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#11
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On Sat, 3 May 2008 16:25:37 EDT, Doug Smith W9WI
wrote: 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. Because they probably bought cheap amateur equipment, opened it out, and then found out that there weren't any channels available in the 450-470 MHz band that they could get licenses and frequency coordination for. Several sports events did just that until they got caught. One of my "day jobs" is as frequency coordinator for systems in the 450 MHz band, and we run into this all the time. The Congress refuses to give the FCC the necessary funding to apprehend them, and the Justice Department refuses to prosecute what they claim is petty offenses. I've ranted about this before. I'm glad that Chris Imlay (ARRL General Counsel) got on this thing as hard as he did. We all owe a round of thanks to him. -- 73 de K2ASP - Phil Kane ARRL Volunteer Counsel email: k2asp [at] arrl [dot] net |
#12
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#13
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On May 6, 5:12 am, "Ivor Jones" wrote:
, typed, for some strange, unexplained reason: : Secondary status means no interference need be : tolerated by the primary. I should have been more clear, and qualfied the above as "here in the USA" Not always, we're the primary users of 2m over here, but we can't complain about interference. : There used to be a 50 watt limit on 420-450 MHz for amateurs due to : the possibility of interference to radar. Don't recall we ever had that over here, but I may be wrong. It was a US restriction a long time ago. : : 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. Ah, but who is the primary user..? Here it's the military. Amateurs have to put up with anything and everything. On all bands. Well, here in the USA amateurs are definitely the secondary users of 420-450 MHz. So while we can complain, we don't have the same "standing", as it were. 73 de Jim, N2EY |
#14
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On May 4, 11:13 pm, 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? I think the radar system can indeed discriminate. One problem, I think, may be this: Radar that uses a single antenna for both transmit and receive cannot "see behind" a reflecting obstacle, nor an interfering RF source. So the amateur repeater casts a "shadow" as it were. To make it more of a sporting course, the amateur signal is intermittent, and FM. Which may look like all kinds of things on the radar display. Sounds like some real shoddy engineering took place at taxpayer expense. Maybe, but probably not. Some things are fundamental limitations of the physics involved. 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? Of course the processing system may be able to be programmed to ignore the amateur repeater - which would make it the perfect place to hide something. Remember that the radar system in question is probably being used in roles it was not originally designed for. That's probably why the problem didn't show up before. For example, if the radar was meant to look for high-altitude intruders, things like ground clutter and RF sources below a few hundred feet could simply be ignored. If the system is now being adapted to look for low-altitude and water-bourne intruders, those RF sources become a big headache that the system wasn't designed to handle. 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. Maybe. But the result would probably be just the opposite: firing up that setup would announce his exact bearing and altitude. IOW, announcing "HERE I AM" to the radar system. With no legitimate sources of RF in the area, and no "shadows" to hide behind, finding the intruder would be easier and faster. This sort of thing isn't new. When you don't know the exact threat, you try to plug every possible hole. Way back in WW2, the Allies spent a lot of time and expense developing receivers that had extremely low local-oscillator radiation. Only approved receivers could be used aboard Allied vessels. The concern was that enemy U-boats could detect and find Allied convoys by listening for the local-oscillator radiation. When you have dozens of ships all monitoring the same frequency using big antennas and unshielded receivers, the total LO radiation could be heard a long way off. And while radio silence could be maintained in a convoy most of the time, the receivers were needed for weather reports, U-boat warnings, distress calls and such. It turned out that the U-boats did not listen for the LO radiation after all. But this was not known until after the war. 73 de Jim, N2EY |
#15
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#16
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#17
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On May 5, 8:04Â pm, wrote:
On May 3, 11:16�pm, Bill Horne wrote: 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. Incorrect. Amateur radio operating protocol is nothing like what is used in the US military. That "case" might have been valid prior to WWII but that time period was 67 and more years ago. 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". I would suggest you borrow a 'communications receiver' that can tune in the HF spectrum OTHER than amateur radio band allocations. For one thing, the US military had all but abandoned morse code mode before 1953 for any mass-volume messaging connecting North America to military bases around the rest of the world. For another thing, the US military has abandoned HF for any mass- volume messaging and now uses secure military communications satellites, troposcatter, and the DSN (Digital Switched Network) for 24/7 communications. DSN has very robust security and is the major system of 'flash' alerts to land bases. Alerts for submarines (to listen to HF thru microwaves for the main message) are slow-speed encrypted data at VLF that can be received while submerged. The US military still keeps HF radios on a standby basis but only uses them for periodic operational checks. MARS is not a part of the daily US military messaging routine, although it is much closer to the use of operations protocol than amateurs. We hams continue to use Morse Code on the air - extensively, too! Please define "extensively" (with or without exclamation mark). No one has stated or implied that amateur use of morse code was not "extensive." In an unofficial poll at the ARRL website some time ago, #1 communications mode on amateur bands was voice. MARS is running Morse Code nets again, on an experimental basis. Military Affiliate Radio System mission was changed about five years ago to act in accord with other US government agencies to (ostensibly) link them together. Army MARS Hq is at Fort Huachuca, AZ, the same military base that houses the Army Military Intelligence training facilities. It's true that Morse Code has all but been eliminated by the US military for its own communications uses. That is not true. For routine tactical or strategic communications the US military has abandoned morse code. The M.I. school at Fort Huachuca still trains some in morse code signal intercept analysis but that is NOT communications per se. To attempt stating that SIGINT operations "use morse code" is like saying the Army still uses muskets and Revolutionary War uniforms because one Army unit in Washington, DC, has them for ceremonial duties. That's no surprise, even though Morse Code was used extensively by the US military in both World Wars, Korea, and Vietnam. Morse code was used "extensively" in World War ONE. In that 1914 to 1918 period voice communications was relegated to wireline communications circuits. Teleprinter circuits had already been established before the US entry into WWII, including its use on USN ships (see the 'SIGABA' descriptions on various websites for online encryption capability over teleprinter as early as 1940). As a soldier during and just after the Korean War, doing mass- volume communications via HF, I can assure you that morse code was NOT used for such communications about logistics or military planning plus (in a secondary basis) broadcasting news and 'health and welfare' messages carried for the Red Cross and other agencies to military members. The vast majority of communications carried on during the recognized active period of US involvement in Vietnam was voice and teleprinter. Like the Korean War, the Vietnam War was not a 'true' war yet service members were killed or wounded as a part of that actual warfare. During the prosecution of the Korean War, the US military routinely handled about a quarter million messages a month through military facilities. That was nearly doubled for the Vietnam War. Morse code communications MIGHT have been used in rare instances for both wars but its role was so minor as to be discounted compared to the MASS of messaging needed to maintain troops and equipment far from the USA. All of that military communications information is public and available to anyone who cares to look for it. I would suggest the U.S. Army Center For Military History as a starting point for very detailed historical accounts of the US Army since the Revolutionary War. But that doesn't mean hams should stop using Morse Code. NOBODY has said "hams should stop using" it. Please try to restrain generating another sub-thread about it. Please try to educate yourself about radio uses outside of amateur radio as described other than the ARRL publications or website. In order to EDUCATE THE PUBLIC, I would suggest channeling your promotion OUTSIDE of amateur radio venues. The general public and lawmakers don't much look into ham radio venues. AF6AY |
#18
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#19
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On May 6, 12:54�am, Bill Horne wrote:
AF6AY wrote: 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. The ham who gave me my novice exam, WA1BGR (SK), had a 10 KW generator in his backyard that he received from Air Force surplus via MARS. Not your $2,000.00 toilet seat, to be sure, but certainly a step up from the equipment available to the average ham, especially in 1964 New Hampshire, where power failures were a regular event. Would you be more comfortable if I said "poor relation" instead? In 2004 electric power failures in western Washington state were a regular event. All rural homes in Kitsap County, WA, have fireplaces and stacks of wood outside for that...despite electric power rates there being among the lowest in the USA. The fact is that equipment and expertise flowed from the military to the hams who were willing to work for it. That couldn't have happened by accident, and I don't believe it was an accident that ham allocations in shortwave bands survived during the era before geostationary satellites, when there was pressure from other governments and from corporate users here to carve out larger portions for broadcasting or commercial use. 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. � Welcome Home. There is no need for sarcasm. I returned to the States in 1956. The active phase of the Korean War stopped in June of 1953. ['truce talks' continue to this day in Korea along the DMZ] The Vietnam War ended for the USA 35 years ago. I would reply to more of your message but Google doesn't like it or something. AF6AY |
#20
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In ,
AF6AY typed, for some strange, unexplained reason: : On May 5, 8:04 pm, wrote: : On May 3, 11:16�pm, Bill Horne wrote: : : 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. : : Incorrect. Amateur radio operating protocol is nothing like what : is used in the US military. [snip] Well, I seem to have sparked quite a debate..! However, a lot of it seems to have gone more than a little OT (which doesn't surprise me and is actually quite interesting, so don't consider it a moan..!) But.. what are the thoughts on my original point, that of the differences in attitude of the authorities in the US and UK about protection from interference from commercial operators using frequencies within the amateur bands..? It seems to me, unless I've misunderstood, that in the US you can still claim a certain degree of protection from other users, whereas here we can't. 73 Ivor G6URP |
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