HDMI to Coaxial - AVS Forum
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post #1 of 10 Old 11-08-2011, 08:33 AM - Thread Starter
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I have multiple TVs in a building which has coaxial wires under the wall.

I want to output my computer's HDMI output to these TVs through Coaxial(RG-6) cables at the best possible quality.

Current Solution :
step 1 :
I converted VGA signals to A/V using this box on ebay which takes VGA as input and output VGA/Video/S-video



step 2 :

Now i used Video from above and used RF-Modulator(SAW filter + channel 3/4) to output RF signals



Issue :

VGA to Video conversion is blurred and hazzy. Texts are not readable.
I tried with both ubuntu & windows 7 .
Moreover i have tested the Rf modulator with my Canon SLR A/V out and it works awesome which means that the issue is in step 1.

Requirement :
Is their a direct hardware to convert HDMI to RF or VGA to RF in a single step??
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post #2 of 10 Old 11-08-2011, 10:26 AM
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You're never going to get readable text this way. 480i, which is all that modulator will do, is just to low a resolution. You need to get the video from the PC to the display at the native panel resolution of the display.
I'd go straight HDMI to the TV or HDMI to DVI to the tv. If distance is an issue, you would want to look at an extender (HDMI over cat5/6).
If the TV is so old it has neither HDMI or DVI ports or if there are none free, you can convert HDMI to component at 1080i (monoprice has a converter), but then you deal with overscan on the TV that may make a computer interface unusable.
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post #3 of 10 Old 11-08-2011, 11:19 AM - Thread Starter
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Thanks for ur reply .

Few things:
  • TVs are latest LCD ones with HDMI,VGA, component video but the only communication medium is the conventional RG-6 coaxial cables and thr is no option to put in LAN or HDMI cables through walls
  • when you say ...monoprice has a converter... does it mean that i can convert HDMI to Coaxial ?
  • Is there any VGA option available instead of HDMI?

I know i am not asking too much but still not convinced with the 2 step process i used above. No Idea how cable operators broadcast their private local channels in the city
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post #4 of 10 Old 11-08-2011, 01:35 PM
 
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Quote:
Originally Posted by get2abhi View Post

Thanks for ur reply .

Few things:
  • TVs are latest LCD ones with HDMI,VGA, component video but the only communication medium is the conventional RG-6 coaxial cables and thr is no option to put in LAN or HDMI cables through walls
  • when you say ...monoprice has a converter... does it mean that i can convert HDMI to Coaxial ?
  • Is there any VGA option available instead of HDMI?

I know i am not asking too much but still not convinced with the 2 step process i used above. No Idea how cable operators broadcast their private local channels in the city

Let's simplify this - you cannot go from an HDMI cable to a coax with an uncompressed signal.

HDMI cables contain 19 conductors designed to transmit high speed data. Coax does not. However, these signals can be modulated but bandwidth limitations prevent the full video signal from being sent over a single coax connection.

Your best bet would be to take component video output and convert to a modulated signal. Something like this:

http://www.crwww.com/qmod-hd.asp

Maybe someone else knows of a cheaper HD modulator. Unfortunately, unlike the old channel 3/4 480i modulators, the HD versions are relatively rare and not cheap (that I've seen). As the description says, this is how cable operators and small businesses distribute their HD programming on separate channels.

And, HDMI is designed not to be converted (copy protection paranoia), so officially there are no HDMI to anything converters (except for audio conversion and HDMI to DVI).

Finally, converting a computer screen to 480i is going to yield poor results. I've seen a few converters that had the proper sync rates and provided just readable text. The cheaper converters just never really worked right. You have to match the output resolution of the video to really see a good computer screen. The reason it looks OK on regular video is that the video is not small stationary letters and numbers. Your eyes/mind fills in the blanks with moving video.
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post #5 of 10 Old 11-08-2011, 11:12 PM - Thread Starter
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thanks for enlightening me. the 480i RF modulator sucks while rendering texts.
I have now dropped the idea of HDMI to Coax and i am now looking for
VGA to Coax

After much googling and youtubing i got this

www[dot]zeevee[dot]com/zvbox



can you just have a look at zvbox.

its > 1000$ so plz let me know some cheaper alternatives for converting VGA to Coax
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post #6 of 10 Old 11-09-2011, 06:39 AM
 
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Yes, that is an RF modulator for ATSC digital TV. It will convert one video and audio source to the digital channel you choose.

Use "ATSC modulator" (no quotes) as your Google search term and you'll find more hits. However, not all of them can handle HD, so check the reviews. You may also want to try the AVS Forums that pop up on that search. The people who frequent that part of AVS may have more knowledge of ATSC modulators than this HDMI forum.

Also, you're probably still looking upwards of $500+, which is much more than I would pay for repairing sheetrock and repainting. If you are less than 25 feet distance between the devices, HDMI or component would still be cheaper (assuming you are allowed to break into the wall). However, if you go HDMI, you should research how an HDMI splitter would work - only one type of signal can go out to all TV/monitors and all of the TV/monitors have to be compatible with that one type of signal for the splitter to work correctly. Check the archives of this forum for more discussion of "lowest common denominator" if you decide to open-up the wall.
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post #7 of 10 Old 11-09-2011, 08:18 AM
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Have you considered HDMI over fiber instead? You can buy clear fiber cables that allow for routing along baseboards and such without being visible unless you are looking for them. They can also maintain much higher HDMI (4.95 Gbps +) over long distances (100m+). Crestron is one company that I know of that provides such support. There are other companies (Opticis, Gefen, Ophit, Owlink), though whether they supply the clear cables, I can't tell you. Hope this helps
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post #8 of 10 Old 11-09-2011, 03:48 PM
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I believe this is exactly what you are looking for:

http://www.audioauthority.com/product_details/HXE-11

We have used these and they work great
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post #9 of 10 Old 11-10-2011, 06:31 AM
 
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Quote:
Originally Posted by DrDSL View Post

I believe this is exactly what you are looking for:

http://www.audioauthority.com/product_details/HXE-11

We have used these and they work great

Very interesting. Looks like it came out in August 2010. I hadn't seen that before.

Make sure to click on the FAQ tab on the product info page: http://www.audioauthority.com/produc.../Extender/10/1

From reading up on the product, video compression is used. Also audio is limited to stereo. However, every user comment I've seen reports that it works.
http://www.remotecentral.com/cgi-bin...ad.cgi?22293,2

So, thanks for the new information (at least for me).
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post #10 of 10 Old 11-10-2011, 02:09 PM
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Quote:
Originally Posted by alk3997 View Post

From reading up on the product, video compression is used. Also audio is limited to stereo. However, every user comment I've seen reports that it works.
http://www.remotecentral.com/cgi-bin...ad.cgi?22293,2

These extenders don't use any compression. They actually convert HDMI to HD-SDI (which is uncompressed digital video and audio), send HD-SDI over coaxial cable, and convert HD-SDI back to HDMI at each display.
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