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RF Cable and Satellite Tutorial(Information compiled from internal and external sources. Wikipedia.org, etc.)
CATV - Community antenna television system. Offers the transmission of television signals, including those that originate at over-the-air broadcast stations, to customers on a wired network. CATV was the origin of the cable television networks known today.
Types of Splitters
- MATV Splitters - Master Antenna Television (MATV) - Antenna and distribution system which serves multiple dwelling complexes such as hotels, motels and apartments. These splitters are suitable for these applications.
- F Splitters are commonly used for CATV & FM stereo installations.
- Satellite Splitters - Satellite Splitters are used to distribute signals from a dual LNB dish to multiple satellite multiswitches. One splitter is needed on each LNB to feed the LNB signal to 2, 4, or 8 satellite multiswitches. Satellite splitters differ from standard CATV/UHF splitters and one can not be substituted for the other. Satellite splitters can not be used to feed signals from a satellite dish to multiple receivers - they must feed to satellite multiswitches.
Directional CouplersPart Numbers:
- T-Type Directional Couplers - Connections on the sides
- 201-306 6dB, 201-309 9dB, 201-312 12dB, 201-316 16dB, 201-320 20dB, 201-327 27dB, 201-330 30dB
- Plate-Mt Directional Couplers - 2 connections on the top
- 201-356 6dB, 201-359 9dB, 201-366 16dB, 201-370 20dB, 201-374 24dB, 201-377 27dB, 201-380 30dB
Tap Loss - The most important parameter of a directional coupler is the tap loss. Tap loss is how much lower the signal level at the tap output is, compared to the signal level at the input. Common tap loss values range from 3 dB to 28 dB. Directional couplers are placed at various locations throughout a distribution system based upon the required tap loss and signal level needed. If, for example, the signal level on a line is 28 dBm V, a directional coupler having a tap loss of 28 dB would be used to provide the signal of 0dBmV needed for a subscriber tap.
Insertion Loss - The insertion loss of a directional coupler should be quite small, typically about 1.5 dB.
Isolation - The isolation of a directional coupler becomes greater as the tap loss increases, with a typical isolation of 20 dB for a 3 dB directional coupler.
DC Voltage Blocking CouplerDC Voltage Blocking Couplers (DC Blocks) are special connectors which have a capacitor (high pass filter) built into the device. These block DC on splitters and switches on coaxial lines.
LNBF - Low Noise Block ConverterPart Number:
- 200-582 - DSS Dual Hughes-type LNB
There are two main types of LNBs. The most popular type is the LNB that is attached to a feedhorn and uses an external servo motor to turn a probe inside of the feedhorn to select the polarity of the desired channel. The other type of LNB is actually called an LNBF, where the LNB and feedhorn are one unit and the polarity is switched when the receiver changes the voltage (either 13 or 18 volts) going to the LNBF at the dish. Depending on what voltage is sent to the LNBF by the receiver, either the horizontal or vertical antenna probe inside the throat of the LNBF will be selected. LNBFs are also used on the smaller DBS satellite systems.
- CATV Amplifiers - CATV amplifiers are added to a television distribution system to reduce the graininess found on underpowered television channels.
- CATV Drop Amplifiers - Indoor Home / Apartment CATV drop amplifiers compensate for long cable drops or multiple TV sets.
- 2 Way Broadband Amplifiers - Indoor Home / Apartment CATV multimedia amplifiers. Suitable for Internet modem digital applications. Compensate for long cable drops or multiple devices.
- Cascade Trunk Amplifier - Repeater amplifier for cascade multiswitch system.
- Trunk Line - The major distribution cable used in cable television. It divides into feeder lines which are tapped for service to subscribers.
- Trunk Amplifiers - The amplifiers along the trunk line responsible for maintaining signal strength must have low distortion, low noise, and moderate gain. Degradation of the signal along the trunk cannot be corrected downstream, in fact, cascade amplifiers with similar faults simply amplify the fault too. Trunk amplifiers compensate for cable losses with automatic slope control (ASC) and automatic gain control (AGC).
Distribution AmplifiersPart Numbers:
- 200-680 - 30dB 47-750MHz Distribution Amp
To determine whether or not you need a distribution amplifier, remove any signal splitters that may be connected to the TV antenna (or other source) and connect only one TV to the antenna. If the TV reception is good on this one TV, then reconnect the signal splitter(s) and check the reception on the other TV's.
If there is a noticeable reception difference between when the one TV was connected directly to the antenna and when the splitter was reconnected, then a distribution amplifier will probably be needed.
There are many different types of distribution amplifiers. Some are designed to amplify just off-air broadcast channels and others are designed to amplify off-air and cable channels. There are even some that have one, two and four output splitters built right into the amplifier.
Band Seperator CombinersPart Numbers:
Signal CombinersPart Numbers:
Inline Signal AmplifiersPart Numbers:
- Single - Has 1 Input/Output
- Dual - Has 2 Inputs/Outputs
- 201-680 - 12-16dB Sloped Dual Inline Amplifier
Inline Signal Strength Attenuator PadsPart Numbers:
- DC-Block Attenuators - Blocks DC power
- 201-403 3dB, 201-406 6dB, 201-408 8dB, 201-410 10dB, 201-412 12dB, 201-416 16dB, 201-420 20dB
- DC Passing Attenuators - Does not block DC power
- 201-503 3dB, 201-606 6dB, 201-508 8dB, 201-516 16dB, 201-520 20dB
TV - Satellite Diplexer / MixerPart Numbers:
- 201-252 - 2GHz TV-Satellite Mini-Diplexer
- 201-254 - 40-2050MHz TV-Satellie Mini-Diplexer
- 201-738 - 3x8 TV-Satellite Multi-Switch
- Satellite Multiswitches
- 22KHz Satellite Multiswitches
- SkySwitcher Multiswitches
- Cascade Multiswitches
What is the 2x4, 2x8, 3x4, 3x8, 4x4, 4x8, 5x4 & 5x8 designations mean when referring to a multiswitch?
The first number is the number of inputs from the dish (or antenna) the switch has. The second number is the number of outputs the switch has.
A 5x8 multiswitch would handle 4 DTV inputs (Two Dual LNBs looking at the two satellites) and a Cable TV or antenna input if you wanted. It would have 8 outputs that could go to 8 DirectTV receivers, 4 Dual Tuner DirectTivos or any combo in between.
What is a cascadable multiswitch?
The receiver will send a 22khz tone to tell the multiswitch that it wants the 119 degree satellite. This tone is only used by the multiswitch and is not sent back up to the LNB's....if you have two 4xn switches connected or a 4xn multiswitch connected to the built in multiswitch on a dish, the "2nd" one will never tell the "1st" one that it needs to see the 119 so the receivers connected to the "2nd" one would ONLY see the 101 satellite.
There are switches designated as "cascadable" that WILL send that 22khz tone upstream, thereby allowing you to connect it in series with another multiswitch (such as a built in one on the dish).
How many inputs do I need on a multiswitch?
If you have an 18" dual LNB dish, you have 2 outputs from the dish, therefore only need a "2 x n" switch meaning 2 inputs from dish and "n" output (to be determined at next step.
If you have an Elliptical dish (or 2 18" dishes looking at different satellites), you will need a "4 x n" switch meaning 4 inputs (from dish) and "n" outputs.
You will also see switches listed as "3 x n" or "5 x n"...This just means that there is an extra input for Antenna or CableTV. These switches allow you to combine an Antenna/CableTV signal onto the same RG6 cables as your DirectTV signal and split it out at the TV end. This saves you valuable cabling issues since you will only have to run 1 cable to a receiver instead of 2 (or 2 cables instead of 3 in the case of DirectTiVos)
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