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Paul W. Schleck " wrote:
Klystron writes: It still seems like an awfully slow data rate. I have seen people throw 14400 Baud modems in the garbage because they considered them to be so slow as to be worthless. A data rate of 42 bps is about 3 orders of magnitude slower than that. Many types of communications vary over many orders of magnitude of information rate, yet are considered useful and up-to-date. For example, the Casio WaveCeptor on my wrist: http://www.eham.net/reviews/detail/2497 receives a ~ 1 Baud Pulse Position Modulated (PPM) signal from radio station WWVB in Fort Collins, Colorado, which transmits on 60 kHz. It takes about a minute to send the complete time code to synchronize my watch. Slow? Yes. Useful? Yes, very much so, especially when considering the coverage and reliability that can be obtained from such a low-bandwidth, groundwave-propagated, Very Low Frequency (VLF) signal. [...] In your model, only a single axis of data is transmitted - the time of day. That seems like a great deal of infrastructure and energy consumption to transmit a single data quantity. The equivalent infrastructure for weather transmission (marine and air) is even more elaborate and expensive. Can you see that is an outrageously inefficient way to distribute a small quantity of information? One of the most current and widely used communications technologies among young people is cellular telephone text messaging: http://en.wikipedia.org/wiki/Text_messaging (sometimes also called "Short Messaging System" or SMS) According to this recent demonstration on the Tonight Show with Jay Leno: http://www.youtube.com/watch?v=AhsSgcsTMd4 the realizable data rates are comparable in order of magnitude to that of fast Morse code that can be sent and received by human operators. Just try telling a teenager with an SMS-capable cellular telephone that it should be thrown in the trash because it isn't fast enough, or isn't of sufficiently novel technology, and see his or her reaction. My understanding is that they use SMS for fairly trivial communications, like what they will have for lunch or where they will meet at the mall. A rough equivalence might be SMS users objecting to the use of the SMS system by people who are sitting at full-size computers or by people who have connected keyboards to their phone. If they were to complain that "typing" pidgin English (like "HOW R U?") with your thumbs on a tiny telephone keypad was the one true way to use SMS, then I think I could agree that there was an equivalence. You might ask those kids why they also use conventional e-mail, despite having SMS availability. To give you an amateur radio example, the Automated Position Reporting System (APRS): http://www.aprs.org uses 1200 Baud AFSK packet. Faster, but still an order of magnitude slower than technologies you imply should be thrown out. [...] Again, it is for the exchange of a single axis of data - geographic location. Please stop tying to pass off these single purpose, dedicated systems as examples of general purpose communications. To even give you a Morse code example, consider the simplicity and effectiveness of the NCDXF beacons running on the HF bands: http://www.ncdxf.org/beacons.html My understanding is that Morse-based beacon identifications are read by computerized devices and are not "copied" by the pilots. I doubt that you could find very many current pilots who could copy any Morse at all. [...] There are even a number of excellent software packages linked from the NCDXF site above that could automatically monitor the signals, decode the Morse, and record the quality of the communications paths over time. One such package is Faros: http://www.dxatlas.com/Faros/ one of many advanced signal processing software packages for amateur radio that exploits the ubiquitousness of of inexpensive personal computers with sound cards in most home ham "shacks." There is nothing about that that is unique to Morse. Any type of RF link would be usable in that way. Focusing simply on information rate disregards other aspects of the communications and the channel over which it is transmitted. These important aspects include the bandwidth and propagation characteristics of the available channel, the complexity of the required transmitting and receiving equipment, the amount of data that needs to be transmitted, and how quickly and often it needs to be conveyed. Single-attribute measuring contests may be fun, even ego-boosting to some, but are really not very useful or impressive to those who actually design and use practical communications systems. It just seems inconsistent with the way that so many hams have fought tooth and nail to hold onto Morse and to hinder the move toward digital modes. I'm not sure that I understand your line of reasoning here. You are implying cause-and-effect. In other words, use and advocacy of Morse code somehow directly contributed to the obstruction of other technologies. Can you give direct evidence of specific examples? Hams used to deride digital communications as "pulse" and tell tales about the way that it squandered bandwidth. They made it out to be something along the lines of spark-gap. Look for articles about "pulse" communications in old (1960's and 70's) issues of QST and Popular Electronics. Considering the lead time needed to develop a new mode, I think it is unreasonable not to go back at least that far. I believe that the anti-digital curmudgeons delayed the implementation of digital modes by a matter of decades. It is interesting to note that the most widely used digital modes (for 2-way radio, not for broadcast) were developed either in Japan (Icom/JARL DV) or under the auspices of a police organization that has no ties to radio, except as consumers (APCO 25). [...] Furthermore, if the only technologies that you believe should be saved from being thrown away are those at 14.4 kBaud and up, Can you point to something in my post that makes such a claim? The only technology that I have derided as being too slow as to have value is Morse code that is sent by hand (less than 100 baud). The Navy shut down its VLF network on the grounds that the data rate was inadequate. Perhaps it is time for the amateur community to take a similar step. those technologies are only practically realizable on amateur radio bands at high VHF and up. Such bands have been open to licensees without need of a Morse code test for going on 17 years now. Even before then, these bands were accessible to Technician-class amateurs since at least shortly after World War II, with a license that only required a minimal, 5 WPM (essentially individual character-recognition) Morse code test. If you are saying that someone *else* should have developed these technologies (other than you, of course), and that since they haven't, then someone *must* be to blame, well, you can't really dictate how the world should turn out without taking an active role to help make it that way. That last paragraph is incoherent. Could you rephrase it? -- Klystron |
#12
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On Mar 23, 2:33�pm, Klystron wrote:
�Paul W. Schleck " wrote: For example, the Casio WaveCeptor on my wrist: http://www.eham.net/reviews/detail/2497 receives a ~ 1 Baud Pulse Position Modulated (PPM) signal from radio station WWVB in Fort Collins, Colorado, which transmits on 60 kHz. �It takes about a minute to send the complete time code to synchronize my watch. �Slow? �Yes. �Useful? �Yes, very much so, especially when considering the coverage and reliability that can be obtained from such a low-bandwidth, groundwave-propagated, Very Low Frequency (VLF) signal. In your model, only a single axis of data is transmitted - the time of day. That seems like a great deal of infrastructure and energy consumption to transmit a single data quantity. Actually, it's a very small infrastructure, and very efficient. I've been there, btw. The time standard info is already present at the WWVB transmitter site, so that's no cost. All that's necessary is a system to encode it, and the WWVB transmitter and antenna. While an impressive installation by amateur radio standards, the WWVB transmitter is not overly large for the wavelength. But WWVB's 60 kHz signal serves large numbers of clocks of many types all over North America - by radio. It keeps them all synchronized via radio, without any user intervention. What alternative technology would do the same job with less infrastructure and energy consumption? The equivalent infrastructure for weather transmission (marine and air) is even more elaborate and expensive. Of course. But it's also very important from a safety standpoint. Can you see that is an outrageously inefficient way to distribute a small quantity of information? What alternative technology would do the same job with greater efficiency? One of the most current and widely used communications technologies among young people Not just "young people". A lot us find text messaging very useful. is cellular telephone text messaging: http://en.wikipedia.org/wiki/Text_messaging (sometimes also called "Short Messaging System" or SMS) According to this recent demonstration on the Tonight Show with Jay Leno: http://www.youtube.com/watch?v=AhsSgcsTMd4 the realizable data rates are comparable in order of magnitude to th at of fast Morse code that can be sent and received by human operators. The facts are even more telling. In that Leno clip, the text messager is the Guinness-book world-record-holder. The Morse Code ops are a couple of hams who were going less than 30 wpm - which is less than 40% of the world-record Morse Code speed. The text messager was allowed to use common text-message abbreviations, while the Morse Code ops just sent the straight text with no abbreviations at all. The Morse Code ops also produced a hard-copy in real time. IMHO, what was most telling was that the audience was sure the text messager would win. But a much older technology proved to be faster. Just try telling a teenager with an SMS-capable cellular telephone that it should be thrown in the trash because it isn't fast enough, or isn't of sufficiently novel technology, and see his or her reaction. The answer will be that it's fast enough for what it's used for. Isn't that the ultimate test of any technology - that it's good enough for what it's used for? My understanding is that they use SMS for fairly trivial communications, like what they will have for lunch or where they will meet at the mall. I can say for a fact that's not true. While a lot of text - and cell phone - communications is trivial, much is not. For example, something as simple as a meeting place or time can be critical information. A rough equivalence might be SMS users objecting to the use of the SMS system by people who are sitting at full-size computers or by people who have connected keyboards to their phone. Actually the system can be used that way, in that a message generated by a cell can be delivered as an email, and the reverse. The point is that speed isn't the only criterion. To give you an amateur radio example, the Automated Position Reporti ng System (APRS): http://www.aprs.org uses 1200 Baud AFSK packet. �Faster, but still an order of magni tude slower than technologies you imply should be thrown out. � �Again, it is for the exchange of a single axis of data - geographic location. Please stop tying to pass off these single purpose, dedicated systems as examples of general purpose communications. No one is trying to do that. The point being made is that speed is not the only criterion. What is meant by "general purpose communications"? My computer allows internet access, email and some other things, but I still have POTS and a cell phone. TV and radio come to my house over the air. I'm not sure that I understand your line of reasoning here. �You are implying cause-and-effect. �In other words, use and advocacy of Morse code somehow directly contributed to the obstruction of other technologies. �Can you give direct evidence of specific examples? Hams used to deride digital communications as "pulse" and tell tales about the way that it squandered bandwidth. I don't know any hams who used the term "pulse" to refer to digital communications. Nor have I heard tales about squandered bandwidth. However, note that not all digital signals are designed with bandwidth efficiency as the primary consideration. For example, classic 850 Hz shift 45.45 baud RTTY uses almost a kHz of band to transmit about the same info (actually less) as PSK31 which uses maybe 50 Hz. They made it out to be something along the lines of spark-gap. If you mean spark, I have not seen that comparison anywhere. Could you provide a specific reference? Look for articles about "pulse" communications in old (1960's and 70's) issues of QST and Popular Electronics. I have all the QSTs back to the mid-1920s, and have read all of them. I do not recall any comparison of digital modes to "pulse" in any of them. Could you provide a specific reference? I do recall some QST articles back in the 1950s *advocating* pulse modes for use at microwave frequencies. The idea was that rather than trying to adapt lower frequency narrow band techniques to the microwave bands, broadband/radar techniques would be used for communications. Considering the lead time needed to develop a new mode, I think it is unreasonable not to go back at least that far. PSK31 was developed in a few years by G3PLX and a small group of hams around the world. Lots of other examples. I believe that the anti-digital curmudgeons delayed the implementation of digital modes by a matter of decades. How was this done? The main impediments to the implementation of digital modes by amateurs (at least in the USA) were two: 1) Restrictive regulations, brought about mostly by the FCC's need to be able to monitor amateur transmissions. However, note that digital transmissions other than digital voice are not allowed in the US HF 'phone subbands - which comprise the majority of the bandwidth on those bands. Those rules force the digital data modes to share only with Morse Code users. 2) The high cost of hardware. Only a decade ago, a PC was a significant investment compared to a ham rig. It is interesting to note that the most widely used digital modes (for 2-way radio, not for broadcast) were developed either in Japan (Icom/JARL DV) or under the auspices of a police organization that has no ties to radio, except as consumers (APCO 25). They were developed for specific applications, though. Not for general purpose use. Furthermore, if the only technologies that you believe should be saved from being thrown away are those at 14.4 kBaud and up, Can you point to something in my post that makes such a claim? The statement about throwing 14400 modems in the garbage. The only technology that I have derided as being too slow as to have value is Morse code that is sent by hand (less than 100 baud). PSK31 and most HF RTTY are also less than 100 baud. Are they too slow to have value? The Navy shut down its VLF network on the grounds that the data rate was inadequate. But amateur radio isn't the US Navy. IIRC, the purpose of that network was/is to communicate one-way to submerged missile submarines. Perhaps it is time for the amateur community to take a similar step. What form would that step take? Should amateurs simply not *use* Morse Code any more? The *test* for the mode was an issue of great contention among radio amateurs. But until July 2003 the ITU-R treaty prevented complete elimination of the *test*. However, as far back as 1990 it was possible to get any US amateur radio license with just a basic 5 wpm Morse Code test and a doctor's note. Since April 2000, no doctor's note has been needed, and since Feb 2007 no Morse Code test at all. How any of this has impeded the development or implementation of digital modes is unclear to me. those technologies are only practically realizable on amateur radio bands at high VHF and up. �Such bands have been open to licensees without need of a Morse code test for going on 17 years now. �Even before then, these bands were accessible to Technician-class amateurs since at least shortly after World War II, with a license that only required a minimal, 5 WPM (essentially individual character-recognition) Morse code test. The Technician class license was created in 1951. Its Morse Code test was always 5 wpm, until it was dropped completely in 1991. IOW, as has been pointed out, practically all of the US amateur bands above 30 MHz have been available for the development and implementation of digital modes by amateurs, with no need for any Morse Code test. Lots of bandwidth, too - all those bands except 222-225 are wider than all the HF/MF amateur bands combined. 73 de Jim, N2EY |
#13
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-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1 In Klystron writes: Paul W. Schleck " wrote: Klystron writes: It still seems like an awfully slow data rate. I have seen people throw 14400 Baud modems in the garbage because they considered them to be so slow as to be worthless. A data rate of 42 bps is about 3 orders of magnitude slower than that. Many types of communications vary over many orders of magnitude of information rate, yet are considered useful and up-to-date. For example, the Casio WaveCeptor on my wrist: http://www.eham.net/reviews/detail/2497 receives a ~ 1 Baud Pulse Position Modulated (PPM) signal from radio station WWVB in Fort Collins, Colorado, which transmits on 60 kHz. It takes about a minute to send the complete time code to synchronize my watch. Slow? Yes. Useful? Yes, very much so, especially when considering the coverage and reliability that can be obtained from such a low-bandwidth, groundwave-propagated, Very Low Frequency (VLF) signal. [...] In your model, only a single axis of data is transmitted - the time of day. That seems like a great deal of infrastructure and energy consumption to transmit a single data quantity. The equivalent infrastructure for weather transmission (marine and air) is even more elaborate and expensive. Can you see that is an outrageously inefficient way to distribute a small quantity of information? Transmitting 50 kilowatts from a single site capable of covering most of North America, using groundwave propagation, independent of solar activity, is an "outrageously inefficient way to distribute a small quantity of information?" Well, I do hope that you are hurrying to write your Congressman to demand that the National Institute of Standards and Technology put an immediate end to this grave outrage, and profound waste of taxpayer's money that has been going on for decades. After all, what does the NIST know about technology, or useful communications? Perhaps as little as the engineers and marketers in the economically successful and useful product field of WWVB watches and clocks, in your estimation. One of the most current and widely used communications technologies among young people is cellular telephone text messaging: http://en.wikipedia.org/wiki/Text_messaging (sometimes also called "Short Messaging System" or SMS) According to this recent demonstration on the Tonight Show with Jay Leno: http://www.youtube.com/watch?v=AhsSgcsTMd4 the realizable data rates are comparable in order of magnitude to that of fast Morse code that can be sent and received by human operators. Just try telling a teenager with an SMS-capable cellular telephone that it should be thrown in the trash because it isn't fast enough, or isn't of sufficiently novel technology, and see his or her reaction. My understanding is that they use SMS for fairly trivial communications, like what they will have for lunch or where they will meet at the mall. A rough equivalence might be SMS users objecting to the use of the SMS system by people who are sitting at full-size computers or by people who have connected keyboards to their phone. If they were to complain that "typing" pidgin English (like "HOW R U?") with your thumbs on a tiny telephone keypad was the one true way to use SMS, then I think I could agree that there was an equivalence. You might ask those kids why they also use conventional e-mail, despite having SMS availability. I think you are underestimating the power of SMS. As for the comparison to E-mail, I don't have to ask, as journalists have already done so, including this recent article from Slate: http://www.slate.com/id/2177969/pagenum/all/ Simply put, young people find appeal in the immediacy of small, but low-latency messages sent in relatively large numbers over a long period of time, and the information transmitted is far more rich and meaningful that what you imply above. In many respects, this type of communication is not stilted or limited, but almost provides the immediacy of a conversation, without having to run up your voice minute charges or leave your other callers unable to reach you due to the long-term busy signal. Young people do still use E-mail, but in circumstances for which it is the better choice. They are not seeking some overall best "general purpose communications" to get their messages across to each other. To give you an amateur radio example, the Automated Position Reporting System (APRS): http://www.aprs.org uses 1200 Baud AFSK packet. Faster, but still an order of magnitude slower than technologies you imply should be thrown out. [...] Again, it is for the exchange of a single axis of data - geographic location. Please stop tying to pass off these single purpose, dedicated systems as examples of general purpose communications. I didn't realize that only "general purpose communications" were considered worthwhile. Your previous reply argued that it was undesirable to use such a low-speed technology as Morse code given that there were many higher-speed alternatives (faster by "orders of magnitude" you said). I replied to you that fastest is not always best. Other issues (previously enumerated by me) might actually dictate the choice of lower-speed communications as the best choice. I also don't see "general purpose communications" mentioned in Part 97. Many "single purpose, dedicated systems" are used by amateurs, and help fulfill amateur radio's Basis and Purpose. In many cases, a "single purpose" technology is far more useful than a misfit, one-size-fits-all, "general purpose" one. Before we make too many assumptions about an undefined term, perhaps you can describe what types of "general purpose communications" you would consider to be worthy goals for the Amateur Radio Service, and which "single purpose" technologies you would like to see eliminated? Would you also kindly define what is a "single axis of data," in terms familiar to those involved in communications engineering and technology? What, then, would be "multiple axes of data?" To even give you a Morse code example, consider the simplicity and effectiveness of the NCDXF beacons running on the HF bands: http://www.ncdxf.org/beacons.html My understanding is that Morse-based beacon identifications are read by computerized devices and are not "copied" by the pilots. I doubt that you could find very many current pilots who could copy any Morse at all. So, in other words, you are actually agreeing with my previous reply to you that there are many useful Morse code based communications technologies that do not actually require memorized, in-head, copy of Morse code. I'm glad that we agree on something. [...] There are even a number of excellent software packages linked from the NCDXF site above that could automatically monitor the signals, decode the Morse, and record the quality of the communications paths over time. One such package is Faros: http://www.dxatlas.com/Faros/ one of many advanced signal processing software packages for amateur radio that exploits the ubiquitousness of of inexpensive personal computers with sound cards in most home ham "shacks." There is nothing about that that is unique to Morse. Any type of RF link would be usable in that way. Yes. That is somehow a point of disagreement between us? In what way? I did acknowledge that you could re-engineer the NCDXF beacon system with one that uses, say, PSK31, but the bandwidth and data rate limits would still remain. A PC with a soundcard would still be usable for that system, as you note. I'm sure that the author of Faros could also quickly adapt, and make a PSK31 version of his NCDXF beacon recording software package. Focusing simply on information rate disregards other aspects of the communications and the channel over which it is transmitted. These important aspects include the bandwidth and propagation characteristics of the available channel, the complexity of the required transmitting and receiving equipment, the amount of data that needs to be transmitted, and how quickly and often it needs to be conveyed. Single-attribute measuring contests may be fun, even ego-boosting to some, but are really not very useful or impressive to those who actually design and use practical communications systems. It just seems inconsistent with the way that so many hams have fought tooth and nail to hold onto Morse and to hinder the move toward digital modes. I'm not sure that I understand your line of reasoning here. You are implying cause-and-effect. In other words, use and advocacy of Morse code somehow directly contributed to the obstruction of other technologies. Can you give direct evidence of specific examples? Hams used to deride digital communications as "pulse" and tell tales about the way that it squandered bandwidth. They made it out to be something along the lines of spark-gap. Look for articles about "pulse" communications in old (1960's and 70's) issues of QST and Popular Electronics. Considering the lead time needed to develop a new mode, I think it is unreasonable not to go back at least that far. I believe that the anti-digital curmudgeons delayed the implementation of digital modes by a matter of decades. It is interesting to note that the most widely used digital modes (for 2-way radio, not for broadcast) were developed either in Japan (Icom/JARL DV) or under the auspices of a police organization that has no ties to radio, except as consumers (APCO 25). Wow, these curmudgeons must have been very powerful and effective in their obstructionism if they undermined entire areas of communications technology development in this country over the last 30-40 years. I didn't realize that our national technology infrastructure was so inflexible and lethargic that it could not recover from these influences, even after so many decades. [...] Furthermore, if the only technologies that you believe should be saved from being thrown away are those at 14.4 kBaud and up, Can you point to something in my post that makes such a claim? Just the introduction to your previous article, where you directly compare the Baud rate of Morse code with that of "obsolete" telephone modems. You stated that their data rates differed by "orders of magnitude," implying that communications technologies that were "orders of magnitude" slower than telephone modems could be dismissed as obsolete. Following the natural extension of that argument, then the only technologies that could be favorably compared to such telephone modems, and meet your argued standard of non-obsolete, could only be realized on high VHF and up. As I argued previously, use and advocacy of Morse code has no bearing on the current deployment of such technologies, as no Morse code test has been required to access them for at least 17 years. The Technician-class license has existed for far longer, and has only a minimal Morse code examination. The only technology that I have derided as being too slow as to have value is Morse code that is sent by hand (less than 100 baud). So, to summarize: slow-speed (less than 100 baud) PSK31 : "Good" similar order-of-magnitude speed Morse code: "Bad" So, it's not the speed you object to, it's the use of Morse code? Couldn't you have just stated that, and not gone to the trouble of bringing in other arguments like speed and bandwidth, or whether a communications technology is sufficiently "general purpose" or not, regardless of whether something "general purpose" would be the best choice in a given circumstance? Just say that you don't like Morse code. Others would at least give you credit for honesty. The Navy shut down its VLF network on the grounds that the data rate was inadequate. Perhaps it is time for the amateur community to take a similar step. References please? A Google search returns no evidence that Navy stations like NAA in Cutler, Maine have gone off-line. Are you possibly thinking of their ELF experiments that were recently ended? Even if so, what competing technology is the Navy contemplating that will reliably contact our submarine fleet that has "gone deep" under many fathoms of RF-attenuating sea water? I also didn't realize that amateur radio had similar "networks" that would need to be shut down. those technologies are only practically realizable on amateur radio bands at high VHF and up. Such bands have been open to licensees without need of a Morse code test for going on 17 years now. Even before then, these bands were accessible to Technician-class amateurs since at least shortly after World War II, with a license that only required a minimal, 5 WPM (essentially individual character-recognition) Morse code test. If you are saying that someone *else* should have developed these technologies (other than you, of course), and that since they haven't, then someone *must* be to blame, well, you can't really dictate how the world should turn out without taking an active role to help make it that way. That last paragraph is incoherent. Could you rephrase it? Looked pretty coherent to me, but for your benefit, I'll dissect it in detail: "If you are saying that someone *else* should have developed these technologies ..." In other words, amateur radio has failed to meet some standard of technology development. Other people were somehow "wasting" their time doing other things. "... (other than you, of course) ..." What have you done to make amateur radio a better place? Have you written your Congressman? Petitioned the FCC? Worked in the communications engineering and technology field? Developed amateur radio software and hardware solutions? You seem to be knowledgeable on many technical subjects, including the history of that technology over many decades. Did you try to change things, or are you asserting that you did not have the skills or abilities to help do so, even working with others over many decades? "... and since they haven't, then someone *must* be blamed, ..." I was implying that you were seeking scapegoats, as it is easier to blame others than look in the mirror. "... well, you can't really dictate how the world should turn out without taking an active role to help make it that way." In other words, Lead, Follow, or Get Out of the Way. "Sidewalk Superintendents" have very little influence on society. What is your choice? Also, some people seem to confuse actual solutions to problems (whether in amateur radio, or on the newsgroups) with a contest over who can become the most "outraged." To quote Jim Kelley, AC6XG: "Outrage, and a buck-fifty, will get us exactly what?" -- Klystron - -- 73, Paul W. Schleck, K3FU http://www.novia.net/~pschleck/ Finger for PGP Public Key -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (SunOS) iD8DBQFH5r/66Pj0az779o4RAnicAJ9csNsCmha8ssxAArkza8p3pxwIhACfZ v4O BXSruHeICy8G0AOT+mCOhPo= =tMJk -----END PGP SIGNATURE----- |
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#15
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Paul W. Schleck " wrote:
Transmitting 50 kilowatts from a single site capable of covering most of North America, using groundwave propagation, independent of solar activity, is an "outrageously inefficient way to distribute a small quantity of information?" Well, I do hope that you are hurrying to write your Congressman to demand that the National Institute of Standards and Technology put an immediate end to this grave outrage, and profound waste of taxpayer's money that has been going on for decades. After all, what does the NIST know about technology, or useful communications? Perhaps as little as the engineers and marketers in the economically successful and useful product field of WWVB watches and clocks, in your estimation. Wouldn't it make more sense to include WWV and WWVH along with WWVB? Are you familiar with the Internet-based ntp system? Then, there is the matter of GPS, which has a time capability that is incidental to its navigation function. [...] I think you are underestimating the power of SMS. As for the comparison to E-mail, I don't have to ask, as journalists have already done so, including this recent article from Slate: http://www.slate.com/id/2177969/pagenum/all/ Simply put, young people find appeal in the immediacy of small, but low-latency messages sent in relatively large numbers over a long period of time, and the information transmitted is far more rich and meaningful that what you imply above. In many respects, this type of communication is not stilted or limited, but almost provides the immediacy of a conversation, without having to run up your voice minute charges or leave your other callers unable to reach you due to the long-term busy signal. Young people do still use E-mail, but in circumstances for which it is the better choice. They are not seeking some overall best "general purpose communications" to get their messages across to each other. I don't see anything in that that contradicts my statement that SMS is mainly used for messages of little importance. It is also called CMS, for casual messaging service. I didn't realize that only "general purpose communications" were considered worthwhile. A multi-purpose system that can match a single-purpose system on the performance of the objectives of the single-purpose system is generally, if not universally, considered superior. Your previous reply argued that it was undesirable to use such a low-speed technology as Morse code given that there were many higher-speed alternatives (faster by "orders of magnitude" you said). I replied to you that fastest is not always best. Other issues (previously enumerated by me) might actually dictate the choice of lower-speed communications as the best choice. I also don't see "general purpose communications" mentioned in Part 97. Many "single purpose, dedicated systems" are used by amateurs, and help fulfill amateur radio's Basis and Purpose. In many cases, a "single purpose" technology is far more useful than a misfit, one-size-fits-all, "general purpose" one. Before we make too many assumptions about an undefined term, perhaps you can describe what types of "general purpose communications" you would consider to be worthy goals for the Amateur Radio Service, and which "single purpose" technologies you would like to see eliminated? Why do you want me to reinvent the wheel? Lets go to the source (condensed from Part 97.1): * emergency communications * contribute to the advancement of the radio art * advancing skills in both the communication and technical phases of the art * expansion of the existing reservoir within the amateur radio service of trained operators, technicians, and electronics experts * continuation and extension of the amateurs unique ability to enhance international goodwill Would you also kindly define what is a "single axis of data," in terms familiar to those involved in communications engineering and technology? A single quantity, like time or location What, then, would be "multiple axes of data?" Two or more simultaneous quantities, like time AND location or course AND speed. So, in other words, you are actually agreeing with my previous reply to you that there are many useful Morse code based communications technologies that do not actually require memorized, in-head, copy of Morse code. I'm glad that we agree on something. There is probably no purpose for which Morse can be used as a machine language where there isn't a choice of other, better suited languages available. This includes aeronautical beacons. You are grasping at straws, now. Wow, these curmudgeons must have been very powerful and effective in their obstructionism if they undermined entire areas of communications technology development in this country over the last 30-40 years. I didn't realize that our national technology infrastructure was so inflexible and lethargic that it could not recover from these influences, even after so many decades. When you look at the development of the Internet, Linux and other free software, you have to wonder about the infrastructure behind it. How did it come about? There was no regulatory body. There were no licenses. There were no "Elmers." Until recently, there wasn't even any formal schooling available, except on the sort of machinery that existed only within the Fortune 500. Early Internet users and developers had to read O'Reilly books and figure it out on their own. That showed great initiative. It demonstrated the sort of determined, driven advancement of technology that was once seen in amateur radio. But that sort of thing has passed ham radio by. It has been a long time since ham radio was a source of innovation. I blame the Morse cultists who hijacked amateur radio for use as their personal playground. Just the introduction to your previous article, where you directly compare the Baud rate of Morse code with that of "obsolete" telephone modems. You stated that their data rates differed by "orders of magnitude," implying that communications technologies that were "orders of magnitude" slower than telephone modems could be dismissed as obsolete. An amusing interpretation. It follows that trains and ships should be discarded because they are much slower than airplanes. Following the natural extension of that argument, then the only technologies that could be favorably compared to such telephone modems, and meet your argued standard of non-obsolete, could only be realized on high VHF and up. As I argued previously, use and advocacy of Morse code has no bearing on the current deployment of such technologies, as no Morse code test has been required to access them for at least 17 years. The Technician-class license has existed for far longer, and has only a minimal Morse code examination. You left out the faster mode of communication known as "voice." It is widely used on HF. Further, I once looked at a band plan that showed how DV could be used on HF. They described a system of HF DV that took up just slightly more bandwidth than SSB and substantially less than AM. So, to summarize: slow-speed (less than 100 baud) PSK31 : "Good" similar order-of-magnitude speed Morse code: "Bad" So, it's not the speed you object to, it's the use of Morse code? Couldn't you have just stated that, and not gone to the trouble of bringing in other arguments like speed and bandwidth, or whether a communications technology is sufficiently "general purpose" or not, regardless of whether something "general purpose" would be the best choice in a given circumstance? Just say that you don't like Morse code. Others would at least give you credit for honesty. Who are these "others" and when did they appoint you as their spokesman? References please? A Google search returns no evidence that Navy stations like NAA in Cutler, Maine have gone off-line. Are you possibly thinking of their ELF experiments that were recently ended? Even if so, what competing technology is the Navy contemplating that will reliably contact our submarine fleet that has "gone deep" under many fathoms of RF-attenuating sea water? I am thinking of the site in the Upper Peninsula of Michigan and the increased reliance on TACAMO aircraft (at the time of the shutdown). I also didn't realize that amateur radio had similar "networks" that would need to be shut down. The infrastructure that is being wasted on Morse includes band segments that have, until recently, been reserved for its exclusive use. I am very glad to see that almost all CW segments now allow data modes (50-50.1 and 144-144.1 being the only exceptions). There is also the inclusion of keyer provisions in HF radios. It will be interesting to see what the marketplace does to code tapes and code keys. I don't think they will last long. While Morse supporters often point to treaties, the fact is that the US was one of the last countries to abandon the Morse requirement for an HF license. Other countries began dropping that requirement many years earlier, while still claiming to be in compliance with their treaty obligations. How do you explain that? To me, it sounds like the FCC used the treaties as a pretext to keep the code requirement in order to placate the ARRL and the Morse zealots. Looked pretty coherent to me, but for your benefit, I'll dissect it in detail: "If you are saying that someone *else* should have developed these technologies ..." In other words, amateur radio has failed to meet some standard of technology development. Other people were somehow "wasting" their time doing other things. "... (other than you, of course) ..." What have you done to make amateur radio a better place? Have you written your Congressman? Petitioned the FCC? Worked in the communications engineering and technology field? Developed amateur radio software and hardware solutions? You seem to be knowledgeable on many technical subjects, including the history of that technology over many decades. Did you try to change things, or are you asserting that you did not have the skills or abilities to help do so, even working with others over many decades? I have worked in the electronics industry. I have made my views clear to any and all who had an interest in the subject. I made those views as clear then as I have done in this newsgroup. "... and since they haven't, then someone *must* be blamed, ..." I was implying that you were seeking scapegoats, as it is easier to blame others than look in the mirror. "... well, you can't really dictate how the world should turn out without taking an active role to help make it that way." In other words, Lead, Follow, or Get Out of the Way. "Sidewalk Superintendents" have very little influence on society. What is your choice? Also, some people seem to confuse actual solutions to problems (whether in amateur radio, or on the newsgroups) with a contest over who can become the most "outraged." To quote Jim Kelley, AC6XG: "Outrage, and a buck-fifty, will get us exactly what?" -- Klystron |
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Paul W. Schleck posted on Sun, 23 Mar 2008 12:03:58 EDT:
Many types of communications vary over many orders of magnitude of information rate, yet are considered useful and up-to-date. For example, the Casio WaveCeptor on my wrist: http://www.eham.net/reviews/detail/2497 receives a ~ 1 Baud Pulse Position Modulated (PPM) signal from radio station WWVB in Fort Collins, Colorado, which transmits on 60 kHz. It takes about a minute to send the complete time code to synchronize my watch. Slow? Yes. Useful? Yes, very much so, especially when considering the coverage and reliability that can be obtained from such a low-bandwidth, groundwave-propagated, Very Low Frequency (VLF) signal. The watch only needs to receive the time code at most once per day, which it does so automatically in the early hours of the morning sitting on my desk or dresser. A faster data rate would require something other than a VLF signal, and would not improve much on the quality or usability of the communications. It would definitely increase the price. Witness the much greater success in the marketplace of WWVB-based watches versus more advanced, higher bandwidth, but much more expensive, "Smart Personal Object Technology" (SPOT) watches: Good mention, Paul. Ummm...the data rate is rather exactly one bit per second and takes exactly 60 seconds to send one frame of time and date data. :-) ALL the details are given at www.nist.gov under the 'Time Frequency' page, including propagation charts at various times of the day and for various seasons. This southern California region can regularly receive enough signal to set radio clocks even if at an approximate distance of about 900 miles to Fort Collins. In 2005 my wife and I drove to southern Wisconsin and my La Crosse radio wris****ch never failed to set itself properly even though some of our overnight stays were in hotels having steel structures or in among other buildings. We have two radio wall clocks in our residence and those are exact enough to compare on-the-second with HF time ticks from WWV and WWVH. [I won't quibble about the PPM mode descriptor since the full details of modulation are given at NIST website... :-) ] According to this recent demonstration on the Tonight Show with Jay Leno: http://www.youtube.com/watch?v=AhsSgcsTMd4 Ahem...quibble mode on...that little bit on the Tonight Show was a 'setup' gig that employed two young local male actors as the (described) "text messaging experts" but the two hams (one of which would very soon become marketing director for Heil Sound) were real. That is the input I got directly from a reliable staffer on the Tonight Show. Took a few phone calls to get that information but it is an advantage of living inside the entertainment capital of the USA (aka Los Angeles, CA)...and the NBC western Hq is only about 5 miles south of my place, down Hollywood Way to Alameda and then east about a mile. That whole bit was really a send-up on the popular fad of text messaging done by teeners and young adults. That bit is about as 'real documentary' as Leno's send-ups on the 'street interviews' with ordinary (apparently clueless) younger folk on various kinds of knowledge. In short, ONLY for gag purposes. To even give you a Morse code example, consider the simplicity and effectiveness of the NCDXF beacons running on the HF bands: http://www.ncdxf.org/beacons.html HF beacons are neat for their purposes of checking on HF propagation paths, but they aren't 'communications' in the regular sense. Those were also designed for simplicity at the various receiving sites but require rather precise time-of-day at each receiver in order to get the start of each cycle. While I had not intended to restart some morse-vs-others kind of argument, I have to note where I began HF communications with the US military some 55 years ago. Not a single communications circuit used any form of morse coding to achieve a throughput of nearly a quarter of a million messages per month (average in 1955). The majority was teleprinter of the 5-level 'Baudot' format running at 60 WPM equivalent rates. 24/7 of course with TTY distributors to to automatically start another p-tape reader when the other reader was done. FSK 'spread' was then 850 cycles, not the narrower 170 Hz of today. Radio circuits (where I was assigned) spanned the northern Pacific from Saigon, Seoul, and Manila to Anchorage, Seattle, San Francisco, and Hawaii. In 1955 the Army tried an experiment on a few select radio circuits to push the Teletype Corporation's machines to 75 WPM equivalent. End result of that was a failure rate more than double that of the standard 60 WPM equivalent machines. Teletype seems to have achieved an optimized design for 60 WPM equivalent; their 100 WPM equivalent next-generation machines used a different electromechanical system, were quite reliable at that rate. very fast determination of the link budget to the beacon locations. If you can't remember what a "V" sounds like in Morse Code (". . . _" like the intro to Beethoven's Fifth Symphony), I suppose you could put that on the chart as well. After all, the use of similar charts are how pilots usually decode the Morse code identifications of aeronautical beacons. Quibble mode on again. The LF aeronautical beacoms are what you are writing about but they are NOT used much at all for aircraft radio- navigation now, nor were they a half century ago. Present-day (and in 1962) radionavigation over land is done mainly by VOR (Very high frequency Omnidirectional Radio range) using a unique 30 Hz antenna pattern rotation with a reference phase of 30 Hz sent on a 9.96 KHz subcarrier. Aircraft VOR receivers have used very simple (even for tube circuits) to determine their bearing to a ground station. These were simple enough (and low cost enough) for small private general aviation craft and the US VOR system was adopted internationally in 1955. For distance to a ground station the civil method emplyed a low L-band interrogator sending a (jittered) double pulse and measuring the return delay (plus 50 uSec) from the ground station responder. This DME (Distance Measuring Equipment) was compatible with military TACAN (TACtical Area Navigation) signal format and the FAA combined VOR-DME-TACAN equipments on the ground and those are identified by the contraction VORTAC. On aeronautical charts (from the government, usually reprinted by private companies) there is usually a magnetic bearing compass circle (VOR and civil-use-TACAN reference magnetic reference, not actual north reference)...the VHF frequencies (DME and TACAN frequencies have been paired with VOR), ICAO 3-letter ID, and the dot-dash pattern of that 3-letter ID. The elegant simplicity of VOR is that it will permit AM Voice IN the ground station transmitter without disturbing the antenna pattern modulation or the reference phase subcarrier. In congested urban areas where a lot of general aviation aircraft abound, FAA stations routinely use VOR voice transmissions to aid civil pilots, easing the pilots' workload by providing extra information such as WX, special conditions at an airport. My local airport (BUR) now known as Bob Hope Airport, the FAA used to send a repeating voice announcement of local WX conditions, airport info, etc., all identified by a letter, beginning with A or Alpha at midnight. The tag on the voice tape loop was "please tell the tower you have received 'information Foxtrot or whatever letter'" when requesting landing at that airport. Yes, some VORs transmit the ICAO 3-letter ID as a low-modulation on-off tone in slow morse but I have yet to find any civil pilot, beginner to experienced, who USES that code for radionavigation. Focusing simply on information rate disregards other aspects of the communications and the channel over which it is transmitted. These important aspects include the bandwidth and propagation characteristics of the available channel, the complexity of the required transmitting and receiving equipment, the amount of data that needs to be transmitted, and how quickly and often it needs to be conveyed. Martinez' PSK31 was rather precisely designed for low (500 Hz) bandwidth coincident with non-typists typing rate of about 30 WPM equivalent, all in congested Data slices of amateur radio band 'bandplans' on HF. With relatively simple electronic terminal equipment with microprocessor-aided operation, I/O memory space and programming is a minor addition to handle faster typists' input, even burst typing on a keyboard to 100 WPM or so equivalent. The OLD FSK bandwidths on HF (of a half century ago) took up about a whole KHz while using an 850 cycle shift. On the 3 KHz of an old commercial-format SSB channel (one of four), as many as 8 separate TTY circuits could be frequency-multiplexed. A more reasonable shift (to 170 Hz) occurred later with improvements in terminal equipment technology, is the norm now, even for 100 WPM equivalent teleprinter rates of those still using electromechanical terminals. BANDWIDTH occupancy seems to be the primary driver for modulation rates on HF. YMMV. There are more complex methods of modulation-demodulation that have been available for some time. DRM (Digital Radio Mondial) is one such as has been verified on HF for 'SW BC' (Broadcasting). That DRM has not spread well among broadcasters has little to do with technical details of modulation-demodulation, but rather in the poor propagation conditions of this sunspot cycle limiting broadcasters' range. If a signal can't get through at all, NO modulation method is going to help. Besides, with the availability of satellite radio broadcasting, 'SW BC' has gradually shifted over to that method rather than using HF directly. I'm not sure that I understand your line of reasoning here. You are implying cause-and-effect. In other words, use and advocacy of Morse code somehow directly contributed to the obstruction of other technologies. Can you give direct evidence of specific examples? If you are implying that licensing requirements obstructed the development of advanced digital modes, that really doesn't appear to be the case. Witness the success of Tucson Amateur Packet Radio (TAPR): It is disingenuous to 'force' an argument by introduction of something not overtly stated by the originator. TAPR and its membership have done some excellent technical development and spread of such technology. Note also that its membership is made up of radio amateurs who've been licensed for a while and are NOT technical beginners in radio or electronics. In the view of the ENTIRE world of radio, not just amateur radio, the use of morse code modes to communicate has steadily decreased for over a half century. It has decreased so much so that some non- amateur radio services either stopped using that mode or never considered it for a new radio service introduced in the last half century. As a prime example, the changeover to GMDSS and replacement of the old 500 KHz international distress and safety frequency which used morse code exclusively. Even the USCG stopped monitoring that old 500 KHz frequency. GMDSS was designed and approved by the Maritime Community, not by amateurs. The decline, or perhaps more accurately, the failure to keep up with overall population increase (of USA) amateur licensees is (in my opinion) NOT due exclusively to 'USE' of morse code. US amateur radio license totals peaked 5 years ago. In general, by informal polling, newcomers are NOT embracing morse code modes...nor are they flocking to HF amateur bands. PART of that MAY be due to the insistence of the 'amateur radio community' to hang onto the morse code TEST forever. Part of that is due to the slow acceptance of international amateur radio to change the international amateur Radio Regulations away from old standards. WRC-03 of nearly 5 years ago allowed individual administrations to drop the morse code test for an amateur radio license. The USA did not follow through on that until more than 3 years later. [precisely, the end of July 2003 to 23 February 2007] [in response to 'Klystron'] If you are saying that someone *else* should have developed these technologies (other than you, of course), and that since they haven't, then someone *must* be to blame, well, you can't really dictate how the world should turn out without taking an active role to help make it that way. That's rather strong wording from a leading person of this newsgroup, isn't it? For a very long while, ever since I first began as a pro in HF radio communications, PART of the 'amateur radio community' had been very busy 'dictating' how the amateur radio world should be by the continuation of the morse code test for an amateur radio license. OTHERS, including those of us (like myself) who were NOT licensed in amateur radio have actively campaigned to remove that test from US amateur radio...even though other countries had already preceded the USA in abolishing that code test. I won't say that I've 'been responsible' for any USA changes but I was certainly 'active' in trying to do so. The FCC apparently agreed with some of my views as well as so many others supporting that test elimination. It came to pass. But, that coming might have been too late to change others' interests in US amateur radio. In my electronics work that began (professionally) in 1952, I've been involved in a lot of different electronics and modes and modulations of RF that were never allocated for US amateur radio use. Some of those just wouldn't apply to two-way communications but others would apply. There are still some US regulations that need altering but a very vocal PART of the 'amateur radio community' seems very adamant about NOT upsetting the status quo. The future of US amateur radio does NOT depend solely on them. 73, Len AF6AY First licensed in US amateur radio in March 2007 First licensed in US commercial radio in March 1956 First QSY of a 1 KW HF transmitter in February 1953 |
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On Sun, 23 Mar 2008 22:53:54 EDT, Klystron wrote:
Wouldn't it make more sense to include WWV and WWVH along with WWVB? Are you familiar with the Internet-based ntp system? Then, there is the matter of GPS, which has a time capability that is incidental to its navigation function. Want some fun? Compare the time ticks received from WWVB, WWV, NIST-on-line, and GPS. What, they are not all simultaneous? Welcome to the real world. GPS time does not correlate with UTC by any means (several seconds difference). In one of the first digital military command and control system that I was involved in during the early 1960s, we used rubidium standards at our switching centers to get accurate time synchronization, and even then it was rather crude because the line delays varied so much. HF propagation (WWV/WWVH) is even worse in that regard. -- 73 de K2ASP - Phil Kane From a Clearing in the Silicon Forest Beaverton (Washington County) Oregon e-mail: k2asp [at] arrl [dot] net |
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On Sun, 23 Mar 2008 22:54:34 EDT, AF6AY wrote:
As a prime example, the changeover to GMDSS and replacement of the old 500 KHz international distress and safety frequency which used morse code exclusively. Even the USCG stopped monitoring that old 500 KHz frequency. GMDSS was designed and approved by the Maritime Community, not by amateurs. As those of us who had our ears to the hull, so to speak, know very well, the main reason was to get rid of "Sparks the Radio Operator" who was a very large expense for the traffic that was being handled by non-Morse methods. Some could be retrained as service technicians, many could not and took retirement. Be aware, though, that there are still several Public Coast Stations in the US that are capable and do handle Morse traffic, and twice a year the USCG fires up its Morse stations. It's not all dead. -- 73 de K2ASP - Phil Kane From a Clearing in the Silicon Forest Beaverton (Washington County) Oregon e-mail: k2asp [at] arrl [dot] net |
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On Mar 23, 8:29�pm, Phil Kane wrote:
On Sun, 23 Mar 2008 22:53:54 EDT, Klystron wrote: � Wouldn't it make more sense to include WWV and WWVH along with WWVB? Are you familiar with the Internet-based ntp system? Then, there is the matter of GPS, which has a time capability that is incidental to its navigation function. Want some fun? �Compare the time ticks received from �WWVB , WWV, NIST-on-line, and GPS. �What, they are not all simultaneous? ï ¿½Welcome to the real world. �GPS time does not correlate with UTC by any me ans (several seconds difference). In one of the first digital military command and control system that I was involved in during the early 1960s, we used rubidium standards at our switching centers to get accurate time synchronization, and even then it was rather crude because the line delays varied so much. � HF propagation (WWV/WWVH) is even worse in that regard. I've compared each of our three radio-set clocks at this residence (in Los Angeles) and find excellent correlation between their one-second changes and both WWV and WWVH. Don't have any GPS receiver to try the same. In 1960, while working in the Standards Lab of Ramo-Wooldridge Corp. in Canoga Park, CA, I got to pull some OT on Saturdays to measure the difference between east coast transmissions of WWV and the local General Radio frequency standard. Just a plain old quartz crystal standard oscillator driving divider chains to the built-in clock. I would record the microseconds of difference between local clock ticks and WWV ticks from the east coast. Not much variation in a week's time, don't remember just how much (it was 48 years ago). Yes, propagation on HF does vary but it is sometimes exaggerated. Before R-W went into a business tailspin, the Standards Lab was ready to get a low-frequency HP receiver for 20 KHz to improve on establishing a local, secondary frequency standard. No joy on that corporation which was eventually sold off. All I ever got to see was the 'diurnal shift' of 20 KHz phase recordings at sunrise and sunset. :-) 73, Len AF6AY |
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Jim Haynes posted on Tue, 18 Mar 2008 19:47:44 EDT:
Bill Horne wrote: I'm sure your explanation is correct, but it leaves me confused: I know bps baud, but they're close, and the Model 15 Teletype I used to own operated at 45 baud. It seems illogical that Morse would be so high in the bps count. Your Model 15 Teletype at the nominal 60 wpm speed, which is actually 368 chars/minute and 45.45 baud works out like this. The character length is 7.42 bits long (for ancient, interesting reasons I won't go into right now) and the bit duration is 22 milliseconds. The character duration is therefore 7.42 * 22 = 163.24 milliseconds, and that works out to 6.12595 characters/sec = 367.55 characters/minute. To convert that to words you have to figure 6 characters per word because the space between words is also a character. So the speed is actually 61.26 words/minute. For what it is worth, my paper reference on TTYs is NAVSHIPS 0967-255-0010 "Principles of Telegraphy (Teletypewriter)" from Department of the Navy Electronic Systems Command. I bought it from the US Government Printing Office back in the early 1970s as a reference. [I am an Army veteran, not Navy] The first chapter of Part A in that TM has a nice historical record of 'telegraphy' (which includes teletypewriting). It says only "60 WPM" but mentions other Baud rates. As far as we in Army communications of the mid-1950s were concerned, all the teletypewriters that the Army used were called "60 WPM" and only the teletypewriter maintenance people (and a few carrier systems types) cared about many numbers. We did have Distortion meters used to determine irregularities in a circuit. BTW, the Army and the rest of the military used Teletype Corporation Model 15s through 19s, variation being only the paper tape punch and transmitting distributor (P-tape reader). Now when you get to ASCII, the old Teletype machines transmitted 8 data bits per character and used an 11.0 unit code. This makes 100 wpm work out to 110 baud. Electronic terminals don't need 11 unit code; they can do just fine with 10. Thus the words-per-minute is numerically equal to the baud rate. 100 baud - 10 ms/bit - 100 ms/char - 10 chars/sec - 600 chars/min - 100 wpm. OK on that. Teletype Corporation Model 28s (explained in intimate detail in the NAVSHIPS TM I referenced) would easily do 100 WPM equivalent 24/7 as long as supplied with paper, ribbon, and oil. :-) ...word PARIS contains 50 bit times counting the space. So one word per second is 50 bits per second and 60 wpm. As an aside, the military sends a lot of encrypted 5-letter code groups, so instead of PARIS the Signal Corps uses CODEZ as a test word more statistically correct for their kind of traffic. And CODEZ contains 60 bits. I never encountered any test word 'CODEZ' 1953 to 1956, nor elsewhere in the Signal Corps or in DoD contracts after that. In the mid-50s we simply used a continuous 'R-Y' generator (from Teletype Corporation) for circuit checks with the old 60 WPM equivalent machines. Teletype Corp. also made a 'fox test' generator consisting of a half dozen cams operating as many switches to generate "The quick brown fox jumped..." sentence (with Tx station ID at the end) for radio circuit checks. Electromechanical teletypewriters are now rather passe' in the military and government (I use a French word to replace Obsolete which so many have trouble with). It is all electronic and, for permanent installations, over the DSN (Digital Switched Network) anywhere...including interfaces with the regular civilian telephone infrastructure. The DSN allows encryption on-line as per protocol. For field radios, the electronic data protocols are compatible with hard-wired ones and also allow encryption on-line. It was so in the first Gulf War (1990-1991) which 'battle tested' the whole military communications network DX to no-DX via TDRS (Tracking and Data Relay Satellites) and other military commsats from/to Florida to/from the Middle East. Not having any access to the DSN or intimate details of military cryptographic equipment now, I have no exact knowledge of what is used for a test word, sentence, or whatever. For the OLD electro- mechanical teleprinters, I'd say the specifications for a specific TTY Distortion Meter would tell the exact story on timing for both polar and non-polar TTY circuits and equipment. 73, Len AF6AY |
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