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Other than som electronics, are there any physical or mechanical items that cannot be laser digitized, run through a piece of software to turn into gcode and then automatically be duplicated on a cnc machine.For $100k, I could set up a shop to duplicate most physical objects. Why would I hire 5 engineers for two years to design something that could be copied and put into production and sold for the cost of materials in a month?

Rather than wait until someone notices a large margin of error, why not install immobile beacons in key locations that constantly monitor their locations and report back any differences?

They do.
http://www.navipedia.net/index...
https://en.wikipedia.org/wiki/...
http://www.trimble.com/gps_tut...
https://www.ngs.noaa.gov/CORS/

With regional to local corrections accuracy to 10cm is almost easy.
A number of auto GPS devices have an additional receiver for exactly this.

Surveyors can gather high quality data with the assistance of a recording
stationary receiver (one or more) and post process measurements made
by the moving instrument.

Follow the links to Augmentation https://en.wikipedia.org/wiki/...

Of interest three linked devices on the distal wings of aircraft allow some cool data...

Grr. Corrected link

...they made sure their fiber optic connectors were tightened before they challenged relativity.

FTFA: "According to sources familiar with the experiment, the 60 nanoseconds discrepancy appears to come from a bad connection between a fiber optic cable that connects to the GPS receiver used to correct the timing of the neutrinos' flight and an electronic card in a computer. After tightening the connection and then measuring the time it takes data to travel the length of the fiber, researchers found that the data arrive 60 nanoseconds earlier than assumed. Since this time is subtracted from the overall time of flight, it appears to explain the early arrival of the neutrinos."

Really? It took two independent research teams months to determine that the extra delay was due to an uncalculated-for air gap in a fiber optic connector on the timing system?

If their timing system is this sensitive to things like air gap tolerances in the connectors, then how the hell do you calibrate it properly? OK, a top-of-the-line Trimble Acutime Gold claims 15ns accuracy, but that's +/- 15ns, and presumably if you've got CERN's budget for neutrino measurement you're not going to make the claim that faster-than-light travel is possible based on the timing data close to the margin of error of your COTS GPS timing unit?

They don't automatically work out the precise timing. So if one is using GPS for timing one can't just rely on the standard GPS software and calculations for timing.

That must be bad news for manufacturers of GPS timing receivers. As matter of fact, I was working with this very receiver, it's tiny but it tells you time with 15 ns. accuracy - it is more accurate than the error in the experiment.

But as I understand the OPERA people weren't using the GPS timing, they physically moved a synchronized clock (and compensated for the effect of moving it.)

60 ns translates into 18 meters at the speed of light. If the error was that large any car GPS device would be showing you as driving on some other street.

I was working with some high precision GPS receivers, and they can place you on the map with accuracy of a couple of centimeters. The shape of the Earth is also pretty well understood now.

One unfortunate possibility would be that the clocks are wrong. They had to move them between sites, since they weren't willing or able to synchronize them over the radio where they are (the varying propagation paths would be hard to deal with.) A more pleasing (to me) outcome would be that FTL is real.

http://www.spectracomcorp.com/ProductsServices/TimingSynchronization/GPSTimeFrequencyReferences/tabid/117/Default.aspx

http://www.tekroninternational.com/gps_clocks

http://www.trimble.com/timing/mini-t.aspx?dtID=overview&

and for the gold:

http://www.usno.navy.mil/USNO/time/gps/gps-info#tt

Well, that depends on how much money you would put into such a system. For example, Trimble R8 GNSS Receiver supports all GPS, GLONASS and future Galileo signals. In Europe you could buy such a receiver with ~10000 Euros.

oh really? there is an rs232 NEMA stream coming out the the butt of the iphone?

Not sure about the iPhone (iDoubt it) but my little HTC TouchPro has a USB interface. Going from that to RS-232 should be easy, the cable already exists. Pushing data out that cable wouldn't be hard with an application.

The real problem isn't the interface, nor even the operating system (hint: ArcPad runs on Windows Mobile). The problem is that the accuracy for most smartphone based GPS sucks. I think my TouchPro will get me to within about 30 feet, and not much closer. For most situations that is good enough (driving, finding a restaurant, etc). For actual spatial data collection, that is so horridly poor as to be almost worthless. For that, you are still going to need something like this which will do sub-foot readings without a monster antenna. And will do sub-decimeter with a monster antenna. Of course, I could always get a similar result on my phone with something like this and a bluetooth connection back to my phone, but that would just be silly.

While I agree that specialized GPS isn't going anywhere any time soon (or at least until someone figures out how to do decimeter level GPS in a smartphone) TomTom or other consumer level GPS units are probably going to have trouble staying afloat.

oh really? there is an rs232 NEMA stream coming out the the butt of the iphone?

Not sure about the iPhone (iDoubt it) but my little HTC TouchPro has a USB interface. Going from that to RS-232 should be easy, the cable already exists. Pushing data out that cable wouldn't be hard with an application.

The real problem isn't the interface, nor even the operating system (hint: ArcPad runs on Windows Mobile). The problem is that the accuracy for most smartphone based GPS sucks. I think my TouchPro will get me to within about 30 feet, and not much closer. For most situations that is good enough (driving, finding a restaurant, etc). For actual spatial data collection, that is so horridly poor as to be almost worthless. For that, you are still going to need something like this which will do sub-foot readings without a monster antenna. And will do sub-decimeter with a monster antenna. Of course, I could always get a similar result on my phone with something like this and a bluetooth connection back to my phone, but that would just be silly.

While I agree that specialized GPS isn't going anywhere any time soon (or at least until someone figures out how to do decimeter level GPS in a smartphone) TomTom or other consumer level GPS units are probably going to have trouble staying afloat.

That is why surveyors buy surveyor GPS gear. The shit ain't cheap, but when you want centimeter accuracy, you have to buck up.

http://www.trimble.com/survey/GNSS-Surveying-Systems.aspx

Basically, you set up your own local differential GPS station that sits for a while and figures out its position to a very high degree of accuracy.

You then use very accurate devices capable of sub meter accuracy with time averaging and DGPS, and use the signal from the local station to get even better accuracy than that.

Getting accurate positions for surveying isn't that hard, since you can time average, add local DGPS stations and correct the data even after its been collected. You just need the gear.

Now if you want real time tracking with sub meter accuracy, that is very hard.

Doesn't matter.. you aren't going to get better than 10m accuracy without DGPS and 1m with it. Surveys have to be right to centimetres - no GPS can do that.

Yes, they can. They just aren't consumer handheld GPS receivers:

http://www.trimble.com/survey/GNSS-Surveying-Systems.aspx

They don't give instant position: they accumulate data over a period of time and use that to derive the exact position, usually after correcting it with a comparable stream of data collected from a nearby known reference point.

Under ideal situations the accuracy of GPS equipment can approach 5 millimeter[...]

See my posts above, but essentially... yes, it is possible to get a better position. The methods are different from what you have described however. If the same receiver can receive signals from all of the systems, there are more satellites available giving you the potential for better geometry. Another big factor is the addition of a third frequency, which carries another civilian-accessible code, this signal will allow the effect of the ionosphere to be removed from the range measurements, meaning that your position accuracy will increase.

Receivers that can use both GPS and GLONASS signals already exist, but they do not treat the two systems as separate, they use all the available information from both together to generate the best possible solution. The catch? Price. A receiver capable of GPS and GLONASS measurements will undoubtedly also be capable of carrier-phase measurements and receiving both L1 and L2. This type of receiver will have a geodetic type antenna (not the kind you can carry in your pocket), and probably cost on the order of $10,000-$30,000. These are widely used in land surveying, you are unlikely to find someone who owns one without using it to make a living.

For info on these high-end receivers, see http://trimble.com/, http://leica.com/, http://novatel.com/, or http://professional.magellangps.com/en/

TFA didn't mention this, but they may be talking about Geodetic GPS receivers. These units are often used to measure plate drift and can measure down to 5 millimeters or so. Something like http://www.trimble.com/5800.shtml

I can answer that! I just might work for a Trimble dealer! :)

For mapping, I recommend the new Recon GPS Card Edition. It's under 2K, TerraSync software included, and gets autonomous accuracy of 5-10 meters. The Recon is also rugged, and can withstand drops, mud, sand, floods, etc. If you're worried about charging it, you can buy a car charger for out in the field as well as an international charger that has adapters for quite a few countries.

Trimble is running some really good specials right now on Recons; call your local dealer and see what they can do.

To my knowledge, Trimble makes the best/most rugged GPS units available. They supply the military. They also have specialized equiptment for mapping. Here is the linkage: http://www.trimble.com/

There are also armored/waterproof cases and what not you can get for the more common off-the-shelf units.

As for software and compatability...I'll defer to someone else to post on that.

Don't these people realize how accurate GPS positioning has become?

MGIS-grade equipment can now give positions with sub-foot ( 30cm) postprocessed accuracy. Survey-grade equipment can get within 5-10 cm.

As neat as WPS sounds, I don't think that anyone will be giving up GPS soon if WPS can't get any more accurate than 20-40 meters.

The article is full of common sense; and he's right about India. If you are just a programmer, you are not adding much value to your company; if you are a developer, it is highly unlikely that you will be seeing your job head off to India.

I live in New Zealand which is hardly the centre of the developmental universe. Here in Christchurch we have a thriving electronics industry working on radio communications (Tait Electronics), ethernet switching (Allied Telesyn), innovative laboratory instruments (Syft Technologies), navigation (Trimble and Navman); that means a lot of room for developers. We tend to create products here, but manufacture offshore. Only Tait Electronics manufactures here in Christchurch. Everyone else uses a contract-manufacturer, here or overseas.

Having said that, it's a small market so don't expect to skip from one job to the next. This place got hit by the last economic downturn just like everyone else. It took me two months to find my current job after my last redundancy. Even though my previous position was made redundant, that position did not got to India; the company refocused it's business on hardware instead of consultancy. You need to be a certain size to do consultancy/services and we weren't that big. You can be a lot smaller if you generate your own IP.

Also, I'm not sure that doing a CS is the right way to get into software. Yes, you will get a wonderfully structured introduction to CS theory but you might find the introduction a bit academic withoput sufficient grounding in reality. Frankly, the people I have had trouble working with since I sterted full time employment back in 1989 have had CS backgrounds. The people that I've always got on with started out as engineers, physical scientists or mathematicians. I started out as a Natural Philosopher (i.e. physicist) before being seduced by the computer and, in particular, by the embedded side of things.

Mind you, I am a practical person. I don't find much beauty in abstract theories and multiple layers of abstraction. Perhaps this is why I find CS people a bit hard to work with. Also, the embedded world is full of real-world things that require controlling. I find this fun. I do not find the innards of an enterprise level web server to be as attractive to me.

Sorry, doesn't the DoD regularly recallibrate known GPS satellite positions against the "fixed" stars anyway to check for ephemeris errors? I don't think we have to worry about this from a GPS perspective very much at all.

I found this incredbily useful:
Trimble's tutorial on GPS.

I think all consumer GPS devices do this, but there are lots of commercial/industiral GPS devices, too.

I don't think it would be that hard to integrate one of the chipsets from Trimble into a WAP to provide the feature Woz is describing. Install the WAP in the ceiling, and run some RG-58 to the roof for the antenna, and I think that would make spoofing the GPS a lot harder.

I think all consumer GPS devices do this, but there are lots of commercial/industiral GPS devices, too.

I don't think it would be that hard to integrate one of the chipsets from Trimble into a WAP to provide the feature Woz is describing. Install the WAP in the ceiling, and run some RG-58 to the roof for the antenna, and I think that would make spoofing the GPS a lot harder.

Small point, but GPS uses trilateration, not triangulation. Triangulation uses angles whereas trilateration uses distances.
http://www.trimble.com/gps/triangulation.html

A GPS receiver measures these distances (or pseudoranges) by calculating the time a signal from a satellite took from transmission to reception. Having an accurate clock or time estimate (which 4 satellites will give you) is key to that calculation.

Well, depends on the space you're playing in doesn't it?

Check this unit out: http://www.trimble.com/recon_mgis.html

128MB Internal RAM.

By the time this stuff is ready for prime time 128MB will be common in executive toy type units, and in the application space I develop for devices will not uncommonly have twice that or more.

Actually, GPS indoors is rather cutting-edge. It isn't commercially available on a large scale.

Clicky

Disclaimer: Our company sells trimble gps

Accuracy can be degraded with a single GPS. Differential GPS has one stationary receiver with a known position. It monitors the error of the GPS signal and transmits the error to other receivers in the vicinity. Consequently even DoD's Selective Availability Error can be overcome. Read more here.

So it would be way more efficient to put in a little differential GPS receiver than to try and do some of the image processing suggested in the article ... which has to be good only if you're near a landmark or something. The article downplays the magnitude of the recognition problem signigicantly.

Any 2-frequency receiver will. However, you really have to pay for it. Try Trimble. They make some of the world's most accurate receivers (if you saw that Everest movie made by OmniMax, the GPS receiver they were using to measure Everest's height was a top-of-the-line Trimble). They generally cost in excess of $10000, with an additional $700+ for the antenna.

Any ideas?

Doesnt say if this is capable of GPS-2 or whatever its called. As someone who uses GPS to manage infrastructure, I'd like to see some more precise GPS without having to spend $20,000 on Trimble or Leica equipment.

There are 2 kinds of GPS equipment - mapping grade and survey grade. Survey grade has accuracy down to about 1cm, and mapping grade is generally in the range of 1-10 meter accuracy.

This thing is mapping grade, but of dubious quality. The world leader (also in New Zealand), is Trimble. They will run you about 6k for a submeter accurate unit, that is rugged and comes with a good warranty.

Trimble Navigation sells a high accuracy Windows CE device, GeoXT
Designed for rugged work & completely integrated. Focussed more on submeter GPS, but can be attached to laser rangefinders.

It seems the satelites transmit time correction sgnals, not new postion data. The GPS recivers have that data on file.
I think your reading it wrong, positioning data would be a LOT of info to transmit like that. The time correction signals work the same way, just with less data.
Then again, I could be totally wrong. I think its this that your reffering to.
I know for a fact, however, that the satelites do not transmit their full position data to the handsets, there would be no need for the onboard almanac if that were the case.
I did, however, see something on a system that could transmit a more powerfull, focused GPS signal that could defeat jamming, and allow for a better siganl in a small area. Say the size of Iraq, and even better signals in a really small spot, like Bagdahd. I wonder if this is the system being referred to?

How?
GPS works because the handsets know exactly where the satelites are, and exactly what time it is, and the precise timing of the signals.
They even have to take into account general relativity due to time dialation.
So how could the satelites be moved without them being useless?

Maybe I'm the one who's mistaken here, but with the little knowledge I have on the subject, the writer of this article, and the slashdot community, both look grossly uninformed about GPS in agriculture. I know in my small hometown in Canada, they have been using GPS to guide farm equipment (namely for spreading fertilizers) for at least 5 years now. The equipment is provided by one the largest industrial GPS companies around, Trimble, who has an entire division for agricultural applications, which they dub "AgGPS".

Maybe I'm the one who's mistaken here, but with the little knowledge I have on the subject, the writer of this article, and the slashdot community, both look grossly uninformed about GPS in agriculture. I know in my small hometown in Canada, they have been using GPS to guide farm equipment (namely for spreading fertilizers) for at least 5 years now. The equipment is provided by one the largest industrial GPS companies around, Trimble, who has an entire division for agricultural applications, which they dub "AgGPS".

I think its called differential carrier phase gps
measurements below 1cm can be taken by looking at the wavelengths of the signal

Technically, you *can* use the two station system to land a plane. It works like this...

Receiver 1 is fixed. It is hooked into a computer system that outputs correction data in real time (RTK or real time kinematic), radio recievers coupled with another GPS receiver provide spatially correct location for both Horizontal (XY) and Vertical (Z). Many companies provide solutions for individual-level tracking.

Trimble
Leica

This is another example of the dangerous paranoia you get when earnest idiots get responsibility.

If it weren't for GPS, there'd be nine dead coal miners in Pennsylvania. Precise GPS has never hurt anyone, and has saved lives. It's nice to be able to point to a benefit the U.S. has provided mankind. Count on our jackass government to want to take it back.

Trimble does a rugged GPS/HPC2000 device. It's more aimed at commercial markets, but the large memory models come with 512Mb of non-volatile memory. Everything else Details at here

Pigs might fly, but don't make breast landing Weird News

This sounds similar to the triangulation the cell phone companies tried to use to locate phones when ordered to do so by law enforcement (to comply with CALEA and ostensibly E-911.) That didn't work well enough in rural cell areas, however, thus the move to on-board GPS receivers in cell phones.

The thing that amused me the most was the error in the Salon article's description of the technology involved:

The location-tracking software itself, developed by a 15-year-old student at the university, draws upon triangulation technology used by global positioning system (GPS) devices. The PDAs figure out their locations by comparing the strength levels of signals traveling from the devices to various Wi-Fi antennas.

GPS does not use signal strength. GPS uses differential timing. This system and software work like a GPS in the same way that a kitchen stove works like a microwave oven. Love them Salon facts.

Quite close, but you missed on a rather small point. With GPS, they don't send Pings in the same way that you would ping a server.

How it works is that all GPS's are synched time-wise. Now, every millisecond (or smaller fractions) all of them broadcast their times. Now the GPS device takes the times broadcasted from 3 or 4 GPS satellites and calculates the time differentials.

Click here to see a very good flash demo of GPS Triangulation

The way that you mentioned, simplified the complexity of the system, however, your method will not SCALE at all nor work at all. First of all, as more and more GPS devices are used, the satellite will be bogged down by requests. It will turn into a DDoS to the GPS sat. Secondly, your way would require that the GPS device not only receive but also broadcast. That would require a significant amount of energy and add to the cost. Lastly, when you are worried about a signal going to and from the satellite, you introduce a number of possible sources of errors. In addition, it would take more time to get to a satellite that you're farther away than the one that you are closer to. This would require that it takes longer to calculate your triangulation due to the fact that you have to wait for the slowest response.

But yes, you did make it understandable to a layman.

No shit sherlock. Jammers are usually on the ground, i.e. below you if you are a missle or a plane and the GPS constellation is above you. Hell, use GPS and a laser-ring INS to get your position and you can easily do phase comparison for a phased array receiver.

Btw, high-end GPS products are able to "count" the number of wavelengths to a satellite to determine position w/ 95% confidence interval within Differential GPS or kinematic (position is accurate while moving) differential GPS can get down to the SUB-centimeter range !!! This requires an accurately measured fixed based station and a broadcast channel for updates; mostly for farms, mines (the mineral kind), power plants, construction, etc. On the conus (the us mainland), the coast guard and others broadcast DGPS corrects that are publically available.

Differential GPS also defeats the old inserted error for non-military keyed receivers, it's a mute point because there is no error.

Here are some links to help out with gps:
(nothing to cosmic, I just did a google search)

Nulling Antennas:

Navy
Mayflower
Owego

How GPS Works

Info about L1, L2, p-code, etc

Some info on GPS NMEA sentences

-jim

LOL! I haven't read anything that funny in hours!

Of course, if anyone's wondering, GPS receivers determine position by solving a set of equations for the four variables of position (3 dimensions) and time (1 dimension).

There is a really nice (but Shockwave, unfortunately) overview of GPS at Trimble's site.

Although I tried to find evidence on Aspen's site, it wasn't much use (I think they just win an award for terseness - particularily their history). There was some more info on Trimble's website. The AgGPS 132 is the receiver used - it uses satellite-based private subscription differential correction services and the public WAAS.

My initial guess was that the system computer-controlled the sprayers, so that when the GPS system detected that the aircraft was over the correct field and over a not-already-sprayed area, it would trigger the sprayers. To compensate for overlap, some individual sprayer jets may not fire so as to not re-apply over the same area.

But that thinking was all wrong. The Trimflight 3 brochure pdf describes the system very well - it's a precise guidance system aimed at cropdusters-- it includes measuring the field, determining a coverage pattern, guiding the pilot through that coverage pattern (with the help of a lightbar to indicate how far off-track they are), and then doing the recordkeeping to record what was sprayed where. It interfaces to a Crophawk flowmeter, but doesn't look like it controls the flow. This brochure also shows a helicopter doing application - the spray looks like a normal fixed-wing spray; I'm not sure why the downwash isn't blowing it all over!

Although I tried to find evidence on Aspen's site, it wasn't much use (I think they just win an award for terseness - particularily their history). There was some more info on Trimble's website. The AgGPS 132 is the receiver used - it uses satellite-based private subscription differential correction services and the public WAAS.

My initial guess was that the system computer-controlled the sprayers, so that when the GPS system detected that the aircraft was over the correct field and over a not-already-sprayed area, it would trigger the sprayers. To compensate for overlap, some individual sprayer jets may not fire so as to not re-apply over the same area.

But that thinking was all wrong. The Trimflight 3 brochure pdf describes the system very well - it's a precise guidance system aimed at cropdusters-- it includes measuring the field, determining a coverage pattern, guiding the pilot through that coverage pattern (with the help of a lightbar to indicate how far off-track they are), and then doing the recordkeeping to record what was sprayed where. It interfaces to a Crophawk flowmeter, but doesn't look like it controls the flow. This brochure also shows a helicopter doing application - the spray looks like a normal fixed-wing spray; I'm not sure why the downwash isn't blowing it all over!

Although I tried to find evidence on Aspen's site, it wasn't much use (I think they just win an award for terseness - particularily their history). There was some more info on Trimble's website. The AgGPS 132 is the receiver used - it uses satellite-based private subscription differential correction services and the public WAAS.

My initial guess was that the system computer-controlled the sprayers, so that when the GPS system detected that the aircraft was over the correct field and over a not-already-sprayed area, it would trigger the sprayers. To compensate for overlap, some individual sprayer jets may not fire so as to not re-apply over the same area.

But that thinking was all wrong. The Trimflight 3 brochure pdf describes the system very well - it's a precise guidance system aimed at cropdusters-- it includes measuring the field, determining a coverage pattern, guiding the pilot through that coverage pattern (with the help of a lightbar to indicate how far off-track they are), and then doing the recordkeeping to record what was sprayed where. It interfaces to a Crophawk flowmeter, but doesn't look like it controls the flow. This brochure also shows a helicopter doing application - the spray looks like a normal fixed-wing spray; I'm not sure why the downwash isn't blowing it all over!

A Trimflight 3 system. I work next to the people who designed this system here in New Zealand. And they might have even been using the GPS receiver that I write firmware for, the Ag214 (Also known as the MS750). But they were probably using the Ag132 which only does DGPS instead of RTK.

I'm sure this URL will be circulating around the Ag division of Trimble tomorrow :-)

A Trimflight 3 system. I work next to the people who designed this system here in New Zealand. And they might have even been using the GPS receiver that I write firmware for, the Ag214 (Also known as the MS750). But they were probably using the Ag132 which only does DGPS instead of RTK.

I'm sure this URL will be circulating around the Ag division of Trimble tomorrow :-)

A Trimflight 3 system. I work next to the people who designed this system here in New Zealand. And they might have even been using the GPS receiver that I write firmware for, the Ag214 (Also known as the MS750). But they were probably using the Ag132 which only does DGPS instead of RTK.

I'm sure this URL will be circulating around the Ag division of Trimble tomorrow :-)