GT-Sat GT-S1DCSS24 SCR/dCSS Single Cable Unicable II LNB Specifications

[CRMS]

This is in the GT-Sat GT-S1DCSS24 SCR/dCSS Single Cable Unicable II LNB specs:

Gain 42 ~ 62 dB (Programmable with 1dB step)

Can someone please explain???

[adm]

This is in the GT-Sat GT-S1DCSS24 SCR/dCSS Single Cable Unicable II LNB specs:

Gain 42 ~ 62 dB (Programmable with 1dB step)

Can someone please explain???

The LNB has a programmable gain stage :)

The attenuation (signal reduction) from your LNB to your receiver is dependant on cable length, cable type and the number of splitters used (splitters for a unicable LNB).

The attenuation in a cable is dependant on its length. While on a domestic property the length of cable from the LNB to your receiver may be 10 metres in a block of flats it may be considerably more, maybe 100+ metres.

A good quality Webro WF100 cable may have an attenuation of 32dB (per 100m) at the top end of the frequency band that a unicable LNB uses but something lesser, or thinner, you may buy on ebay for satellite use may have an attenuation of 42dB (per 100m), or even 48db (per 100m) for the thinner shotgun cable now favoured by sky installers. Note the dB scale is log not linear

32db attenuation is a reduction in signal level of approx x40
48db attenuation is a reduction in signal level of approx x250
(For 100 metres of cable at the top frequency that a unicable LNB will push down the lead – worst case)

Every splitter that you place in the system adds to the signal attenuation
Each two way splitter adds 4dB of attenuation
Each 4 way splitter adds 8dB of attenuation

If external to the receiver you were splitting the signal 8 ways you would introduce an attenuation of perhaps 16db (worst case)

I assume that on the LNB you quote the manufactures have added a facility to amplify the signal to take into account any losses between the LNB and the receiver input, or possibly any variation in different installations. More is not always better. Too much signal may actually overload the input of your receiver (in a non-critical way) and provide a less reliable picture. Greater amplification of signal also results in greater amplification of noise. Probably best to leave the default value of gain for a domestic installation.

Old article on cable so prices are way out of date and related more to terrestrial digital TV but it does highlight why good quality cable is essential.



http://www.wrightsaerials.co.uk/articles/coax-cable-quality.shtml


Edit:
You may need other equipment to change any of the default settings


https://3af9835c-9418-4410-bbb4-06ab10bdb4c7.filesusr.com/ugd/daa89c_fcdd7be94a0a47f98d6ad25a14ad8ab3.pdf