A Duo LNB is a double

low-noise block downconverter A low-noise block downconverter (LNB) is the receiving device mounted on satellite dishes used for satellite TV reception, which collects the radio waves from the dish and converts them to a signal which is sent through a cable to the receiver i ...

(LNB) developed by

SES SES, S.E.S., Ses and similar variants can refere to: Business and economics * Socioeconomic status * Scottish Economic Society, a learned society in Scotland * SES, callsign of the TV station SES/RTS (Mount Gambier, South Australia) * SES S.A., ...

for the simultaneous reception of satellite television signals from both the

Astra 23.5°E Astra 23.5°E is a group of Astra (satellite), Astra communications satellites co-located at the 23.5° east position in the Clarke Belt owned and operated by SES S.A., SES based in Betzdorf, Luxembourg. 23.5° east is one of the major TV satellite ...

and

Astra 19.2°E Astra 19.2°E is the name for the group of Astra communications satellites co-located at the 19.2°East orbital position in the Clarke Belt that are owned and operated by SES based in Betzdorf, Luxembourg. Astra 19.2°E used to be commonly k ...

satellite positions. It is a

monoblock LNB A monoblock (or monobloc) LNB is a type of low-noise block downconverter used in communications satellite reception, this multiple combined LNBs is the simplest solution to achieve multifeed reception for two, three or four satellites. This desi ...

, which comprises two feedhorns with a single body of electronics containing the LNB stages along with switching circuitry to select which received signal is passed to the output(s). The Duo LNB uses linear polarisation.

Availability

A Duo LNB can be purchased in most parts of Europe but it is particularly marketed to

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, the

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Belgium Belgium, ; french: Belgique ; german: Belgien officially the Kingdom of Belgium, is a country in Northwestern Europe. The country is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeast, France to th ...

Czechia The Czech Republic, or simply Czechia, is a landlocked country in Central Europe. Historically known as Bohemia, it is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the southeast. The Cz ...

and

Slovakia Slovakia (; sk, Slovensko ), officially the Slovak Republic ( sk, Slovenská republika, links=no ), is a landlocked country in Central Europe. It is bordered by Poland to the north, Ukraine to the east, Hungary to the south, Austria to the s ...

.SES ASTRA "Duo LNB" (August, 2008). Company factsheet Duo LNBs operate as universal LNBs and are manufactured under various brand names, such as Maximum and Inverto, in single, twin-output and quad-output versions – with one, two and four outputs (independently selectable for polarisation and frequency band), respectively, for one, two or four receivers/tuners. The Duo LNB is available in two versions - the original Duo LNB for dishes of 80 cm or 85 cm diameter and the Duo LNB II for dishes of 60 cm.

Background

The Astra 23.5°E orbital position was established as a major source of

direct-to-home Satellite television is a service that delivers television programming to viewers by relaying it from a communications satellite orbiting the Earth directly to the viewer's location. The signals are received via an outdoor parabolic antenna commo ...

(DTH) broadcasts for central and western Europe with the launch of

Astra 3A Astra 3A is one of the Astra communications satellites owned and operated by Société Européenne des Satellites, launched in March 2002 to the Astra 23.5°E orbital position to provide digital television and radio for direct to home (DTH) an ...

at the end of 2007, and some channels moved there from other satellite positions (in particular 19.2° east) so viewers, who were unable to erect two dishes to receive transmissions from both positions, had to choose between them. In particular, the Czech CS Link and Slovak SkyLink networks moved to Astra 23.5°E, and the Dutch Canal Digitaal launched a new thematic bouquet at 23.5° east in October 2007. The Dutch regional broadcasters all moved to Astra 23.5°E in September 2007, to be lost to viewers without access to the new satellite position. The Duo LNB was introduced to enable a single satellite dish to be used to receive all the channels from 19.2° east and 23.5° east. The

ASTRA2Connect SES Broadband (previously ASTRA2Connect) is a two-way satellite broadband Internet service available across Europe, which launched in March 2007, and uses the Astra series of geostationary satellites. SES Broadband is owned and operated by SES ...

satellite internet Satellite Internet access is Internet access provided through communication satellites. Modern consumer grade satellite Internet service is typically provided to individual users through geostationary satellites that can offer relatively high d ...

service also operates from 23.5° east. In May 2010 the

Astra 3B Astra 3B is one of the Astra communications satellites owned and operated by SES, launched in 2010 to the Astra 23.5°E orbital position providing digital television and radio for direct-to-home (DTH), and the AstraConnect two-way satellite ...

satellite was launched to the Astra 23.5° east position to release the

Astra 1E Astra 1E is one of the Astra communications satellites in geostationary orbit owned and operated by SES. It was launched in October 1995 to the Astra 19.2°E orbital slot initially to provide digital television and radio for direct-to-home (DT ...

and

Astra 1G Astra 1G is one of the Astra communications satellites owned and operated by SES. History SES ordered its Hughes 601HP satellite, in 1994 for Astra 1G. Launch Astra-1G was launched on 2 December 1997 at 23:10:37 UTC, by a Proton-K / DM ...

satellites previously in that position for use at other orbital positions. The launch had been much postponed due to technical problems with the

Ariane 5 Ariane 5 is a European heavy-lift space launch vehicle developed and operated by Arianespace for the European Space Agency (ESA). It is launched from the Centre Spatial Guyanais (CSG) in French Guiana. It has been used to deliver payloads int ...

launch rocket. In February 2011, Bulgarian DTH operator Satellite BG launched a package of more than 60 standard definition channels and 12 high definition channels using three transponders on Astra 3B, further increasing the appeal for viewers to receive both satellite positions.

Technology

The basic technology behind the Duo LNB is not new. It takes advantage of the fact that signals hitting a dish off-axis will be focused (albeit with some diffusion) off axis in the opposite direction. So, with the dish aligned so that the central LNB is receiving one satellite, a secondary offset LNB can be aligned on the focus of a second satellite spaced away from the first. This effect has been exploited for many years to receive signals from two satellites at once with a single dish, and two LNBs have been most commonly arranged on a dish in this way for reception of Astra 19.2°E and the Hot Bird satellites at 13° east, primarily for the abundance of TV channels from 19.2° east, and some additional channels (especially adult channels) from 13° east. A monoblock LNB provides a convenient alternative to fixing and aligning two LNBs to a dish independently. The two feedhorns are positioned at the correct spacing for reception from the two satellites required and the

DiSEqC DiSEqC (; short for Digital Satellite Equipment Control) is a special communication protocol for use between a satellite receiver and a device such as a multi-dish switch or a small dish antenna rotor. DiSEqC was developed by European satellit ...

switching system is used to select between the signals from the two satellites with commands from the connected receiver. In other respects, the monoblock LNB acts as a normal LNB to the connected receiver. The required separation of the monoblock's feedhorns depends on the angular separation of the satellites to be received, the position of the receive site on the Earth's surface and the focal length of the dish. Fortunately, monoblock LNBs can be standardised for sites across Europe provided that a "standard" offset dish with a focal length/diameter (f/D) ratio of 0.6 is used. Monoblock LNBs for 19.2° east and 13° east have been widely available for several years (indeed, the

switching system was originally designed for just this setup). However, these do not function correctly for Astra 23.5°E and Astra19.2°E because these satellites are at a different angular separation. In fact, it can be difficult to physically fit two separate LNBs onto a dish at the correct separation for Astra 23.5°E and Astra 19.2°E because their bulk may prevent the feedhorns sitting close enough together. The Duo LNB is carefully designed with the correct spacing of the feedhorns, DiSEqC level 1.0 switching between the satellites and a low noise amplifier and conversion system.

Installation

The Duo LNB is designed to be fitted with the feedhorn for Astra 23.5°E mounted on the dish's feedarm, and the 19.2°E feedhorn sticking out to the right - as viewed standing in front of the dish, with the satellites behind you. The Astra 23.5°E feedhorn is identified with a "23.5" marking on the casing. The dish is then aligned on the 23.5°E satellite position, using a signal strength meter, in the normal way.''Duo LNB installation''
SES Installation video (in German). Accessed May 27, 2014 The Duo LNB is rotated in the feed clamp to a certain tilt angle to provide both the correct 'skew' angle for the feedhorns to align with the incoming signals, and the necessary height difference between the feedhorns to accommodate the different elevations of the two satellite positions. The correct skew angle and height difference depend on the position of the receive site on Earth's surface, and in most locations the tilt angle from the LNB is a compromise between their ideal settings. However, within Europe the single tilt angle adjustment provides sufficient accuracy for both settings for reliable reception. The tilt angle for the Duo LNB at the receive site location may be found in maps or city tables (a scale is marked on the LNB's 23.5°E feedhorn casing) or found by adjustment with a signal meter connected. By setting the correct tilt angle and aligning the whole dish in azimuth and elevation, the two feedhorns of the LNB are optimally aligned for both orbital positions.

Name Confusion

The Duo LNB is a monoblock type LNB designed for accessing two satellite positions with a single dish and it should not be confused with a "dual LNB", which is the common (US) name for an LNB with a single feedhorn but two separate outputs. A double LNB called just a "Monoblock" will usually be for reception of 19.2° east and 13° east, and not a Duo LNB suitable for Astra 23.5°E and Astra 19.2°E.

References

External links

SES fleet information and map

Official SES site
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