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Decent speaker cables at last! (soft troll)
Here ya go darlin's - knock yerselves out on these speaker cables:
Siltech Signature G6 - only £30,000 a pair...... Find 'em on http://www.siltechcables.com/nfhomepa.html Noise floor of 180 dB - how can they *not* be worth the money? Beats the crap out of that 79 strand 70p/m unbranded ****e you lot use....... (Dave Whitter's already got a pair on order... :-) |
Decent speaker cables at last! (soft troll)
On Wed, 23 Jul 2003 15:13:59 +0100, Kurt Hamster
wrote: On Wed, 23 Jul 2003 15:11:16 +0100, Keith G used to say... Here ya go darlin's - knock yerselves out on these speaker cables: Siltech Signature G6 - only £30,000 a pair...... Find 'em on http://www.siltechcables.com/nfhomepa.html Noise floor of 180 dB - how can they *not* be worth the money? Beats the crap out of that 79 strand 70p/m unbranded ****e you lot use....... (Dave Whitter's already got a pair on order... :-) I especially like this description they give in their digital interconnects bit... "All digital signals are, in fact, analogue. A digital signal is a square wave, which consists of sine waves, all with much high frequencies. These sine waves added together reproduce the square wave. If one of these sine waves is missing because of, for example, reduced bandwidth, the square wave becomes distorted and subsequently timing errors may occur." Heheheheheh, so digital is actually analogue eh? :) There is indeed a wealth of crap on that website, but this isn't it. Digital signals are in fact no different to any other signals, and they are most assuredly analogue. It is just the information they contain that isn't, but as far as the signals themselves are concerned, all the normal analogue factors of frequency response, phase response and distortion have their part to play. d _____________________________ http://www.pearce.uk.com |
Decent speaker cables at last! (soft troll)
There is indeed a wealth of crap on that website, but this isn't it. Digital signals are in fact no different to any other signals, and they are most assuredly analogue. For a very simple network pulses will be put direct onto the wire, eg at any time it will be either 0v or 5v, and nowhere imbetween, this will create the square wave that is sometimes called a digtal signal. The distinction is much less clear for a modulated signal, which is just about every signal these days, but I don't think its correct to simply say Digital == Analogue. However... It is just the information they contain that isn't, but as far as the signals themselves are concerned, all the normal analogue factors of frequency response, phase response and distortion have their part to play. ....this is complely true. That's why repeaters exist to transmit digital signals over long distances. However on plain old cat5 a high speed signal can travel (IIRC) 200meters without special equipment. I've said before, digtal HiFi interconnects are possibly the least demanding application imaginable. People who buy high-end just don't like to think *anything* their equipment does is actually easy! -- Jim H |
Decent speaker cables at last! (soft troll)
Keith G in uk.rec.audio:
Here ya go darlin's - knock yerselves out on these speaker cables: Siltech Signature G6 - only £30,000 a pair...... Find 'em on http://www.siltechcables.com/nfhomepa.html Noise floor of 180 dB - how can they *not* be worth the money? Beats the crap out of that 79 strand 70p/m unbranded ****e you lot use....... (Dave Whitter's already got a pair on order... :-) What I don't get is why someone who needs THAT good a signal transfer would use phono plugs anyway? By my understanding pros use quite ordinary quality XLR cable, because by design it is almost immune to noise. I wonder why XLR hasn't filtered down to the mass market? It couldn't be because they do quite well selling us overdesigned phono cable! -- Jim H |
Decent speaker cables at last! (soft troll)
"Jim H" wrote in message ... There is indeed a wealth of crap on that website, but this isn't it. Digital signals are in fact no different to any other signals, and they are most assuredly analogue. For a very simple network pulses will be put direct onto the wire, eg at any time it will be either 0v or 5v, and nowhere imbetween, this will create the square wave that is sometimes called a digtal signal. I don't think this is quite correct even for the most basic pulses. If you examine a "digital signal" at a high resolution you will see "ringing" occur when the voltage changes so the signal isn't either 0v or 5v but an approximation of a square wave such as http://mathworld.wolfram.com/Fourier...quareWave.html The signal becomes "digital" because the resolution of the receiving equipment is set such that the subtle variation per cycle is not detectable or is ignored. -- RobH The future's dim, the future's mono. |
Decent speaker cables at last! (soft troll)
In article ,
Jim H wrote: By my understanding pros use quite ordinary quality XLR cable, because by design it is almost immune to noise. There's no such thing as XLR cable - an XLR is the connector. And the cable used with these is balanced twin screened. It also comes in several different flavours. ;-) I wonder why XLR hasn't filtered down to the mass market? It couldn't be because they do quite well selling us overdesigned phono cable! Creating balanced inputs and outputs costs - and introduces extra electronics since possibly most domestic gear is unbalanced internally. And XLR connectors are really designed for heavy duty use - domestic equipment doesn't normally get unplugged each time it's used. -- *Could it be that "I do " is the longest sentence? * Dave Plowman London SW 12 RIP Acorn |
Decent speaker cables at last! (soft troll)
What a waste of money for such little gain.
-- Nathan D Higgins Website: http://nathan.link9.net/ Email: nathan[at]link9[dot]net Hosting: http://www.link9.net WAP: http://wap.link9.net [dot]NET: nathan[at]link9[dot]net |
Decent speaker cables at last! (soft troll)
"Jim H" wrote in message
By my understanding pros use quite ordinary quality XLR cable, because by design it is almost immune to noise. It's not the cable, its the equipment at both ends that makes the difference. There are three main differences between consumer and true audio production grade equipment vis-a-vis inputs and outputs: (1) Balanced I/O. Audio production equipment sends the signal down two wires in the audio cable, with opposite polarity. Consumer equipment sends only one signal. The benefit comes at the receiving end where the signals are subtracted, canceling out any noise that is picked up by both wires and doubling the desired signal. (2) Higher signal levels. CD players generate some of the highest working voltages of any piece of consumer audio equipment, which generally peak out at about 2 volts. Audio production equipment generally works with signals that peak out at 6.8 volts or more, often quite a bit more. (3) Lower impedances. Consumer audio gear generally involves input impedances of 100K, 50K, 2K, but rarely lower. Audio production equipment has input impedances of no more than 20K, often 10K frequently 6.8 K or 2K and sometimes as low as 600 ohms. Low impedance inputs are less susceptible to interference and generate less thermal noise. I wonder why XLR hasn't filtered down to the mass market? Mass market systems are simple and relatively non-critical. Audio production equipment is often used in complex setups which are more prone to have grounding problems and pickup other kinds of noise. It couldn't be because they do quite well selling us overdesigned phono cable! That would be the high end... To be fair, there is some high end equipment that uses balanced I/O and standard audio production signal levels and impedances. |
Decent speaker cables at last! (soft troll)
"Kurt Hamster" wrote in message
On Wed, 23 Jul 2003 15:11:16 +0100, Keith G used to say... Here ya go darlin's - knock yerselves out on these speaker cables: Siltech Signature G6 - only £30,000 a pair...... Find 'em on http://www.siltechcables.com/nfhomepa.html Noise floor of 180 dB - how can they *not* be worth the money? Beats the crap out of that 79 strand 70p/m unbranded ****e you lot use....... (Dave Whitter's already got a pair on order... :-) I especially like this description they give in their digital interconnects bit... "All digital signals are, in fact, analogue. True. A digital signal is a square wave, False. These guys obviously never looked at a SP/DIF signal with a 'scope. which consists of sine waves, all with much high frequencies. These sine waves added together reproduce the square wave. If one of these sine waves is missing because of, for example, reduced bandwidth, the square wave becomes distorted and subsequently timing errors may occur." Rounding of digital signals does not in and of itself lead to timing errors. There needs to be some source of nose as well. Furthermore, various means for eliminating the effects of probable timing errors on digital signals are well-known. Heheheheheh, so digital is actually analogue eh? :) On several levels... However digital-domain audio signals have several properties that analog-domain signals lack: (1) digital-domain audio signals can be readily transmitted, and stored with zero linear and nonlinear distortion. (2) The residual noise in digital-domain audio signals can be reduced until it is arbitrarily small by fairly simple means. In short, perfect sound forever! ;-) |
Decent speaker cables at last! (soft troll)
"Keith G" wrote Here ya go darlin's - knock yerselves out on these speaker cables: Siltech Signature G6 - only £30,000 a pair...... Find 'em on http://www.siltechcables.com/nfhomepa.html Noise floor of 180 dB - how can they *not* be worth the money? Beats the crap out of that 79 strand 70p/m unbranded ****e you lot use....... Keith said...... (Dave Whitter's already got a pair on order... :-) Just spent a few bob on Russ Andrews Kimber 8TC and 4TC for all three systems :-) very nice after that its going to be a power purifier block, then thats it for this year!!!! UNLESS I can get a good deal with Quad for another pair of Quad II-forties amps so I can bi amp me 804's regards Dave xxxxxx |
Decent speaker cables at last! (soft troll)
RobH in uk.rec.audio:
I don't think this is quite correct even for the most basic pulses. If you examine a "digital signal" at a high resolution you will see "ringing" occur when the voltage changes so the signal isn't either 0v or 5v but an approximation of a square wave such as http://mathworld.wolfram.com/Fourier...quareWave.html The signal becomes "digital" because the resolution of the receiving equipment is set such that the subtle variation per cycle is not detectable or is ignored. True. There is no perfect 'digital wave'. However, for the reciving end, the voltage isn't sampled at transitions between bits, meaning it should (in theory) only see the logical extremes and not the ringing. Either way, beacuse a digital signal shares some analogue properties doesn't mean it has to be treated with analogue care. At least for the tiny bandwidth hifi needs. -- Jim H |
Decent speaker cables at last! (soft troll)
Dave Plowman in uk.rec.audio:
In article , Jim H wrote: By my understanding pros use quite ordinary quality XLR cable, because by design it is almost immune to noise. There's no such thing as XLR cable - an XLR is the connector. And the cable used with these is balanced twin screened. It also comes in several different flavours. ;-) In the same way as there's no such thing as a phono cable. I wonder why XLR hasn't filtered down to the mass market? It couldn't be because they do quite well selling us overdesigned phono cable! Creating balanced inputs and outputs costs - and introduces extra electronics since possibly most domestic gear is unbalanced internally. And XLR connectors are really designed for heavy duty use - domestic equipment doesn't normally get unplugged each time it's used. My point was that as soon as you need to spend £30k on a cable, you should be using studio-quality technology, which should be ballanced internally. -- Jim H |
Decent speaker cables at last! (soft troll)
"Jim H" wrote in message
True. There is no perfect 'digital wave'. However, for the receiving end, the voltage isn't sampled at transitions between bits, meaning it should (in theory) only see the logical extremes and not the ringing. But there is a perfect "digital wave" as received by a proper line receiver. Either way, because a digital signal shares some analogue properties doesn't mean it has to be treated with analogue care. At least for the tiny bandwidth hifi needs. In fact a digitized wave can be transmitted, received, stored and recovered with zero linear and nonlinear distortion, and as little noise as is desired by fairly simple means. |
Decent speaker cables at last! (soft troll)
Nathan Higgins in uk.rec.audio:
What a waste of money for such little gain. No gain. Consider that you could travel the world seeking out the best *live* music for the price of that cable. -- Jim H |
Decent speaker cables at last! (soft troll)
In short, perfect sound forever! You must work for Phillips :-) |
Decent speaker cables at last! (soft troll)
Here ya go darlin's - knock yerselves out on these speaker cables: Siltech Signature G6 - only £30,000 a pair...... Find 'em on http://www.siltechcables.com/nfhomepa.html Mmmmmm yea in this months Hi-Fi news :-) I'm gonna dream tonight of these gorgeous pair of beuties transforming my Hi-Fi into another dimension! Yea baby yea...... how's my sweet jar looking :-) Steve |
Decent speaker cables at last! (soft troll)
"Jim H" wrote in message
False. These guys obviously never looked at a SP/DIF signal with a 'scope. Presumably it would be square if looked at on a scope plotting phase against time. Don't bet on it. Typically, it is low-pass filtered which means that it doesn't do anything sudden. (IIRC, spdif is phase modulation. could be somithng else, but same idea) Regardless, it destroys their basic argument. |
Decent speaker cables at last! (soft troll)
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Decent speaker cables at last! (soft troll)
My point was that as soon as you need to spend £30k on a cable, you should be using studio-quality technology, which should be ballanced internally. Could you elaborate what you mean by"balanced internally"? |
Decent speaker cables at last! (soft troll)
In article , Keith G
wrote: Here ya go darlin's - knock yerselves out on these speaker cables: Siltech Signature G6 - only £30,000 a pair...... Find 'em on http://www.siltechcables.com/nfhomepa.html Noise floor of 180 dB - how can they *not* be worth the money? 180 dB with respect to what, exactly, and under what conditions of use? Measured how, and under what assumptions? Even given the above has a relevant meaning, I'm not sure why it woud matter given that I'd suspect most audio sources will have dynamic ranges of less than 100 dB wideband. I looked at their site a while ago, and I'm afraid it seemed a lot like technobabble to me at the time. Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
Decent speaker cables at last! (soft troll)
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Decent speaker cables at last! (soft troll)
A certain Kurt Hamster, of uk.rec.audio "fame", writes :
Heheheheheh, so digital is actually analogue eh? :) Taken to extremes, everything is analogue, including digital. The article you quoted is of course complete bunkum. -- "Jokes mentioning ducks were considered particularly funny." - cnn.com |
Decent speaker cables at last! (soft troll)
In article , Stevie Boy wrote:
In short, perfect sound forever! Member of Pavement, surely? (Now there's a late lamented band.) You lost me completley. "Perfect Sound Forever" was Pavement's first EP. - Andrew |
Decent speaker cables at last! (soft troll)
In article , Chesney Christ
wrote: A certain Kurt Hamster, of uk.rec.audio "fame", writes : Heheheheheh, so digital is actually analogue eh? :) Taken to extremes, everything is analogue, including digital. The article you quoted is of course complete bunkum. Taken to extremes, we could say everything apparently behaves as described by Quantum Mechanics, so is neither 'analog' or 'digital'. 'Analog' and 'digital' are human inventions. Models we employ to help us underdtand and manipulate the real world. However this does not mean that the real world *is* either 'analog' or 'digital'. There is a risk here of confusing the object with its labels. :-) Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
Decent speaker cables at last! (soft troll)
"Jim Lesurf" wrote in message
In article , Arny Krueger wrote: However digital-domain audio signals have several properties that analog-domain signals lack: (1) digital-domain audio signals can be readily transmitted, and stored with zero linear and nonlinear distortion. I think I would prefer to express the above in a slightly different way. The *information content* can be conveyed using digital coding schemes in a way that tends to ensure that modest distortions and nonlinearities of the modulated waveform should not change the recovered content. i.e. the actual digital waveform may be distorted (often is in my experience) but this should not normally lead to a distortion of the recovered information. I think that pussyfoots around how robust digital transmission and storage usually is. Given that transmission and storage have always been monumental sore spots for analog signals, digital is really quite a breath of fresh air. (2) The residual noise in digital-domain audio signals can be reduced until it is arbitrarily small by fairly simple means. In short, perfect sound forever! Or at least, all being reasonably well, pretty good quite a lot of the time. :-) Digital transmission and storage is far better than "reasonably well". For audio, it is practically speaking perfect. Now if we could only solve those problems with rooms, speakers and microphones! |
Decent speaker cables at last! (soft troll)
In article , Arny Krueger
wrote: "Jim Lesurf" wrote in message I think I would prefer to express the above in a slightly different way. The *information content* can be conveyed using digital coding schemes in a way that tends to ensure that modest distortions and nonlinearities of the modulated waveform should not change the recovered content. i.e. the actual digital waveform may be distorted (often is in my experience) but this should not normally lead to a distortion of the recovered information. I think that pussyfoots around how robust digital transmission and storage usually is. Given that transmission and storage have always been monumental sore spots for analog signals, digital is really quite a breath of fresh air. In general terms I'd agree - although I'd probably call it "academic caution" on my part rather than pussyfooting. :-) Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
Decent speaker cables at last! (soft troll)
Arny Krueger in uk.rec.audio:
In short, perfect sound forever! With digital hifi/radio/tv you'll normally get either a perfect feed or nothing. There is a /little/ space imbetween with video formats robust enough to loose the odd byte to pixellation, or error correction Consider analogue tv, where quality is roughly proportional to signal strength, but with digital you either get it or you don't. It's like that with digital hifi, if you are getting any signal at all its likely perfect already and no amount of silver wire can improve it. It really bothers me sometimes when people pay this much to be fed techno- superstition. Maybe it's because anyone THAT dumb is unlikely to have earned the money. -- Jim H 3.1415...4999999 and so on... Richard Feynman |
Decent speaker cables at last! (soft troll)
Jim H wrote:
Arny Krueger in uk.rec.audio: In short, perfect sound forever! With digital hifi/radio/tv you'll normally get either a perfect feed or nothing. There is a /little/ space imbetween with video formats robust enough to loose the odd byte to pixellation, or error correction My thoughts exactly, no cable, no matter how cheap it is (within reason) should be disrupting a digital signal, even though it is an analogue signal in essence the quality of the signal should not effect the sound - digital signals have a readable threshold much lower than analogue, low signals below this threshold should not occur on any distance shorter than say, 10m. Interruptions of square waves only occur in cable runs which have such a high resistance and the source is producing such a low voltage that the signal is attenuated dramatically before arriving at the destination. Usually the source transmitter or the destination receiver is at fault in digital audio, either for low signals or _very_ bad error correction - NOT the connecting cable. Consider analogue tv, where quality is roughly proportional to signal strength, but with digital you either get it or you don't. It's like that with digital hifi, if you are getting any signal at all its likely perfect already and no amount of silver wire can improve it. It really bothers me sometimes when people pay this much to be fed techno- superstition. Maybe it's because anyone THAT dumb is unlikely to have earned the money. -- Nathan D Higgins Website: http://nathan.link9.net/ Email: nathan[at]link9[dot]net Hosting: http://www.link9.net WAP: http://wap.link9.net [dot]NET: nathan[at]link9[dot]net |
Decent speaker cables at last! (soft troll)
Nathan Higgins in uk.rec.audio:
Jim H wrote: Arny Krueger in uk.rec.audio: In short, perfect sound forever! With digital hifi/radio/tv you'll normally get either a perfect feed or nothing. There is a /little/ space imbetween with video formats robust enough to loose the odd byte to pixellation, or error correction My thoughts exactly, no cable, no matter how cheap it is (within reason) should be disrupting a digital signal, even though it is an analogue signal in essence the quality of the signal should not effect the sound - digital signals have a readable threshold much lower than analogue, low signals below this threshold should not occur on any distance shorter than say, 10m. Right here I have an 80m run of cheap cat5. That works fine at 100 megabits per second with £4 network cards! Interruptions of square waves only occur in cable runs which have such a high resistance and the source is producing such a low voltage that the signal is attenuated dramatically before arriving at the destination. Usually the source transmitter or the destination receiver is at fault in digital audio, either for low signals or _very_ bad error correction - NOT the connecting cable. Digital signals genarally do not use 'square' waves, their signal is added to a carrier wave. [1] For example, a sine wave may be used to carry the signal. While the wave is 'in phase' could stand for binary zero, while 180° out of phase could be binary one. In the real world it is likely more than two phases will be used, eight states used to be comon, to represent 3 bits at a time. The advantage of this is that several different signals can be transmitted at once, using different frequencies, which is the basis of broadband comunication. Consider analogue tv, where quality is roughly proportional to signal strength, but with digital you either get it or you don't. It's like that with digital hifi, if you are getting any signal at all its likely perfect already and no amount of silver wire can improve it. It really bothers me sometimes when people pay this much to be fed techno- superstition. Maybe it's because anyone THAT dumb is unlikely to have earned the money. [1] This technique is not exclusive to digital transmision, normal FM radio is done by applying Frequency Modulation to a carrier wave, AM is amplitude modulation. If the signal were digital phase modulation is most likely used. -- Jim H 3.1415...4999999 and so on... Richard Feynman |
Decent speaker cables at last! (soft troll)
On Sat, 26 Jul 2003 13:37:03 +0100, Jim Lesurf
wrote: In article , Jim H wrote: Nathan Higgins in uk.rec.audio: Digital signals genarally do not use 'square' waves, their signal is added to a carrier wave. IIUC S/PDIF is a form of byphase modulation which essentially xors the data with a clock to aid signal recovery using a fresh clock at the receiver. The bandwidth should not, in principle, be critical, but may matter of the recovery method is not well implimented. That's correct, it's a 'Manchester' biphase modulation system. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
Decent speaker cables at last! (soft troll)
On Sat, 26 Jul 2003 13:37:03 +0100, Jim Lesurf
wrote: IIUC S/PDIF is a form of byphase modulation which essentially xors the data with a clock to aid signal recovery using a fresh clock at the receiver. The bandwidth should not, in principle, be critical, but may matter of the recovery method is not well implimented. From memory, biphase mark (as used in S/PDIF) is a form of frequency modulation with zeros represented by the clock frequency and ones by twice the clock frequency. (Much like the FSK used in 300 baud modems - remember them?) It is not bandwidth efficient, but makes clock extraction at the far end very easy. It's very similar to Manchester encoding used for 10base Ethernet. So both your VHF tuner and S/PDIF links are FM - one with analogue signals and the other with digital. -- Chris Isbell Southampton UK |
Decent speaker cables at last! (soft troll)
In message , Chris Isbell
writes On Sat, 26 Jul 2003 13:37:03 +0100, Jim Lesurf wrote: IIUC S/PDIF is a form of byphase modulation which essentially xors the data with a clock to aid signal recovery using a fresh clock at the receiver. The bandwidth should not, in principle, be critical, but may matter of the recovery method is not well implimented. From memory, biphase mark (as used in S/PDIF) is a form of frequency modulation with zeros represented by the clock frequency and ones by twice the clock frequency. (Much like the FSK used in 300 baud modems - remember them?) It is not bandwidth efficient, but makes clock extraction at the far end very easy. It's very similar to Manchester encoding used for 10base Ethernet. So both your VHF tuner and S/PDIF links are FM - one with analogue signals and the other with digital. Although you sometimes see the various types of Bi-phase modulation described as 'frequency modulation', this is really not the case, and the books that describe it as 'FM' are targeted at a fairly unlearned market. These digital modulation schemes like biphase-M, biphase-S, WAL-1 and WAL-2 are, as others have pointed out, controlled digital phase inversions of the clock according to a particular algorithm. They are a way of encoding the clock in with the data to ease recovery, and in some cases, to provide a means of compensating for the HF roll-off and dispersion caused to the signal by the characteristics of the cable. The easiest way to see the effect of cable degradation of the signal is still the 'text book' eye diagram. The clock shouldn't be though of as a carrier. -- Chris Morriss |
Decent speaker cables at last! (soft troll)
On Sat, 26 Jul 2003 21:17:51 +0100, Chris Morriss
wrote: Although you sometimes see the various types of Bi-phase modulation described as 'frequency modulation', this is really not the case, and the books that describe it as 'FM' are targeted at a fairly unlearned market. I not sure that I agree. Consider a bit stream of all zeros. This will result in only the clock frequency appearing on the output. Likewise a stream of all ones will only produce double the clock frequency. How is this different from frequency modulation? In other words, a zero results in no transition in the middle of the clock period whilst a one does. (I have just been working on a project implementing HDLC with bi-phase mark encoding in firmware. All good clean fun! We had to get it right because the receiver was a Zilog communication controller which had the algorithms built into its guts and therefore outside of our control.) -- Chris Isbell Southampton UK |
Decent speaker cables at last! (soft troll)
On Sun, 27 Jul 2003 08:12:42 +0100, Chris Morriss
wrote: I'm not saying it can't be described as synchronous FM, but that it's misleading. Your description only applies to biphase-M (or S). The commoner WAL-1 (Biphase-L) can't really be described as FM in that the coding algorithm is that a 1 has a 01 transition in the middle of the bit period, while a 0 has a 10 transition. (With other transitions at the bit boundaries to sort everything out or course.) I completely agree that my description only applies to biphase-mark and you point about it being misleading is well taken. However, I personally found it easier to understand why there are more 'efficient' coding methods after realising that biphase-mark is essentially FM (or FSK). (But then I have been told on a number of occasions that I have a warped mind. :-) The similarities between the digital S/PDIF and analogue FM radio are interesting, notwithstanding the considerable differences. This ties in quite nicely with the recent discussions here on the blurred boundaries between digital and analogue systems. (I especially like Jim Lesurf's analysis of an analogue record player as a digital system that is on his Web pages.) -- Chris Isbell Southampton UK |
Decent speaker cables at last! (soft troll)
In article , Chris Isbell
wrote: On Sun, 27 Jul 2003 08:12:42 +0100, Chris Morriss wrote: I'm not saying it can't be described as synchronous FM, but that it's misleading. Your description only applies to biphase-M (or S). The commoner WAL-1 (Biphase-L) can't really be described as FM in that the coding algorithm is that a 1 has a 01 transition in the middle of the bit period, while a 0 has a 10 transition. (With other transitions at the bit boundaries to sort everything out or course.) I completely agree that my description only applies to biphase-mark and you point about it being misleading is well taken. Actually, I found your description quite neat as an explanation of S/PDIF as it makes it very easy to see how the clock becomes relatively easy to recover. However, I personally found it easier to understand why there are more 'efficient' coding methods after realising that biphase-mark is essentially FM (or FSK). (But then I have been told on a number of occasions that I have a warped mind. :-) My mind must be of a similar distorted shape to yours. ;- Mind you, I spent *years* trying to explain to military types why an FM system that had smooth modulation did not *have* 'hop slots'. (And found it even harder to get them to understand that things like this are bad news if you want to reduce the signature of transmissions. :-) ) The similarities between the digital S/PDIF and analogue FM radio are interesting, notwithstanding the considerable differences. i have also found it interesting that you can argue that the 'Zenith' stereo system used for FM radio is either frequency division *or* time division, whichever suits the points you're trying to make. My own view of many of these matters is that the 'standard' explanation is just the one that most people find most convenient on most occasions. Yet alternative explanations can sometimes be useful for illuminating specific points. (Another example was the approach Don took to amp loads and feedback loops a while ago.) This ties in quite nicely with the recent discussions here on the blurred boundaries between digital and analogue systems. (I especially like Jim Lesurf's analysis of an analogue record player as a digital system that is on his Web pages.) OK, the cheque is in the post... :-) Unfortunately, I could not do a precise calculation due to not knowing some specific values - e.g. the typical size/shape of the 'PVC' sic molecules used for LPs. Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
Decent speaker cables at last! (soft troll)
In message , Chris Isbell
writes On Sun, 27 Jul 2003 08:12:42 +0100, Chris Morriss wrote: I'm not saying it can't be described as synchronous FM, but that it's misleading. Your description only applies to biphase-M (or S). The commoner WAL-1 (Biphase-L) can't really be described as FM in that the coding algorithm is that a 1 has a 01 transition in the middle of the bit period, while a 0 has a 10 transition. (With other transitions at the bit boundaries to sort everything out or course.) I completely agree that my description only applies to biphase-mark and you point about it being misleading is well taken. However, I personally found it easier to understand why there are more 'efficient' coding methods after realising that biphase-mark is essentially FM (or FSK). (But then I have been told on a number of occasions that I have a warped mind. :-) The similarities between the digital S/PDIF and analogue FM radio are interesting, notwithstanding the considerable differences. This ties in quite nicely with the recent discussions here on the blurred boundaries between digital and analogue systems. (I especially like Jim Lesurf's analysis of an analogue record player as a digital system that is on his Web pages.) Thanks, I'll have a look at that! -- Chris Morriss |
Decent speaker cables at last! (soft troll)
Chris Morriss in uk.rec.audio:
In message , Jim H writes Digital signals genarally do not use 'square' waves, their signal is added to a carrier wave. [1] Wrong. 10 and 100 baseT Ethernet use digital signals. The leading edge has digital pre-emphasis, but it's still done digitally. I said generally. Yes, ethernet is baseband. I think your missing the point to say a plot of pd against which produces 'square' signal that it IS digital, whereas if it looks curvy it IS analogue. It is often said that a modulated signal is analogue because a pd/time plot shows a series of continuous values. However, if a phase/time plot were made instead (for Phase Modulated signal) the values would be best expressed as square line. It could be said therefore that since it occupies discrete space, the phase of this signal is digital, whereas the pd is continuous and therefore analogue. The point I'm making is that digital and analogue shouldn't be thought of in such absolute terms. They are ideas, a signal may be thought to be both simultaneously if it helps. The main diference is in the data, not how it is put on a wire. Dgital data may only have discrete values, mhich may be perfectly copied. This is imposible for analogue data, however a signal most comonly thought of as analogue may carry digital data with the same perfection. -- Jim H 3.1415...4999999 and so on... Richard Feynman |
Decent speaker cables at last! (soft troll)
In article , Jim H
wrote: It is often said that a modulated signal is analogue because a pd/time plot shows a series of continuous values. However, if a phase/time plot were made instead (for Phase Modulated signal) the values would be best expressed as square line. It could be said therefore that since it occupies discrete space, the phase of this signal is digital, whereas the pd is continuous and therefore analogue. I am not quite sure I know what you mean by "square line". Do you mean the path of the phase on a polar vector plot would show a square? If so, are you not assuming an infinite bandwidth for the modulated signal? Not clear what you mean... Of course, this opens up discussion of what we mean by 'phase' and even 'frequency'. ;- The point I'm making is that digital and analogue shouldn't be thought of in such absolute terms. They are ideas, a signal may be thought to be both simultaneously if it helps. Need to be careful with the term 'signal' as well. :-) The actual variations of field or poential or current or whatever physical property that is being used to convey the 'signal' are, I would say, neither analog or digital. The chosen scheme for creating and understading the meaning of the 'signal' (i.e. the resulting information-bearing pattern) may be analog or digital, though, depending upon the choices made. The main diference is in the data, not how it is put on a wire. Agreed. Dgital data may only have discrete values, mhich may be perfectly copied. Not quite 'perfect' as there is always a finite chance of errors produced by noise, etc. We can reduce this chance to a very low level, but not guarantee to exclude it entirely. The advantage of digital is that it provides some level of error immunity, and provides relatively easy methods for error detection and correction. Slainte, Jim This is imposible for analogue data, however a signal most comonly thought of as analogue may carry digital data with the same perfection. -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
Decent speaker cables at last! (soft troll)
Jim Lesurf in uk.rec.audio:
In article , Jim H wrote: It is often said that a modulated signal is analogue because a pd/time plot shows a series of continuous values. However, if a phase/time plot were made instead (for Phase Modulated signal) the values would be best expressed as square line. It could be said therefore that since it occupies discrete space, the phase of this signal is digital, whereas the pd is continuous and therefore analogue. I am not quite sure I know what you mean by "square line". Do you mean the path of the phase on a polar vector plot would show a square? If so, are you not assuming an infinite bandwidth for the modulated signal? Not clear what you mean... I don't like the term square line, maybe there is a better word for it? For square I imagine cartesean axis showing a line which (ideally) jumps quickly between values it stays at for some amount of time, in which all lines are perpendicular to one axis. Away from the particulars, the real point I was trying to make is that however digital data is encoded, a plot can be made which shows the data as descrete values, otherwise the digital data could not be retrieved at the other end. I don't like, for example, for someone to describe the output from a computer modem as analogue, given that at some level it contains possibly perfect representatitions of descrete values. I consider 'contains possibly perfect representatitions of descrete values, to be a pretty good definition of digital. Of course, this opens up discussion of what we mean by 'phase' and even 'frequency'. ;- The point I'm making is that digital and analogue shouldn't be thought of in such absolute terms. They are ideas, a signal may be thought to be both simultaneously if it helps. Need to be careful with the term 'signal' as well. :-) Yes, agreed. medium may have been a beter word here. (although that implys physical distribution) The actual variations of field or poential or current or whatever physical property that is being used to convey the 'signal' are, I would say, neither analog or digital. The chosen scheme for creating and understading the meaning of the 'signal' (i.e. the resulting information-bearing pattern) may be analog or digital, though, depending upon the choices made. Agreed. I don't really think there is such thing as digital whilst the signal is in the wire, other than if we think of it that way. Therefore if it helps our understanding I don't think it is a contradiction to think of a single wave to be simultaneously digital and analogue, or that one property of the wave is digital whilst another is analogue. The main diference is in the data, not how it is put on a wire. Agreed. Dgital data may only have discrete values, mhich may be perfectly copied. Not quite 'perfect' as there is always a finite chance of errors produced by noise, etc. We can reduce this chance to a very low level, but not guarantee to exclude it entirely. The advantage of digital is that it provides some level of error immunity, and provides relatively easy methods for error detection and correction. The important word was 'may'! There is a possiblity that a digital piece of data sent will be exactly what arrives. This is in contrast to an analogue medium which can never be copied exactly. I agree that no checking can ever rule out the possibility an error was made. So whilst digital data may be perfectly copied, we never really know if it was. This is imposible for analogue data, however a signal most comonly thought of as analogue may carry digital data with the same perfection. -- Jim H 3.1415...4999999 and so on... Richard Feynman |
Decent speaker cables at last! (soft troll)
In article , Jim H
wrote: Jim Lesurf in uk.rec.audio: In article , Jim H wrote: It is often said that a modulated signal is analogue because a pd/time plot shows a series of continuous values. However, if a phase/time plot were made instead (for Phase Modulated signal) the values would be best expressed as square line. It could be said therefore that since it occupies discrete space, the phase of this signal is digital, whereas the pd is continuous and therefore analogue. I am not quite sure I know what you mean by "square line". Do you mean the path of the phase on a polar vector plot would show a square? If so, are you not assuming an infinite bandwidth for the modulated signal? Not clear what you mean... I don't like the term square line, maybe there is a better word for it? For square I imagine cartesean axis showing a line which (ideally) jumps quickly between values it stays at for some amount of time, in which all lines are perpendicular to one axis. I'd simply say the path drawn out on such a display was a square. The signal may dwell for relatively long periods at the 'corners' of the square, though. Away from the particulars, the real point I was trying to make is that however digital data is encoded, a plot can be made which shows the data as descrete values, otherwise the digital data could not be retrieved at the other end. From what you say I recognise one of the standard display methods which is used to show multiple-state AM/PM modulations. Typically giving an 'array' of blobs on the screen with some fuzzyness or tracking inbetween if you are using a simple 'analogue' display that shows the state on a time averaged continuous basis. (As opposed to a processed display which would simply group the states into a pre-defined set of locations and suppress the low-level effects of noise, finite bandwidth, etc.) I don't like, for example, for someone to describe the output from a computer modem as analogue, given that at some level it contains possibly perfect representatitions of descrete values. I consider 'contains possibly perfect representatitions of descrete values, to be a pretty good definition of digital. You need to distinguish between the actual time-voltage variations and the way they are *used* to convey the information according to a specified coding scheme. So far as the phone lines are concerned, the signal is just like speech, and is a continuously varying voltage/current. However the method used to impose information is 'digital'. Of course, this opens up discussion of what we mean by 'phase' and even 'frequency'. ;- The point I'm making is that digital and analogue shouldn't be thought of in such absolute terms. They are ideas, a signal may be thought to be both simultaneously if it helps. Need to be careful with the term 'signal' as well. :-) Yes, agreed. medium may have been a beter word here. (although that implys physical distribution) There are a set of standard definition in Information Theory for these things - although, despight having written a book about this, I often muddle them myself! Hence I tend to try and distinguish between the physical quantity used to carry or store the info with the coding method employed to associate specific information with specific patterns of variation of this quantity. Not quite 'perfect' as there is always a finite chance of errors produced by noise, etc. We can reduce this chance to a very low level, but not guarantee to exclude it entirely. The advantage of digital is that it provides some level of error immunity, and provides relatively easy methods for error detection and correction. The important word was 'may'! There is a possiblity that a digital piece of data sent will be exactly what arrives. Indeed, and with well designed and used systems, the probability of this is quite high. :-) The snag is that - in information theory terms - we can never be absolutely certain this *has* just happened, or will occur on the next try. This is in contrast to an analogue medium which can never be copied exactly. Need to be careful with the words 'exactly' and 'medium' here. :-) The recovered infomation with analogue is always subject to noise, etc. Hence the output can never be a 'perfect' representation of what was intended. Each time we play the LP the noise will be different, and so we can expect a slightly different result *if* true random noise is the problem as opposed to systematic imperfections of the LP surface producing the same 'noise' each time. With digital systems the behaviour is slightly different as 'most of the time' channel noise does not alter the output. However for a finite but small amount of the time there will still be unintended changes due to the finite risk of uncorrected errors, etc. Digital systems - properly used - are much better than analogue in avoiding effects due to noise added during transmission/storage. But they are not perfect in the strict sense, just potentially very good if done well. You still have to add some dither prior to sampling to avoid other problems, so the output will still have a finite noise level, but this is systematic Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
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