| 1. |
To receive all kinds of wireless broadcasts, an antenna is necessary.
The type of antenna varies with the kind of broadcast to be received. Satellite broadcasts require a special satellite antenna called "dish" or "satellite dish".
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| 2. |
Currently satellite broadcasts use two different frequency bands: C-Band with a frequency range from 3.7 to 4.2GHz and Ku-Band, which is divided in a low band from 10.7GHz to 11.7GHz (Lo: 9.75 GHz) and a high band from 11.7GHz to 12.75GHz (Lo: 10.6GHz).
* Lo = Local Oscillation
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| 3. |
The satellite signal is reflected from the dish to the Freed-Horn and from there directed to the LNB (Low Noise Block Down Converter).
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| 4. |
The LNB detects the signal relayed from the feed, converts it to an electrical current, amplifies it and lowers its frequency. The output level of a typical LNB is around 55-65dBuV.
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| 5. |
The European satellite TV system:
Low band: 10.7GHz - 11.7GHz (Lo: 9.75GHz)
High band: 11.7GHz - 12.75GHz (Lo: 10.6GHz)
Therefore the frequency range from the LNB for the Low band is:
950MHz-1950MHz (10.7GHz minus 9.75GHz) to (11.7GHz minus 9.75GHz) and
for the High band:
1100MHz-2150MHz (11.7GHz minus 10.6GHz) to (12.75GHz minus 10.6GHz)
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| 6. |
To avoid interference between odd and even numbered channels, adjacent frequencies are polarized in opposite directions. Satellites usually broadcast signals with either vertical, horizontal, left hand circular (counter-clockwise rotation) and right hand circular (clockwise rotation) polarization.
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| 7. |
The receiver uses different voltages to signal the LNB to select between
vertical (V) and horizontal (H) satellite signals.
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| 8. |
The voltage used by the receiver to signal the LNB to choose between vertical and horizontal signals is 12-14V for vertical and 15-18V for horizontal mode. Therefore multi-switches usually operate at a voltage range of 14.6V+/-0.3V.
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| 9. |
Currently LNBs can be divided into "Universal" LNB, "Twin LNB" (Universal Twin LNB) and "Quattro LNB".
What is a "Universal LNB" ?
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LNB's Lable :
One Outlet |
Note:
Only one F-type outlet |
Lo band (10.7-11.7GHz)
Hi band (11.7GHz-12.75GHz) |
Can receive two bands, analog Lo band and digital Hi band. |
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LO (9.75GHz + 10.6GHz) |
Two oscillation frequencies for Lo and Hi band. |
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1x H+V |
1 (one F-type outlet), H (horizontal), V (vertical). |
This type of LNB has one F-type outlet and can receive "Lo band H+V" and "Hi band H+V". It is often used for normal family type setups.
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What is a "Twin LNB" (Universal Twin LNB) ?
An "Universal Twin LNB" is two "Universal LNBs" in a twin box (for both Hi and Lo band). A "Twin LNB" or "Analog Twin LNB" is two analog LNBs in a twin box (only analog Lo band). See also ASTRA webpage.
What is a "Quattro LNB" ?
This type of LNB is used in SMATV systems. It has four F-type connectors: "Lo band V", "Lo band H", "Hi band V", "Hi band H" and is often used with a 5xn or 9xn multiswitch.
* "Quattro LNB" is also called "Quattro-band LNB" or "Quad LNB", see also ASTRA webpage.
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| 10. |
3x4 or 2x4 multiswitches are used with Twin LNBs. When more than two receivers share one satellite dish multiswitches are also necessary.
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