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Fringe Reception General
Badr 4,6. 26 E
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<blockquote data-quote="dovercat" data-source="post: 650581" data-attributes="member: 274033"><p>The satellite transponder list _http://www.lyngsat.com/badr.html</p><p>has links to the footprint maps, it is somewhat misleading as I get MBC channels easily with a 1mtr dish in Oxfordshire and it claims that is completely out of the footprint. </p><p></p><p>With Badr 26E dish size - dish beamwidth and accurate dish alignment are crucial as you need to isolate Badr 26E from Astra 28.2E. </p><p></p><p>Using _http://www.dishpointer.com/ My location gives 28.2E as Azimuth 144.3 and 26E as 146.7, so only 2.4 degrees difference. </p><p>I get it fine on a 1mtr dish. Half beamwidth to -15dB with a 1mtr dish is 2.4 degrees at 9.7GHz, 1.949 degrees at 11.7GHz, 1.82 degrees at 12.75GHz. Signals from Badr start at around 11.7GHz so I do not get interference from Astra effecting reception of Badr.</p><p></p><p>An 80cm dish has a half beamwidth to -15dB at 9.7GHz of 2.99 degrees, at 11.7GHz of 2.48 degrees, at 12.75GHz of 2.28 degrees. A 60cm dish has a half beamwidth to -15dB at 9.7GHz of 3.99 degrees, at 11.7GHz of 3.31 degrees, at 12.75GHz of 3.04 degrees. Satellites with footprints aimed at the same location usually have 3 degree spacing.</p><p></p><p>_http://www.satsig.net/pointing/antenna-beamwidth-calculator.htm</p><p></p><p>Bear in mind that not all dish manufactures 1mtr dishes are the same they vary from less than 95cm to over 105cm wide, as some round up and others use the height instead of correctly using the width for their dish sizes. I have seen posts on forums giving the following actual sizes</p><p>Gibertini 1mtr is apparantly only 95x102cm</p><p>Orbital 1mtr is apparantly only 95x110cm or 98x107 </p><p>Triax 1.1mtr is apparantly only 102x110cm</p><p>Televes 1mtr I have is 102x113cm</p><p>Prodeline 1mtr is apparantly 105x115cm</p><p>Andrews 1mtr is apparantly 106x116cm</p><p>The actuall illumination of the dish will be less than the dish size, as you do not want edge noise, and generic universal Lnbs are designed for a standard F/D ratio, so they maybe not be looking at the whole dish, which is why I currently use a lnb by my dish manufacturer.</p><p></p><p>Going back somewhat off topic to Lnbs the main thing that makes me very skeptical is their unbelievable noise figures. My understanding is that the minimum noise level possible of an Lnb is dictated by the pin diode used in the detector circuit. These diodes used to be rated as adding about 40 degrees K, which translates as >0.5dB. So how can manufactures honestly claim noise figures lower than 0.6dB 43K or 0.5dB 35K. I have read that they might be able to get as low as 0.3dB in a small part of the frequency range rather than a average across the frequency range. But most seem to claim noise figure of 0.2dB 14K and 0.1dB 7K which are I think unbelievable. The old low noise Lnbs claiming 0.7dB were probably alot more honest.</p><p></p><p>While I am rambling on about Lnbs, might as well mention that phase noise is one of the most important specs for digital reception as it corrupts the digital data stream, this is a different spec to the headline Lnb noise figure a larger negative number is better.</p><p>Local oscillator stability is also crucial to the receiver getting maximum signal quality from the lnb, and especially important with narrow - low symbol rate signals.</p><p>Discrimination between Polarities is also important particularly if the satellite signal has one polarity at the same or close frequency giving alot stonger signal than the signal on the other polarity. </p><p>Finally Lnb gain usually between 40-65dB increased gain is always at the expense of increased noise but may improve reception if your receiver is a bit deaf or the cable run is very long, but you can have too much shouting too loud at the receiver as well as too little.</p><p></p><p>When putting the dish together, and checking the setup, you want to check the lnb is looking correctly at the dish to get best results. A old tip for doing this is putting a torch where the lnb will go and seeing if it is being aimed at the center of the dish, alternatively using a piece of dowling to check the lnb is aimed at the center of the dish.</p><p></p><p>Once the lnb is in place and you are receiving pictures, adjusting how far the lnb sticks through its holder towards the dish for best signal quality, the nearer its feedhorn to the dish the less area it is collecting from lower signal strength, like a torch in reverse, but also the less edge noise, and if the lnb is actually looking past the edges of the dish you are going to be getting alot of noise. </p><p></p><p>Then you have rotating the lnb for best signal quality on horizontal and vertical polarization, as this determines how much signal cross contamination there is between the polarized signals, lots of cross contamination equals higher signal strength but lower quality. On a motorized dish you want to adjust lnb skew with the dish pointed at the satellite highest in the arc, closest to the motor pointing true south, motor position O. As when the dish rotates on the mount it skews the dish. With a motorized system lnb skew is a compromise, old analogue systems had a seperate system for adjusting the skew per satellite but satellites are alot stronger now and lnbs better.</p></blockquote><p></p>
[QUOTE="dovercat, post: 650581, member: 274033"] The satellite transponder list _http://www.lyngsat.com/badr.html has links to the footprint maps, it is somewhat misleading as I get MBC channels easily with a 1mtr dish in Oxfordshire and it claims that is completely out of the footprint. With Badr 26E dish size - dish beamwidth and accurate dish alignment are crucial as you need to isolate Badr 26E from Astra 28.2E. Using _http://www.dishpointer.com/ My location gives 28.2E as Azimuth 144.3 and 26E as 146.7, so only 2.4 degrees difference. I get it fine on a 1mtr dish. Half beamwidth to -15dB with a 1mtr dish is 2.4 degrees at 9.7GHz, 1.949 degrees at 11.7GHz, 1.82 degrees at 12.75GHz. Signals from Badr start at around 11.7GHz so I do not get interference from Astra effecting reception of Badr. An 80cm dish has a half beamwidth to -15dB at 9.7GHz of 2.99 degrees, at 11.7GHz of 2.48 degrees, at 12.75GHz of 2.28 degrees. A 60cm dish has a half beamwidth to -15dB at 9.7GHz of 3.99 degrees, at 11.7GHz of 3.31 degrees, at 12.75GHz of 3.04 degrees. Satellites with footprints aimed at the same location usually have 3 degree spacing. _http://www.satsig.net/pointing/antenna-beamwidth-calculator.htm Bear in mind that not all dish manufactures 1mtr dishes are the same they vary from less than 95cm to over 105cm wide, as some round up and others use the height instead of correctly using the width for their dish sizes. I have seen posts on forums giving the following actual sizes Gibertini 1mtr is apparantly only 95x102cm Orbital 1mtr is apparantly only 95x110cm or 98x107 Triax 1.1mtr is apparantly only 102x110cm Televes 1mtr I have is 102x113cm Prodeline 1mtr is apparantly 105x115cm Andrews 1mtr is apparantly 106x116cm The actuall illumination of the dish will be less than the dish size, as you do not want edge noise, and generic universal Lnbs are designed for a standard F/D ratio, so they maybe not be looking at the whole dish, which is why I currently use a lnb by my dish manufacturer. Going back somewhat off topic to Lnbs the main thing that makes me very skeptical is their unbelievable noise figures. My understanding is that the minimum noise level possible of an Lnb is dictated by the pin diode used in the detector circuit. These diodes used to be rated as adding about 40 degrees K, which translates as >0.5dB. So how can manufactures honestly claim noise figures lower than 0.6dB 43K or 0.5dB 35K. I have read that they might be able to get as low as 0.3dB in a small part of the frequency range rather than a average across the frequency range. But most seem to claim noise figure of 0.2dB 14K and 0.1dB 7K which are I think unbelievable. The old low noise Lnbs claiming 0.7dB were probably alot more honest. While I am rambling on about Lnbs, might as well mention that phase noise is one of the most important specs for digital reception as it corrupts the digital data stream, this is a different spec to the headline Lnb noise figure a larger negative number is better. Local oscillator stability is also crucial to the receiver getting maximum signal quality from the lnb, and especially important with narrow - low symbol rate signals. Discrimination between Polarities is also important particularly if the satellite signal has one polarity at the same or close frequency giving alot stonger signal than the signal on the other polarity. Finally Lnb gain usually between 40-65dB increased gain is always at the expense of increased noise but may improve reception if your receiver is a bit deaf or the cable run is very long, but you can have too much shouting too loud at the receiver as well as too little. When putting the dish together, and checking the setup, you want to check the lnb is looking correctly at the dish to get best results. A old tip for doing this is putting a torch where the lnb will go and seeing if it is being aimed at the center of the dish, alternatively using a piece of dowling to check the lnb is aimed at the center of the dish. Once the lnb is in place and you are receiving pictures, adjusting how far the lnb sticks through its holder towards the dish for best signal quality, the nearer its feedhorn to the dish the less area it is collecting from lower signal strength, like a torch in reverse, but also the less edge noise, and if the lnb is actually looking past the edges of the dish you are going to be getting alot of noise. Then you have rotating the lnb for best signal quality on horizontal and vertical polarization, as this determines how much signal cross contamination there is between the polarized signals, lots of cross contamination equals higher signal strength but lower quality. On a motorized dish you want to adjust lnb skew with the dish pointed at the satellite highest in the arc, closest to the motor pointing true south, motor position O. As when the dish rotates on the mount it skews the dish. With a motorized system lnb skew is a compromise, old analogue systems had a seperate system for adjusting the skew per satellite but satellites are alot stronger now and lnbs better. [/QUOTE]
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Badr 4,6. 26 E
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