Question about HDMI cable and PS3

Originally Posted by Tokyo Slim

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HDMI has 0 analog bandwidth. It doesn't transmit an analog signal at all.

The digital signal is a series of on/off voltage changes. As how "fast" those are both pushed out and recognized, it depends on your sending unit and receiving unit, not on your cable. Its not like HDMI for 1080p has more wires or terminals than one for 1080i.

You don't know what you're talking about.

HDMI has analog bandwidth because it uses analog waveforms for its digital signalling, like every other electrical digital cable out there.

The speed that you can push out those on-off voltages is directly proportional to the analog bandwidth you have.

--Andre

Originally Posted by A Y

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You don't know what you're talking about. HDMI has analog bandwidth because it uses analog waveforms for its digital signalling, like every other electrical digital cable out there. The speed that you can push out those on-off voltages is directly proportional to the analog bandwidth you have. --Andre
I think you are the one who's confused. An analog signal is a continuous signal, digital transmission is not. Digital signals are essentially on/off electrical pulses along a wire, not an amplitude or wave pattern signal. Analog Digital

Originally Posted by Tokyo Slim

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I think you are the one who's confused.

An analog signal is a continuous signal, digital transmission is not. Digital signals are essentially on/off electrical pulses along a wire, not an amplitude or wave pattern signal.

Those pulses have an amplitude. If they didn't, how does the other side know whether it's a 1 or 0? Also, if you try to push more pulses out over the same time period, those pulses need to be skinnier so more of them fit in the same time period. Guess how you make them skinny? That's right: more analog bandwidth.

Digital is an encoding protocol. You still need to transmit that protocol somehow. For HDMI, you use analog electrical signals for transmission. For high-speed digital designs, like HDMI, you need to worry about the underlying analog behavior.

You could also try to explain why a 100-foot HDMI cable with low analog bandwidth will get massive signal dropouts. Because if you're right, then length doesn't matter, but it clearly does in the real world as you can see from reports all over AVS and other places of people seeing sparklies and signal loss.

--Andre

Originally Posted by Tokyo Slim

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Digital

So tell me how those square signals get transmitted if you're not using analog waveforms. Also, have you actually put a scope to actual digital signals and seen what they look like? They look nothing like the squared-off waveforms in that picture because of analog bandwidth constraints. Google for "eye pattern" for lots and lots of examples of this.

--Andre

You can absolutely, 100% tell the difference between 1080i and 1080p when playing games. The PS3 will tell you what resolutions it is capable of. Get Wipeout HD, then any 720p game (Uncharted is a very good one), and you will notice the difference in resolution very easily.

720p vs 1080p, sure. 1080p vs 1080i on a tv under 50 inches...maybe

Originally Posted by A Y

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Those pulses have an amplitude. If they didn't, how does the other side know whether it's a 1 or 0? Also, if you try to push more pulses out over the same time period, those pulses need to be skinnier so more of them fit in the same time period. Guess how you make them skinny? That's right: more analog bandwidth. Digital is an encoding protocol. You still need to transmit that protocol somehow. For HDMI, you use analog electrical signals for transmission. For high-speed digital designs, like HDMI, you need to worry about the underlying analog behavior. You could also try to explain why a 100-foot HDMI cable with low analog bandwidth will get massive signal dropouts. Because if you're right, then length doesn't matter, but it clearly does in the real world as you can see from reports all over AVS and other places of people seeing sparklies and signal loss. --Andre
I honestly don't understand why this is such a hard concept. Analog bandwidth and electrical (or digital) bandwidth are two different things. You have confused them. HDMI, nor DVI, nor any other digital transfer protocol send analog signal through a wire. If it did, you'd probably have much less signal degradation over extended lengths, ironically enough. If you'd like to explain the length of the cable mattering, and an HDMI digital signal in general, its a pretty scientifically simple concept but it takes a long time to explain. And Blue Jeans Cable already did it for me, so go read that. Also, for explanation on HDMI and its NOT analog signal. For your information The HDMI 1.0 single link standard signal is fully capable of passing information on 164million pixels per second of video through a wire from the source to the television. 1080p at a 60hz refresh rate uses only 144million pixels per second. HDMI 2.0 double link standard can do 1080p at over 330mhz. So its not a BANDWIDTH problem (more information won't help, since its already able to put out way more information than today's televisions need or can use). It is an attenuation problem, and an error checking problem, and a real time streaming problem. And even that would be LESS of a problem if HDCP wasn't such a ************* and add another interruption to the data stream.

sounds great. all over my head. so it looks like I won't be needing a new HDMI cable.

Originally Posted by teddieriley

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sounds great. all over my head. so it looks like I won't be needing a new HDMI cable.

You overpaid, but you won't need a new one.

Anyway, follow my recommendations. Get Little Big Planet, Wipeout HD and Uncharted.

Originally Posted by Tokyo Slim

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Analog bandwidth and electrical (or digital) bandwidth are two different things. You have confused them.
Yeah... that's where the issues are for A Y.

Digital bandwidth - how fast you fetch data.
Analog bandwidth - think of it as sort of the frequency response of a filter. It's really just the range between the -3 dB.

I guess what he was aiming to say was increase the frequency of the signal rather than the analog bandwidth. To be honest, I'm still confused about what he's talking about with the analog bandwidth. It sounds like he's talking about the "analog bandwidth" of a signal. However it could also be interpreted as the analog bandwidth of the cable.

Changing the analog bandwidth of a cable does make a little more sense. You could treat the cable as a big resistor; have one end as the input voltage and the other as the output voltage. Calculate the decibels across different frequencies. However, increasing an analog bandwidth this way still doesn't make any sense. You could change the frequency response from 20 Hz - 2 kHz to something like 15 Hz - 2 kHz. It would be increasing the bandwidth, but not in your favor. It also doesn't make sense because that would mean a piece of wire has a frequency response.

He's right that a square wave is considered an analog signal though. Although, since it's interpreted digitally, it doesn't really matter what the waveform looks like. Highs (3-5V) will still be considered a logical true or 1, lows (0-2V) will still be considered a logical false or 0. The 2V leeway and 1V transition means you can go longer distances because the impedance of the cable doesn't have as big of an effect. It's always going to matter when you look at Ohm's Law and the definition of resistance (R = {\ho}L/A).

He's also wrong about square waves not really looking square. At 10 MHz, square waves look pretty square to me. I haven't had the chance to work with anything greater than 10 MHz. I suppose theoretically, you could increase the frequency so much that it sort of appears as a sine wave.

Also, being digital doesn't mean it's an encoded protocol. It's just a different system. Here he seems to be mixing up a digital signal from the "digital world." It's almost like binary, hexadecimal or octals compared to decimals. They're not encoded, just a different system. I think here he's thinking of the clash between reality and signals. In reality, things appear to move continuously, although on a quantum mechanics level, everything is quantized; it's just too small to see. In the world of signals, you can only take very quick snapshots and string it together. In terms of human interpretation, yeah it's encoded. However strictly speaking in the world of signals, being digital doesn't mean it's encoded. Encoded means it's been compressed; unnecessary information has been stripped. So for audio, anything outside, more or less, of 20 Hz and 20 kHz is removed; for video, the fps can be dropped to 30 fps. More information is usually removed and when the decoder is used, information is "restored." It's completely false to say that digital is a protocol though. A protocol is a means to pass messages along. Typically what happens is first a connection is recognized, there's a handshake between the client and server, an establishment of how to recognize how a message starts, ends and is formated is determined, along with how to deal with corrupt or ill formatted messages and what to do in case the connection is dropped. A protocol may be applied to a translate information into binary. For example, first two bits signal the start, a toggle bit on the third, 4 bits for the address, and 5 bits for the command.

An analog or analogue signal is any continuous signal for which the time varying feature (variable) of the signal is a representation of some other time varying quantity, i.e analogous to another time varying signal. It differs from a digital signal in that small fluctuations in the signal are meaningful.

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Helpful?

Originally Posted by Brian SD

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You overpaid, but you won't need a new one. Anyway, follow my recommendations. Get Little Big Planet, Wipeout HD and Uncharted.

No Gran Turismo? It's clearly too late after Tokyo Slim's explanation, but 8 feet is getting towards lengths you'll notice variations in signal quality. Monster is overhyped and overpriced compared to no-names and some of the good budget cables, but it's kind of a baseline quality where you know the cable is generally decently put together. I don't think you'd get that ripped off buying them for your use.

I ordered a PS3 for someone that should be arriving soon. I went to monoprice to get a cable and there are a million choices. Can someone tell me the differences? And is there an advantage to monoprice over blue jeans?

And next question (sorry teddie for derailing your thread), but what's a good game to get for a girl? She said she liked mortal kombat but is prone to saying stupid things that don't pan out.

Originally Posted by Berticus

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Yeah... that's where the issues are for A Y.

Digital bandwidth - how fast you fetch data.
Analog bandwidth - think of it as sort of the frequency response of a filter. It's really just the range between the -3 dB.

I guess what he was aiming to say was increase the frequency of the signal rather than the analog bandwidth. To be honest, I'm still confused about what he's talking about with the analog bandwidth. It sounds like he's talking about the "analog bandwidth" of a signal. However it could also be interpreted as the analog bandwidth of the cable.

Changing the analog bandwidth of a cable does make a little more sense. You could treat the cable as a big resistor; have one end as the input voltage and the other as the output voltage. Calculate the decibels across different frequencies. However, increasing an analog bandwidth this way still doesn't make any sense. You could change the frequency response from 20 Hz - 2 kHz to something like 15 Hz - 2 kHz. It would be increasing the bandwidth, but not in your favor. It also doesn't make sense because that would mean a piece of wire has a frequency response.

He's right that a square wave is considered an analog signal though. Although, since it's interpreted digitally, it doesn't really matter what the waveform looks like. Highs (3-5V) will still be considered a logical true or 1, lows (0-2V) will still be considered a logical false or 0. The 2V leeway and 1V transition means you can go longer distances because the impedance of the cable doesn't have as big of an effect. It's always going to matter when you look at Ohm's Law and the definition of resistance (R = {\ho}L/A).

He's also wrong about square waves not really looking square. At 10 MHz, square waves look pretty square to me. I haven't had the chance to work with anything greater than 10 MHz. I suppose theoretically, you could increase the frequency so much that it sort of appears as a sine wave.

Also, being digital doesn't mean it's an encoded protocol. It's just a different system. Here he seems to be mixing up a digital signal from the "digital world." It's almost like binary, hexadecimal or octals compared to decimals. They're not encoded, just a different system. I think here he's thinking of the clash between reality and signals. In reality, things appear to move continuously, although on a quantum mechanics level, everything is quantized; it's just too small to see. In the world of signals, you can only take very quick snapshots and string it together. In terms of human interpretation, yeah it's encoded. However strictly speaking in the world of signals, being digital doesn't mean it's encoded. Encoded means it's been compressed; unnecessary information has been stripped. So for audio, anything outside, more or less, of 20 Hz and 20 kHz is removed; for video, the fps can be dropped to 30 fps. More information is usually removed and when the decoder is used, information is "restored." It's completely false to say that digital is a protocol though. A protocol is a means to pass messages along. Typically what happens is first a connection is recognized, there's a handshake between the client and server, an establishment of how to recognize how a message starts, ends and is formated is determined, along with how to deal with corrupt or ill formatted messages and what to do in case the connection is dropped. A protocol may be applied to a translate information into binary. For example, first two bits signal the start, a toggle bit on the third, 4 bits for the address, and 5 bits for the command.

Square waves are most definitely not square. They don't have instantaneous rise and fall times and they often have a good deal of ringing. Sure in the range that you're looking at for digital signals you're usually not going to be bothered by these facts but it doesn't mean that the waves are actually square.

And in the world of digital signals encoded can mean a lot of different things than compressed. For example look at error correcting codes. When you encode a data stream with one of these you'll usually increase the size of the message being sent but will decrease the error rate assuming you're still getting a high enough signal strength.

Originally Posted by Tokyo Slim

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Analog bandwidth and electrical (or digital) bandwidth are two different things. You have confused them.
I have not confused them. Digital bandwidth is fundamentally limited by analog bandwidth.

HDMI, nor DVI, nor any other digital transfer protocol send analog signal through a wire. If it did, you'd probably have much less signal degradation over extended lengths, ironically enough.

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Of course they do. The information carried by HDMI is digital --- the video signal itself is digital. However, that information has to be transmitted on a wire. That is all analog. And your second sentence is wrong, because cables can't tell how you've chosen to encode your information. They only see an analog waveform and will degrade that waveform the same way regardless of whether you're trying to transmit digital information or not. Of course, there are certain digital encodings that resist cable degradation better than others, but that's always done by reducing the digital bandwidth of the information being transmitted --- the protocol will be less efficient because of added redundancy or greater sparseness.

HDMI 2.0 double link standard can do 1080p at over 330mhz. So its not a BANDWIDTH problem (more information won't help, since its already able to put out way more information than today's televisions need or can use).

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I'm not sure we disagree here. If you have a cable that is incapable of 330 MHz of bandwidth, you will drop bits when you use that cable for 1080p. That was my original point.

It is an attenuation problem, and an error checking problem, and a real time streaming problem. And even that would be LESS of a problem if HDCP wasn't such a ************* and add another interruption to the data stream.

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Guess what? Attenuation is a purely analog phenomena. Attenuation happens because of resistive losses on the cable, low-pass filtering due to the interaction of the cable's capacitance and various resistances (source and termination) in the circuit, and low-pass filtering by the inductance of the cable. All of these effects are analog. Attenuation reduces the voltage levels so that the receiving end may not recognize the difference between a 0 and 1. Low pass filtering turns square waves into sine waves, and smears transition edges so that you can't differentiate as many pulses per second. Both cause bit errors. HDCP has nothing to do with this.

Originally Posted by Berticus

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Digital bandwidth - how fast you fetch data. Analog bandwidth - think of it as sort of the frequency response of a filter. It's really just the range between the -3 dB.
So if I have a cable whose analog bandwidth makes the edges of my signal be really shallow, how do you think that affects how quickly I can send or fetch data? When the edges become shallower, it becomes progressively more difficult to recover edges, and hence tell where one bit begins and another ends.

It sounds like he's talking about the "analog bandwidth" of a signal. However it could also be interpreted as the analog bandwidth of the cable.

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Both are important. If the bandwidth of your signal exceeds that of your cable, then you're going to lose information.

You could change the frequency response from 20 Hz - 2 kHz to something like 15 Hz - 2 kHz. It would be increasing the bandwidth, but not in your favor. It also doesn't make sense because that would mean a piece of wire has a frequency response.

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When engineers talk about increasing bandwidth, we generally mean the top end. In signal transmission, you don't worry about the bottom end. In your example, I would be talking about going from 20Hz-2kHz to 20 Hz-4kHz.

He's right that a square wave is considered an analog signal though. Although, since it's interpreted digitally, it doesn't really matter what the waveform looks like. Highs (3-5V) will still be considered a logical true or 1, lows (0-2V) will still be considered a logical false or 0.

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Of course it matters. It's not just the level of the waveform, but also the shape. Why do you think CPU manufacturers have to go to progressively lower voltages and more exotic signalling schemes (eg. Hypertransport, SATA, etc.) when they go faster?

He's also wrong about square waves not really looking square. At 10 MHz, square waves look pretty square to me. I haven't had the chance to work with anything greater than 10 MHz. I suppose theoretically, you could increase the frequency so much that it sort of appears as a sine wave.

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You are talking about an ideal situation. Square waves don't look square in real life situations, especially in a cable that limits bandwidth. Also, the way you produce a sine wave from a square wave is to reduce the square wave's bandwidth. A sine wave is the lowest bandwidth signal possible --- in theory, it has zero bandwidth. This is like basic Fourier theory.

Also, being digital doesn't mean it's an encoded protocol. It's just a different system. Here he seems to be mixing up a digital signal from the "digital world." It's almost like binary, hexadecimal or octals compared to decimals. They're not encoded, just a different system.

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Digital is an encoding because it is an arbitrary assignment of values to meaning. 'a' = 97 in ASCII is an encoding, because you now need an external reference to decode it. It is completely arbitrary that the number 97 refers to lowercase 'a' in ASCII. Lossless compression (like zip) is also an encoding because you need an external reference to unpack the information. If you told me that every time you said "shoe", you mean "duck", that is an encoding. Similarly, digital is an encoding protocol because the meaning of the protocol is not intrinsically carried by the information being encoded. We encode in digital because it is more convenient to do certain operations in digital than in other forms of encoding. However when you want to transmit this information over a cable, you have to encode this in some form that works over a cable, and that's analog. Think about it this way: you have a video signal that's encoded in digital which is in turn encoded in a specific analog form (as spec'ed by the HDMI standard) for transmission over an HDMI cable. I seriously can't believe we're fighting over this. This is like information theory 101. --Andre