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WPM to BPS calculation
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WPM to BPS calculation
On Mar 28, 4:46�pm, Klystron wrote:
(Dave Platt) wrote: I do, however, object in principle to the idea that these are the highest (or only) criteria, or that they're somehow sacred. � � �I think of them as matters of economics and practical r eality. To wit: it should be obvious that we cannot have every possible mode available on every band. Well, not every *possible* mode. Some limits must be imposed on the number of modes and the way in which they share limited bandwidth. This is one of the reasons why the FCC exists. Of course. But there are other factors, such as how popular a mode is, how much bandwidth it occupies, how it is implemented, etc. This is one of the (ostensible) reasons why digital modes were not allowed for many years. Please elaborate, particularly on the dates and where you got thise idea. The information I have seen says that the main reason FCC limited the modes amateurs could use was that FCC has to be able to monitor amateur transmissions. So if they allowed hams to use a new mode, their monitoring stations had to be able to decode it. 45.45 baud 5 level Baudot RTTY was authorized for amateurs in the USA about 1948. Analog SSTV (an image mode) followed in the very early 1960s. In the late 1970s-early 1980s, new monitoring equipment made it possible for FCC to decode lots of modes, so US amateurs were authorized to use ASCII RTTY, AMTOR, packet, and lots of other modes. We're talking 20-25 years. Of course not all modes are well-adapted to all bands. HF packet as used by amateurs turned out to be a bit of a bust, due to being ill- suited to HF propagation. PSK31, OTOH, has been a big hit. The biggest impediment to digital modes in the ARS, IMHO, is the cost of implementing them. Inexpensive PCs and "soundcard modes" have changed all that. And, I also object to the idea (which I think is implied by the tone of your other messages - please correct me if I'm wrong) that the choice of communication methods is somehow exclusive... that the fact that a method which is superior (by your criteria, perhaps) means that other methods that you find inferior should be wiped out or abandoned... or that people who prefer to use the other methods are somehow responsible for Holding Back The True Progress. My own perspective is that people may have *many* criteria for chosing a means of communication (by radio or otherwise). � Bandwidth, or bandwidth*reliability is not the sole criterion that people use, in practice, nor do I think there's any reason that it should be. � Life is full of tradeoffs between different criteria - information bandwidth per Hz of spectrum, robustness of encoding, suitability for multi-point communication, resistance to different sorts of interference, cost of equipment, availability of equipment, and so forth. �I communicate with my wife by voice, by email, by telephone, by scribbling half-illegible notes on scraps of paper, and by bringing home flowers... different methods, for different types of information- passing under varying conditions. � �Again, if you can't fit every possible mode onto a give n band (by the way, every possible mode means exactly that, not just modes that are commonly used by hams - otherwise, we would have APCO 25, in addition to DV, to give just one example). Therefore, we must prioritize; some modes will be authorized, while some other modes will be excluded. This goes back to my claim that it is a matter of economics; it represents a managed resource (a limited "supply") in the face of potentially unlimited demand. With all due respect, I think you are avoiding the question. Under current FCC rules, almost any conceivable mode can be used on the amateur bands if it is properly documented, does not involve encryption, and is reasonably spectrum-efficient. Look at how PSK31 came to amateur radio for an example. It was developed by hams, not manufacturers. It's relatively easy to implement without a big investment of special equipment, it's well- adapted to HF conditions and spectrum-efficient. Most of all, a considerable number of hams find it to be fun. It is from that perspective that I claim that old time Morse zealots are impeding progress and are attempting to arrogate to themselves a finite public good, much like cattlemen grazing their cows on public grasslands while excluding others from using those public lands for other purposes. How have "Morse zealots" done what you claim? In the US regulations, there are no Morse-code-only segments of the HF bands - all are shared with either data modes or voice modes. Every Hz. And it's been that way at least 46 years. Except for 2.5% of 6 and 2 meters, all of VHF/UHF and 160 are wide open to all authorized modes for the various bands. How are Morse-Code-using hams doing what you claim? The cows-grazing-on-public-land analogy isn't really valid, because amateur radio isn't a commercial venture, nor does the use of one mode damage the band for use by others at a later time. Try this one: The amateur bands are like a public park system. Some are small, some are large, some easily accessible, some remote. Depending on their characteristics, different parks/bands are used for different activities at different times. The question is how to best allocate the resources to accomodate those who want to use them. In commercial communications and public-safety, bandwidth (or payload) and reliability and cost all play a big factor. �In military communications, reliability and security seem big, bandwidth is important, and cost (of equipment at least) tends to take a back seat. Ham radio is a much more diverse motivation-space. �Some people optimize their operations as for public safety and commercial (the EMCOM folks), others for "most distance per watt" or "per dollar spent on the radio" (QRP folks, homebrewers, and other experimenters), others for portability, others for plain ordinary fun (according to their own definition of fun... for some folks, using single-frequency crystal-oscillator transmitters is just what gets their rocks off :-) Nice pun! There's plenty of room in ham radio for different modes of operation. Saying that we all *have* to abandon Morse (or SSB, or voice, or AM, or...) and strap computers to all of our rigs, in order to encourage experimentation and use with newer modes, is really missing the point... it's implicitly denying a large percentage of hams the right to explore those aspects of ham radio that *they* find interesting and worthwhile. That's exactly the point. Well worth repeating! If we were all being paid to do all of this stuff, then the people paying us would perhaps have the right to set our agendas. �We aren't (and by the rules of the game, cannot be... at least, not here in the US) and so we get to set our own priorities, operating-mode and otherwise. � �Considering the small, aggregate size of the HF bands, can you offer some suggestions as to how many modes can plausibly 'share the road?' That depends on the modes and their characteristics. For example, it's not a good idea to allow 30 kHz FM voice on 40 meters, because that band is only 300 kHz wide, but the same mode is fine for VHF/UHF bands. What modes must be forbidden so that the modes that you like can be allowed? If you say that there are none, then perhaps we can have APCO 25, DV and DD on HF? If they meet the criteria of not being encrypted, being suitable for HF use, and being reasonably spectrum-efficient, why not? As long as they are grouped with similar modes, what's the problem? What do you say to the hams who claim that AM shouldn't be used on HF, because it uses to much bandwidth? That depends on how "too much bandwidth" is defined. Certainly transmitting hi-fi AM that's 10-15 kHz wide on a busy HF band is spectrum-inefficient and inconsiderate. OTOH, good-quality voice AM can be had in 6 kHz or so, and when a band is not too busy, why not use it? Similar It seems odd that "Morse zealots", whose favorite mode uses only a few hundred Hz at most, are being held responsible for "impeding progress", when most of the HF amateur bandspace in the US are allocated to voice modes that take up much more spectrum. Should hams stop using Morse Code? Or any other mode they now use? 73 de Jim, N2EY |
WPM to BPS calculation
In article ,
Klystron wrote: I think of them as matters of economics and practical reality. To wit: it should be obvious that we cannot have every possible mode available on every band. We can't have all of the modes, simultaneously, with an unlimited number of users, on every band band, at the same time. Bandwidth is limited - granted. It does not follow from that, that we must be limited to a strictly-enumerated set of modes at all times. The FCC used to assert that this was the case, but has eliminated many of those constraints in favor of an approach which favors more experimentation and development. Some limits must be imposed on the number of modes and the way in which they share limited bandwidth. I agree that a policy that users of the band must share bandwidth in a reasonable and respectful way, is reasonable and proper. I do *not* agree that this necessitates that only a specific set of modes be allowed. Again, if you can't fit every possible mode onto a given band (by the way, every possible mode means exactly that, not just modes that are commonly used by hams - otherwise, we would have APCO 25, in addition to DV, to give just one example). Therefore, we must prioritize; some modes will be authorized, while some other modes will be excluded. This goes back to my claim that it is a matter of economics; it represents a managed resource (a limited "supply") in the face of potentially unlimited demand. It is from that perspective that I claim that old time Morse zealots are impeding progress and are attempting to arrogate to themselves a finite public good, much like cattlemen grazing their cows on public grasslands while excluding others from using those public lands for other purposes. The portion of the band which is restricted to CW-only by the FCC is *tiny* - small portions of the 2- and 6-meter bands, plus a portion of 80 which is CW-only for Novices and Technicians but not for anyone else. Almost all of the non-phone portions of the band are *already* open to various digital modulations (per the FCC regs and per the ARRL bandplans and gentlepersons' agreements), and are quite extensively used in that fashion today. From where I sit out here in the cheap seats, your own attitude strikes me as more zealous, and less willing to cooperate and share, than what I observe in the people I know who operate a lot of CW. Considering the small, aggregate size of the HF bands, can you offer some suggestions as to how many modes can plausibly 'share the road?' I don't think it's a question which can meaningfully be measured in "number of modes". Some modes co-exist well, others do not. I think it's a question of the number of _users_ of the band, at any given time, and the type and quality of the conversations that they can carry on. What modes must be forbidden so that the modes that you like can be allowed? Well, I tend to agree with the FCC that broad-spectrum audio (e.g. SSB with a DC-to-10-kHz bandwidth, or [worse] AM with a similar passband) is excessively wide - it's using more bandwidth than is reasonable for the conversation in question. If you say that there are none, then perhaps we can have APCO 25, DV and DD on HF? What do you say to the hams who claim that AM shouldn't be used on HF, because it uses to much bandwidth? I think there's room for AM, and that SSB is more bandwidth-efficient, and that the de facto practice of having AM operators voluntarily hang out in a sub-portion of the HF band works pretty well. I guess I just don't see why you're so intent on suppressing a mode of operation which allows quite a lot of individual operators to carry on multiple independent conversations within a limited bandwidth, at one of the lowest potential equipment costs per operator of any mode. Granted, other modes may get more *total* data traffic through the same amount of spectrum width... but these modes tend to use more spectrum width per conversation/session, and you end up with less individual users of the band at any given time. Applying a purely "economic" model to the ham spectrum (i.e. most traffic per available Hz of bandwidth) rather misses the point, I think, because it completely discounts all of the other values (personal enjoyment, learning, development of personal skills and knowledge) in ham radio. Ham radio is *NOT* a commercial service with just a single agenda. -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
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