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#1
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![]() Just perusing the ARRL letter on rec.radio.info and the lead story was very interesting. It's about the ARRL objecting to the use of some 70cm frequencies for a commercial event. This paragraph in particular caught my eye: "The ARRL called the Miller Motorsports Park choice of channels 'completely inappropriate. The radio amateurs who are licensed to use these frequencies are under no obligation to either tolerate interference or to cease their own operation, regardless of the interference that might be suffered at any time' by Miller Motorsports." Just goes to show how things are different in the US to here in the UK. Over here we are only secondary users of the 70cm band (the primary user of just about everything above 2m is the Ministry of Defence) and so we have to put up with anything and everything, including car alarm keyfobs on 433.92 MHz as an example. We also only get 430-440 MHz rather than your 420-450. Even in the 2m band (144-146 not 144-148 MHz..!), of which we are primary users,we cannot claim protection from interference. Ah well..! 73 Ivor G6URP |
#2
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On Sat, 03 May 2008 07:57:45 -0400, Ivor Jones wrote:
Just perusing the ARRL letter on rec.radio.info and the lead story was very interesting. It's about the ARRL objecting to the use of some 70cm frequencies for a commercial event. ..... Just goes to show how things are different in the US to here in the UK. Over here we are only secondary users of the 70cm band (the primary use r of just about everything above 2m is the Ministry of Defence) and so we have to put up with anything and everything, including car alarm keyfob s on 433.92 MHz as an example. We also only get 430-440 MHz rather than your 420-450. If I recall properly we're secondary to the military in that band as well. Indeed, 70cm repeater operators are learning that the hard way... as many repeaters are having to reduce power or even go QRT at the request of our military, to protect a radar system. But the motorsports folks have no regular authority in that band at all. I'm not sure I understand why they thought they needed amateur spectrum for that project. |
#3
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Doug Smith W9WI wrote:
If I recall properly we're secondary to the military in that [70cm] band as well. Indeed, 70cm repeater operators are learning that the hard way... as many repeaters are having to reduce power or even go QRT at the request of our military, to protect a radar system. But the motorsports folks have no regular authority in that band at all. I'm not sure I understand why they thought they needed amateur spectrum for that project. The Pave/Paws system that is pushing some repeaters off 70cm predates the complaints by several decades, and I take the military's new attitude to be another nail in the coffin of ham radio's former "favorite son" status at the Pentagon. It used to be that we hams were a corps of operators who could be pressed into service quickly during a war or other crisis. Now, with Morse as deeply buried as its creators and military electronics too secret to be entrusted to soldiers and sailors who haven't been vetted for security clearances, we're yesterday's news in the E ring. We'll have to find another reason to justify the allocations we enjoy. It's going to be hard work, and not nearly as easy as learning Morse (not that that would help now). We're going to have to get better - in fact, much better - at public relations: the Red Cross and other disaster relief agencies have known the importance of image all along, but now hams have got to get in the game and advertise ourselves as an anlternative to traditional communications during hurricanes, floods, earthquakes, etc. Of course we've had this debate before. Older hams such as I feel that we followed the program and did what was expected of us, and now I resend being pushed aside in favor of a Federal Emergency Management Agency which is, to my jaundiced eye, proficient only at promising what others will have to deliver and claiming credit for what others have done. It's a cold, cruel world, and we must get better at telling the public and the their elected officials how much we do. Bill -- Bill Horne, W1AC (Remove QRM from my address for direct replies.) |
#4
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![]() Anyone with some level of technical knowledge might wonder why a billion dollar (boondoggle) "radar system" can't discriminate between a fixed, known "target" (like a repeater)and one that is moving, comes from over the horizon which might be something nasty? Sounds like some real shoddy engineering took place at taxpayer expense. I can think of 3 or 4 ways to remove false targets w/o loosing any system level accuracy or sensitivity. In fact, didn't they perfect that during the cold war? Gee... Thinking about it some. All Abdulah (or Ivan or whoever) needs to do is buy a 440 rig, an amp and a yagi and go out as a "rover"; 3 or 4 kW ERP down the bear's craw for a while then move. Sigh.... On Sat, 3 May 2008 23:16:09 EDT, Bill Horne wrote: Doug Smith W9WI wrote: If I recall properly we're secondary to the military in that [70cm] band as well. Indeed, 70cm repeater operators are learning that the hard way... as many repeaters are having to reduce power or even go QRT at the request of our military, to protect a radar system. But the motorsports folks have no regular authority in that band at all. I'm not sure I understand why they thought they needed amateur spectrum for that project. The Pave/Paws system that is pushing some repeaters off 70cm predates the complaints by several decades, and I take the military's new attitude to be another nail in the coffin of ham radio's former "favorite son" status at the Pentagon. It used to be that we hams were a corps of operators who could be pressed into service quickly during a war or other crisis. Now, with Morse as deeply buried as its creators and military electronics too secret to be entrusted to soldiers and sailors who haven't been vetted for security clearances, we're yesterday's news in the E ring. We'll have to find another reason to justify the allocations we enjoy. It's going to be hard work, and not nearly as easy as learning Morse (not that that would help now). We're going to have to get better - in fact, much better - at public relations: the Red Cross and other disaster relief agencies have known the importance of image all along, but now hams have got to get in the game and advertise ourselves as an anlternative to traditional communications during hurricanes, floods, earthquakes, etc. Of course we've had this debate before. Older hams such as I feel that we followed the program and did what was expected of us, and now I resend being pushed aside in favor of a Federal Emergency Management Agency which is, to my jaundiced eye, proficient only at promising what others will have to deliver and claiming credit for what others have done. It's a cold, cruel world, and we must get better at telling the public and the their elected officials how much we do. Bill |
#5
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In article ,
Bill Powell wrote: Anyone with some level of technical knowledge might wonder why a billion dollar (boondoggle) "radar system" can't discriminate between a fixed, known "target" (like a repeater)and one that is moving, comes from over the horizon which might be something nasty? Sounds like some real shoddy engineering took place at taxpayer expense. I can think of 3 or 4 ways to remove false targets w/o loosing any system level accuracy or sensitivity. In fact, didn't they perfect that during the cold war? Take a look at this month's issue of CQ for a possible explanation of the problem. To sum it up briefly: PAVE PAWS is a phased-array radar system, with a large number of individual turnstile antennas on each side. During reception, the signals picked up by the various individual antennas are combined electrically/electronically, in ways which cause them to mix in-pase for signals coming from the desired direction and out-of-phase for other directions. Older-generation phased array antenna systems perform the phase shifting by switching individual phase shifters (delay lines or similar) in series with the feedlines from the individual antennas. The delayed signals are then combined and detected. If you want to point the beam in a different direction, you change all of the phase-shifter delays. The newer generation of phased-array radar systems actually digitizes the incoming signal at each antenna, and then does the linear mixing (addition/subtraction) entirely in the digital domain. Why the change? I gather that it allows for both a finer degree of control of the delays (allowing higher resolution in beam-pointing), and also allows multiple different delay-and-combine operations to be performed in parallel (just add banks of DSPs), allowing one to track multiple targets simultanously. The disadvantage of this new system (as stated in CQ): it has rather less ability to reject off-axis signals than the older delay-line method of phasing. In the delay-line system, off-axis interference would tend mix out-of-phase *before* it was detected, and would largely cancel out. In the new system, *every* individual antenna and digitizer receives the interfering signal at full strength - there's no phase cancellation in the analog domain. This would leave the newer systems at a significant disadvantage with regard to saturation and desensitization by strong off-axis signals. It's not so much a question of false targets appearing, I think, but a question of the system losing the ability to detect the real targets. The digigal method of doing phase-shifting and beamforming is faster and more precise than the switched-analog method, but apparently somewhat less robust in this regard. As Scotty said, "The more complicated they make the plumbing, the easier it is to plug up the drains." -- 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! |
#6
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Bill Powell wrote:
Anyone with some level of technical knowledge might wonder why a billion dollar (boondoggle) "radar system" can't discriminate between a fixed, known "target" (like a repeater)and one that is moving, comes from over the horizon which might be something nasty? Even weather radar can do that with drops of water. :-) -- 73, Cecil http://www.w5dxp.com |
#8
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Bill Horne wrote on Sat 3 May 2008 under the thread 'Discussions' in
RRAM: The Pave/Paws system that is pushing some repeaters off 70cm predates the complaints by several decades, and I take the military's new attitude to be another nail in the coffin of ham radio's former "favorite son" status at the Pentagon. As a veteran of the US Army Signal Corps 1952 to 1960 and as an engineer who has been involved in DoD electronics during my civilian career, I've seen NO evidence that US amateur radio was ever in some "favorite son" status in the US military. It used to be that we hams were a corps of operators who could be pressed into service quickly during a war or other crisis. Perhaps this was true in 1941. It was NOT true in 1952 when I voluntarily entered US Army service (during the Korean War active phase), trained at the Signal School at Fort Monmouth, NJ, and subsequently assigned to long-distance, high-volume message traffic handling on a 24/7 basis at a Far East Command Hq station in Tokyo. I served in that assignment for three years, had access to documents and reports on communications within the military and queried many on the (then) modern methods of communications by radio. From the military point of view of 56 years ago, having an interest in radio or the more general electronics field is only important towards assignment in a particular military occupation specialty (still familiarly called 'MOS'). Knowing on-off keying CW skills via amateur radio MIGHT get one assigned to Field Radio school (then the only Army MOS actually requiring OOK CW skill). Field Radio MOS then involved using HF from a truck-transportable station that was also equipped with teleprinters; teleprinted messaging was the norm in the Korean War (active phase '50-'53). The MAJORITY of 'radio' communications back then, a half century ago, was by VOICE and that over line-of-sight ranges. Military radio plans in the field were already organized into three overlapping radio bands from high HF into low VHF, the bands subdivided for infantry-artillery-armor unit use. No one needed any morse code skills to operate those radios then. Indeed, it was more akin to one-way talking on a telephone, something that most civilians had already done in the 1950s. Now, with Morse as deeply buried as its creators and military electronics too secret to be entrusted to soldiers and sailors who haven't been vetted for security clearances, we're yesterday's news in the E ring. I have NOT seen any of that "burial" nor of the "secrecy" alleged to any Pentagon "ring" in my Army service nor in the many years that followed as a civilian working on DoD contracts involving communications. The "secrecy" is actually on a very low Confidential level, the lowest of the three classifications. As a matter of fact, most Army radios of a half century ago where NOT used by signal personnel nor did they ever require any sort of security classification; no more so than revealing ANY military information to the enemy on anything. I have no personal knowledge of what actually transpires in ANY "ring" of the Pentagon. I must depend on periodicals and documents published by defense electronics and electronics professional associations to yield such information. In those, and in archived copies of "Signal" (a quarterly of the Army Signal Corps, available new to signal personnel) there has been NO such statements of any "favoritism" expressed from a half century ago to today. SECRECY in communications is regularly carried out today by UNvetted "soldiers and sailors" using a variety of cryptologically embedded (but selectable) means within radios. The standard small-unit (battalion or below) field radio is the SINCGARS family operating 30 to 88 MHz. The first SINCGARS went operational in 1989, almost two decades ago. Over 300,000 R/Ts basic to the AN/PRC-119 man-pack transceiver have been built by ITT, Fort Wayne, IN. More are available in HTs built by other firms plus the contracts awarded to Harris Corporation for newer, smaller SINCGARS-compatible multi- band radios. All of that family have their coding set by a "hopset" entry (encryption key and frequency-hopping sequence settings) which IS controlled by a "vetted" signal officer. The actual coding method is digital, beginning with a pseudo-random sequence generator involving digital feedback of a digital shift register could be known by an unfriendly...but the permutations of possible keys is so large that it is impractical for them to carry around super- computers in the field to defeat the cryptology in time to be effective. Note: The electronics technology to do all that has been known (and most things published about it openly) for over three decades, some of it public for four decades. In short, today's US military CAN use very robust, secure codes to allow UNvetted military personnel to communicate. They have had the capability to do so for nearly two decades. PAVE PAWS has been around for decades. It is in the technology classification using multiple receivers to decrease the antenna beam width with an ability to enhance phase shifting of the incoming wavefront (allows other processing refinements of returns). Anyone can gather information on its general technological structure. Since it IS primary in its assigned operating frequency and IS part of National Defense, that National Defense ought to be considered primary by US citizens who wish to survive. Is a radio hobby more important than national survival? We'll have to find another reason to justify the allocations we enjoy. It's going to be hard work, and not nearly as easy as learning Morse (not that that would help now). We're going to have to get better - in fact, much better - at public relations: the Red Cross and other disaster relief agencies have known the importance of image all along, but now hams have got to get in the game and advertise ourselves as an anlternative to traditional communications during hurricanes, floods, earthquakes, etc. Please leave the morse code test issue OUT. That has been settled for US amateur radio by the FCC after much, much debate for too long a time. IMAGE for the general public MUST be aimed OUTSIDE of amateur radio publications. It cannot remain the insider topic WITHIN amateur radio groups or publications. If it is REALLY there then it could (and should) get out into the mainstream. Such emergency good works news just haven't gotten out to the general public. The public sees FCC issues as they affect broadcasting and cell phones in the national news. maybe something about business radio of public safety radio. Amateur radio news is not an important issue for such media. The public has rarely seen amateur radio communications during emergencies during national news...it HAS seen various National Guard units and local government agencies doing communications on the news, including FEMA equipment (going back to 1994 and the Northridge Earthquake in January with quickly-transported video message displays relayed by satellite for their own health-and-welfare messages seen in handwriting of senders and shown on local TV). I'm not going to comment on the Katrina hurricane situation. That involves many more NON-amateur radio policies among local and state agencies. The Katrina hurricane happened over two years ago and the USA has had more emergencies since then. Rehashing the Katrina situation does NO good in attempting to get the word out to the general public about amateur radio. If ham radio is really as good as some declare it, it should be worth national attention. It has gotten very little on the national news in the last half century. QED. One thing that should NOT continue is to keep thinking in the paradigms of pre-WWII 'radio' as is often presented in amateur radio magazines. Technology has gone through several plateau jumps of advancement since that long-ago time. Fantasies of some amateur radio licensees are still rooted to back then. Those are lost in the reality of today's radio capabilites and uses. The general public has its own fantasies and it is foolish to attempt trying to tell them other fantasies. Amateur radio is a HOBBY. Let's try to focus on that. Model vehicles are a hobby for others. The Academy of Model Aeronautics doesn't pretend to advance the state of the art of aviation but it was successful in lobbying for a hundred frequency channels for radio-control two decades ago. Consider that hobbyists are citizens and that the US government does listen to its citizens. Work from that basis. Leonard H. Anderson AF6AY (Life Member) |
#9
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On Mon, 5 May 2008 11:34:06 EDT, Bert Hyman wrote:
(Bill Powell) wrote in : Sounds like some real shoddy engineering took place at taxpayer expense. I can think of 3 or 4 ways to remove false targets w/o loosing any system level accuracy or sensitivity. In fact, didn't they perfect that during the cold war? If I was trying to do real-time analysis of such weak signals with the goal of protecting the nation, I'd take advantage of every technical and legal option available to me to limit or remove the potential for interference from very strong local signal sources. Technical for sure but it appears that even technology available to the general public isn't in (effective) use. A known and fixed "target" in ANY digital processing system is very easily noted and then removed from the data stream. Legal resources? Sounds like the typical "When all else fails, blame the ham" excuse. Do you also object to the "National Radio Quiet Zone" in West Virginia? Absolutely not! And, all a ham has to do there is to coordinate in advance. They have MANY issues with RFI from non-ham sources to contend with there. Wonder if PAVEPAWS is going to start shutting down microwave ovens and wireless dog fences next? :-) Bp PS - No complaints w/ the government entity but w/ the contractor(s). |
#10
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On May 3, 11:16�pm, Bill Horne wrote:
Doug Smith W9WI wrote: If I recall properly we're secondary to the military in that [70cm] band as well. But the motorsports folks have no regular authority in that band at all. I'm not sure I understand why they thought they needed amateur spectrum for that project. � They obviously don't understand what amateur radio is all about. The Pave/Paws system that is pushing some repeaters off 70cm predates the complaints by several decades, and I take the military's new attitude to be another nail in the coffin of ham radio's former "favorite son" status at the Pentagon. Maybe - or maybe not. Secondary status means no interference need be tolerated by the primary. There used to be a 50 watt limit on 420-450 MHz for amateurs due to the possibility of interference to radar. It used to be that we hams were a corps of operators who could be pressed into service quickly during a war or other crisis. That's still the case. But it doesn't mean that the primary users of a band have to put up with interference from secondary users. Now, with Morse as deeply buried as its creators and military electronics too secret to be entrusted to soldiers and sailors who haven't been vetted for security clearances, we're yesterday's news in the E ring. I'm not sure what you mean by "Morse as deeply buried as its creators". We hams continue to use Morse Code on the air - extensively, too! MARS is running Morse Code nets again, on an experimental basis. It's true that Morse Code has all but been eliminated by the US military for its own communications uses. That's no surprise, even though Morse Code was used extensively by the US military in both World Wars, Korea, and Vietnam. But that doesn't mean hams should stop using Morse Code. We'll have to find another reason to justify the allocations we enjoy. How about these: 1) Public service communications (not just in emergencies, but for events like parades, marathons, bike races, etc.) Remember the search for Space Shuttle debris a few years back? Amateurs provided communications for at least some search groups, and it turned out to be more useful and flexible than cell phones or other radio services. 2) Education in radio and electronics. Learn-by-doing, IOW. Recently, ARRL ran a homebrew contest to design a 40 meter CW/SSB transceiver that would use less than $50 in parts. Several entries met all the requirements, and a winner was recently announced. What better way to learn radio than by building an operating a homebrew station? 3) Historical preservation. We have museums, historic districts, etc., in other areas, why not in radio? We hams have shown that old and new technologies can coexist, and an active operation is so much better than a dry nonfunctional museum display. 4) Experimentation/wilderness area. Most of the rest of the radio spectrum is channelized, digitized, and carefully planned as to its users and uses. The amateur bands are like a wilderness area, without all the central planning and channelization, where operator skill and technical knowhow can try all sorts of new and old things. And where all citizens who can pass the basic tests for a license have access to lots of spectrum, modes, and activities. It's going to be hard work, and not nearly as easy as learning Morse (not that that would help now). Morse Code is still worth learning, IMHO. We're going to have to get better - in fact, much better - at public relations: the Red Cross and other disaster relief agencies have known the importance of image all along, but now hams have got to get in the game and advertise ourselves as an anlternative to traditional communications during hurricanes, floods, earthquakes, etc. Agreed - but also as a fun thing to do. Emergency and public service comms are just one part of what hams do. The key factor is that the "served agencies" want different things today in the way of communications. In some emergencies they won't need hams at all, in others they will really need amateurs to help out. But they're the customer, as it were. 73 de Jim, N2EY |
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