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Combine aerial FM radio with coaxial CATV into a single coaxial cable


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#1 of 5 johnpre13

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Posted November 10 2012 - 11:26 PM

My CATV supplier provides analog and DVB-C channels over a coaxial cable. No decryption CAM/CI needed. No internet/DOCSIS. So far so good, but - there are also no radio channels - neither analog (88-108MHz) nor over DVB-C. In my home the coaxial cable goes trough simple splitters/amplifiers (40-862MHz) and goes to multiple TVs (analog and DVB-C), TV tuners (analog and DVB-C) and FM radio tuners (analog). I want to "inject" the aerial broadcast FM radio channels (~32 in my area) from an external antenna into the coaxial cables inside my home. I would prefer some "one-way injector" (so that it doesn't influence the neighbors’ CATV, so that CATV isn't broadcast by the antenna damaging the spectrum and so that no signal power is lost in those directions). I would prefer the "injector" to transform the 32 FM radio channels into one DVB-C "frequency block" to be transmitted over one of the unused DVB-C TV channels in the 40-862MHz range (as done right now at one of the aerial broadcast DVB-T channels). Alternatively, analog re-broadcast at 88-108MHz over the coaxial cable (that range is currently free/unused, so I won't lose any CATV channel). Even better If it supports both FM-to-DVB-C and FM-to-FM-over-coax and the best will be if it can do this simultaneously. Whatever the case I would like to have RDS also re-transmitted, if possible. If the device is an active one, then a surge protection for both CATV and antenna inputs would be welcome. That's the device I search for: coaxial CATV 40-88, 108-867MHz analog and DVB-C --> injector input1 antenna 88-108MHz FM radio --> injector input2 combined CATV channels + radio channels --> injector output1

#2 of 5 Wayne A. Pflughaupt

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Posted November 11 2012 - 06:34 AM

From what I see in Wikipedia, a common diplexer should do the trick. Regards, Wayne A. Pflughaupt
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#3 of 5 johnpre13

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Posted November 12 2012 - 04:23 AM

I think you are right, thank you! I found one such diplexer - http://www.soontai.com/DPX1-TVFM.html - but I can't find it or any equivalent for sale at the usual places (amazon, ebay, radioshack, etc.) ... Also, what about converting the FM to DVB-C (to have FM radio with RDS on my TVs)? Maybe by utilizing some carrier grade device?

#4 of 5 Wayne A. Pflughaupt

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Posted November 12 2012 - 06:30 AM

I think you are right, thank you! I found one such diplexer - http://www.soontai.com/DPX1-TVFM.html - but I can't find it or any equivalent for sale at the usual places (amazon, ebay, radioshack, etc.) ...

I’m not sure if that will work. That looks like something that would combine FM with the old analog TV protocol, which were all in the same frequency range. What you want is something combining say, a TV antenna with a DirecTV antenna. Even then, it’s possible that would have to be one that was for the analog TV standard (FM operates in a frequency-slot between the old Channels 6 and 7, or something like that). I’m not sure what the operating frequency range of broadcast digital TV is.

Also, what about converting the FM to DVB-C (to have FM radio with RDS on my TVs)? Maybe by utilizing some carrier grade device?

You’re talking about converting low-frequency analog RF to high-frequency digital RF. I expect that requires a piece of pricey professional-grade gear. Regards, Wayne A. Pflughaupt
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#5 of 5 johnpre13

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Posted November 14 2012 - 06:14 AM

Digital TV (or at least DVB-C) utilizes the same frequencies as analog TV, so I think an old TV/FM diplexer sould work. But I can't find such (or a TV/FM/SAT triplexer) for sale... About the FM to DVB-C - I found some DVB-C transponders (without FM input) and they were out of my price range... and obviously adding FM-in wouldn't make them cheaper.




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