV is distinct. The output port on this catv splitter for your TV’s output port is known as that of the BR out port whereas it is the CATV TAP output port. CATV TAP port is an out port that outputs to the TV.
4. CATV TAP distributes the signals equally, and is commonly utilized in cable television. The Cable television splitter pulls away a portion that is the primary road, and then sends this to the high power CATV TAP part that is connected to the branch port that is known as the cable TV splitter.
5. Signal Amplifiers’ output and input levels aren’t identical, CATV TAP output and input levels are totally equal.
6. Whatever the number of tolmnts coaxial cable splitter has, there is one primary out port (OUT) and numerous branches ports (TAP) or (BR) as well as three cable TV splitters have three branch ports and so on. catv splitters and taps The attenuation (ie the loss of insertion) that the output port (out) receives (OUT) on the output signal quite minimal, typically around 1dB. The loss for the branch port (TAP) (or (BR) differs depending on the specific model.
Attenuation for catv tappings and splitters can be adjusted according to the needs of the user typically ranging from 830dB. This is due to the fact that the output attenuation of the catv amplifier splitter is so small that, in real-world situations, multiple cable television splitters are usually utilized in series for the distribution of signals for multiple terminals connected to the same line.
CATV TAP is CATV TAP can be described as an input port (IN) as well as multiple out ports (OUT). Its role will be to spread the balance of signal across all output ports.
The attenuation amount is about 2dB higher for each additional port. In other words, the attenuation for 2 CATV TAPs is four decibels as well as the other three
CATV TAPs have a 6dB attenuation. In this case, if the incoming signal from three
CATV TAPs has a 100dB signal, then the signal from 3 output ports (OUT) is 100-6 = 94dB, which is why the CATV TAP described as a balanced distribution signal.
In actual situations, it’s typically employed for events that require balanced distribution of signals and floor trunk lines for distribution. For instance the hotel has six floors. The front computer room is able to install six-way signal Amplifiers in the line’s incoming location.
Signal Amplifiersg and CATV TAP don’t solely serve to distribution of power signals However they also play an impedance matching function to the equipment that is at the port as well as dispersing the signal. This is crucial in high-frequency broadband circuits.