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Thread: Check your signal loss with this handy calculator

  1. #1

    Check your signal loss with this handy calculator



    Thanks again to our resident RF maven VOS for this great little tool! If you are worried about signal loss between points in your system, this excel spreadsheet will help you figure out where you might be running into problems.

    Simply feed in the distances into the top row, measured in feet, between your cinema connection kit and your splitter, then feed in the cable lengths between each splitter and the receiver. If any number on the bottom is greater than 45, you will surely have signal loss problems. Of course there can be other factors such as loose connections or unknown cabling issues, so use this as a starting guide, and give yourself some leeway when planning cable runs.

    Click on the image above to use the calculator!
    SolidSignal.com SignalMarine.com // 25225 Regency Drive // Novi, MI 48375 // 1.877.312.4547

  2. #2
    Wow that's a great tool. Thanks VOS!
    -Scott

  3. #3
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    Quote Originally Posted by Scott K. View Post
    Wow that's a great tool. Thanks VOS!
    These are for figuring out the DECA signal losses.
    That one is for when you're using the NAS 9501M diplexers to combine SWiMs.

    Now if you are planning to use one SWiM-16 this is what you want:

    Cloud loss calculator for SWiM-16.xls
    The left & center are for 4-ways, and if you need to use an 8-way, then it's the left and far right.
    Last edited by VOS; 07-21-2012 at 01:17 AM.

  4. #4
    I have a few questions about this excellent cloud loss calculator if you don't mind. I am operating under the assumption that the numbers it is calculating are based on a setup like that in the picture on page 3 in the More than 16 tuners in the home white paper.

    The white paper shows use of 4 way SWM splitters. If the spreadsheet assumes that for its calculations, I would need to add around 4db to the numbers for any receivers attached on an 8 way leg to account for that extra loss, correct? I guess the easier way would be to add something like 50 feet of coax as a "cheat factor" to account for this, does that sound about right?

    Likewise, I assume the calculations are based on the 4 way splitter at the CCK as shown. If I have 3 SWM-16s, I would need 6 NAS diplexers and an 8 way splitter at the CCK, so I'd need to once again add a 50 foot cheat factor, this time for all receivers, to account for that.

    Since I want to use a wired network, can I use a DCA2SR0 rather than the CCK as shown?

  5. #5
    I'm going to get our resident rf maven VOS, who wrote this spreadsheet to answer your questions.
    SolidSignal.com SignalMarine.com // 25225 Regency Drive // Novi, MI 48375 // 1.877.312.4547

  6. #6
    I will say that you can use a powered deca instead of a cinema connection kit... They are equivalent.
    SolidSignal.com SignalMarine.com // 25225 Regency Drive // Novi, MI 48375 // 1.877.312.4547

  7. #7
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    Quote Originally Posted by dsiebert View Post
    I have a few questions about this excellent cloud loss calculator if you don't mind. I am operating under the assumption that the numbers it is calculating are based on a setup like that in the picture on page 3 in the More than 16 tuners in the home white paper.

    The white paper shows use of 4 way SWM splitters. If the spreadsheet assumes that for its calculations, I would need to add around 4db to the numbers for any receivers attached on an 8 way leg to account for that extra loss, correct? I guess the easier way would be to add something like 50 feet of coax as a "cheat factor" to account for this, does that sound about right?

    Likewise, I assume the calculations are based on the 4 way splitter at the CCK as shown. If I have 3 SWM-16s, I would need 6 NAS diplexers and an 8 way splitter at the CCK, so I'd need to once again add a 50 foot cheat factor, this time for all receivers, to account for that.

    Since I want to use a wired network, can I use a DCA2SR0 rather than the CCK as shown?
    You seem to have a fairly good understanding.
    There looks to be a few problems or questions about what I think you're trying to do.

    You can't combine 3 SWiM-16s into the same DECA cloud.
    The main reason is the DECA cloud is limited to a maximum of 16 DECA nodes, "I guess" with the Genie and it's five tuners but being only one DECA node, I might have to rethink this.
    8-way splitters tax the loss budget even on just one SWiM-16, so the coax loss has to be less.
    The Cloud loss cal linked in the post above yours, has an option for two 4-ways, or one 4-way and one 8-way. "A-D" is one 4-way, "E-H" the other, and "I-P" is the 8-way.

    The Cloud loss for two SWiM-16s does only have 4-ways, and uses a 4-way to combine the DECA from the diplexers. The added loss of this combining 4-way is mainly why I created the calculator as the splitter and coax losses get fairly complicated and it was easy to "miss" where a long coax on one leg would have too much loss to another.

    Maybe it would be a good idea to post what you're trying to put together and I'll see which [of several] calculators is best.

    If you're going to have more than 16 DECA nodes, you'll need to have more than one DECA cloud and bridge them through ethernet.

  8. #8
    Quote Originally Posted by VOS View Post
    You seem to have a fairly good understanding.
    There looks to be a few problems or questions about what I think you're trying to do.

    You can't combine 3 SWiM-16s into the same DECA cloud.
    The main reason is the DECA cloud is limited to a maximum of 16 DECA nodes, "I guess" with the Genie and it's five tuners but being only one DECA node, I might have to rethink this.
    8-way splitters tax the loss budget even on just one SWiM-16, so the coax loss has to be less.
    The Cloud loss cal linked in the post above yours, has an option for two 4-ways, or one 4-way and one 8-way. "A-D" is one 4-way, "E-H" the other, and "I-P" is the 8-way.

    The Cloud loss for two SWiM-16s does only have 4-ways, and uses a 4-way to combine the DECA from the diplexers. The added loss of this combining 4-way is mainly why I created the calculator as the splitter and coax losses get fairly complicated and it was easy to "miss" where a long coax on one leg would have too much loss to another.

    Maybe it would be a good idea to post what you're trying to put together and I'll see which [of several] calculators is best.

    If you're going to have more than 16 DECA nodes, you'll need to have more than one DECA cloud and bridge them through ethernet.

    I know about the 16 node DECA limit, I'm planning ahead as Directv is telling me that Genie will soon be permitted on commercial accounts. She couldn't give me a date, and couldn't say for sure about WHDVR and multiple Genies, but I'm hoping that I can eventually have three Genies. There's a good reason why I want three but it would take a bit of explaining and is irrelevant to this thread.

    Right now I have two SWM-16s but would need a third if I add three Genies. I suppose if I was forced I could determine what receivers I want to participate in the DECA cloud and make it fit on two SWM-16s, but I'd prefer maximum flexibility to add/remove any receiver from the cloud on the fly. I assume it is possible to disable DECA in Setup? If not I can easily enable/disable them from getting an IP address at the router which should accomplish the same end. The goal is to avoid the need to physically touch cables and move them from one SWM to another to change the membership of my DECA cloud. I strongly believe "if it ain't broke don't fix it" when it comes to making cabling changes, and more important because they are not located in a convenient spot.

    What's this you're saying about bridging multiple DECA clouds? I assume you could have separate clouds. For example, if you have two SWM-16s, SWM-A and SWM-B, each with a Genie and 10 receivers, you could set it so you have two 11 node DECA clouds that are independent from each other. Each would need their own CCK/DECA. The 10 receivers on SWM-A could only watch programs recorded on the Genie on SWM-A and the 10 on SWM-B could only watch programs on the Genie on SWM-B. They might be plugged into separate routers, or in the same router with the two ports in separate VLANs. You're talking about bridging those two routers/two VLANs so the two clouds can communicate, right? Are you saying that if I did this the receivers on SWM-A could watch programs on the Genie on SWM-B, and vice versa? If so, I'm definitely interested in learning more! If not, what exactly does bridging them accomplish? Is there any documentation out there you could point me to?

  9. #9
    First of all you can use a band stop filter to disable the coax networking on any receiver. It's not a software switch, but it's easy. Just connect the filter between the coax line and any receiver you don't want in the DECA cloud. Unfortunately even disabling DHCP does not stop the devices from communicating as part of a DECA cloud, and without DHCP they always have a link local address .

    You are definitely on the right track in your understanding of DECA clouds. You can use a simple switch and multiple CCKs. What you do need to know is that the "official" DIRECTV word is no more than 16 receivers on a cloud, and DIRECTV only supports a single DECA cloud. If you do bridge them, it "usually" works but know that the further they are logistically the less chance that they will work. In other words, two clouds on the same switch is more likely to work than two clouds on two different routers or even two different subnets.

    At that point, cloud-to-cloud MRV "usually" works. I'm sorry to use that weasel-word twice but you have to understand that once you go beyond the design parameters of this equipment, it's hard to promise anything.

    Also, because you're talking commercial, you probably know that DVRs are only allowed in Private Viewing accounts, not in any public place. If you operate a sports bar or have a waiting room, DIRECTV's policy is that you cannot have a DVR, because of copyright restrictions on the programming.

    Our Signal Connect team has also heard that at some point Genies will be allowed on commercial Private Viewing accounts but it could be next week, next month, or next year.
    SolidSignal.com SignalMarine.com // 25225 Regency Drive // Novi, MI 48375 // 1.877.312.4547

  10. #10
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    The 16 node limit is a "hard limit" of the MoCa 1.1.
    If DirecTV moves to MoCa 2.0 the node limit increases.
    If you're looking at more than 16 nodes, then this would be how to keep each DECA cloud under the 16 node limit and still have all the receivers share:
    WHITE PAPER: More than 16 tuners in the home - Signal Group Forums - Page 2

    With the HR2x when there are around 10 DVRs the software starts having problems as it's getting to the limit of what the software can handle.

    I don't know of anyone yet that has connected more than two Genies, so it's hard to know what will happen.

    No matter how I look at combining two SWiMs into one cloud, I can't find a need for using 8-way splitters.

    "Say you could get several Genies", with each using 5 tuners, it leaves only 3 tuners for each SWiM output. A Genie + 3 receivers, so 8 tuners and 4 nodes, and still only a 4-way.
    The Genie can act as a CCK, so one Genie supplies internet to the cloud. Two SWiM-16s could support 4 Genies & 12 receivers, which is the 16 node limit.

    If you use Genie mini clients instead of receivers, while they don't use a SWiM channel, so you could use an 8-way splitter, each one is still a DECA node, so you hit the node limit [again].

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