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 ·TekSavvy Cable
1 edit | [TV] FibeTV (HPNA) + OTA on same coaxial?Hello all,
My HDTVs all have built in ATSC tuners, and I have a roof mounted antenna for OTA.
I'd like to use a single cable run per location to feed both FibeTV (which uses HPNA v3 (4-36Mhz) from what I can tell online), and OTA which I believe is all UHF, living closer to 700Mhz.
Just going by the frequency ranges, I thought this should be easy and any old 2-way splitter could be used to combine, and then split the signal.
Example:
OTA ]-------] ]--------[ATSC Tuner
Splitter]-------[Splitter
HPNA]-------] (coaxial) ]--------[FibeTV Box
When I do this, the OTA signal comes in just fine, but the HPNA feed stops working, with the receiver struggling to keep up, and often times simply displaying a no signal message.
Maybe I need to isolate the signals using a diplexer? That raises my next question/problem - where does one find such an item? It seems that most "standard" diplexers are designed for Satellite and CATV. The CATV spectrum is what we need for OTA, but the Satellite frequency range is much higher again.
I've found a local guy in Toronto who can make custom diplexers, but they cost a ton as they aren't mass produced...
The obvious solution is to just run a 2nd cable for OTA, but I really want to avoid that if possible as I don't want to start poking holes in freshly remodeled rooms...
Any other suggestions?
-- SS |
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| HPNA frequencies are also used in the air for shortwaves radio (ham radio, shortwave radio station like BBC, Voice of America, etc...). So you are picking up these signals with your Antenna and combining to the Bell Fibe signal using the same frequencies. Just run a second coaxial cable.... |
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 mlernerPremium
join:2000-11-25
Nepean, ON
kudos:5 | I wonder why the manufacturer couldn't just use MoCA which is far superior.. |
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·TekSavvy Cable
| reply to news
said by news :HPNA frequencies are also used in the air for shortwaves radio (ham radio, shortwave radio station like BBC, Voice of America, etc...). So you are picking up these signals with your Antenna and combining to the Bell Fibe signal using the same frequencies. Just run a second coaxial cable....
Thanks for that - I didn't realize that my antenna could be picking up those signals as it was only rated for much higher frequencies. I think I've found a diplexer that will work - its called a "SUB-BAND/CATV Separator/Joiner".
The way I understand these devices, the CATV port should reject the "Sub-Band" frequencies at the 1st diplexer, correct (see above)?
On a side note, how do you place uploaded attachments/images where you want them in a post? Is there a way to do this gracefully without loading them via a URL?
-- SS |
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Reviews:
·TekSavvy Cable
1 edit | reply to mlerner
said by mlerner:I wonder why the manufacturer couldn't just use MoCA which is far superior..
I think it has to to with interoperability. It is my understanding that MoCA uses frequencies which I believe can't co-exist (easily) with other services found in residential applications, where in theory at least, HPNA is specified to only use frequencies not commonly found on coaxial and/or telephone cabling. The main idea being that for users like me, you can run multiple services over a single cable.
The result is less bandwidth (vs. MoCA), but HPNA v3.1 is supposed to offer 320Mbit (200Mbit throughput). Tests I've read about on this forum with FibeTV's implementation seem to peak at 65Mbit. I haven't found a definitive place listing the version Bell uses, but the modem's page says V.3, and not 3.1 - so I think they are only using 4-36Mhz.
-- SS |
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mlernerPremium
join:2000-11-25
Nepean, ON
kudos:5 | From what I'm reading is the exact opposite. MoCA is in the 2 GHz+ range, works with digital cable and DOCSIS etc.
They're working on the gigabit spec now I believe. |
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Reviews:
·TekSavvy Cable
| said by mlerner:From what I'm reading is the exact opposite. MoCA is in the 2 GHz+ range, works with digital cable and DOCSIS etc.
They're working on the gigabit spec now I believe.
From »mocablog.net/tag/actiontec/ :
"MoCA has specified 2 frequency bands at which the network can be operated: High-RF MoCA for Cable MSOs and Verizon FiOS from 850-1500 MHz, and Mid-RF MoCA for DirecTV from 500-850 MHz. Our more advanced readers may recognize that cable TV broadcasts below 850 MHz on the coax and satellite TV broadcasts above 950 MHz, hence the need for MoCA to avoid interfering with current signals on the line and 2 separate RF bands."
I may be wrong, but I thought these ranges would interfere with other TV signals, where the sub-band range of HPNA would not.
That being said, I'm the first to admit that I'm not an expert in this area, and will quickly defer...
-- SS |
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| reply to ssherwood
25 dBmV rejection doesn't seems a lot to me. Off air signals are very strong, maybe it can be better with high pass filter like MODEL HPF-54H (45 dB rejection) . You have to use good quality splitters, good connectors installed with proper tools, it's suppose to be a closed circuit. I never tried that, so there's no garantee it will works...
»www.3starinc.com/manuals/Filters.pdf |
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| reply to ssherwood
I see your post in the OTA forum as well (Phobia). That is where you will most likely find your answer...run a second feed is my response. |
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·TekSavvy Cable
| reply to news
said by news :25 dBmV rejection doesn't seems a lot to me. Off air signals are very strong, maybe it can be better with high pass filter like MODEL HPF-54H (45 dB rejection) . You have to use good quality splitters, good connectors installed with proper tools, it's suppose to be a closed circuit. I never tried that, so there's no garantee it will works...
»www.3starinc.com/manuals/Filters.pdf
Thanks again - will running a high pass filter in series with the diplexer make the rejection stronger?
-- SS |
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RickStepPremium
join:2002-11-25
Hamilton, ON
kudos:1
1 edit | reply to ssherwood
You could try a VHF/UHF splitter to filter out the low frequency radio signals.
Diagram 1-1 might work instead of a splitter.
Diagram 1-2 should work. No other devices should be needed. If the OTA signal is strong, you could add an attenuator in series with the antenna to drop all signals.
I couldn't find any specifications for the VHF/UHF splitter so it is impossible to know the VHF pass band. The UHF filter is probably a high pass filter to pass everything above 470MHz. The VHF/UHF device should probably provide 30 - 60dB attenuation to signals from the opposite input which is probably adequate unless there is a ham radio operator close by.
Diagram 2 is of a VHF/UHF splitter/combiner. They can be purchased online here for US $2.49:
»www.techtoolsupply.com/ProductDe···ode=UVSJ
The Source or others may have these locally.
Rick |
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| If you look further on the Holland Elctronics site, you will find HPNA splitters as well. Not sure if they do exactly what you want. |
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RickStepPremium
join:2002-11-25
Hamilton, ON
kudos:1 | said by William777:If you look further on the Holland Elctronics site, you will find HPNA splitters as well. Not sure if they do exactly what you want.
Most splitters have a response of 5MHz. to either 1GHz. or for satellite use to 2.4GHz.
The HPNA band goes down to 4MHz. (1MHz. lower that the design response of typical splitters) which may improve HPNA signal quality.
As posted earlier:
said by news :HPNA frequencies are also used in the air for shortwaves radio (ham radio, shortwave radio station like BBC, Voice of America, etc...). So you are picking up these signals with your Antenna and combining to the Bell Fibe signal using the same frequencies. Just run a second coaxial cable....
radio signals can be picked up by any antenna; even those designed for other frequencies.
The HPNA band is shown above from this link here:
»www.homenetworkingdepot.com/html···c.I.html
Rick |
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| reply to William777
said by William777:If you look further on the Holland Elctronics site, you will find HPNA splitters as well. Not sure if they do exactly what you want.
The way Bell deploys FibeTV is different from the way UVerse is in the US. The coaxial comes from the VDSL modem, and not from the NID. I was mightily confused when I first saw VDSL on the coaxial splitters photoed online until I realized they implement the CPE differently from Bell.
Anyway - I believe the diplexer linked above should do the trick, the only question is will the rejection signal be strong enough. I hope it is - I will update this thread when I have received the diplexers.
-- SS |
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RickStepPremium
join:2002-11-25
Hamilton, ON
kudos:1
1 edit | reply to ssherwood
Typical rejection levels to avoid interference is between -68dB and -90dB.
These were the design standards for channel selection for tuners that were designed to tune the analogue channels.
The issue here; it seems to me; is can you make it work. 40 or more dB attenuation may be enough.
Keep in mind that decibels are logarithmic.
A chart is here to convert gain or loss in decibels to a gain or loss in voltage:
»www.sengpielaudio.com/calculator···loss.htm
A 0 dB gain or loss is the reference of 1
A 20dB gain or loss results in a gain or loss of 10 times or 1/10 (0.1)
A 40 db gain or loss results in a gain or loss of 100 times or 1/100 (0.01)
A 60 db gain or loss results in a gain or loss of 1000 times or 1/1000 (0.001)
A 80 db gain or loss results in a gain or loss of 10,000 times or 1/10,000 (0.0001)
A 100 db gain or loss results in a gain or loss of 100,000 times or 1/100,000 (0.00001)
Simply put an additional gain or loss of 10dB results in a voltage gain or loss of 10 times; 20 dB – 100 times; 40 dB 1000 times etc.
A -40 dB signal reduction will reduce the signal to 1/1000 of its original strength and may be enough to correct a specific problem without expensive devices.
I’m the type of person that would gamble on the economical solution before I looked at expensive ones. Spending or wasting $10.00 to $15.00 to buy a VHF/UHF combiner/splitter on line seems to me a great way to save a ton of money and keep a solution very simple.
Rick
Edit: Simplified table dB to voltage |
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| If I ran a high pass filter with a 40db rating for signals lower than 54Mhz in series with the diplexer, would that be sufficient? |
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RickStepPremium
join:2002-11-25
Hamilton, ON
kudos:1 | said by ssherwood:If I ran a high pass filter with a 40db rating for signals lower than 54Mhz in series with the diplexer, would that be sufficient?
It could work. The issues are the potentially interfering signals. Without a spectrum analyser, it is speculative.
However, a signal reduction of 1000 - 1 is a huge drop.
If the OTA stations you want are all local (not Buffalo and Rochester) a 20 dB Attenuator in the antenna line would reduce all signals. The unwanted signals would be at -60dB (1/10,000) and the local signals are probably strong enough to still produce a clear picture.
My post here was to give you options. Without knowing explicitly what is happening, all options are a crap shoot.
Rick |
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RickStepPremium
join:2002-11-25
Hamilton, ON
kudos:1 | As a serviceman going back 45 years, the first & second solutions to any problem are the simple solutions & the economical solutions, even before you spend time on equipment resources or doing an extensive analysis.
Some things to keep in mind:
1. If you are doing the work yourself; you are saving the labour cost. If you buy components that don't work, the eventual cost will likely be cheaper than hiring a professional, even if there is no solution. A professional can still tell you to run 2 cables and bill you $100.00 for the advice.
2. Is it possible that the 2 way splitter that you are using is an old device that doesn't respond well below 40MHz? Newer splitters operate between 5MHz. and 1GHz.
3. Is the splitter defective? Try interchanging the connections to the inputs (swap the OTA and HPNA cables).
4. If you are using a 3 way splitter the loss on 1 terminal is -3.5 dB and about -6.5dB on the other 2. On a 4 way splitter the losses are about -7.0 dB on all terminals.
5. If you are using a 3 way or a 4 way splitter, all unused terminals MUST be terminated with a 75 ohm terminator. Un-terminated devices can cause standing waves (reflections) in the coax cable resulting in lower signal levels as well as other issues.
Rick |
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RickStepPremium
join:2002-11-25
Hamilton, ON
kudos:1 | reply to ssherwood
I forgot this.
Any fliter can be connected in series with a filter that is the same. While the value of the 2 filters will not add to the value equal to the first, filters in series can help.
The second filter will add a value equal to about 1 divided by the square root of 2 (0.707).
For a 40 dB filter in series with a 40dB filter the value would be 40 + 40*1 divided by the square root of 2= 68.3dB
Adding filters together is more complicated that the description above but the premise of increasing attenuation is true.
Rick |
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| Thanks, Rick.
Attached is my planned implementation. I should receive the diplexers and filter soon, and when I do I will hook it all up and report back.
-- SS |
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