Running with GPS just got better.
Question:
Actually, if a military situation dictated the need, you’d better believe they’d turn it off. That’s the reason SA was supposedly implemented – to prevent other "powers" from using the technology against us for pinpoint accuracy in targeting. If the situation arose, I’d sure as hell hope they’d jam or turn SA back on. Mike Tennent "IronPenguin" Ironman Canada ‘98 16:17:03 Great Floridian ‘99, 17:13:38
I understand that a military situation caused SA to be turned off during the Gulf War. There were not enough military receivers and civilian units were purchased. I never understood why one branch of the government had SA while the Coast Guard broadcast DGPS signals to improve the accuracy of GPS. Palmer
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My guess is an atom bomb really doses’t have to be dropped to within three or four feet accuracy. Of course I’m not an expert…..
When people talk about measuring "position" on the surface of the earth to an accuracy of 1 meter, 1 foot, 1 inch, …, there must surely come a point where the notion of position to such an accuracy becomes meaningless. The earth is not a rigid body. Its moment of inertia varies constantly due to tidal effects, tectonics, atmosphere dynamics, etc. This, in turn, causes the axis to wander on a scale of meters. So when we say we have measured a position accurate to x meters, what is that position measured relative to? Is everything referred to some mean position of the axis and mean location of the earth’s surface? Any experts on surveying or geodesy out there? — Terry R. McConnell Mathematics/304B Carnegie/Syracuse, N.Y. 13244-1150
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Actually, if a military situation dictated the need, you’d better believe they’d turn it off. That’s the reason SA was supposedly implemented – to prevent other "powers" from using the technology against us for pinpoint accuracy in targeting. If the situation arose, I’d sure as hell hope they’d jam or turn SA back on.
Mike, What you say is true but the idea that turning the SA on provides some protection, does not make much sense to me. The idea behind the DGPS system was to provide more accurate positioning data in confined waters of US ports, rivers, and near coastal areas. All the intruders need to do is buy a DGPS capable reciever and then they get far better accuracy than GPS with the SA turned off. Jim
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Do you have inside info from the GPS JPO, work with DoD on GPS issues, etc or are you just speculating? Julius SA is not turned off for good. DoD can re-activate SA if necessary. They can, but they won’t. First of all, they wouldn’t have turned it off unless they had other alternatives such as local jamming. Secondly,
Actually, if a military situation dictated the need, you’d better believe they’d turn it off. That’s the reason SA was supposedly implemented – to prevent other "powers" from using the technology against us for pinpoint accuracy in targeting. If the situation arose, I’d sure as hell hope they’d jam or turn SA back on. Mike Tennent "IronPenguin" Ironman Canada ‘98 16:17:03 Great Floridian ‘99, 17:13:38
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Besides, it would make Bill look like an idiot. Does he care? Ivo
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Do you have inside info from the GPS JPO, work with DoD on GPS issues, etc or are you just speculating? Julius – Hide quoted text — Show quoted text – SA is not turned off for good. DoD can re-activate SA if necessary. They can, but they won’t. First of all, they wouldn’t have turned it off unless they had other alternatives such as local jamming. Secondly,
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OTOH no more miles in the kitchen just looking at the thing. Palmer
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Where does one find these devices? Are they comfortable to wear? Features to look for??? Thanks for the info, — Andrew Hall (Now reading Usenet in rec.running…)
I have a Garmin 12XL which I carry in my hand. Wal-mart, REI, EMS and Cabela’s all carry GPS receivers plus many websites have them. For running light weight and small size are what I looked for. Computer interface is nice, you may want a unit with maps for car trips. Also being able to run from car battery is nice on long trips. Palmer
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I have read that the GPS will be more accurate than your cyclocomputer (the main reason is most people do not set up the cyclocomputer with the greatest accuracy—most just look at wheel size and put the numbers in that the owner’s manuel says. I have checked mine with me on the bike and fully inflated tires and me off the bike—-the rollout difference is measureable).
Errors that result from mis-calibrating a cyclocomputer are cumulative and would grow linearly with distance. Even if perfectly calibrated there would be random error (due to inability to ride a perfectly straight path) that would grow as the square root of the distance. In any case, one would expect the GPS method to do better and better relative to the other methods as the distance measured got longer. At the opposite extreme, measuring the distance across the top of your desk, say, you’d do much better with a ruler than a GPS. I’m assuming in the previous paragraph that the GPS is used to measure the straight line distance between two points. A system that makes many GPS observations and integrates the result would be subject to the same systematic and random errors as the other methods, though perhaps to a lesser degree. From what I’ve read here, I still think the Jones counter easily beats the GPS for accuracy over normal road race distances. — Terry R. McConnell Mathematics/304B Carnegie/Syracuse, N.Y. 13244-1150
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I just finished my first post-SA run. 10.1 miles and all of my mileage landmarks were dead on, unlike the old SA days. Speed was zero when I stopped. While most the time SA did not affect mileage one run I did on the first day of Spring SA added over 1/2 mile on a 5 mile loop. No more fuzzy lines on repeated loops. Palmer
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I just finished my first post-SA run. 10.1 miles and all of my mileage landmarks were dead on, unlike the old SA days. Speed was zero when I stopped. While most the time SA did not affect mileage one run I did on the first day of Spring SA added over 1/2 mile on a 5 mile loop. No more fuzzy lines on repeated loops.
Ironically, probably your fitness will decrease. No more running a bit extra just to be sure. — Terry R. McConnell Mathematics/304B Carnegie/Syracuse, N.Y. 13244-1150
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<snip I haven’t been out running yet today so I haven’t experienced this first-hand, but I’m sure going to start remapping all of my standard routes starting today. If any of you already have GPS devices or were planning to buy one, I just thought you might be happy to hear the good news. — Dan
I was just planning on getting a Garmin GPS-III+, mainly for use on my motorcycle, but I was already wondering how it would work if I carried it while running. Sounds like it might be fun to try (unless it turns out that the 5-mile course that I’ve been running for the past x years turns out to be 4.5 miles long!). Doug Before you buy.
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Keep in mind that although GPS and DGPS can provide accurate position information and distance between two points, the distance is in a straight line. This may be much shorter than the course run.
Things are not quite as bad as this caution implies. Many GPS receivers have trip functions that will sample position every second or two, effectively breaking your course down into very short line segments. Then they’ll add them up to yield a course distance for you based on those short segments. Especially with the new cleaner signals, this calculation should be pretty good. You have to have clear signal over the whole course, though. They’ll give you speed between samples too. How long will it take to hook a GPS and a heart rate monitor into a Palm VII that will transmit position (including altitude,) speed, heart and respiration rates to your personal trainer sitting at his desktop console. Ahh, the loneliness of the long distance runner. Fred
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SA is not turned off for good. DoD can re-activate SA if necessary.
They can, but they won’t. First of all, they wouldn’t have turned it off unless they had other alternatives such as local jamming. Secondly, there is going to be a flurry of commercial and other civilian activity taking advantage of the sudden increase in accuracy, including a planned Enhanced 911 (emergency call) service that can quickly locate the distressed caller. Once there is a dependence on accurate GPS devices it will no longer be feasible to go back to SA. Besides, it would make Bill look like an idiot. PS For more detailed info and links to GPS sites please consult the ng sci.geo.satellite-nav. — Dan Before you buy.
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ref: "Running with GPS just got better.": [...] I haven’t been out running yet today so I haven’t experienced this first-hand, but I’m sure going to start remapping all of my standard routes starting today. If any of you already have GPS devices or were planning to buy one, I just thought you might be happy to hear the good news.
I definetely second Chuck. PLEASE post a report on how accurate these things are now, if they are any useful for a runner and if there are any problems or limits to these things… Thanks in advance ! — Christian Herboth ICQ # 52515902
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Thanks for posting. Any more info on devices – prices and the like? — Ivo van der Putten http://vdpcoffee.nl
– Hide quoted text — Show quoted text – Dan – Side benefits also include: * Your speed will be more accurate * Distance measured will be more accurate * You’ll be so engrossed, you’ll run into a lamp post! Karen Nakamura Global Mapping Systems Macintosh GPS Solutions http://www.gpsy.com I recently purchased a small (5.3 oz) handheld GPS (satellite navigation) device so that I could record and accurately measure my various running routes. Unfortunately, the thing was practically useless for this purpose due to the intentional degradation of the satellite signal by the US government (this feature is called SA for "selective availability"). Anyway, after many years of SA, the US finally turned off SA for good last night. The folks over at sci.geo.satellite-nav are beside themselves with joy over this development. I haven’t been out running yet today so I haven’t experienced this first-hand, but I’m sure going to start remapping all of my standard routes starting today. If any of you already have GPS devices or were planning to buy one, I just thought you might be happy to hear the good news. — Dan Before you buy.
Response:
- Hide quoted text — Show quoted text – I recently purchased a small (5.3 oz) handheld GPS (satellite navigation) device so that I could record and accurately measure my various running routes. Unfortunately, the thing was practically useless for this purpose due to the intentional degradation of the satellite signal by the US government (this feature is called SA for "selective availability"). Anyway, after many years of SA, the US finally turned off SA for good last night. The folks over at sci.geo.satellite-nav are beside themselves with joy over this development. I haven’t been out running yet today so I haven’t experienced this first-hand, but I’m sure going to start remapping all of my standard routes starting today. If any of you already have GPS devices or were planning to buy one, I just thought you might be happy to hear the good news. — Dan
I hadn’t heard that. It’ll make the GPS units much more useful. Good news for boaters, too. Mike "According to the charts and my GPS that’s either Fiji or Jamaica." Tennent "IronPenguin" Ironman Canada ‘98 16:17:03 Great Floridian ‘99, 17:13:38
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Dan – Side benefits also include: * Your speed will be more accurate * Distance measured will be more accurate * You’ll be so engrossed, you’ll run into a lamp post! Karen Nakamura Global Mapping Systems Macintosh GPS Solutions http://www.gpsy.com – Hide quoted text — Show quoted text – I recently purchased a small (5.3 oz) handheld GPS (satellite navigation) device so that I could record and accurately measure my various running routes. Unfortunately, the thing was practically useless for this purpose due to the intentional degradation of the satellite signal by the US government (this feature is called SA for "selective availability"). Anyway, after many years of SA, the US finally turned off SA for good last night. The folks over at sci.geo.satellite-nav are beside themselves with joy over this development. I haven’t been out running yet today so I haven’t experienced this first-hand, but I’m sure going to start remapping all of my standard routes starting today. If any of you already have GPS devices or were planning to buy one, I just thought you might be happy to hear the good news. — Dan Before you buy.
Response:
If you wouldn’t mind why don’t you report back to this group on the accuracy of your GPS device? Will it, for example, tell you that the distance from point A to point B is 1.2 miles and from B to C 2.3 miles, etc. etc. How does the accuracy of your GPS compare with the measurement of a bicycle ridden over the same course? With the prices of these devices coming down it might be something that some of us would like to consider purchasing. Chuck
One problem you’ll encounter if you run between high buildings etc is loss of signal due to blocking. Phil. – Hide quoted text — Show quoted text – I recently purchased a small (5.3 oz) handheld GPS (satellite navigation) device so that I could record and accurately measure my various running routes. Unfortunately, the thing was practically useless for this purpose due to the intentional degradation of the satellite signal by the US government (this feature is called SA for "selective availability"). Anyway, after many years of SA, the US finally turned off SA for good last night. The folks over at sci.geo.satellite-nav are beside themselves with joy over this development. I haven’t been out running yet today so I haven’t experienced this first-hand, but I’m sure going to start remapping all of my standard routes starting today. If any of you already have GPS devices or were planning to buy one, I just thought you might be happy to hear the good news. — Dan Before you buy.
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Will it, for example, tell you that the distance from point A to point B is 1.2 miles and from B to C 2.3 miles, etc. etc. How does the accuracy of your GPS compare with the measurement of a bicycle ridden over the same course?
I believe the advertised accuracy of GPS, with the scrambling turned off is a radius of 18 meters around a given point. With the scramble on it was 100 meters, so this is a big improvement. If you want better accuracy, buy a reciever that will process DGPS (differential GPS). The differential signal is transmitted by a network of transmitters, operated by the US Coast Guard. Although the network is set up to primarily provide coverage of major harbors, the Great Lakes, coastal waters, and the major river systems, the signal transmitts much further than expected and many inland area recieve useable signals. Under ideal conditions, with the right equipment, DGPS can produce sub-meter accuracy. Keep in mind that although GPS and DGPS can provide accurate position information and distance between two points, the distance is in a straight line. This may be much shorter than the course run. Jim
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I recently purchased a small (5.3 oz) handheld GPS (satellite navigation) device so that I could record and accurately measure my various running routes. Unfortunately, the thing was practically useless for this purpose due to the intentional degradation of the satellite signal by the US government (this feature is called SA for "selective availability"). Anyway, after many years of SA, the US finally turned off SA for good last night. The folks over at sci.geo.satellite-nav are
SA is not turned off for good. DoD can re-activate SA if necessary. Julius
Response:
I have read that the GPS will be more accurate than your cyclocomputer (the main reason is most people do not set up the cyclocomputer with the greatest accuracy—most just look at wheel size and put the numbers in that the owner’s manuel says. I have checked mine with me on the bike and fully inflated tires and me off the bike—-the rollout difference is measureable). I saw in the paper that the accuracy will be within 30 to 60 feet.
– Hide quoted text — Show quoted text – If you wouldn’t mind why don’t you report back to this group on the accuracy of your GPS device? Will it, for example, tell you that the distance from point A to point B is 1.2 miles and from B to C 2.3 miles, etc. etc. How does the accuracy of your GPS compare with the measurement of a bicycle ridden over the same course? With the prices of these devices coming down it might be something that some of us would like to consider purchasing. Chuck I recently purchased a small (5.3 oz) handheld GPS (satellite navigation) device so that I could record and accurately measure my various running routes. Unfortunately, the thing was practically useless for this purpose due to the intentional degradation of the satellite signal by the US government (this feature is called SA for "selective availability"). Anyway, after many years of SA, the US finally turned off SA for good last night. The folks over at sci.geo.satellite-nav are beside themselves with joy over this development. I haven’t been out running yet today so I haven’t experienced this first-hand, but I’m sure going to start remapping all of my standard routes starting today. If any of you already have GPS devices or were planning to buy one, I just thought you might be happy to hear the good news. — Dan Before you buy.
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Mike, the real benefit comes in emergency vehicles since they often could not distinguish between roads that overlapped or ran close together. A firefighter buddy thinks this will save a lot of lives since they can get there faster and not spend as much time looking around.
– Hide quoted text — Show quoted text – I recently purchased a small (5.3 oz) handheld GPS (satellite navigation) device so that I could record and accurately measure my various running routes. Unfortunately, the thing was practically useless for this purpose due to the intentional degradation of the satellite signal by the US government (this feature is called SA for "selective availability"). Anyway, after many years of SA, the US finally turned off SA for good last night. The folks over at sci.geo.satellite-nav are beside themselves with joy over this development. I haven’t been out running yet today so I haven’t experienced this first-hand, but I’m sure going to start remapping all of my standard routes starting today. If any of you already have GPS devices or were planning to buy one, I just thought you might be happy to hear the good news. — Dan I hadn’t heard that. It’ll make the GPS units much more useful. Good news for boaters, too. Mike "According to the charts and my GPS that’s either Fiji or Jamaica." Tennent "IronPenguin" Ironman Canada ‘98 16:17:03 Great Floridian ‘99, 17:13:38
Response:
If you wouldn’t mind why don’t you report back to this group on the accuracy of your GPS device? Will it, for example, tell you that the distance from point A to point B is 1.2 miles and from B to C 2.3 miles, etc. etc. How does the accuracy of your GPS compare with the measurement of a bicycle ridden over the same course? With the prices of these devices coming down it might be something that some of us would like to consider purchasing. Chuck
– Hide quoted text — Show quoted text – I recently purchased a small (5.3 oz) handheld GPS (satellite navigation) device so that I could record and accurately measure my various running routes. Unfortunately, the thing was practically useless for this purpose due to the intentional degradation of the satellite signal by the US government (this feature is called SA for "selective availability"). Anyway, after many years of SA, the US finally turned off SA for good last night. The folks over at sci.geo.satellite-nav are beside themselves with joy over this development. I haven’t been out running yet today so I haven’t experienced this first-hand, but I’m sure going to start remapping all of my standard routes starting today. If any of you already have GPS devices or were planning to buy one, I just thought you might be happy to hear the good news. — Dan Before you buy.
Response:
I recently purchased a small (5.3 oz) handheld GPS (satellite navigation) device so that I could record and accurately measure my various running routes. Unfortunately, the thing was practically useless for this purpose due to the intentional degradation of the satellite signal by the US government (this feature is called SA for "selective availability"). Anyway, after many years of SA, the US finally turned off SA for good last night. The folks over at sci.geo.satellite-nav are beside themselves with joy over this development. I haven’t been out running yet today so I haven’t experienced this first-hand, but I’m sure going to start remapping all of my standard routes starting today. If any of you already have GPS devices or were planning to buy one, I just thought you might be happy to hear the good news. — Dan Before you buy.
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