Satellite LNB LNBF Terms & Info Page
A brief discussion of Satellite TVRO LNB terms and uses for C Band and Ku Band Satellite Signals.
LNBs
LNB stands for Low Noise Block downconverter. Early Satellite systems used what was called a LNA or Low Noise Amplifier and no conversion was done in the LNA.
Ku Types
"DBS" LNB works from 11.7 - 12.5 GHz. Has a 10.75 GHz local oscillator (LO) and is used with a receiver having a .95 - 1.75 GHz tuner. We currently sell these with a noise temperature down to .5 dB. This type of LNB will need a polarizer to change polarity.Here is a picture of a typical DBS LNB:
"STANDARD" LNB has a 10 GHz LO and works for one band only. Normally has
a feed horn assembly built onto the LNB. This LNBs polarization switching
is done by a DC voltage on the coax - 12.5 to 14.5 volts gives vertical
and 15.5 to 18 volts gives horizontal.
"UNIVERSAL" LNB works in two bands, 10.8 to 11.8 GHz and 11.6 to 12.7 GHz while
having LOs of 9.75 and 10.60 GHz. Band switching is done via a 22 KHz tone
sent from the satellite receiver. With the tone on the LO is 10.6 GHz, otherwise
it is 9.75 GHz. Polarization is controlled the same as in the "STANDARD" LNB.
"ENHANCED" LNB works from 10.7 to 11.7 GHz and has a 9.75 GHz LO. These were designed for the Astra satellites and have a built in feed assembly. Polarization is controlled the same as the "STANDARD" LNB. Br>
"C BAND" - Here is a picture of one type of C-Band LNB that we sell. We won't get into C Band LOs since most current consumer models are the same for all practical purposes. One caveat on LNBs - spending more money isn't the way to get a better LNB. We have used a vast number of LNBs from many different companies over the last 20 years and most of today's LNBs are basicly of the same engineering and design. Claims of a high suggested retail price, best of the market, and other snake oil pitches are like asking a Chevy salesman what he thinks of Fords. Fall for the pitch and your wallet will suffer, but your satellite won't work any better. There are certain specific applications that require a "High Stability" type LO, but again unless your application demands it, most of the current ones are fine. 4DTV and MPEG-2 receivers get along just fine with the normal LNB.
Here is a typical C Band LNB that we sell...
OK ... BUT WHAT IS THIS LO BUSINESS ANYWAY ?
LO stands for local oscillator and the function of the LNB is to reduce the frequency of the satellite signal to a signal your satellite receiver can acutally tune. This is done by subtracting the LO frequency from the satellite frequency. Different LOs give different frequency ranges.
Lets assume for example that you are receiving a satellite signal on a frequency of 12 GHz. For your receiver to work, this signal must be converted to something usable. Let pretend you have a DBS LNB...
12 GHz minus 10.75 GHz gives a frequency of 1.25 GHz (or 1250 MHz). Since most receivers have a tuning range of about .950 to 1.450 GHz or more (950 to 1450 MHZ), this is usable and within the tuning range of the receiver.
SIMPLE ? You bet !
Whats this 22 KHz stuff ?
The UNIVERSAL LNB noted above can switch bands, one high - one low. How this is done is by sending a tone to the LNB. The tone frequency is 22 KHz. When the LNB hears the tone it switches to the high range. Without the tone, the LNB is switched to the low range. Simple! Most receivers of modern vintage are including this tone function built in. A seperate tone box is available for those receivers that do not have it.
Expanding on this idea, one can also do other things. For example, we sell switches that use this tone. Say you have one receiver, but two dishes. Now, you could run two lines, use a manual switch box or manually hook and unhook the coax, etc. Save some time with a 22 KHz switch. Place the switch out by your dishes, run one coax, and run the coax from each LNB to the switch. When the switch either hears or doesn't hear the tone, it is going to switch coaxes.
DiSEqC is a more expanded concept of this switching arrangement. DiSEqC stands for Digital Satellite Equipment Control. Through various level of the DiSEqC versions one can switch LNBs, move dishes, etc.
The Astrotel 15 Degree C Band LNB Has Excellent Specs:
Need more information on C & Ku Band equipment, please contact us.
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ENJOY !
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