It is good to note the reception area in question ... where in the US we have DISH and DirecTV satellites in a maximum "18 degree" or "20 degree" arc that is not the full story. Most of our dishes are designed for use anywhere in the contiguous US. The difference in apparent spacing between the satellites is different in Bangor, Maine vs Miami, Florida or Seattle, Washington vs San Diego, California. The closer one gets to the equator the further apart the satellites appear to be.
Engineers have managed to design dishes that can pick up "18 degree" spaced DBS satellites, relying on the higher power and wider spacing to allow one dish to be used nationally (with the differences between dishes being what satellites are needed, not what area of the country one is in).
Take a look at the Azimuth difference on the two images above ... the satellites are 20 degrees apart when viewed from the center of the earth. Quite a bit more when viewed from the surface. Which would make a "single dish" reception of these two satellites from Columbia a bit more challenging.
Not quite. Picking a random middle of the US city (Kansas City. MO) it is azimuth 227.3 to 129 and 147.5 to 72.7 - a spread of about 80 degrees. The numbers above for seeing 58 and 78 from Bogata are a spread of 120 degrees azimuth. While it would be possible to design a dish that would do that spread the outside LNBs would need to be further apart than the one you linked. Certainly not a twin LNB.
... The numbers above for seeing 58 and 78 from Bogata are a spread of 120 degrees azimuth. While it would be possible to design a dish that would do that spread the outside LNBs would need to be further apart than the one you linked. Certainly not a twin LNB.
Perhaps true, though really an academic study here I think ....
As was stated by the earlier poster, SKY Mexico appears to be leaving 58W for 76 and 79W where ultimately a twin linear LNBF similar to Shaw Direct's current LNBF for 107 and 111W will likely be used with the LNBs placed 1° closer.
Anyone care to explain, or a best guess at it at least, how the LNBF for the new SKY Mexico service from 76 and 79W actually operates?
It's listed by the mfr. WNC under the acronym "MDual" for a "Monoblock Dual Stacked LNBF."
As you can see from the photos of an installation the LNBF has the two outputs via two coax line runs to the 18v/22 KHz and 13v/22 KHz inputs of a (repurposed?) DIRECTV SWiM-8 module.... Huh?
I have a theory as to what it might be in that both output lines are frequency stacked at 950-1450 MHz for the (SKY Mex. uses linear pol. BTW) odd xpndr set and 1650-2150 MHz for the even set.
And perhaps 18v + 22 KHz tone line signals the satellite at 76W (when it exist) or the current SKYM-1 satellite at 79W. And the 13v + 22 KHz tone line signals the opposite satellite position than the other.
If a translation for some of the material is needed by someone I'll post it. But I can say there is nothing in it (outside of just general installation instructions and tips along with the specifications), that really explains how this LNBF works.
Is both outputs of the LNBF independent ? Each one get signals from one sat ?
I'm wondering how the two coax connections between duo LNBFand SWiM will works for both satellites in a future ?
Now both outputs locked by 22 KHz tone.
Doesn't say specifically, at least just from these excepts of the installation manual.
My best assumption for now is that one LNBF port generates a stacked signal for one satellite slot. and the particular voltage level with tone selects whether it's from the 76W or 79W slot.
And perhaps if there is no tone detected for when someone wishes to connect a receiver directly to the LNBF, then it's won't stack transponder sets at all, but revert to a basic mode of sending either the odd or even channel sets over the 950-1450 MHz range depending on whether the control voltage is 13 or 18 volts.
A 13v+22 KHz tone signal to either LNBF port will bring in a stacked 950-1450 (for odd transponders) 1650-2150 (for even transponders) from the 76W slot.
And a 18v+22KHz tone signal to either LNBF port will bring in a stacked 950-1450 MHz (odd xpdrs.) 1650-2150 MHz (even xpdrs.) from the 79W slot.
Or vice-versa for the above as to the satellite slots.
And of course the SWiM-8's or a directly connected receiver's firmware for SKY Mex. service is designed to recognize this frequency stacking arrangement.
I also retract something I thought earlier ...
I think this LNBF always produces a stacked signal on it outputs, and always requires voltage plus tone to work properly if at all. Therefore if a receiver for SKY Mex. service is connected directly to it the firmware must be designed to generate only voltage together with tone for the control signals.
Again, just best guessing here. Hopefully a SKY Mex. subscriber in the know "down south" can chime in with the actual info. and end the speculation
Maybe the LNB doesn't care about tone at all, and the only reason it is shown connected to the 22 KHz ports is that Directv had to choose some standardized place for it to connect so the receiver would know what to ask the SWM for. If you think about it, it is going to be simpler to use the two middle ports - those are easy to locate no matter which way the SWM8 is oriented, and since there's no 76 or 79 printed on it to tell you which ones to use you want it to be simple.
Maybe the LNB doesn't care about tone at all, and the only reason it is shown connected to the 22 KHz ports is that Directv had to choose some standardized place for it to connect so the receiver would know what to ask the SWM for. If you think about it, it is going to be simpler to use the two middle ports - those are easy to locate no matter which way the SWM8 is oriented, and since there's no 76 or 79 printed on it to tell you which ones to use you want it to be simple.
If that's the reason for connecting to the Sat B/B+C inputs of the SWiM-8 then good.
I really don't see any need for the 22 KHz tone since two control voltage levels on either of the LNBF's ports should be sufficient to select either a stacked frequency set from 76 or 79W. But was just trying to account for the reason the two 22 KHz tone producing outputs on the switch were selected in the photo.
I'm not getting how internal analog switch inside the duo-LNBF working; especially if both sats are running?
Why need the 22 KHz tone if the LNBF is stacked kind, eg both polarities sending down to an IRD?
I've only one explanation IMO for this setup: the LNBF outputs are separate for each sat; both polarities sending down in stacked mode; the current connection should cover new sat also; the SWiM switch is controlling by own FW (?) and IRD's FW different way as we knew for US.
If someone from South running the setup and DVR would like to help us and come here ...
The more I think about this LNBF off and on since my last post, plus researching online the way other dual stacked LNBFs operate, I wonder if the hookup in the photo might just be wrong. And it should be one port of the LNBF is connected to say the 13v/22 KHz port on the SWiM-8 module and the other port to the 13v/without tone port of the SWiM-8.
Either this or use only the 18v ports, tone and no tone, on the SWiM-8 module instead.
Because I find no other examples of frequency stacked LNBFs using the 13v/18v voltage switch method which is virtually always used for polarization selection since there are no signal polarizations switch. They just operate the same producing a stacked xpndr set over a range of voltages tipically between about 10-20 volts.
However, I do customarily find the 22 KHz tone signal commonly used for a two satellite position LNBF for orbit slot selection.
So I think this LNBF is like other dual stacked designs internally comprised of two LNBFs for the two satellite positions together with an integrated 2 x 2 22 KHz tone multiswitch. So voltage without tone perhaps selects satellite position A for SKYM-1 at 79W. And voltage with tone selects satellite position B at 76W for Intelsat 16 (interim until KU-76W is launched as SKYM-2?).
Oh, no - usually dual output made for run two independent IRDs, so internal matrix switch would send any sat+polarity down to particular output, IF it's not stacked LNBF;
perhaps 22 KHz tone turning on high half ?
Oh, no - usually dual output made for run two independent IRDs, so internal matrix switch would send any sat+polarity down to particular output, IF it's not stacked LNBF;
perhaps 22 KHz tone turning on high half ?
No, I understand it as the LNBF can send to either of it's ports the stacked xpndrs of the satellite at 76W (currently Intelsat-16) or those from the bird at 79W (SKYM-1).
Such that for instance ...
13v w/o 22 KHz tone = Sat. at 76W, 950-1450 MHz contains vert. xpndrs, 1650-2150 MHz contains horiz. xpndrs.
13v with 22 KHz tone = Sat. at 79W, 950-1450 MHz contains vert. xpndrs, 1650-2150 MHz contains horiz xpndrs.
Or vice-versa for the above where 13v with or without tone is for the opposite satellite.
Or it uses 18v with or without tone that sends the stacked xpndrs from either satellite this way, I don't know.
Why should how other dual stacked LNBs operate have any bearing on this one? This a designed for a captive market, Directv can do it however they want. If you're comparing with ones designed for the Euro/Asian market they need to abide by some sort of standards or common practice so everything is compatible with each other. Directv doesn't care if their gear is compatible with FTA equipment because it isn't designed to work with it.
Why should how other dual stacked LNBs operate have any bearing on this one? This a designed for a captive market, Directv can do it however they want. If you're comparing with ones designed for the Euro/Asian market they need to abide by some sort of standards or common practice so everything is compatible with each other. Directv doesn't care if their gear is compatible with FTA equipment because it isn't designed to work with it.
Actually I was drawing both from the example of the Canadian Shaw Direct (Starchoice) design of their dual stacked LNBFs to access linear pol. 11.7-12.2 MHz xpndrs from satellites at 107.3 and 111.1W.
And the fact I could find no stacked LNBF designs for use anywhere in the world that used a 13v/18v switching process. They always operated at a single voltage like 13v to power the LNBF and internal stacker within some tolerable range of about 10-20v usually listed in the specs. along with or without the 22 KHz tone or some DiSEqC signaling to change satellite positions for dual stacked designs if necessary.
Wow .... even WNC doesn't even seem to know how one of their own LNBFs function, lol;
My email to WNC's Chaucer Chen, head WNC sales rep. for DBS satellite products on 12/28/2015;
Hello Mr. Chen;
Hoping you can help shed some light on the operation for this LNBF produced by WNC for the new SKY Mexico service from 76 and 79 degrees W.L. Have some SKY Mexico subscribers who come to our discussion board on occasion, dbstalk.com. for various technical assistance for dish installation and trouble shooting.
It's titled as shown (with no specific model number known here) the "MDUAL Dual Stacked Monoblock LNBF" as shown in one of the accompanying photo attachments.
By its name "we" (i.e. the satellite techs. on the board) assume that it can produce stacked frequency signals on either of its output ports from either of the satellite positions comprising perhaps the odd numbered transponders from a satellite on the "low band" of 950-1450 MHz and the even number transponders from that same satellite atop on the "high band" of 1650-2150 MHz, or maybe its vice-versa?
However, for the life of us, none of the satellite techs. here can really quite understand how the control signals a receiver or a multiswitch (as in the photos) generates to operate this particular LNBF. For instance for the multiswitch hookup as shown in one of the photos, this LNBF has its two ports connected to the 18v + 22 KHz tone and 13v + 22 KHz tone generating input ports of a DIRECTV SWiM 8 channel multiswitch which we assume is modified for the SKY Mex. service.
But can you describe or provide technical literature detailing the type of voltage with tone control signals this LNBF requires to generate the frequency stacking and satellite position selection?
Thank you for your time and any assistance you can offer here on this matter.
Well, of course it wasn't "my" connection, but was someone else's in the photo I supplied him along with all the others. and I was questioning it's correctness.
But anyway, WNC doesn't really seem to know for sure as I can't see how this LNBF can function like a "traditional/legacy," 13/18v or with tone, LNBF and perform frequency stacking.
Frequency stacking LNBFs just don't work that way from every other example I could find as I stated earlier.
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