How to "piggyback" dual tuner receivers

[larsh74]

I was reading the features that are avaliable on DPP dual tuner receivers and found something interesting. The manual says that it is possible to use one cable for both the dish and TV 2 through diplexers. It refered to this as "piggyback." This would be an ideal solution for homes that are prewired with only one cable. Anyone ever tried this?

 

[Van]

Techs do it all the time, its called diplexing.

 

[larsh74]

I guess what I am really trying to found out is if it is possible and how to do it.

 

[RandallA]

It's very common to use diplexers. Here are a couple of examples:

http://www.solidsignal.tv/dishnetwork/DISH_Pro-DISH_Pro_Plus_Diagrams/DistributionExample3.pdf

http://www.solidsignal.tv/dishnetwork/DISH_Pro-DISH_Pro_Plus_Diagrams/DistributionExample9.pdf

 

[jklein]

diplexing is taking to signals and sending them through one wire/line. example is taking a satellite dish and a outside antenna (diplexing) putting both through one line and bringing them into the house and separating them in there one wire less mess and hanging wires, it is really cool and easy.

 

[OoTLink]

Yep, you can do such a thing, it's a little nutty but it can be done - you get the 2 wires outta the box, run them into a DPP err.. splitter whatever they call this, that gets you to 1 wire, then you shove a diplexer there and diplex the TV2 output into the same line as well.

At TV2, you diplex off the same line, then run the 'leftover' line to the dish where it gets its signal. Yay!

For further confusion and/or fun, add in a splitter in front of the diplexer and hook that newly found extra line to the receiver's TV2 remote antenna hookup, and from the TV2 location, run a splitter off the diplexer nad plug the antenna into one end (tv into the other) -- note how I say splitter, not diplexer!

Then the proud new owners of whatever model receiver you set up have 3 dongles and a bunch of short wires behind their TV. :clap

*edits* an insane little idea jumped into my head - is there any limit on how many duplexers you can use on a line? I have a feeling as long as you do it right and use quality parts the possibilities are endless, meaning with RF modulators you could make your own local cable system

 

[bhelms]

Understand that a diplexer pair combines then splits-off again two separate bands of frequencies. There are several considerations that limit how often that can be done and how many different frequency bands can be combined into a single system. As long as the frequency bands don't overlap at all and have a reasonable separation at the "split", then this technology works well. There is also some loss in any passive device like a diplexer or splitter/combiner that reduces the signal strength. One could diplex (combine and resplit) many times as long as there is adequate signal strength at the equipment end. And more than 2 frequency bands can be placed on a single system as long as there is adequate separation at the split frequencies to accommodate the filter roll off characteristics without significant signal loss in the desired passbands. How many times that can be done is determined by the max. frequency response of the transmission system (cable and any devices inserted into it), how wide the passbands need to be, how sharply the roll-offs can be made at the split frequencies, and what is the minimum signal strength needed at the equipment end. Steeper filter roll-off (needed to "pack" more passbands into a given transmission system) generally means more loss in a passive diplexer, so that becomes a limiting factor. There can also be some signal degradation other than just loss of strength. The system designer needs to manage all of these factors...

 

[webbydude]

I've actually diplexed 2 different TV#2 signals on the same coax that was ALSO supplying the SAT feed to one of the dual-tuners. Not sure what the "limit" is as to regarding that.

 

[bhelms]

I've actually diplexed 2 different TV#2 signals on the same coax that was ALSO supplying the SAT feed to one of the dual-tuners. Not sure what the "limit" is as to regarding that.

Unless you frequency-shifted either of those TV2 signals, then probably you combined the two TV2 signals into one relatively lower frequency passband and then diplexed those two with the higher frequency sat. down-converted channels. I don't know the limits either; the major limiting factors are what I posted above.

(One possibility for diplexing two "TV2" signals is the use of UHF/VHF combiner/splitters if one of the TV2 signals was in the VHF band and the other in the UHF band. That's an older example of diplexing that's been around a lot longer than DBS...)

 

[larsh74]

Thanks for all the input everyone. The DPP distrubution examples were especially helpful. Thnx again.