[eshark]

So I've got two questions regarding my new DirecTV service, and I live in a building where we have a community dish on the roof of the building, and each unit has one cable drop feeding a distribution block in the unit.

I've got an HD-DVR receiver (brand new - just shipped from DTV). Right now I have DSL, but I'd like to go back to Comcast Cable internet. From the wiring closet in the building, I was wondering if I could use a diplexer (or other device) to put the comcast internet and DTV service over one line to bring it into the unit, and then split it back out so they would both work....?

 

[BattleZone]

No. The cable signal uses some of the same frequencies as your DirecTV signal, so they cannot co-exist on the same line of coax. Diplexing is only possible when you are combining two signals in different, non-overlapping frequency bands onto the same cable.

Now, having said that, there is a "maybe" solution. There is a new device called a SWM (Single-Wire Multiswitch) that can feed 8 DirecTV tuners over a single coax, AND can often be diaplexed with cable. The likely problem for you is that you'd need FOUR lines coming from the "community" multiswitch to feed into the SWM, or it won't work. Getting them to give you 4 lines may be a problem. Also, you'd need to purchase and be responsible for the SWM yourself. They have been significantly reduced in price recently, though.

 

[AntAltMike]

You can diplex Comcast Internet and DirecTV "wideband" (250 - 2,150 MHz) Ka/Ku signals, provided you use a diplexer that passes the low frequency Comcast return signal. Generally, any diplexer that says the TV port passes signals above 5 Mhz will do. I have had no trouble using the Sonora diplexers that only claim to pass 15MHz and above with a cable system that had its return signal on 10.5 MHz. Sonora publishes more honest frequency specs than do most other manufacturers, so the fact that a cheap diplexer says it passes 5 Mhz on its label doesn't mean it is any more favorable to the return signals than a Sonora that guarantees the passage of 15 MHz and up.

A stickier problem may develop if you try to diplex DirecTV SWM signals and a cable signal with a low frequency return path. There are special, SWM compatible diplexers that pass the 2.3 MHz SWM return signal along with the DC and 22 KHz tones to their Sat ports, but so far, I have not seen anyone evaluate the low end roll-off contour of their cable TV passband, so I don't know how much they may degrade or impede low frequency return signals.

FWIW, I couldn't find the special diplexer on NAS's website when I looked for it last week. Can anyone confirm that there actually are any DirecTV-approved SWM/Cable TV diplexers even being made at present?

 

[joe diamond]

I think they would work IF you turn one off while using the other. It seems the DTV usage blocks the internet usage but the CATV signal doesn't affect the DTV signal. The few service calls I have done over this were all interference with the internet but the DTV was ok.

Anyone?

Joe

 

[veryoldschool]

This isn't a simple yes or no. DirecTV doesn't support diplexing.
"Some" have gotten it to work, but the BBC [up converter] needs to be moved before the first diplexer, so the 250-750 band is converted above the CATV band.
As posted earlier: not all diplexers are the same, nor the frequencies used for cable modems, so it "might work" for you.

 

[eshark]

This isn't a simple yes or no. DirecTV doesn't support diplexing.
"Some" have gotten it to work, but the BBC [up converter] needs to be moved before the first diplexer, so the 250-750 band is converted above the CATV band.
As posted earlier: not all diplexers are the same, nor the frequencies used for cable modems, so it "might work" for you.

I don't use the BBC now, so you're saying I should start using it in fron of the diplexer that would be combining the the two signals?

 

[veryoldschool]

I don't use the BBC now, so you're saying I should start using it in fron of the diplexer that would be combining the the two signals?

Maybe "we" need to know a bit more about "your system".
What type of dish are you using?
If you're not used the BBC(s), it sounds like you're not using a 5 LNB dish, but instead the older 3 LNB.

 

[eshark]

I'm not sure what kind of dish is up on the roof of our building, but there are about 100 units in the building. Each unit has 1 coax run that gets split inside my unit (I have an HD-DVR, and 2 HD boxes), with what appears to be a traditional splitter (5-2450).

 

[veryoldschool]

I'm not sure what kind of dish is up on the roof of our building, but there are about 100 units in the building. Each unit has 1 coax run that gets split inside my unit (I have an HD-DVR, and 2 HD boxes), with what appears to be a traditional splitter (5-2450).

This is starting to "sound" like you're in a SWM based system.
Your receivers need to send a 2.3 MHz comm signal to the SWM, and the rest of your channels are above 970 MHz.
This "should make" the band free for your Internet, but as has been posted, the 2.3 MHz going to the SWM and the return path for your cable modem, "may" have problems, depending on what frequency is used for the return path and how well your diplexers work at these frequencies.

 

[joe diamond]

Is it time to discover who the MDU contractor is? Somebody built the system.

Joe

 

[AntAltMike]

Eshark: check your PM.

 

[Slowhand]

I am a SO in the Washington DC area. The problem is in many of my properties there is a single wire from the telco closet to the customers unit. We have already installed DirecTV MFH2 systems in the building.

The problem is people want DirecTV for the video services and Comcast for the internet service and there is only one wire.

Most of the previous posters have stated that diplexing is not a solution to the problem since DirecTv sub-band swm control signals and internet are too close to each other. But what about using a 2 set hybrid splitter used as a splitter/combiner which combines both the Comcast internet signal and the DirecTV signal.

I am aware that this will increase the signal loss between 3-4 dB where it is combined and an additional 3-4 dB when it is split again.

Now, befor anyone says that this will not work I want to say that it did work for me today. What I am concerned about is if it will keep working and what you all think about this way to let customers have both mfh-2 hd programming and comcast internet where there is only one wire to the unit.

I am concerned how comcast is going to react when they see the combiner in the telco closet and start disconnecting wires.

If there is no workable solution for this problem then I guess that we will have to tell customers to switch to dsl if they want DirecTV.

Slowhand