A low-noise block downconverter, or LNB, and coaxial cable are two important components of a satellite television system. Those looking to put together their own satellite reception systems before subscribing to a satellite television service should be familiar with these components and how they work with one another. This helps ensure successful transmission of as strong satellite signal from the satellite dish to the television. Those looking to watch satellite television on multiple televisions in a home should also be familiar with quad LNBs. These are capable of outputting to multiple receivers without degrading the signal. Learning how quad LNBs work with coaxial cables to deliver satellite signals from satellite dishes to televisions can help consumers understand both coaxial cables and quad LNBs and how they work in conjunction with one another.Further, owners should successfully establish working connections between their satellite dishes and the multiple televisions in their homes using quad LNBs and coaxial cables.
Understand Coaxial Cable
The following section presents basic information about a coaxial cable, including an explanation of what it is and describes the different types available for use in satellite television systems.
What Is Coaxial Cable?
A coaxial cable is important to many types of telecommunication because it transfers radio frequency signals. It carries signals from antennas to radio transmitters and receivers and televisions. It also transmits radio frequency signals from cable television outlets and satellite dishes to receivers and then on to televisions. It usually features a four-layer construction of a conducting wire in the middle, wrapped in an insulating layer with another tubular conducting layer around it and a protective outer layer made from plastic or rubber.
Which Types of Coaxial Cable Are Best for Satellite Television?
There are many types of coaxial cable, but a few are suitable for satellite television because of their combination of low-cost and effectiveness. The table below points out and briefly describes the best types of coaxial cable for satellite television.
Diameter of about 4.8mm
Flexible and difficult to kink
Signal loss is high, at 0.5 decibels per metre when connected to an LNB.
Diameter of about 6.7mm
More flexible than WF65
Bends further without kinking
Loses less signal strength
Similar to RG6, though slightly wider with a diameter of about 6.8mm
Signal loss of 0.29dB/m when connected to an LNB
Diameter of 7.1mm
Not too flexible, but does bend quite far without kinking
Signal loss with an LNB is 0.27dB/m
The quality of the coaxial cable is a contributing factor to how strong the signal is, which reaches the receiver. It is also important to be aware that coaxial cables designed for television systems, including satellite, are not capable of transmitting extraordinarily high frequency signals. Satellite signals have frequencies outside of the range that is compatible with these coaxial cables, meaning that the signals must be processed in order for the coaxial cables to deliver them. The following section on LNBs explains this in greater depth.
LNBs are responsible for processing satellite signals so that coaxial cables can carry them to satellite receivers. This section describes this process and points out a few different types of LNBs based on how many coaxial outputs they have.
How Does an LNB Work?
An LNB features a low-noise amplifier, an oscillator, a frequency mixer, and an intermediate frequency amplifier. Modern LNBs are also constructed with a feedhorn and a polariser, which used to be separate components outside of the LNB housing.
The dish collects satellite signals and the feedhorn collects a signal from the dish after the polariser chooses between vertically and horizontally polarised signals. Digital satellite signals have a general frequency range of 10-14 GHz and are weak since they come from satellites above the earth’s atmosphere. The low-noise amplifier strengthens the signal while adding a minimum of noise. The oscillator produces a second signal inside the LNB and the frequency mixer blends this signal with the amplified satellite signal. One signal contains the sum of the two signals’ frequencies and the other the difference between the two signals’ frequencies. The lower-frequency signal in the UK is between 950-1950 MHz or 1100-2150 MHz, depending on the frequency of the original satellite signal. The LNB filters out the higher-frequency signal and passes the lower-frequency signal, which is considered an intermediate frequency, to another amplifier that strengthens the signal again before outputting it to the coaxial cables.
Different Types of LNBs
One way to characterise LNBs is by the number of outputs they have. An LNB with two outputs is a twin LNB, an LNB with four outputs is a quad LNB, and one with eight outputs is an octo LNB. There are also quattro LNBs that have four outputs, but these divide the signals into channel blocks with each output handling its own block of signals. A quattro LNB then connects to a multiswitch, to which dozens of satellite receivers can connect. A quattro is thus useful in an apartment building where all of the tenants share a single satellite dish. It should not be confused with a quad LNB, which outputs directly to multiple receivers (up to four).
Using a Quad LNB with Cable
This section describes using a quad LNB with coaxial cable. It gives the reasons for using a quad LNB, explains how to connect coaxial cables to a quad LNB, and provides advice about running coaxial cable through a home and manipulating the satellite signal.
Why Use a Quad LNB?
A quad LNB is useful for anyone planning to connect three or four different satellite receivers to the same satellite dish. It is capable of running four coaxial cables to different receivers, allowing people in different rooms to watch whatever they please on the television. Sky and Freesat satellite receivers that allow viewers to record a programme on one station while they watch a different programme on another station have two inputs, one for viewing and the other for recording to a hard drive in the receiver. Users that want full-functionality out of such receivers must dedicate two outputs on the LNB to such a receiver, limiting the total number of receivers they can connect to a quad LNB. Sky satellite subscribers should also be aware that Sky LNBs are limited in the number of satellite dishes with which they are compatible. These subscribers should consult Sky as to the compatibility of quad LNBs they are interested in buying.
Connecting Cable to a Quad LNB
Connecting coaxial cable to a quad LNB is a relatively simple process, assuming that the satellite dish is reachable without any special equipment. If it is, simply screw the metal male f connectors on one side of the coaxial cables onto the female f connectors on the quad LNB. Before doing this though, be sure to apply silicone grease to the male ends. This helps keep them free from rust that bad weather can cause over time. Some f connector systems feature a spring-loaded male end on which the user pulls back the metal sheath to expose the metal male piece. The user inserts this piece into the female end and releases the sheath, which forms a connection with the cylinder on the female end.
After all of the coaxial cables are connected to the quad LNB, use a tie cable to fix them to the arm on which the LNB rests. This keeps the cables orderly and prevent unsightly dangling. Next, put self-amalgamating tape around the coaxial cable connections to the LNB. This keeps the connections from getting wet when it is raining, which causes the signal to degrade to the point where it is unwatchable on televisions. Seal any unused coaxial outputs on the LNB with a product such as Blu Tack to keep the LNB from absorbing moisture through these unused outputs.After taking these measures, connect the other male ends of the coaxial cables to the receivers inside the house. The LNB and coaxial cable system should now be ready for use.
Running Cable Through a Home
It is best to use coaxial cables that are as short as possible. The signal loses strength, or attenuates, the further it has to travel through coaxial cable. If a cable is not long enough to reach a receiver, it is possible to buy an f barrel, which is a barrel with female f connector parts on both ends, and another length of coaxial cable. It should be possible, therefore, to reach every receiver in a home with coaxial cable.
Manipulating the Signal
Many people interested in installing satellite television in their homes and many who already have it want to know if it is possible to manipulate the signal coming from the LNB. This section explains the implications of trying to split and amplify a satellite signal.
Splitting the Signal
Although it is possible to split a cable television signal so that two receivers can connect to the same output, this is not possible for a satellite signal. The receivers that share an LNB outlet compete with one another over the signal from that outlet with one receiver winning control over it by obtaining reception. It is therefore not possible to have all four receivers work at the same time when they are attached to a twin LNB. A quad LNB would be necessary instead.
Amplifying the Signal
Signal amplification is another popular modification. This can be helpful for satellite signals that attenuate while running through long lengths of coaxial cable. The first thing to do is to check whether or not placing the receiver closer to the LNB and on a shorter length of coaxial cable improves the signal. If it does, a satellite signal amplifier may help on a longer length of cable. Place the amplifier between the LNB output and the coaxial cable input. Placing it by the satellite receiver amplifies the signal as well, but also any noise that the signal picked up along its journey through the cable.
How to Buy Coaxial Cable and a Quad LNB on eBay
It is possible to buy coaxial cable from a wide variety of sources, including local and online shops that sell audio and video equipment. Those looking for quad LNBs may find them at local and online shops that sell satellite television equipment. Many of these also sell various kinds of coaxial cable, providing for one-stop shopping. eBay has many listings for both quad LNBs and coaxial cable. To find either, go to any eBay page, enter a term such as "quad LNB" or "RG6 coaxial cable" into the search bar, and click the search button. You should get a list of results relevant to your search. The coaxial cable may not come with connectors, so you may have to search for f connectors separately.
eBay makes it possible to filter the search results by distance from your postcode. The closer sellers are located to you, the less time and money is likely necessary for shipping. You may even be able to arrange an in-person pickup if the seller agrees to it.
LNBs are important devices in satellite television systems because they strengthen a satellite signal in order to make it viewable on a television. Of equal importance, they also reduce the frequency of satellite signals to make them suitable for delivery via inexpensive coaxial cables. This guide has explained how LNBs and coaxial cables work together to make satellite signals viewable on television. It has focused on the use of quad LNBs because many satellite television subscribers and many of those interested in subscribing to a service, want to use a single satellite dish for watching programming on multiple televisions. This guide has explained how to connect coaxial cables to quad LNBs and provided a few tips for maintaining the integrity of the connections. It has also pointed out a few key points about manipulating a satellite signal coming through a quad LNB, including pointing out the limitations of splitting the signal and the possibility of amplifying the signal. Using the knowledge gained from this guide, readers should be able to effectively use quad LNBs with coaxial cables to deliver the best signal possible from their satellite dishes to their televisions.