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#121
Posted to rec.audio.tubes
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The decibel
In article ,
Eeyore wrote: John Byrns wrote: Eeyore wrote: Have you even the tiniest idea what a telegraph line looks like ? Now it is back to open wire lines again, you really seem to have a thing for open wire lines. Because it's the only type of 'phone line' that has a characteristic impedance of 600 ohms. And *I* don't have a thing for 600 ohms, *YOU* do ! You are the one that seems to be fixated on open wire lines and 600 Ohms, not me. If you go back to the beginning of the thread, you will see that the first points I made were that the impedance of "standard telephone line", a.k.a. 19 gauge toll cable, varies with frequency across the audio band. I also pointed out more than once that when being used for Hi-Fi audio transmission, this cable should be terminated in 150 Ohms not 600 Ohms. So if anything it would be more accurate to say that I have a thing for 150 Ohms. The phrase "600 Ohms" didn't cross my lips until the phantom posted a link to a web page that discussed the variation of impedance vs. frequency that I had originally brought up. As a point of interest I pointed out that the web page opened with a statement to the effect that 600 Ohm's was a good approximation to the characteristic impedance of "UTP" at 1 kHz. The phantom next posted a table of calculated impedance values vs. frequency which illustrated the variation of the characteristic impedance vs. frequency. I then pointed out that the table perfectly illustrated what I had originally said about the variation of the characteristic impedance vs. frequency of these cables, and based on the table I observed that 600 Ohms did seem to represent a good approximation to the characteristic impedance across the voice band. This was simply an observation and did not mean that I was abandoning my claim that the characteristic impedance varied greatly across the band, it simply meant that that if you were looking for an average impedance value 600 Ohms is not a bad choice. I believe that at that point I also reiterated again that for Hi-Fi audio applications the line should be terminated in 150 Ohms. I will go out on a limb here and state that 600 Ohms would probably be a better choice for terminations in telephony applications because it would produce lower attenuation in the voice band. I don't have the slightest clue how to distinguish a telegraph line from a telephone line Speaks volumes about your ignorance. The fact that you are unable to explain the difference after stating that the construction of open wire telephone lines was patterned after telegraph lines seems to say more about your ignorance than mine. If you actually had any more of a clue than I do, you would simply explain how to distinguish between the two types of line, the fact that you haven't speaks volumes. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#122
Posted to rec.audio.tubes
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The decibel
John Byrns wrote: If you go back to the beginning of the thread, you will see that the first points I made were that the impedance of "standard telephone line", a.k.a. 19 gauge toll cable, varies with frequency across the audio band. WTF is a 'toll cable'. You're making yourself impossible to understand by talking Americanese. Graham |
#123
Posted to rec.audio.tubes
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The decibel
In article ,
Eeyore wrote: John Byrns wrote: If you go back to the beginning of the thread, you will see that the first points I made were that the impedance of "standard telephone line", a.k.a. 19 gauge toll cable, varies with frequency across the audio band. WTF is a 'toll cable'. You're making yourself impossible to understand by talking Americanese. While the word Toll may not be used in connection with telephony in Anglospeak, I would be surprised if you couldn't find the meaning of the word in any good British dictionary. In any case understanding the meaning of the word toll is not necessary for a technical understanding of the operation of telephone cables. Simply delete the word toll from the phrase 19 gauge toll cable so that it reads 19 gauge cable and you should be able to easily understand. When I looked in my Telephony book for the closest match to the characteristics of Iain's standard telephone line, I found it was a cable described as 19 gauge toll cable, unfortunately I didn't know the Anglospeak word for toll, so I was unable to edit the phrase so you would be able to understand it, but for the purposes of this discussion no meaning is lost if you simply ignore the word. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#124
Posted to rec.audio.tubes
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The decibel
John Byrns wrote: Eeyore wrote: John Byrns wrote: If you go back to the beginning of the thread, you will see that the first points I made were that the impedance of "standard telephone line", a.k.a. 19 gauge toll cable, varies with frequency across the audio band. WTF is a 'toll cable'. You're making yourself impossible to understand by talking Americanese. While the word Toll may not be used in connection with telephony in Anglospeak, I would be surprised if you couldn't find the meaning of the word in any good British dictionary. A toll simply means a charge or fee. As in toll road, toll bridge etc. I failt to see how that helps and I HAVE Googled for "toll cable" and found bugger all. Are you totally incapable of explaining what you mean ? Graham |
#125
Posted to rec.audio.tubes
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The decibel
John Byrns wrote: When I looked in my Telephony book for the closest match to the characteristics of Iain's standard telephone line, I found it was a cable described as 19 gauge toll cable So what's the damn conductor spacing ? Graham |
#126
Posted to rec.audio.tubes
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The decibel
In article ,
Eeyore wrote: John Byrns wrote: Eeyore wrote: John Byrns wrote: If you go back to the beginning of the thread, you will see that the first points I made were that the impedance of "standard telephone line", a.k.a. 19 gauge toll cable, varies with frequency across the audio band. WTF is a 'toll cable'. You're making yourself impossible to understand by talking Americanese. While the word Toll may not be used in connection with telephony in Anglospeak, I would be surprised if you couldn't find the meaning of the word in any good British dictionary. A toll simply means a charge or fee. As in toll road, toll bridge etc. I failt to see how that helps and I HAVE Googled for "toll cable" and found bugger all. They say "a picture is worth a thousand words", I tried Googling "toll cable" and found a nice picture of both twisted pair and coaxial cables on the 3rd hit: http://scienceservice.si.edu/pages/005026.htm The 4th hit was a discussion of "Fault Location on 19 AWG nonloaded quadded toll telephone cable." I think the purpose of quading twisted pair cable is to facilitate implementing phantom circuits Are you totally incapable of explaining what you mean ? As I explained in the paragraph you edited out, it is not necessary to understand the meaning of the word "toll" to understand the technology of telephone cables, simply forget you ever saw the word "toll", just pretend it wasn't even there in the first place and you should be fine. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#127
Posted to rec.audio.tubes
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The decibel
In article ,
Eeyore wrote: John Byrns wrote: When I looked in my Telephony book for the closest match to the characteristics of Iain's standard telephone line, I found it was a cable described as 19 gauge toll cable So what's the damn conductor spacing ? I don't know the conductor spacing, but to be of any use you would also probably need to know the type of insulating material used and its thickness, as well as a few other construction details. More useful for our purposes are the distributed constants per loop-mile, which are as follows. R = 86.0 Ohms L = 0.001 Henry C = 0.062 uFarad G = 1.4 umhos Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#128
Posted to rec.audio.tubes
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The decibel
flipper wrote: Eeyore wrote: John Byrns wrote: If you go back to the beginning of the thread, you will see that the first points I made were that the impedance of "standard telephone line", a.k.a. 19 gauge toll cable, varies with frequency across the audio band. WTF is a 'toll cable'. Toll Cable -- Cable in which there are low capacitance quads or pairs for long distance voice frequency transmission. More searching suggests it simply means a 'long distance' cable. No mention of quads whatever. Please provide evidence of the use of quads in telephony. http://www.insulators.com/articles/openwire/ Graham |
#129
Posted to rec.audio.tubes
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The decibel
John Byrns wrote: Eeyore wrote: John Byrns wrote: When I looked in my Telephony book for the closest match to the characteristics of Iain's standard telephone line, I found it was a cable described as 19 gauge toll cable So what's the damn conductor spacing ? I don't know the conductor spacing, but to be of any use you would also probably need to know the type of insulating material used and its thickness, as well as a few other construction details. More useful for our purposes are the distributed constants per loop-mile, which are as follows. R = 86.0 Ohms L = 0.001 Henry C = 0.062 uFarad G = 1.4 umhos Per loop-mile of *WHAT* ? Graham |
#130
Posted to rec.audio.tubes
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The decibel
John Byrns wrote: Eeyore wrote: A toll simply means a charge or fee. As in toll road, toll bridge etc. I fail to see how that helps and I HAVE Googled for "toll cable" and found bugger all. They say "a picture is worth a thousand words", I tried Googling "toll cable" and found a nice picture of both twisted pair and coaxial cables on the 3rd hit: http://scienceservice.si.edu/pages/005026.htm So you want to discuss coax now do you ? Why didn't you say so ? I though you were talking about widely spaced parallel conductors or twisted pairs. Maybe you simply don't know what you're talking about ? It certainly sounds like it. Graham |
#131
Posted to rec.audio.tubes
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The decibel
flipper wrote: Eeyore wrote: http://www.insulators.com/articles/openwire/ And why, for a discussion on toll cables, are you pasting a link that specifically says "The principal types of toll or long distance wire facilities are considered separately in the following Articles" that you don't provide? It's the only article that provided any info of value I found about so-called 'toll cables'. Graham |
#132
Posted to rec.audio.tubes
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The decibel
In article ,
Eeyore wrote: flipper wrote: Eeyore wrote: http://www.insulators.com/articles/openwire/ And why, for a discussion on toll cables, are you pasting a link that specifically says "The principal types of toll or long distance wire facilities are considered separately in the following Articles" that you don't provide? It's the only article that provided any info of value I found about so-called 'toll cables'. Go to this web site: http://www.pmillett.com/tecnical_books_online.htm and download the book "Principles of Electricity Applied to Telephone and Telegraph Work, A T &T, 1953, 354 pages". This may be the book that is quoted on the "insulators.com" web site, at any rate it includes extensive information on "toll cables" as well as many other telephony related subjects. Page 167 does discuss the "standard cable mile" and indicates that it has been dropped as a unit of measurement. Page 181 mentions wire "quads" in passing, although it does not mention what they were used for. I don't know for sure, but I suspect the wire "quads" were used to maintain balance and reduce noise on "phantom" circuits. Phantom circuits are extensively discussed in the book, although mostly with respect to open wire lines. Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#133
Posted to rec.audio.tubes
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The decibel
flipper wrote: Eeyore wrote: flipper wrote: Eeyore wrote: http://www.insulators.com/articles/openwire/ And why, for a discussion on toll cables, are you pasting a link that specifically says "The principal types of toll or long distance wire facilities are considered separately in the following Articles" that you don't provide? It's the only article that provided any info of value I found about so-called 'toll cables'. Your difficulty in finding something appropriate doesn't make just whatever you find appropriate and it won't be easy to find what you seem to be looking for because direct voice on wire toll lines haven't been in general use for half a century, or more. 'Toll' lines are long distance and called 'toll' because it's been traditional to levy a per call/time used 'toll'. It's traditional to levy a charge for local calls here as well, so the name makes no sense to me. Graham |
#134
Posted to rec.audio.tubes
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The decibel
flipper wrote: To wit, the question was answered the first time someone explained it meant 'long distance' I think that only appeared in the last 24 hours. Quite how you expect me to know about a curious Americanism is beyond me. Graham |
#135
Posted to rec.audio.tubes
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The decibel
flipper wrote: Eeyore wrote: It's traditional to levy a charge for local calls here as well, Bummer. I'm glad I don't have a phone line over there. OTOH, our national long distance calls cost no more than a local one these days ! And many telecom providers have a cheap package that bundles 'free' calls at certain times of the day/week or even 24/7. I can call the USA (an international call) and most of the 'developed world' international destinations for no more than a couple of pence a minute. Beat that ! Graham |
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