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#1
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an obsession with truth (or the facts, at least)
As friendly professor Peter Schickele once said... "Truth is truth. You can't
have opinions about truth." I'm accused of having obsessions no one else cares about. (I'm willing to confess to an excessive fondness for gerbils.) But I do care about the truth, and make no apologies for it. Part of the reason for this obsession is that, as an under-employed technical writer and editor, I see technically incompetent people with little or no ability to write or edit /being paid/ to do so. * Is it any wonder I blow my stack over errors that a competent editor would have caught? Anyhow... Here are the excerpts from Frenzel's "Electronics Explained" that disturbed me. I believe in encouraging people to think for themselves, so instead of explaining what's wrong, I invite people to say what /they/ think is wrong (including "important stuff" that's been left out). I might prompt a little, but I prefer that people figure out these things on their own. The purpose of this exercise is not to start arguments, but to get people thinking about what they understand or don't understand. (Frenzel is a master of tautological writing. He says the same thing over and over in a slightly different way each time, rather than expressing it once, simply. He would have had a great career as a paid-by-the-word pulp-fiction writer.) ---------------------------------------------- p89 Recall that there are two basic types of electronic signals -- analog and digital. A digital signal is one that varies in discrete steps. Unlike an analog signal, which varies continuously, a digital signal has two levels or states. The signal switches or changes abruptly from one state to the other. Figure 5.1 shows a DC digital signal that switches between two known levels such as zero volts or close to it (0.1 volts) or 0V and +3.3V. The positive voltage can be anything between about 1 volt and 12 volts with 3.3 and 5 being the most common. [Those who can get p89 to appear might ask themselves whether the figure actually shows a digital signal. How do you know it's digital and not analog? Can a pulsed signal be analog? Can a sine wave be digital?] Digital signals with two discrete levels are also referred to as binary signals. Binary means two -- two states or two discrete levels of voltage. Humans use the decimal number system that represents quantities with digits 0 through 9. However, digital equipment and computers do not. Internally, digital equipment processes binary data. ---------------------------------------------- p118ff Analog-to-Digital Conversion The process of converting an analog signal into a digital one is called analog-to-digital conversion, and is performed by an analog-to-digital converter (ADC). The process, also referred to as sampling, is illustrated in Figure 5-26. The ADC looks at the analog input and periodically takes a sample of the voltage at that instant, captures it, then converts it into a proportional binary number. We say that we are digitizing the signal. The sample points are shown by the dots on the analog curve. The binary value of the sample is shown to the right of the curve. The conversion process actually results in a sequence of binary numbers that represent the analog waveform. These values are usually stored in a RAM or transmitted to other circuits as shown in Figure 5-27. Note the symbol for an ADC. Digital-to-Analog Conversion To recover the original signal, we put the data sequence previously captured by the ADC into a digital-to-analog converter (DAC) (see Figure 5.28). The output is a version of the analog signal. The DAC output is not a perfect reproduction, but just an approximation. This is shown in more detail in Figure 5.29. Each binary input results in a constant voltage output from the DAC during the sample period. The result is a stepped approximation to the original signal. The rate at which the binary data is [sic] sent to the DAC must be the same as the sampling interval to recover the original frequency information in the signal. Resolution and Sampling Interval The key to good data conversion is to use greater resolution and faster sampling rates. Resolution refers t the number of bits used in the data conversion. In Figure 5.27, only 4 bits are used, so the resolution is poor. The voltage range is only divided into 16 intervals, meaning that amplitude variations at [sic] less than 0.625 volt are missed. This problem can be corrected by using more bits. ADCs are available in many bit sizes. The most common are 8, 10,, and 12 bits, but 14 and 16 bits are available. Some methods of ADC produce resolutions of 20 to 26 bits. The result is a finer conversion of amplitude detail. As an example, if the 0- to 10-volt range in Figure 5.27 was [sic] a 12-bit ADC, the individual smallest voltage increment that can be detected is 10/2^12 = 10/4096 = 2.44mV instead of the 0.625 volt[s] in the figure. Another critical specification is sampling rate. To retain all the frequency detail in a signal, the sampling rate must be at least twice the highest frequency in the signal. This called the Nyquist criterion. For example, when digitizing music with a frequency range of 20 Hz to 20 kHz, the sampling rate must be at least double the 20-kHz frequency. In most systems, a rate of 44.1 kHz or 48 kHz is used. ---------------------------------------------- For those who haven't fallen asleep (or died), here's part of my review of another bad book, "Signals and Systems Using MATLAB". I wrote "...on p9, he confuses "analog" with "continuous time" -- which is NOT correct. One can have analog data that are discrete-time." One reader responded "...it is impossible to have an analog signal that is discrete time. An analog signal can be represented by a discrete time signal very well, but an analog signal IS continuous, where a discrete time signal is defined as being discontinuous. Since it is impossible to have a continuous signal be equal to a discontinuous signal, your argument is invalid." This confusion of time and amplitude remains common. (Note also the confusion between "signal" and "data".) You might want to chew on it a bit. (ar-ar) Thanks for your interest. Have at it! * Several years ago I complained to a Wiley editor about a miserable book on the history of radio. He was a very nice person -- but admitted he had almost no technical knowledge. So what made him think he could edit technical books? He'd applied for and taken a job he was unqualified for. I think I have a right to be outraged. "'We already know the answers -- we just haven't asked the right questions." -- Edwin Land |
#2
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an obsession with truth (or the facts, at least)
It's obvious that Frenzel has a muddled understanding of what's going on. I also suspect that English is not his first language; it's possible that this book was written in another language, then translated -- usually a bad idea for a technical work.
Peace, Paul |
#3
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an obsession with truth (or the facts, at least)
On 6/17/2013 2:17 PM, William Sommerwerck wrote:
Here are the excerpts from Frenzel's "Electronics Explained" that disturbed me. I believe in encouraging people to think for themselves, so instead of explaining what's wrong, I invite people to say what /they/ think is wrong (including "important stuff" that's been left out). I might prompt a little, but I prefer that people figure out these things on their own. Thanks. In order to play editor here, I'd need more context. If this was an audio book, I'd treat the subject differently than if it was a general electronics book, which I infer from the title. But either way, it looks like the author is either confused about the digital representation of an analog signal or else he just edited himself too brutally (or an editor who didn't get it did) and over-simplified to the point that it's incomplete. -- For a good time, call http://mikeriversaudio.wordpress.com |
#4
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an obsession with truth (or the facts, at least)
"PStamler" wrote in message
... It's obvious that Frenzel has a muddled understanding of what's going on. You caught that? grin I also suspect that English is not his first language; it's possible that this book was written in another language, then translated -- usually a bad idea for a technical work. Frenzel has been with "Electronic Design" for some years. I don't think he's a "furriner". Given how cheap most publishers are, it's unlikely they would pay to have something translated. I'm currently studying Merhaut's "Theory of Electroacoustics", which was written in Czech. The English version -- which was translated by a physics teacher and has the author's approval -- is a pretty clear read. |
#5
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an obsession with truth (or the facts, at least)
"Mike Rivers" wrote in message ...
On 6/17/2013 2:17 PM, William Sommerwerck wrote: Here are the excerpts from Frenzel's "Electronics Explained" that disturbed me. I believe in encouraging people to think for themselves, so instead of explaining what's wrong, I invite people to say what /they/ think is wrong (including "important stuff" that's been left out). I might prompt a little, but I prefer that people figure out these things on their own. Thanks. In order to play editor here, I'd need more context. If this was an audio book, I'd treat the subject differently than if it was a general electronics book, which I infer from the title. But either way, it looks like the author is either confused about the digital representation of an analog signal or else he just edited himself too brutally (or an editor who didn't get it did) and over-simplified to the point that it's incomplete. This book is an introduction to electronics for the "unknowing". (I use that in both senses of the word.) The book reads throughout like an unedited first draft. I suspect Frenzel was trying to be "quick and breezy" without regard for the little (and sometimes big) details. The other day I started to write an explanation of "digital" from scratch -- and it is not easy. There is so much preliminary material to present (such as why one would want to represent information as quantized values, rather than continuous variation) it can be daunting. That, however, is no excuse for getting so much wrong. |
#6
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an obsession with truth (or the facts, at least)
On Monday, June 17, 2013 5:52:14 PM UTC-5, William Sommerwerck wrote:
This book is an introduction to electronics for the "unknowing". (I use that in both senses of the word.) Not an easy task. I do that for a living myself, as does Mike Rivers (and as you used to do back in the Stereophile days), and it's always a fine line to walk. In this case I think the author fell off the line. The book reads throughout like an unedited first draft. I suspect Frenzel was trying to be "quick and breezy" without regard for the little (and sometimes big) details. He also writes an endless string of short declarative sentences. That's deadly. Maybe Hemingway got away with it, but he wrote *good* short sentences. The other day I started to write an explanation of "digital" from scratch -- and it is not easy. There is so much preliminary material to present (such as why one would want to represent information as quantized values, rather than continuous variation) it can be daunting. That, however, is no excuse for getting so much wrong. No, it's not easy. At the beginning of this discussion I offered my definitions of "analog" and "digital", and I found I had to use many weasel words, to cover the many ambiguities. And yes, it's important for the reader to know the "prior art" -- the explanations for the explanations, if you will, or the foundational material we take for granted but most "civilians" have never been exposed to. Peace, Paul |
#7
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an obsession with truth (or the facts, at least)
"PStamler" wrote in message
... The other day I started to write an explanation of "digital" from scratch -- and it is not easy. There is so much preliminary material to present (such as why one would want to represent information as quantized values, rather than continuous variation) it can be daunting. That, however, is no excuse for getting so much wrong. No, it's not easy. At the beginning of this discussion I offered my definitions of "analog" and "digital", and I found I had to use many weasel words, to cover the many ambiguities. You're touching on an issue that hasn't been discussed yet. The word "signal" has two meanings -- the waveform coming out of or going into a circuit, and the information carried by that waveform. The failure to recognize this causes writers to talk about analog or digital signals (waveforms), when in reality, there are no such things. "Analog" and "digital" refer to the way the data is represented or "coded" -- not the waveform that carries that representation or coding. You thus have writers stating that pulsed signals (waveforms) represent digital information, when in reality the waveform has nothing whatever to do with "analog" or "digital" information. |
#8
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an obsession with truth (or the facts, at least)
"William Sommerwerck" wrote in message
... "PStamler" wrote in message ... The other day I started to write an explanation of "digital" from scratch -- and it is not easy. There is so much preliminary material to present (such as why one would want to represent information as quantized values, rather than continuous variation) it can be daunting. That, however, is no excuse for getting so much wrong. No, it's not easy. At the beginning of this discussion I offered my definitions of "analog" and "digital", and I found I had to use many weasel words, to cover the many ambiguities. You're touching on an issue that hasn't been discussed yet. Of course it's been discussed. You've gone through this whole rigmarole in the past, and you're rehashing it. Do you have a short memory? None of this is new to many of us, and it seems that none of it new even to the newsgroup. The word "signal" has two meanings -- the waveform coming out of or going into a circuit, and the information carried by that waveform. Actually, it has even more meanings. "Continuous" also has multiple meanings, and your failure to distinguish between them caught you up last time. You called a discrete-time signal "continuous", although in the mathematical sense usually used in Signals and Systems, a discrete-time signal cannot be continuous, as it is a series of discontinuous points with no continuity anywhere. Perhaps this kind of careless writing in technical discussions is part of the reason for people disagreeing with you, despite your ridiculous claim that you are (almost) always right. In fact, you have shown yourself to be wrong, ambiguous, and unclear in many cases here in RAP. The whole point of this redundant charade seems to be to fail, once again, to prove how wonderful you are. QED. Long ago, not so long ago, and now, once again. When you're wrong, you simple deny it. No doubt, after the dust settles, you'll be back again with the same horse****. If anyone wants to jump ahead to the punch line, they can simply search for the previous re-runs of the Willie Thinks He's Always Right Comedy Hour. |
#9
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an obsession with truth (or the facts, at least)
On 6/17/2013 6:52 PM, William Sommerwerck wrote:
The other day I started to write an explanation of "digital" from scratch -- and it is not easy. There is so much preliminary material to present (such as why one would want to represent information as quantized values, rather than continuous variation) it can be daunting. That's why I didn't attempt a rewrite. At $100/hour, I don't think that rec.audio.pro can afford it. It's possible that the book only got a grammatical edit, not a technical one, and it's really hard to edit your own writing. I did the technical editing for Ethan Winer's book The Audio Expert. It wasn't all that difficult because Ethan knows his stuff and didn't really make any errors. The sort of things that i contributed were changes that made the language easier to understand, and occasionally suggest an different example that made the point clearer than what he used. But I knew the subject matter. If I was handed, say, a book about using Pro Tools to produce hip hop, I couldn't have done as good a job. My own writing tends to be pretty breezy and informal, but at least I try to get the technical parts correct. A brutal editor could probably cut my word count by 25 to 50 percent, but I can't. -- For a good time, call http://mikeriversaudio.wordpress.com |
#10
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an obsession with truth (or the facts, at least)
"William Sommerwerck" wrote in message
... The purpose of this exercise is not to start arguments, Of course it is. Are you now writing Monty Python skits? but to get people thinking about what they understand or don't understand. No, it's for you to engage in an auto-erotic display of egotism. He says the same thing over and over in a slightly different way each time, rather than expressing it once, simply. He would have had a great career as a paid-by-the-word pulp-fiction writer. If you have any self-awareness left, you should stand in front of a mirror, and read that to yourself until it sinks in. You might want to clear your calendar. |
#11
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an obsession with truth (or the facts, at least)
The word "signal" has two meanings -- the waveform coming out of or going
into a circuit, and the information carried by that waveform. Actually, it has even more meanings. "Continuous" also has multiple meanings, and your failure to distinguish between them caught you up last time. You called a discrete-time signal "continuous", although in the mathematical sense usually used in Signals and Systems, a discrete-time signal cannot be continuous, as it is a series of discontinuous points with no continuity anywhere. I never said anything of the sort. You either can't read (likely) or you're lying (not so likely). A discrete-time signal can be analog. Analog and continuous do not mean the same thing. Sorry, but I am always always right. Sorry about that. |
#12
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an obsession with truth (or the facts, at least)
"Mike Rivers" wrote in message ...
My own writing tends to be pretty breezy and informal, but at least I try to get the technical parts correct. A brutal editor could probably cut my word count by 25 to 50 percent, but I can't. I have the same problem. You can learn to do this but it's difficult. |
#13
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an obsession with truth (or the facts, at least)
On 6/17/2013 6:28 PM, None wrote:
"William Sommerwerck" wrote in message ... The purpose of this exercise is not to start arguments, Of course it is. Are you now writing Monty Python skits? but to get people thinking about what they understand or don't understand. No, it's for you to engage in an auto-erotic display of egotism. He says the same thing over and over in a slightly different way each time, rather than expressing it once, simply. He would have had a great career as a paid-by-the-word pulp-fiction writer. If you have any self-awareness left, you should stand in front of a mirror, and read that to yourself until it sinks in. You might want to clear your calendar. 100% Agreed. Nobody who wants to learn about electronics is going to rely on one book anyways. For anyone who will end up designing circuits, it all sinks in eventually. Maybe if William was actually duly employed, he'd have less time to tear down the work of others. I'm still waiting for his magically lucid description of the "truth". |
#14
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an obsession with truth (or the facts, at least)
"William Sommerwerck" wrote in message ... The word "signal" has two meanings -- the waveform coming out of or going into a circuit, and the information carried by that waveform. Actually, it has even more meanings. "Continuous" also has multiple meanings, and your failure to distinguish between them caught you up last time. You called a discrete-time signal "continuous", although in the mathematical sense usually used in Signals and Systems, a discrete-time signal cannot be continuous, as it is a series of discontinuous points with no continuity anywhere. I never said anything of the sort. You either can't read (likely) or you're lying (not so likely). A discrete-time signal can be analog. Analog and continuous do not mean the same thing. Sorry, but I am always always right. Sorry about that. Masturbating in public is impolite, but I guess you really crave the attention that you can't get in real life. I'm sure you're accustomed to being ignored and reviled, because that's what you demand. And you have confirmed what most of us already knew: you don't mean it when you apologize. Your recent sham apology was not sincere, which you have confirmed at least four time now, since you puked it onto Usenet. |
#15
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an obsession with truth (or the facts, at least)
On 6/17/2013 10:14 PM, Paul wrote:
On 6/17/2013 6:28 PM, None wrote: "William Sommerwerck" wrote in message ... The purpose of this exercise is not to start arguments, Of course it is. Are you now writing Monty Python skits? but to get people thinking about what they understand or don't understand. No, it's for you to engage in an auto-erotic display of egotism. He says the same thing over and over in a slightly different way each time, rather than expressing it once, simply. He would have had a great career as a paid-by-the-word pulp-fiction writer. If you have any self-awareness left, you should stand in front of a mirror, and read that to yourself until it sinks in. You might want to clear your calendar. 100% Agreed. Nobody who wants to learn about electronics is going to rely on one book anyways. For anyone who will end up designing circuits, it all sinks in eventually. Maybe if William was actually duly employed, he'd have less time to tear down the work of others. I'm still waiting for his magically lucid description of the "truth". Were I truly cynical I might tend to think that he's waiting to review our responses before he (contrives) and presents his spin of the absolute truth. Ah, but can anyone actually be that cynical? == Later... Ron Capik cynic--training -- |
#16
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an obsession with truth (or the facts, at least)
"Paul" wrote in message ...
Maybe if William was actually duly employed, he'd have less time to tear down the work of others. If I were duly employed, that's what I'd be paid to do. It might not bother you that most technical books are overpriced toilet paper, but it bothers me. |
#17
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an obsession with truth (or the facts, at least)
I'm still waiting for his magically lucid description of the "truth".
I started writing it, but (as I said to Mike), it's not easy. I'll complete it if you (Ron) agree to give it a //serious// review in this group. I doubt you would, because it would be too easy to call it everything in it wrong and say I didn't know what I was talking about. I'm calling you out on this. |
#18
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an obsession with truth (or the facts, at least)
On 6/17/2013 10:41 PM, William Sommerwerck wrote:
"Paul" wrote in message ... Maybe if William was actually duly employed, he'd have less time to tear down the work of others. If I were duly employed, that's what I'd be paid to do. It might not bother you that most technical books are overpriced toilet paper, but it bothers me. However it seems the free market isn't buying what you're selling. You may sit and stew, change your marketing, or change your product. Seems you've opted for the first state. I opted for retirement, thus have no dogs in the fight. [OK, I may still care about accuracy ...at some level.] == Later... Ron Capik -- |
#19
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an obsession with truth (or the facts, at least)
On 6/17/2013 7:23 PM, None wrote:
"William Sommerwerck" wrote in message ... The word "signal" has two meanings -- the waveform coming out of or going into a circuit, and the information carried by that waveform. Actually, it has even more meanings. "Continuous" also has multiple meanings, and your failure to distinguish between them caught you up last time. You called a discrete-time signal "continuous", although in the mathematical sense usually used in Signals and Systems, a discrete-time signal cannot be continuous, as it is a series of discontinuous points with no continuity anywhere. I never said anything of the sort. You either can't read (likely) or you're lying (not so likely). A discrete-time signal can be analog. Analog and continuous do not mean the same thing. Sorry, but I am always always right. Sorry about that. Masturbating in public is impolite, but I guess you really crave the attention that you can't get in real life. I'm sure you're accustomed to being ignored and reviled, because that's what you demand. And you have confirmed what most of us already knew: you don't mean it when you apologize. Your recent sham apology was not sincere, which you have confirmed at least four time now, since you puked it onto Usenet. 100% agreed. William is like most "know-it-all" personalities: only he knows the truth, and everyone else is a dumb****. Get over yourself, William, you've got the attention you wanted... now put your dick back in your pants.... |
#20
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an obsession with truth (or the facts, at least)
"William Sommerwerck" wrote in message
... I'm still waiting for his magically lucid description of the "truth". I started writing it, but (as I said to Mike), it's not easy. I'll complete it if you (Ron) agree to give it a //serious// review in this group. I doubt you would, because it would be too easy to call it everything in it wrong and say I didn't know what I was talking about. I'm calling you out on this. LOL! "Calling you out". What a ****ing asshole! In a world where you could invent your own definitions, and no other definitions ever have any validity, you could probably make a case that you're always right. But in the real world, where definitions exist by common understanding, your refusal to accept common understanding just leaves you behind as an unemployable loser. You repeatedly come here and pretend that you and you alone know the one and only true definition of some term or other, and then you pretend that it makes you superior. The truth is, that your inability to engage in productive communication, and your condescending attitude that your pig-headedness makes you superior, is one of the reasons that you deserve the mockery and contempt that you get. When you are proven wrong, you simply refuse to hear it, because your head is so far up your asshole that you can see your back teeth. And now, like a petulant bratty child, you demand that others dance to your tune. But in fact, you can't play a tune, and nobody wants to dance with you. |
#21
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an obsession with truth (or the facts, at least)
On 6/17/2013 8:08 PM, None wrote:
"William Sommerwerck" wrote in message ... I'm still waiting for his magically lucid description of the "truth". I started writing it, but (as I said to Mike), it's not easy. I'll complete it if you (Ron) agree to give it a //serious// review in this group. I doubt you would, because it would be too easy to call it everything in it wrong and say I didn't know what I was talking about. I'm calling you out on this. LOL! "Calling you out". What a ****ing asshole! In a world where you could invent your own definitions, and no other definitions ever have any validity, you could probably make a case that you're always right. But in the real world, where definitions exist by common understanding, your refusal to accept common understanding just leaves you behind as an unemployable loser. You repeatedly come here and pretend that you and you alone know the one and only true definition of some term or other, and then you pretend that it makes you superior. The truth is, that your inability to engage in productive communication, and your condescending attitude that your pig-headedness makes you superior, is one of the reasons that you deserve the mockery and contempt that you get. When you are proven wrong, you simply refuse to hear it, because your head is so far up your asshole that you can see your back teeth. And now, like a petulant bratty child, you demand that others dance to your tune. But in fact, you can't play a tune, and nobody wants to dance with you. Jesus, I couldn't agree more. No wonder no one wants to hire this idiot..... |
#22
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an obsession with truth (or the facts, at least)
Well, if no one else is going to answer you I will try.
The biggest problem that I see in the text is that he thinks the digital file will not be a perfect copy of the analog input, and that digital waveforms are a connect the dots stair stepped approximation of the analog. That would be a serious error. Gary Eickmeier William Sommerwerck wrote: As friendly professor Peter Schickele once said... "Truth is truth. You can't have opinions about truth." I'm accused of having obsessions no one else cares about. (I'm willing to confess to an excessive fondness for gerbils.) But I do care about the truth, and make no apologies for it. Part of the reason for this obsession is that, as an under-employed technical writer and editor, I see technically incompetent people with little or no ability to write or edit /being paid/ to do so. * Is it any wonder I blow my stack over errors that a competent editor would have caught? Anyhow... Here are the excerpts from Frenzel's "Electronics Explained" that disturbed me. I believe in encouraging people to think for themselves, so instead of explaining what's wrong, I invite people to say what /they/ think is wrong (including "important stuff" that's been left out). I might prompt a little, but I prefer that people figure out these things on their own. The purpose of this exercise is not to start arguments, but to get people thinking about what they understand or don't understand. (Frenzel is a master of tautological writing. He says the same thing over and over in a slightly different way each time, rather than expressing it once, simply. He would have had a great career as a paid-by-the-word pulp-fiction writer.) ---------------------------------------------- p89 Recall that there are two basic types of electronic signals -- analog and digital. A digital signal is one that varies in discrete steps. Unlike an analog signal, which varies continuously, a digital signal has two levels or states. The signal switches or changes abruptly from one state to the other. Figure 5.1 shows a DC digital signal that switches between two known levels such as zero volts or close to it (0.1 volts) or 0V and +3.3V. The positive voltage can be anything between about 1 volt and 12 volts with 3.3 and 5 being the most common. [Those who can get p89 to appear might ask themselves whether the figure actually shows a digital signal. How do you know it's digital and not analog? Can a pulsed signal be analog? Can a sine wave be digital?] Digital signals with two discrete levels are also referred to as binary signals. Binary means two -- two states or two discrete levels of voltage. Humans use the decimal number system that represents quantities with digits 0 through 9. However, digital equipment and computers do not. Internally, digital equipment processes binary data. ---------------------------------------------- p118ff Analog-to-Digital Conversion The process of converting an analog signal into a digital one is called analog-to-digital conversion, and is performed by an analog-to-digital converter (ADC). The process, also referred to as sampling, is illustrated in Figure 5-26. The ADC looks at the analog input and periodically takes a sample of the voltage at that instant, captures it, then converts it into a proportional binary number. We say that we are digitizing the signal. The sample points are shown by the dots on the analog curve. The binary value of the sample is shown to the right of the curve. The conversion process actually results in a sequence of binary numbers that represent the analog waveform. These values are usually stored in a RAM or transmitted to other circuits as shown in Figure 5-27. Note the symbol for an ADC. Digital-to-Analog Conversion To recover the original signal, we put the data sequence previously captured by the ADC into a digital-to-analog converter (DAC) (see Figure 5.28). The output is a version of the analog signal. The DAC output is not a perfect reproduction, but just an approximation. This is shown in more detail in Figure 5.29. Each binary input results in a constant voltage output from the DAC during the sample period. The result is a stepped approximation to the original signal. The rate at which the binary data is [sic] sent to the DAC must be the same as the sampling interval to recover the original frequency information in the signal. Resolution and Sampling Interval The key to good data conversion is to use greater resolution and faster sampling rates. Resolution refers t the number of bits used in the data conversion. In Figure 5.27, only 4 bits are used, so the resolution is poor. The voltage range is only divided into 16 intervals, meaning that amplitude variations at [sic] less than 0.625 volt are missed. This problem can be corrected by using more bits. ADCs are available in many bit sizes. The most common are 8, 10,, and 12 bits, but 14 and 16 bits are available. Some methods of ADC produce resolutions of 20 to 26 bits. The result is a finer conversion of amplitude detail. As an example, if the 0- to 10-volt range in Figure 5.27 was [sic] a 12-bit ADC, the individual smallest voltage increment that can be detected is 10/2^12 = 10/4096 = 2.44mV instead of the 0.625 volt[s] in the figure. Another critical specification is sampling rate. To retain all the frequency detail in a signal, the sampling rate must be at least twice the highest frequency in the signal. This called the Nyquist criterion. For example, when digitizing music with a frequency range of 20 Hz to 20 kHz, the sampling rate must be at least double the 20-kHz frequency. In most systems, a rate of 44.1 kHz or 48 kHz is used. ---------------------------------------------- For those who haven't fallen asleep (or died), here's part of my review of another bad book, "Signals and Systems Using MATLAB". I wrote "...on p9, he confuses "analog" with "continuous time" -- which is NOT correct. One can have analog data that are discrete-time." One reader responded "...it is impossible to have an analog signal that is discrete time. An analog signal can be represented by a discrete time signal very well, but an analog signal IS continuous, where a discrete time signal is defined as being discontinuous. Since it is impossible to have a continuous signal be equal to a discontinuous signal, your argument is invalid." This confusion of time and amplitude remains common. (Note also the confusion between "signal" and "data".) You might want to chew on it a bit. (ar-ar) Thanks for your interest. Have at it! * Several years ago I complained to a Wiley editor about a miserable book on the history of radio. He was a very nice person -- but admitted he had almost no technical knowledge. So what made him think he could edit technical books? He'd applied for and taken a job he was unqualified for. I think I have a right to be outraged. "'We already know the answers -- we just haven't asked the right questions." -- Edwin Land |
#23
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an obsession with truth (or the facts, at least)
On 6/17/2013 10:41 PM, William Sommerwerck wrote:
It might not bother you that most technical books are overpriced toilet paper, but it bothers me. Not very good toilet paper. The covers are too slick, and the pictures aren't very interesting. I suspect that the problem is with the publishing industry rather than with the authors. Publishers don't want a thick book with a lot of details about a very small range of topics because they'd only sell a handful. They want a book that covers a wider scope. For example, I've been thinking for a couple of years about writing a book, probably 100-150 pages, about connections between elements of a PA system. But who'd buy it if it didn't tell them how to mic a drum kit or compress a bass? -- For a good time, call http://mikeriversaudio.wordpress.com |
#24
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an obsession with truth (or the facts, at least)
On 6/18/2013 2:01 AM, Gary Eickmeier wrote:
Well, if no one else is going to answer you I will try. The biggest problem that I see in the text is that he thinks the digital file will not be a perfect copy of the analog input, and that digital waveforms are a connect the dots stair stepped approximation of the analog. That would be a serious error. I don't think he even got far enough to make that error. When you know that this is what most people who aren't about to present the sampling theorem will say about digital representation of an analog signal, it's easy to infer even from an incomplete explanation, that he's telling you that the digital representation isn't smooth. And in fact, it isn't smooth. It's a series of binary numbers that represent analog levels sampled at discrete intervals. It's only an accurate representation of the analog signal when you take a further step and remove information that is out of bounds of the sampling theory. And that's a very simplified and not entirely precise explanation. -- For a good time, call http://mikeriversaudio.wordpress.com |
#25
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an obsession with truth (or the facts, at least)
"William Sommerwerck" wrote in message
... / The other day I started to write an explanation of "digital" from scratch -- and it is not easy. There is so much preliminary material to present (such as why one would want to represent information as quantized values, rather than continuous variation) it can be daunting. That, however, is no excuse for getting so much wrong. Part of the problem may be that the word digital is a word that is something like the word fridge. Everybody thinks they know what it means but tend to forget that when you start formulating formal definitions, fuzz around the edges becomes intolerable. When I think of the word digital what I really mean is "Discrete value, discrete time" or "Quantized value, quantized time". Once you agree with that, life seems to become considerably easier. Those definitions also admits what I find to be an amazingly large number of different kinds of signals and brings in a lot of history. I lived through a lot of it. For example, binary signals are only a subset of all of the possible kinds of digital signals. |
#26
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an obsession with truth (or the facts, at least)
Arny Krueger wrote:
"William Sommerwerck" wrote in message ... / The other day I started to write an explanation of "digital" from scratch -- and it is not easy. There is so much preliminary material to present (such as why one would want to represent information as quantized values, rather than continuous variation) it can be daunting. That, however, is no excuse for getting so much wrong. Part of the problem may be that the word digital is a word that is something like the word fridge. Everybody thinks they know what it means but tend to forget that when you start formulating formal definitions, fuzz around the edges becomes intolerable. When I think of the word digital what I really mean is "Discrete value, discrete time" Which I would define as "Taking the nearest value of the signal, selected from a number of such, encoded as a number, at the instant when the clock ticks". The way a normal ADC works. or "Quantized value, quantized time". Which I would take as meaning "Taking a known value at a known instant". The known value is not necessarily encoded, but could, for instance, be represented as the amount of charge on a capacitor as measured by an analogue meter, and the time can be arbitrary, not exactly defined by a clock. The way a "Sample and hold" circuit works. If the timing is set by a clock ticking and you have a number of sample and hold circuits, in series, then you have the principle of a bucket brigade delay. At the ultimate resolution, though, all signal values are quantised by the charge of an electron, and the time resolution is limited by the Planck time, which is (5.39106(32) × 10-44 s). -- Tciao for Now! John. |
#27
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an obsession with truth (or the facts, at least)
"Gary Eickmeier" wrote in message ...
Well, if no one else is going to answer you I will try. The biggest problem that I see in the text is that he thinks the digital file will not be a perfect copy of the analog input, and that digital waveforms are a connect the dots stair stepped approximation of the analog. That would be a serious error. That seems to be what he's saying, and it /is/ a serious error. There are others. Frenzel doesn't properly address -- even in passing -- the issue of how accurate a quantized representation can be. Indeed, he says that faster sampling and a deeper bit depth give a better representation -- but this isn't necessarily true. |
#28
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an obsession with truth (or the facts, at least)
"Arny Krueger" wrote in message
... "William Sommerwerck" wrote in message ... The other day I started to write an explanation of "digital" from scratch -- and it is not easy. There is so much preliminary material to present (such as why one would want to represent information as quantized values, rather than continuous variation) it can be daunting. That, however, is no excuse for getting so much wrong. Part of the problem may be that the word digital is a word that is something like the word fridge. Everybody thinks they know what it means, but tend to forget that when you start formulating formal definitions, fuzz around the edges becomes intolerable. You mean... A fridge isn't a Frigidaire? And if it's not an Amana, it's not a Radarange? (I shouldn't have to mark this as a joke, but it seems necessary.) When I think of the word digital what I really mean is "Discrete value, discrete time" or "Quantized value, quantized time". Once you agree with that, life seems to become considerably easier. Those definitions also admits what I find to be an amazingly large number of different kinds of signals and brings in a lot of history. I lived through a lot of it. For example, binary signals are only a subset of all of the possible kinds of digital signals. What he said. It's all correct. Thank you. |
#29
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an obsession with truth (or the facts, at least)
"No wonder no one wants to hire this idiot..."
Those who have hired me, and let me do my job without telling me how to do it, have been happy with my work. At Data I/O I rewrote the horrible user manual for the schematic-capture software Data I/O had recently purchased. When the product went out the door, it immediately received kudos from customers who'd had trouble with the previous manuals. At Microsoft, I rewrote material I was told /not/ to rewrite -- and got uninvited compliments. I rewrote Software Bisque's user manuals. SB got compliments from customers -- and fewer phone calls. At AccessLine, I had a "love affair" with my boss. If you've ever had a manager who demands your best work, and supports you in achieving it, you know how great going to work can be. I'm "sorry", Mr No-Name, but as a technical writer, I usually know what I'm doing. I don't need your approval, nor will I grovel in front of you asking for permission to speak in public on subjects I know something about. |
#30
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an obsession with truth (or the facts, at least)
"None" wrote in message
m... "William Sommerwerck" wrote in message ... LOL! "Calling you out". What a ****ing asshole! In a world where you could invent your own definitions, and no other definitions ever have any validity, you could probably make a case that you're always right. But in the real world, where definitions exist by common understanding, your refusal to accept common understanding just leaves you behind as an unemployable loser. And in all your long, rich existence, you have never had the experience of reading or hearing some "expert" say something. and reacting "Wait. That's wrong."? It's interesting that Mike Rivers and Ron Capik -- who have writing experience -- aren't so quick to dump on me. (I'm /not/ saying they approve of everything I say or do.) Could it be they know you can't write well about things you don't understand? "But in the real world, where definitions exist by common understanding..." Which is another way of saying that common belief is fact -- which it isn't. Most people believe what they're told by their parents or "experts", without questioning it. More than anything, this is what I'm fighting. I've always been weak on acoustics. I've just started studying Merhaut's "Theory of Electroacoustics", and this time I seem to be understanding it. |
#31
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an obsession with truth (or the facts, at least)
"Mike Rivers" wrote in message ...
On 6/17/2013 10:41 PM, William Sommerwerck wrote: It might not bother you that most technical books are overpriced toilet paper, but it bothers me. Not very good toilet paper. The covers are too slick, and the pictures aren't very interesting. I suspect that the problem is with the publishing industry rather than with the authors. Publishers don't want a thick book with a lot of details about a very small range of topics because they'd only sell a handful. They want a book that covers a wider scope. For example, I've been thinking for a couple of years about writing a book, probably 100-150 pages, about connections between elements of a PA system. But who'd buy it if it didn't tell them how to mic a drum kit or compress a bass? How about a book titled "Installing and Maintaining PA Systems"? Wouldn't there be a market for that? |
#32
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an obsession with truth (or the facts, at least)
"Ron C" wrote in message
... On 6/17/2013 10:41 PM, William Sommerwerck wrote: "Paul" wrote in message ... Maybe if William was actually duly employed, he'd have less time to tear down the work of others. If I were duly employed, that's what I'd be paid to do. It might not bother you that most technical books are overpriced toilet paper, but it bothers me. However it seems the free market isn't buying what you're selling. You may sit and stew, change your marketing, or change your product. Seems you've opted for the first state. I opted for retirement, thus have no dogs in the fight. [OK, I may still care about accuracy ...at some level.] I sincerely thank Ron for (more or less) agreeing with me. My marketing approach has always been "I can help you provide better customer support and improve customer satisfaction". It has worked in only one case that I remember. Isn't anyone bothered that the expensive books they buy are often poorly written and organized? Or that they have only rarely been edited for technical accuracy? |
#33
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an obsession with truth (or the facts, at least)
On 6/18/2013 9:49 AM, William Sommerwerck wrote:
How about a book titled "Installing and Maintaining PA Systems"? Wouldn't there be a market for that? There are already a couple of books that cover that subject pretty well, the Yamaha Sound Reinforcement Handbook and Sound System Engineering (the Don Davis bunch). A title like that would scare away the people I want to write for. This would be a book for the person who posts on a fourm: "I just bought a new mixer. Can someone tell me the best way to hook it up?" -- For a good time, call http://mikeriversaudio.wordpress.com |
#34
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an obsession with truth (or the facts, at least)
"Mike Rivers" wrote in message ...
On 6/18/2013 9:49 AM, William Sommerwerck wrote: How about a book titled "Installing and Maintaining PA Systems"? Wouldn't there be a market for that? There are already a couple of books that cover that subject pretty well, the Yamaha Sound Reinforcement Handbook and Sound System Engineering (the Don Davis bunch). A title like that would scare away the people I want to write for. This would be a book for the person who posts on a fourm: "I just bought a new mixer. Can someone tell me the best way to hook it up?" I see a couple of issues... A mixer is necessarily /part of/ a larger system. Is it possible to explain how to hook it up without the context of the system as a whole? I'm not sure it is. To put it a slightly different way... It's usually assumed that if you understand how trees work, you won't have trouble assembling them into a forest. That is rarely true for a newcomer -- they often don't even understand the trees. I once tried to twist Mr Mackie's arm into letting me rewrite the mixer manual. It was /locally/ well-written, but poorly organized. It needed to be laid out from the perspective of someone who had no practical experience with mixers, and had to be instructed from the ground up, starting with the simplest things (ie, where do you plug in a mic and how do you set its level?). Basically, it's the manufacturers' responsibility to provide this sort of documentation. To the extent they don't, you have a market. How about "The Big Dummy's Guide to Installing and Using a Mixer"? |
#35
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an obsession with truth (or the facts, at least)
Mike Rivers writes:
On 6/18/2013 9:49 AM, William Sommerwerck wrote: How about a book titled "Installing and Maintaining PA Systems"? Wouldn't there be a market for that? There are already a couple of books that cover that subject pretty well, the Yamaha Sound Reinforcement Handbook and Sound System Engineering (the Don Davis bunch). A title like that would scare away the people I want to write for. This would be a book for the person who posts on a fourm: "I just bought a new mixer. Can someone tell me the best way to hook it up?" How about joining the "Idiots Guide" franchise? I've seen some surprising topics in that area (sorry, escapes me now; something like the "Idiot's Guide to Funerals", or some such was one; there are some other arcane topics as well). So, "The Idiot's Guide to Small PA Systems"... Personally, the entire franchise is somewhat annoying to me, but hey, if you can sell them on your writing in your field but using their editorial guidelines, why not? Frank Mobile Audio -- |
#36
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an obsession with truth (or the facts, at least)
On 6/18/2013 12:28 PM, William Sommerwerck wrote:
I see a couple of issues... A mixer is necessarily /part of/ a larger system. Is it possible to explain how to hook it up without the context of the system as a whole? I'm not sure it is. The question, of course, is naive. What they really mean to ask, and what I would answer in the book, is to how to hook up the sort of sound system that a person who would ask a question that way would be likely to buy. To put it a slightly different way... It's usually assumed that if you understand how trees work, you won't have trouble assembling them into a forest. That is rarely true for a newcomer -- they often don't even understand the trees. And that's why there needs to be a good book. Every mixer instruction manual tells you where the Auxiliary Send controls are, but few explain that they feed signals to a bus and that bus is where you connect your monitors (and why), or outboard effect processors. I'll leave the rigging and line arrays for another book if I ever think I have enough experience to write about them. I once tried to twist Mr Mackie's arm into letting me rewrite the mixer manual. It was /locally/ well-written, but poorly organized. It needed to be laid out from the perspective of someone who had no practical experience with mixers, and had to be instructed from the ground up, starting with the simplest things (ie, where do you plug in a mic and how do you set its level?). Are you talking about my big mixer book, or the manual for one of their mixers? I used to point people to the Mackie 1604 VLZ manual because it had several suggested hook-up diagrams that covered real situations. The first page or so of all of their manuals back then had "The Mackie Level Setting Procedure" that offered one way of setting the channel trims so that there was enough headroom in the mixer. Trouble was that people looked at the meters and said "my mixer isn't hot enough." The problem was one of gain structure in the system and a meter scale that covered too wide of a range. How about "The Big Dummy's Guide to Installing and Using a Mixer"? I'd probably get sued by John Wiley, the folks who publish the "For Dummies" books. I was thinking about "PA Systems For Drummers" but the bass player might feel slighted. -- For a good time, call http://mikeriversaudio.wordpress.com |
#37
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an obsession with truth (or the facts, at least)
On Tue, 18 Jun 2013 06:51:38 -0700, William Sommerwerck wrote:
"Ron C" wrote in message ... On 6/17/2013 10:41 PM, William Sommerwerck wrote: "Paul" wrote in message ... Maybe if William was actually duly employed, he'd have less time to tear down the work of others. If I were duly employed, that's what I'd be paid to do. It might not bother you that most technical books are overpriced toilet paper, but it bothers me. However it seems the free market isn't buying what you're selling. You may sit and stew, change your marketing, or change your product. Seems you've opted for the first state. I opted for retirement, thus have no dogs in the fight. [OK, I may still care about accuracy ...at some level.] I sincerely thank Ron for (more or less) agreeing with me. My marketing approach has always been "I can help you provide better customer support and improve customer satisfaction". It has worked in only one case that I remember. SNIP You're marketing approach is probably fine. I suspect that potential employers spend a few minutes in conversation with you or in written communication with you and conclude that you are trouble with a capital T, unable to play or work effectively with others, and likely to harm the enterprise more than you might help. Steve King |
#38
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an obsession with truth (or the facts, at least)
I'm answering this directly.
I once tried to twist Mr Mackie's arm into letting me rewrite the mixer manual. It was /locally/ well-written, but poorly organized. It needed to be laid out from the perspective of someone who had no practical experience with mixers, and had to be instructed from the ground up, starting with the simplest things (ie, where do you plug in a mic and how do you set its level?). Are you talking about my big mixer book, or the manual for one of their mixers? I used to point people to the Mackie 1604 VLZ manual because it had several suggested hook-up diagrams that covered real situations. The first page or so of all of their manuals back then had "The Mackie Level Setting Procedure" that offered one way of setting the channel trims so that there was enough headroom in the mixer. Trouble was that people looked at the meters and said "my mixer isn't hot enough." The problem was one of gain structure in the system and a meter scale that covered too wide of a range. I didn't know you'd written a mixer book. I was thinking of the manual. I have an odd approach to learning things. I'm more interested in principles than facts. With respect to mixers (I used to own a Mackie, which I used solely as a mic preamp), I wanted to /understand/ how it worked and how it was used. I don't like having to be dependent on a diagram. In general, a manual should help the user understand the product sufficiently that he rarely, if ever, has to refer to the manual. |
#39
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an obsession with truth (or the facts, at least)
William Sommerwerck wrote:
"PStamler" wrote in message ... The other day I started to write an explanation of "digital" from scratch -- and it is not easy. There is so much preliminary material to present (such as why one would want to represent information as quantized values, rather than continuous variation) it can be daunting. That, however, is no excuse for getting so much wrong. No, it's not easy. At the beginning of this discussion I offered my definitions of "analog" and "digital", and I found I had to use many weasel words, to cover the many ambiguities. You're touching on an issue that hasn't been discussed yet. The word "signal" has two meanings -- the waveform coming out of or going into a circuit, and the information carried by that waveform. Sort of... The failure to recognize this causes writers to talk about analog or digital signals (waveforms), when in reality, there are no such things. "Analog" and "digital" refer to the way the data is represented or "coded" -- not the waveform that carries that representation or coding. But these are a dual of each other - in the mathematical sense of "dual". There's no metaphysical dualism; it's simply a matter of the domain in which the signal is being discussed. There exist devices or algorithms that perform a conversion between these two domains. There is a perfectly useful bijective mapping. A bijective mapping can be construed as "equivalence". So... Of course there are domains over which this distinction matters, but those are much less likely than a general case. They mainly matter to people implementing converters. You thus have writers stating that pulsed signals (waveforms) represent digital information, when in reality the waveform has nothing whatever to do with "analog" or "digital" information. When one takes measurements in the digital domains, one will see classes of waveforms. Ditto analog domains. -- Les Cargill |
#40
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an obsession with truth (or the facts, at least)
My marketing approach has always been "I can help you provide
better customer support and improve customer satisfaction". It has worked in only one case that I remember. SNIP Your marketing approach is probably fine. I suspect that potential employers spend a few minutes in conversation with you or in written communication with you and conclude that you are trouble with a capital T, unable to play or work effectively with others, and likely to harm the enterprise more than you might help. You suspect far too much. In many cases I have offered my services as an independent contractor who would work off site. What you don't understand is that most businesses aren't interested in high-quality documentation, and don't go running after what they (think) they don't need. Otherwise I and many other writers wouldn't be begging for work, and you and I probably wouldn't be having this discussion. When you buy a product with a lousy user manual, it's for one reason and one reason only -- the manufacturer doesn't care. |
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