Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!seismo!rutgers!ames!sdcsvax!ucbvax!SIMTEL20.ARPA!W8SDZ From: W8SDZ@SIMTEL20.ARPA (Keith Petersen) Newsgroups: comp.dcom.modems Subject: Public Digital Radio Service wireless modem proposal Message-ID: Date: Tue, 11-Aug-87 23:02:00 EDT Article-I.D.: SIMTEL20.KPETERSEN.12325781935.BABYL Posted: Tue Aug 11 23:02:00 1987 Date-Received: Fri, 14-Aug-87 00:36:59 EDT Sender: daemon@ucbvax.BERKELEY.EDU Distribution: world Organization: The ARPA Internet Lines: 109 The following files was just uploaded to my BBS. I am NOT the author. Replies to the author, not me, please. --Keith Petersen Arpa: W8SDZ@SIMTEL20.ARPA Uucp: {bellcore,decwrl,harvard,lll-crg,ucbvax,uw-beaver}!simtel20.arpa!w8sdz GEnie: W8SDZ RCP/M Royal Oak: 313-759-6569 - 300, 1200, 2400 (V.22bis) or 9600 (USR HST) --cut-here--PDRS-ANS.TXT--cut-here-- Mr. Decker's comments on amateur radio need some commentary by someone who knows more about it than he evidently does. First, he is totally inaccurate and misleading about the dissimilarity between ham radio and computer 'hobbying.' Both involve electronics, mathematics, and an interest in transferring and processing data. The dissimilarity between stamp collecting and travel is not a good analogy and tends to lead to a false conclusion. Moreover, Mr. Decker seems to feel that ham radio is a single, homogeneous activity. It isn't. It actually involves dozens of 'sub-hobbies', of which talking to people in foreign countries via radio-telegraphy is only one, and a small one at that. Other areas include VHF/UHF/microwave use of ham satellites, one of which (now under development) will have a radio BBS built in. One of the most esoteric sub-hobbies in ham radio is two-way communication on VHF/UHF by means of signals bounced off the moon. So, lumping all hams into one "boring" pigeon hole isn't accurate, let alone fair. One sub-hobby of widespread popularity involves relaying messages through an organized network of stations. This networking concept is going through a metamorphosis as a result of the introduction of computer technology. Networking, of course, is what we are talking about with radio modems. Hence, attracting computerists into ham radio is a 'natural' which will benefit everyone. Mr. Decker made the point that hams need to learn electronic theory. He feels that this is an unnecessary imposition on computerists. I disagree. Anyone engaged in any activity involving any type of sophisticated hardware will benefit from knowing how that hardware does its thing. Hams shook their heads in disbelief when they saw CB'ers being ripped off by false advertising claims of people selling various types of CB equipment. For example, those twin antennas on trucks are worthless unless they are separated by at least one half of one wavelength at the operating frequency (18 feet on the Citizens' Band). Another rip-off is the 'power mike'. Almost all of the additional power output they produce is in the form of distortion products which actually degrade communications intelligibility. If CB'ers had known some theory, they would have spotted the lies. To be even more pointed about the value of electronic theory being useful to computer hobbyists, Mr. Decker would never have made his suggestion about putting radio modems on 160-190 khz if he had had the slightest notion of the mathematics and physics of communication. If radio modems are to be of any practical use for more than one pair of terminals every 40 miles, they must use very high data rates. (56,000 data bits per second as a minimum.) This, of course, means wideband radio transmission. At 1750 meters, even the simplest antenna acts as a very sharp tuned filter which prevents wideband transmission. (That's why the subs must use radio-telegraphy!) Moreover, putting radio modems on 1750 meters will produce a VOCIFEROUS outburst from the electric power industry, which uses that frequency range for carrier current remote control of transmission lines and substations. The solution is to go UP in frequency. 900 mhz is being suggested as the best place to put PDRS. Mr. Decker suggested extending range by using digital repeaters. Hams have found that in practice using more than two such links in a row tends to bog down, although the newer NETROM modification to the conventional TAPR TNC software seems to be a big help in linking. Mr. Decker stated that the American Radio Relay League opposed the original PDRS proposal by Don Stoner (who's a ham, by the way) without explaining that they opposed it because 52-54 megahertz is half of the amateur 6 meter band. If you leave that part of it out, it makes the ARRL opposition sound mindlessly obstructive. Mr. Decker's comments on the inappropriateness of ham radio as a solution for computer hobbyists is based in part on a lack of knowledge of some of the reform and revitalization movements within ham radio. Pressure to end the Morse requirement is growing even among hams. Also, some influential people within the FCC are beginning to say publicly that some of the restrictions now put on hams (particularly the ones on message content) are unrealistic and unreasonable. Mr. Decker says that technical development is needed and acknowledges his own lack of expertise in that area. And yet he is trying to tell his constituency to pursue their interest in isolation from the very group who 'invented' packet radio and who are still leading in developing its potential -- radio hams. Mr. Decker suggested that Part 15 tinkering would show the FCC that PDRS is needed. The FCC already knows that; the only doubt is what's the best way to go about it. Finally, do not misunderstand my motives in writing this. I am not saying that there ought not be a PDRS separate from ham radio. I can see a lot of benefits from an independent PDRS. I am saying only that computer hobbyists should not reject the option of pursuing ham radio as a medium for radio modeming solely on the basis of erroneous statements made by someone who obviously doesn't know whereof he speaks. If you (and he) want to learn more from an authoritative source, try the Bald Hill Tech Center BBS, 1-516-736-2208. It is run by Norm Sternberg, W2JUP, who, among other things, writes the technical manuals for the AEA TNC's. Another good source of information is the HamNet SIG on CompuServe, which is used as a coordinating medium by several of the leading minds in the field. /s/ Jim Grubs, W8GRT 6817 Maplewood Ave. Sylvania, Ohio 43560 GEMail address: W8GRT Friday, August 7, 1987.