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Discussion Starter · #1 ·
At the risk of finding out this question has been previously asked...


I'm getting ready to do a major upgrade to my entertainment system, including getting an HDTV set. As part of that, I'd obviously like to upgrade from my existing non-HD DirecTV source to an HD setup. I can get local HD signals OTA, but would like the DirecTV HD feed. No problem yet, but I'd also like to future-proof this with an HDTiVo in mind, which would want two independent satellite feeds. Now, it was hard enough running one cable to the viewing location, and running a second my be nigh impossible.


My understanding of the technical issues tells me that a stacking system of some sort. However, I believe standard satellite stackers work by driving one input at a constant 12V and the other at a constant 18V. From what I think I know of the DirecTV HD setup, there is an additional 22kHz tone required to switch between the Sat A and Sat B/C feeds, which makes using the "standard" stacker impossible.


Given this, I've found a unit manufactured by a European company called Unitron, under the brand name Johansson, which seems like it might work. Rather than driving its two inputs constantly, then distributing the paired signals to one or more destackers, it appears to pass independent 12/18V and 0/22kHz signals for each leg between a single stacker and destacker. It also supports a control protocol called DiSEqC, which to the best I can see, is used exclusively by the European market. So, my first question is, looking at this product, would it do what I want; namely, would it allow me to have two independently controlled lines which could access either transponder polarity on either satellite. Details about the product are available through Johansson's online catalog at http://www.johansson.be/htmen/stacke...hp?ref=9633KIT .


So, if I'm right, and this would work, my problem then becomes actually acquiring the equipment. Although Johansson's website says they have distributors world-wide, I haven't been able to locate one in the US (much less Texas, where I live), nor have I found any Internet retailers who carry it. Of course, since I can't find anyone selling it, I have no way to actually get a price point in the first place. I may find out that this is considered studio-quality equipment costing thousands of dollars. (I don't really think so, but I just don't know.) So, my second question: Anyone have any idea how I might go about procuring one of these stacker/destacker kits?


Many thanks for any information any of you might have, and many apologies for the long post. I tend to ramble a bit, I suppose. :)
 

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No matter how you go, you will need a switch somewhere.......You either need 4 coaxes from the dish down to the switch, or a coax from the switch to each receiver (i.e., tuner input). A stacker will allow you to have both the LHCP and RHCP polarities from ONE satellite at a time, determined by the receiver that has priority (sends the voltage and 22 KHz tone),but you would not be able to "see" the other satellites on the lower-priority receivers. There just isn't enough bandwidth to stack more than one satellite (2 sets of 500 MHz-wide L-band frequencies) in a single coax.
 

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That is one doozie of a product line. The stacker and destacker claim to have frequency response ranges of 5 to 3,550 Mz.


The problem is getting it to interface properly with the 950-1,450 US domestic DBS intermediate frequency LNB outputs and also getting the destacker to respond to the 13/18v, 22Kz tones in a manner consistent with the expectations of the receivers. The fact that the destacker may respond to voltage and tone switching doesn't necessarily mean that it will respond in the way that you would need it to.


European DBS doesn't break down and allocate the available frequencies exactly like the US does. They use something called a universal LNB that I think has an input bandwidth of about 1.2Gz and they downconvert part of it with a local oscillator offset that is not compatible with US domestic DBS hardware.


Unfortunately, I did not find enough information on their website to determine if that system would be compatible with US standardized hardware, and the translations were so poor that I would expect any efforts to communicate with that company to be a battle. I'd be surprised if anyone could make this work in a US DBS multisat application. And the coax loss at 3Gz would be absolutely brutal, like maybe 20dB per hundred feet.
 

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The so-called MPEG FTA recievers commonly used in Europe and used in the US for a few consumer services have intermediate frequency input windows of 950Mz to 2,150Mz. The equipment you are looking at takes one of these bands and apparently boosts it to maybe 2,350-Mz to 3,550Mz. It probably does that in response to a 22Kz tone switch, so that much would be compatible with US DBS technology.


If you are willing to blow a thousand dollars or so, you could put Sonora stackers on both of your DirecTV LNBs, and feed those outputs into one if these Unitron stackers, send its output to a Unitron destacker, and then connect the Unitron destacker's output to a Sonora D575P destacker input, rather than a regular D575 destacker, because the D575P will pass a 22Kz tone signal, whereas a regular D575 blocks it.


The only way this might not work is if the 13/18 volts that passes through the Sonora D575P along with the 22Kz tone triggers some switching circuitry in the Unitron destacker that you do not want triggered.
 

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In which case, you might then installed a so-called VBC (voltage blocking coupler) on the coax between the two destackers and hope that a VBC does not also block a 22Kz tone signal.
 

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Discussion Starter · #6 ·
I'm learning more about the way this stuff works. Fun. Anyway, I see what you're saying, and I think I may have a way around the tone problem. See if I've got this laid out right:


Start with the triple satellite dish, running four lines from the internal multiswitch, plus an external antenna. Two satellite lines are connected to a S575 stacker (possibly needing an external power inserter on one line to drive to the other polarity?). The other two lines are hooked to another S575 stacker with a 22kHz tone generator on the lines, (again, possibly with an external power inserter). Now, we diplex the non-tone stacked line with the external antenna, then feed that and the tone stacked line into the Unitron stacker. Line runs through the house, hither and yon, until we come to the entertainment center. Unitron de-stacker, diplex the OTA antenna signal off the non-tone line. D575 to destack the non-tone and tone lines, then feed those four lines into a 4xN multiswitch, making sure each line feeds the right port, then let the hypothetical HDirecTiVo feed from that.


Sounds like a lot of equipment, but my inexperience tells me it should work. This is, of course, provided the 3.x GHz signal will actually be usable after it's travelled hither and yon, and passed through a couple of couplers. I noticed in the Sonora catalog that their basic F couplers are only rated to handle 2150 MHz; I wouldn't expect there to be an actual limit there, but I can't discount the possibility.


So, with all that, the question still remains: Can I even get that equipment in the States, and if so, will the total for all this be more than it would cost to have an electrician run the stupid second line in the first place?


(After thinking about it a bit more, I think I'd also need to add in another 4x8 multiswitch back at the head end, possibly with matching tone generators/power inserters so that I could still feed my other receiver. This is giving me a headache.)
 
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