FAQ: Satellite dishes and LNBs


FAQ B.1
How can I improve the quality of a signal received from satellite?


The highest quality of a signal received from the satellite is obtained at the output of LNB. To improve the quality of the received signal is necessary to increase the diameter of the satellite dish. Small improvements can also be obtained using an LNB with lower noise figure.
The other devices (such as amplifiers, switches or multiswitches) are not able to improve the signal quality.
LNBs
Steel satellite dishes
Aluminium satellite dishes

FAQ B.2
What kind of dish is more advisable to choose between the steel and the aluminium models?


Steel satellite dishes have a lower cost than the aluminium versions, but aluminium satellite dishes have higher immunity to adverse conditions that assures a longer duration in time (e.g. they aren't subject to rust).

FAQ B.3
Can I install the satellite dish on the same mast to which are fixed the TV antennas?


Yes, but being careful to check beforehand that the chosen model can be mounted in this conditions. E.g., satellite dishes PO88 series are equipped with mast clamp with a maximum elevation of 48° that allows to mount the satellite dish throughout Italy not only on the top of the mast, without using cantilevered brackets.

FAQ B.4
At 1800 MHz on the SAT frequency spectrum there is a peak: what is it?


This may be a disturbance generated by 4G systems in LTE band. To overcome this drawback OFFEL has a wide range of LTE ready LNBs,  characterized by a high shielding efficiency.

FAQ B.5
Are the LNBs all alike?

No. Depending on the application, there are different types of LNBs:
● Legacy LNB: LNB with 1, 2, 4 or 8 independent outputs (depending on the model), to each of which it can be connected at a time a single receiver that uses 13÷18 V 0÷22 KHz switching commands;
● H-V-H-V LNB: LNB with 4 outputs (each of which distributes one of the 4 polarities V/H, H/H, V/L, H/L), used in centralized systems in combination with multiswitches;
● SCR LNB: LNB with 1 SCR output (and, depending on the model, with 1 or 2 Legacy outputs), to which it is possible to connect up to 4 devices, independent of each other, which use the switching commands typical of SCR/dCSS standard;
● dCSS LNB: LNB with 1 dCSS output, capable of generating up to 16 User Bands, to which it is possible to connect as many devices with dCSS or SCR technology (limited to the first 4 User Bands), that use the switching commands typical of SCR/dCSS standard;
Finally, there are optical LNBs, which have an output which is connected to fiber optic patch cords. The optical signal coming from the optical LNB output has to be converted by suitable devices (optical receivers) into an electrical signal in order to be finally distributed to the decoders via coaxial cable.

FAQ B.6
Can I connect more decoders, independent of each other, to the same output of the LNB?

Yes, but only if the LNB is a SCR model or dCSS model.
With SCR model you can connect up to 4 independent tuners on the same cable thanks to the employ of 4 user bands.
With dCSS model, instead, you can connect up to 16 independent tuners on the same cable thanks to the employ of 16 user bands.
dCSS LNBs

FAQ B.7
Some time ago I installed a SCR LNB in a system, but now it doesn't work anymore and my trusted dealer told me that it is an obsolete product. What product can replace it?

To replace a SCR LNB you can purchase a dCSS LNB, minding that dCSS LNB has no Legacy output.
The dCSS technology (see FAQ K.6), indeed, is none other than the evolution of SCR technology (see FAQ K.5) in digital key.
Exploiting the 4 frequencies already used by the SCR plus other 12 frequencies to allow multiple users, connected to a unicable distribution, to receive satellite programs independently from each other, the dCSS technology is fully backward compatible with SCR technology.
For more info on the two types of LNBs see FAQ B.5.

FAQ B.8
I replaced the universal LNB with single output in my possession with a new dCSS LNB, but the decoder is not able to receive any channels anymore. How can I solve my problem?

If the decoder considers as switching commands those of SCR/dCSS standard, it will be simply enough program the decoder in SCR (such as in case of the today decoders with SCR technology) or dCSS mode (such as in case of the next-generation multituner decoders).
If the decoder only considers 13÷18 V 0÷22 KHz switching commands, it can be only connected to devices (LNBs or multiswitches) equipped with Legacy outputs.

FAQ B.9
What kind of decoders can be connected to the output of a dCSS LNB?

Since the dCSS technology is backwards compatible with SCR technology, you can connect to the output of a dCSS LNB both the next-generation multituner decoders (with dCSS technology) and the today decoders with SCR technology.

FAQ B.10
Can I distribute satellite signals within a condominium exploiting the pre-existing unicable distribution?

If previously laid cables, splitters/taps and outlets are suitable for satellite signals distribution, you can leverage the existing distribution using a dCSS LNB cod. 13-210 LNB dCSS 32 porte, programmed in static mode, and a SAT in line amplifier.
This LNB, indeed, if programmed in static mode, can assign to a maximum of 32 transponders as many frequencies in band 1 IF. The 32 selected transponders can be distributed to a potentially unlimited number of users.
A detached programmer (cod. 15-701 P-MSW dCSS) allows to reconfigure the LNB setup whenever it is necessary to change the selected frequencies.
If in a TV system there is already a H-V-H-V LNB installed on the satellite dish, a multiswitch cod. 15-700 MSW52 dCSS 32 porte can be used alternatively to cod. 13-210 LNB dCSS 32 porte.

FAQ B.11
What's the difference between cod. 13-205 LNB dCSS WHITE 16 porte and cod. 13-210 LNB dCSS 32 porte?

Both of these models are equipped with a dCSS output, which allows to distribute a potentially unlimited number of transponders to a maximum of 16 devices, independent of each other.
Furthermore, cod. 13-210 LNB dCSS 32 porte can be alternatively programmed to assign to a maximum of 32 transponders as many frequencies in band 1 IF. The 32 selected transponders can be distributed to a potentially unlimited number of users.
dCSS LNBs

FAQ B.12
What is the practical utility of dCSS programmer?

The dCSS programmer (cod. 15-701 P-MSW dCSS) is a device that allows the configuration and diagnosis of dCSS LNBs and dCSS multiswitches with 32 User Bands via PC.
It allows to:
• change the operation mode (static or dynamic);
• modify, in static mode, the IF frequencies and the corresponding RF transponders of tunable channels;
• retrieve the pre-existing configuration.

FAQ B.13
What do you mean by "dCSS Ready" TV system?

A TV system can be considered "dCSS Ready" when keeps unchanged performance in the use of today decoders with SCR technology thanks to backwards compatibility and at the same time it is already prepared for next-generation multituner decoders, available in a not too distant future, which will offer more powerful features.

FAQ B.14
What do you mean when you talk about "Wide band" LNBs?

When you talk about Wide band LNBs you mean a category of LNBs able to distribute the signals received from a satellite on two broadband outputs (the first one dedicated to vertical polarization, the other one dedicated to horizontal polarization), in the frequency range 250-2350 MHz. They must be used in combination with multiswitches of the same type (see FAQ H.14).