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Discussion Starter · #1 ·
When you are using your analog video source like DVD and satellite HDTV how does your projector get the sync? RGBHV, RGB with composite sync, three wire input with sync on green, three wire RGB with tri-level sync on green? I'm trying to determine the more common sync inputs for CRT projectors. Thanks for sharing your info.
 

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I guess that depends on the projector in question. Not sure if it's a source problem or projector problem but, some ECP's won't sync with (memory fades) RGBS. You must put a T in the line and split H and V, or was it the other way around? My ECP's all sync'd fine one way or the other. My NEC would take anything you threw at it. I have come to the conclusion that my 4600 prefers RGBS. It does RGBHV but seems more stable with RGBS. I have not tried sync on green with anything but a big Electrohome/Christie Digital I was having a problem with. This is a great topic of discussion and you will get many different opinions on the subject.


Chip
 

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My barcos are running RGBHV on Port 3 (for the RD801) via DB9 cable, and RGBS on Port 3 on the BG801 via BNC Port 3 mod.

I'm going to be adding a cable for the ceiling mounted BG801 that has six coax lines as part of my ongoing improvements, but for the near term I've gotta finish the damn HT!
 

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Hi Chip,


What kind of problems do you see when you use RGBHV with your 4600, HVsync stability problems, convergence drifting. So you use rgb with sync on blue, what source would that be from as I can't say I've heard of sync on blue very often.
 

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Discussion Starter · #5 ·
My question isn't clear. What does your analog HDTV source or other analog EDTV source output to your projector? How common is sync on green? How about tri-level sync on green? Or are these not common and most sources have RGBHV outputs? Thanks for your answers.
 

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Adelphia Cable, Marshfield MA, only HD STB option is SA8300HD with HDMI (which is inexplicably disabled, or so I was told by Adelphia) and Component. They don't even offer the (lame) SA transcoder... Component only.
 

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Hi tse,


I can say that the Echostar 6000HD box outputs RGBHV bi level or Component and I believe its sync on Y only, I'll have to check to see if its tri or bi. THe NN208 has RGBHV with Bi level, the component out is tri level sync on Y only. Those are the ones I have.
 

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My Sony SAT HD-200 does RGBHV, component, s-video and composite,I know it puts out tri-level on RGBHV. I'm sure it does also on component but I have not tried it. The older AmPro 2000/4000 projectors won't work with it, the 3600/4600 have no problems with it.


Chip
 

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I always use RGBHV, even if the projector accepts component. Only if absolutely necessary, like because I need to feed an HDTV source that isn't available in RGBHV and/or don't have a scaler that can convert it, will I use component.
 

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My barco took composite synch, from the RCV(?) 400 box; my Runco 980 Ultra gets RGBHV, except when I have a bad cable, and then it will live with composite synch; I think it even takes synch on green, tho I haven't tried it. All I know for sure is that I have all 5 BNCs connected; honestly have no idea what my STB is putting out, via the HD15 to BNC breakout cable, but it is the 5 connector cable, and I have all connected.
 

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Hi Techman


Isn't all HDTV native component 4:2:2, so in order to get it to rgb you'd have to convert it and any HDTV sat box for example that has rgbhv outputs has a built in transcoder in it, ie: the echostar 6000HD.
 

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Discussion Starter · #13 ·
Quote:
Originally Posted by WTS
Hi Techman


Isn't all HDTV native component 4:2:2, so in order to get it to rgb you'd have to convert it and any HDTV sat box for example that has rgbhv outputs has a built in transcoder in it, ie: the echostar 6000HD.
Now this is what I'm looking for. Are you saying that an HDTV source with sync on green is going to be outputing component video? An RGB HDTV source will also have H & V sync? What I'm trying to determine is if I need a sync stripper for the green input to my gamma board. If all the analog RGB signals are also going to have H & V sync, or composit sync, there's no need of the stripper.
 

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Quote:
Originally Posted by tse
Now this is what I'm looking for. Are you saying that an HDTV source with sync on green is going to be outputing component video? An RGB HDTV source will also have H & V sync? What I'm trying to determine is if I need a sync stripper for the green input to my gamma board. If all the analog RGB signals are also going to have H & V sync, or composit sync, there's no need of the stripper.
All analog RGB signals DON'T have H&V sync. Also, don't forget that HD has tri-level sync.
 

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Discussion Starter · #15 ·
I'm confused. HDTV 3 wire output. Of course sync on green. Tri-level. Ok.


Is this format component video only?


Is it ever analog RGB that can be connected directly to the RGB inputs of the projector with no decoding, transcoding, encrypting, decrypting, magic decoder ring, or whatever. If the projector works with tri-level sync will the red and green and blue signals be correct as they are?
 

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Quote:
Originally Posted by tse
If the projector works with tri-level sync will the red and green and blue signals be correct as they are?
No, but having tri-level sync (like on some Barco's) is a prerequisite for a projector THAT CAN handle component video directly WITHOUT needing a transcoder.


P.S. that's what made the Samsung SIR-TS360 such an interesting solution for people with projectors that can ONLY accept RGBHV, since it has an RGBHV output. The only other one I know of was the old RCA DTC-100.


Although I am told they exist, I'm not aware of any "cable tv" boxes that have RGBHV outputs.
 

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Hi tse,


As far I know it, RGB never uses tri level sync only bi level. Now my echostar 6000HD sat box outputs RGBHV, the HV are separate bi level syncs. The component outputs of the 6000 have tri level sync on all 3 signals which is standard for component, although my NN208 DVD player only outputs tri level sync on the Y signal not on the PrPb.


Now some RGB signals will have the sync combined with the grn signal and that will be a composite sync. I don't think sync is combined with B or R but I'm not sure, rare if it is I think. If a source has RGBHV then chances are there is no sync combined with either signal. I can't say for sure if all HD boxes output separate syncs with RGB or composite sync on grn.
 

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Discussion Starter · #18 ·
The idea that I'm getting is if it is three wire HDTV you are not going to connect this directly to your projector. The three wire HDTV source will need transcodeing or something to make the seperate red, green , and blue analog signals that the projector is looking for?


If your HDTV source has the analog red, green, and blue signals it will also have composite sync or H & V sync outputs?
 

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Quote:
Originally Posted by tse
The idea that I'm getting is if it is three wire HDTV you are not going to connect this directly to your projector. The three wire HDTV source will need transcodeing or something to make the seperate red, green , and blue analog signals that the projector is looking for?


If your HDTV source has the analog red, green, and blue signals it will also have composite sync or H & V sync outputs?
Only projectors that accept component inputs, like the Sony D & G series and many NEC XGs, as well as Barco's that have the component option. Otherwise, you need to use a transcoder or a scaler that will accept progressive component inputs at HDTV resolutions, or have an HDTV source that outputs RGBHV (which isn't very common).
 

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Quote:
Originally Posted by tse
If your HDTV source has the analog red, green, and blue signals it will also have composite sync or H & V sync outputs?
Component HDTV (Y,Pr,Pb) analog signals have their sync on either RGB (Y,Pr,Pb), or green (Y) only. This system needs conversion before RGBHV use, and proper conversion removes (strips) the sync from all R,G,B, and sends it out separate H & V. So after the conversion process (transcoding), the sync is only on H and V of the RGBHV. Sync on green (SOG) is not used in modern HDTV signals.


However, there is a little monster called "residual sync." It is a very small leftover sync pulse that can be present after sync stripping. It can surface on any or all three of the RGB signals, and its presence depends on the quality of the DAC/transcoding, and since we're dealing with an HDTV standard that stills needs a bit of refinement, there are still subtle difference's in the tri-level sync system that can cause usual sync levels. Why some systems have sync on all three and the others only have it only on "Y" is still a mystery.


Now, if you're using a Marquee VIM with HDTV signals, it's best to remove C52 or R152 from the VIM's SOG feed circuit. Because residual sync on green can activate the SOG circuit on the VIM.
 
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