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Discussion Starter · #1 ·
If you were following the previous thread, you know I solved the problem with noise in the picture by using a 50 ohm network cable.


I've watched a few movies since then and notice the picture is definitely sharper. I have also noticed that bad video transfers are more apparent. I guess this is expected.


Another interesting thing is that deep red areas on screen have an odd sort of "noise" of their own. The deep reds have a sort of glistening shimmer that is very noticeable in some cases. I've attached a photo of a scene from "How High" that shows the phenomenon. The red sweatshirt should be one solid color, but notice it has areas of lighter color. Where the lighter and darker colors meet you get the shimmering effect. Might this be a compression artifact? Tweaking the video settings on the Leeza has no effect.
 

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If it works, then it works. Using the "wrong" cable won't damage anything.


But you and Key Digital are masking a problem. Something is wrong if the system will not function with the "proper" 75ohm cable.


I gotta tell you, this thread and the last one have made me loose any professional respect I had for Key Digital. Clearly they are not "engineers". They have a poorly designed SDI front end and are kludging it to make it work.


I guess this is what happens when consumer electronics manufactures dabble in the professional marketplace.
 

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I don't know Key Digital, but I would love to look at the schematic of the front end receiver in the Silk card. This is digital, Once the timing is right and reflections eliminated the picture should be correct.In looking at the schematic we could easily tell you if the impedances and loop parameters where correfct.

I agree with glimmie, I have been looking at the Belden website concerning SDI and cannot figure out why 75 ohm would not work from 1 ft to 100 ft, or more.

He states he has been running cables for years with SDI and would have to guess that the 75 ohm should be, and is, the correct impedance. Something is wrong if you are having to use a 50 Ohm cable to make this work.
 

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I wonder if the above could be quantization errors from the GeForce card?
 

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Glimmie,


I'm not sure I undestand what you're trying to say...


1. KeyDigital hasn't said that you should use 75 ohm or 50 ohm cables. AFAIK, 75Ohm is the standard, but they have not issued a statement about this - only experimented in a particular and isolated case to switch the cable to 50 ohms (or maybe it was a specific customer that decided that).


2. I use 75 Ohm cable and I have no noise. I had a noise during the first 10 minutes of when the DVD player was ever turned on. That's it.


3.
Quote:
Clearly they are not "engineers". They have a poorly designed SDI front end and are kludging it to make it work.
Clearly you have not seen Mike Tsienberg's resume. You should go on their website and "clearly" see what an amazing engineer he is...


4.
Quote:
I guess this is what happens when consumer electronics manufactures dabble in the professional marketplace.
LOL, you really lost me on that one... KeyDigital has never been a consumer electronic manufacturer... They are a purely professional enterprise selling high end scalers and distribution equipment for broadcasters.


They have probabably more experience in SDI / D1 than most companies on earth...
 

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For all of these SDI products to interact there has to be an impedance standard. My understanding is that this is 75 ohms. At least that is what I was able to dig up on the net.

The reference shcematics all show 75 ohms, I believe this is where glimmie is coming from.


Thanks,

Ray
 

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Discussion Starter · #8 ·
I'm not too interested in the cable problems anymore since that problem has been solved, I'm more interested in the compression artifacts or whatever it is I'm seeing in the red colors. Is this an attribute of DVD that using SDI exposes and I'll just have to live with?


FWIW, I've used a lot of Key Digital products and they have all been the best in their respective categories, often working when another vendor's product wouldn't. They all seem to be well designed and built to me. And when I have had problems, I've gotten all the help I could want.
 

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Quote:
I'm not too interested in the cable problems anymore since that problem has been solved, I'm more interested in the compression artifacts or whatever it is I'm seeing in the red colors. Is this an attribute of DVD that using SDI exposes and I'll just have to live with?
I would say that the 50ohm cable indeed seemed to solve your problem, but it seems to be a band aid on the situation.


As for the smearing/artifacts that you see on the reds. We have very similar equipment (Panasonic DVD w/Immersive modded output, and Rock+/Leeza w/ SDI input) and I do not see any of these artifacts in the image. So to answer your question...no, you should not have to live with this since it is not normal.


BTW, I use an AVcable 1.5 meter 75ohm SDI cable.
 

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Quote:
Originally posted by oferlaor

Glimmie,


I'm not sure I undestand what you're trying to say...


1. KeyDigital hasn't said that you should use 75 ohm or 50 ohm cables. AFAIK, 75Ohm is the standard, but they have not issued a statement about this - only experimented in a particular and isolated case to switch the cable to 50 ohms (or maybe it was a specific customer that decided that).
Oh yes they did, right here. See the first thread on this subject.

>>>>>

Okay, the problem is solved. Mike at Key Digital suggested trying a 50 ohm BNC to BNC cable, like the ones for thinnet ethernet (10 MBPS, RG-58A/U - 50 OHM). I picked up one at Rat Shak and it cleared all the problems up completely and immediately.


It seems a little odd that a 50 ohm cable would work best for this scenario, but it does.


As expected, SDI is noticeably sharper than component, BTW.
 

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Hi,I've read many but certainly not all posts here on the Leeza's with SDI.How many here are having this problem as i don't remember it as being an issue until now.If your not using 75 ohm cable somthing's gotta be wrong.
 

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Hey Glimmie,


Seriously, did KeyDigital post here that 50 Ohm cables should be used?! No, a specific customer was asked to change cables to try and debug a specific problem & you are making it look like they have no idea what they're talking about...


Mike did come out of Toshiba (and quite a few other companies), but what the heck does that have anything to do with things?!


I have no idea what you're talking about with RCAs. All of KeyDigital's products are BNC. Actually, some of their LEEZA customers were annoyed that even the SVideo connectors were two 75 ohm balanced BNC connectors (i.e., they supplied converters for you). They didn't use SVideo connectors because they would have ruined the 75Ohm balancing for these connectors when they were used for other things. LEEZA certainly has no RCA connectors (where did you conjure that up?!).


Again, the fact that Mike worked in Toshiba has no relevance - KeyDigital supplied broadcast upscaling equipment when they started (usually to upscale SD to HD so that broadcasters could broadcast SD material on their HD channels). That's definitely broadcast level, not consumer.


Their first "consumer" item (if you can call it that - it's not exactly a VCR) is the LEEZA.


This is getting to be a shouting match. I am dissapointed that you would basically trash a company (with obviously half-accurate truths) after one customer reports on the forum that he used a 50 Ohm cable to correct a problem...
 

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Quote:
Originally posted by Tom.W
Hi,I've read many but certainly not all posts here on the Leeza's with SDI.How many here are having this problem as i don't remember it as being an issue until now.If your not using 75 ohm cable somthing's gotta be wrong.
I am NOT having this problem (nor any other problem). I've had Leeza, Immersive modified RP56, and BetterCables 75ohm SDI cable for over 2 months now. Everything has worked as advertised since day one. This setup provides me the best DVD images I've seen to date!
 

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"I am NOT having this problem (nor any other problem). I've had Leeza, Immersive modified RP56, and BetterCables 75ohm SDI cable for over 2 months now. Everything has worked as advertised since day one. This setup provides me the best DVD images I've seen to date!"


me too, but with pmdt/vig sdi card, better cable and 5 months.
 

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Quote:
Originally posted by oferlaor
Hey Glimmie,


I am dissapointed that you would basically trash a company (with obviously half-accurate truths) after one customer reports on the forum that he used a 50 Ohm cable to correct a problem...
What is half accurate truth here?


FACT: Key digital did advise a customer to try a 50ohm cable. OK, it worked proving there is a problem with the transmitter or receiver design. The customer in question says it's fine and made no mention Key Digital is doing anything more about it. So they fixed a problem by using an incorrrect component. Is that the performance standard of Key Digital?


FACT: The customer did report that Mike told him the receiver must go through a "balance" period. As posted before I have been involved in the design and installation of very large SDI systems since 1992, HDSDI systems since 1999. I have never heard about "balance" before. I am also a degreed electrical engineer. This is as I said "Monster Cable" talk. Cleary the Leeza or the DVD player has a fault and Mike doesn't want to deal with it head on.


FACT: I didn't say the Leeza uses RCA connectors. But Key Digfital does make analog transcoders with RCA connectors. There is nothing wrong with this as RCA is unfortunatly still the consumer video connection standard. But Key Digital does make consumer products. So does Faroudja.


You claim to know all about broadcast grade equipment. Based on your posts I don't think you work in the broadcast industry. Furthermore you are in Israel. There are differernt standards and engineering cultures between Israel and the US. And FWEIW, European broadcasters do tend to have higher technical stanbdards than the USA. Key Digital is not a big name in broadcast equipment in the USA. They are new and perhaps someday they could be. But suggesting 50ohm cables for SDI and thinking a receiver takes a few days to "balance" is not going to help that progression.
 

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Quote:
Originally posted by Humey
We have our Faroudja bashers, our Taw bashers and even Vigatec bashers, but now we have our first official Key Digital Basher.


Congrats Glimmie
Thank You. I don't don't feel my bashing is biased or unfair at all. It is based on public information gathered on this forum.


"It's better to keep your mouth closed and let people think you don't know what you are doing then to open it and prove it!"


Author unknown but good advice for Key Digital.
 

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Glimmie,


I never claimed to be working in the broadcasting industry (look in my posts, did I ever say what I work at?!).


You make an assumption that their entire line is badly designed over a specific problem at a specific customer site who wrote that someone told him to change cables. God, sounds like a bona-fide open and shut case to me. Have you given thought to getting a law degree?


Whatever Glimmie, I thought you were more serious than that. BTW, congratulations on your engineering degree. I hold a degree in electronics and 2 degrees in computer science, big deal...


I conscede - KeyDigital's transcoders do have RCA connectors, since they are supposed to be connected, as you said to consumer units (e.g., DVD players).


BTW, what does my being in Israel have anything to do with anything?!


Seriously, we've finally gotten rid of those annoying TAW bashing threads & now this...

I've had enough BS, I'm outta this thread.
 

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Quote:
Originally posted by oferlaor
I hold a degree in electronics
I've had enough BS, I'm outta this thread.
Great, then you understand a transmission line model and know it's wrong to use a 50 ohm cable in a 75 ohm circuit at 270mhz.


My point on your location is that you may not be aware of the number of professional manufactures and the level in which SDI is employed in the US broadcast industry.


So much for the 50ohm cable. You seem to be avioding the "balance" claim. Do you agree with this?
 
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