Future Of Satellite Signal Reception

[+shunra]

Currently, GPSrs show a detail of three digits after the decimal in the minutes number (I still use an old one that has only two). New GPSr improvements seem to be mostly in the realm of features, not in the realm of accuracy. Is that because a technical limit has been reached, or are future GPSrs going to be more accurate as well?

 

Also: are there increased accuracy possibilities that were not included when GPSr was made available for civilian uses, but that might be added at a later point?

 

And: is it technically possible for a future administration to restrict our use of GPS, or limit its accuracy, in a reversal of Clinton's policies, without restricting its military use? Is our investment in GPSrs something we can keep enjoying as long as they work and as long as the Satellites are up in the sky, or could it be rendered worthless by governmental intervention?

[+Cat'N'Geo]

Since the government has their software & IP addy's, technically speaking they can do anything they want. Deteriorate the signal in certain areas, throw it off by any distance they want, or plain 'ol block the civilian reception.

 

Or bring the satellites down.

 

Buuut since it is an international resource, hopefully they won't.

 

[Jeremy]

Is that because a technical limit has been reached, or are future GPSrs going to be more accurate as well?

 

Yes. The current technical limit has been reached. Like how my Apple ][E only had a floppy drive. With DGPS you can get down to centimeters, but it is cost prohibitive for a consumer handheld device.

 

Is it technically possible for a future administration to restrict our use of GPS

 

Yes. Politically possible? No. Like shutting down airports is technically possible to improve national security.

 

And: , or limit its accuracy, in a reversal of Clinton's policies, without restricting its military use

 

Yes. It is called Selective Deniability, but it isn't a reversal of the Clinton administration's decision. They removed Selective Availability because they had alternative technology to protect/replace GPS.

 

Is our investment in GPSrs something we can keep enjoying as long as they work and as long as the Satellites are up in the sky, or could it be rendered worthless by governmental intervention?

 

Not only is that political suicide, but a pointless exercise. So no, I don't think you need to worry about your GPSr turning into a door stop, unless you take the batteries out of it.

[+shunra]

Is it technically possible for a future administration to restrict our use of GPS

 

Yes. Politically possible? No. Like shutting down airports is technically possible to improve national security.

Ouch. That's not reassuring at all. If it's technically possible, aren't they likely to do it after the first GPS-based terror attack, or are we enough of a critical mass by now? I somehow doubt it!

[+DustyJacket]

......aren't they likely to do it after the first GPS-based terror attack, or are we enough of a critical mass by now? I somehow doubt it!

The terrorists aren't up to the task of creating GPS Guided munitions. (Heck, the USA doesn't have it perfected). They use people-guided munitions, and unintelligent rockets, and so forth.

 

A lot of commercial companies and emergency services now depend on GPS. It is here to stay IMHO.

Edited November 26, 2003 by DustyJacket

[+Brenin Tegeingl]

With both Russia and Europe, both developing their own GPS technology, which will be on line within the next 10yrs. We will see GPSr's capable of receiving and using signals from all 3 systems. Thus ensuring that no one government has total control over the signals received by the GPSr. The European system is aiming to be acurate for hand helds down to sub metre accuracies, using a series of receiver stations which will transmit corrections for each satellite back thru the satellites, and not use a correction satellite as used by WASS/EGNOS. Dave

[+Johnnie Stalkers]

There has been a huge shift in both funds and focus since 9-11. Police and Fire Deptartments around the country are ALL under the gun (no pun intended) to prepare and train for mass casualty events. Many large cities are well on the way to having a system in place. One of the major obstacles is communication between units, departments and a command center. Every viable solution I have seen involves the use of GPS devices tracking Police cruisers, Fire Engines, Ambulances and so forth. It would make no sense to spend BILLIONS on homeland security and then cripple it by taking away one of the intricate pieces of the puzzle. There is absolutely NO chance of GPS being shut down, even to scramble it again would be a HUGE undertaking.

Rest easy and cache happy.

[+EScout]

GPSr units (my Meridian and Legend) output NMEA in 4 digits (ten thousandths of a minute). Connect it to a PDA using a program that accepts this data and you will see. Very good precision (about a half a foot), but accuracy is another matter.

 

The only risk of GPS being disabled is if the cost to National Security far exceeds the economic costs.....if we are under under severe attack and our enemies use of GPS is hurting us more than helping-- not likely.

[+PDOP's]

...With both Russia and Europe, both developing their own GPS technology, which will be on line within the next 10yrs. We will see GPSr's capable of receiving and using signals from all 3 systems...

Russia has had their own system (GLONASS) for quite a while now and survey grade GPSr's that are able to use both systems at once have been around for a few years.

[Dan Vull]

I would have to agre with most of the above posters that it would be a strange reversal to turn SA back on. The correlators that most survey grade manufacturers had developed made SA irrelevant anyhow. The addition of a civilian freq (L5) in the next generation of sv's should eliminate the worry of SA rearing it's ugly head again. Galileo has a requirement to be capitable with NAVSTAR. The only ugly duckling is GLONASS. The system has been up and down for years due to funding and design problems. WAAS is just the beginning of the FAA programs, LAAS is next and that my friends will land a plane a passenger plane.

P

[Kerry.]

Currently, GPSrs show a detail of three digits after the decimal in the minutes number (I still use an old one that has only two). New GPSr improvements seem to be mostly in the realm of features, not in the realm of accuracy. Is that because a technical limit has been reached, or are future GPSrs going to be more accurate as well?

 

Accuracy is one thing, Precision is another and for a system spec'd at 13 metres 95% of the time (world average) it's much like the calculator syndrome, see 9 decimals it MUST be precise or accurate or whatever one wants to call it.

 

Recreational differential capability is slightly different but still really only valid to 3 decimals.

 

Generally if the equipment is meant to be precise/accurate then the precision will have been allowed for in the software/hardware. Much like the reasoning behind the limitation of 2 decimal minutes, based on a system spec'd at 100m 95%, what was the point of allowing 3 decimals.

 

Also: are there increased accuracy possibilities that were not included when GPSr was made available for civilian uses, but that might be added at a later point?

 

No, apart from the methods used by professionals and add on type augmentation systems. But todays satellite is a much improved version, especially with regards timing and increased timing=increased accurracy so really the system is being improved with basically every new satellite launch (especially these days).

 

At this point in time the first of the modified Block IIR's (Block IIR-M) satellites with the second civil freq is due for launch around April 2004. Civil dual freq won't do much for anybody until there's enough of these satellites in orbit. The expected accuracy is around 1.5 metres. A third civil freq will follow. Second freq = new receiver.

 

And: is it technically possible for a future administration to restrict our use of GPS, or limit its accuracy, in a reversal of Clinton's policies, without restricting its military use?

 

Much more than technically possible but it won't happen. But if it does you'll have a lot more to worry about than a GPS receiver.

 

Is our investment in GPSrs something we can keep enjoying as long as they work and as long as the Satellites are up in the sky, or could it be rendered worthless by governmental intervention?

 

Governmental intervention as mentioned is not past the use by date, it could but it won't.

 

Investment in GPSr's will be like most other things, new investment each time you have to replace the last to take advantage of the future.

 

That second civil freq to enjoy the benefits will require a new receiver, the old receiver will continue but one will have to keep up as fancy using an "old" receiver that's inaccuarte

 

With respect some of the other comments.

 

GLONASS has been around almost as as GPS, just the Russians had some funding/priority issues but this has now changed and there should be a few more replenishment sats launched. basically they are launching 3 at a time but then things were getting fairly desperate.

 

GPS+GLONASS receivers have existed for many years just that the Russians couldn't maintain their system so many companies actually never released their receivers either.

 

As for the accuracy being bandied around regarding Galileo there's apparently a few myths starting to float around regarding "claimed" accuracy. There is no difference in accuracy between "Comparative modes" for either GPS or Galileo.

 

The "commercial accuracy" of Galileo is based on encrypted signals, subscription services and access via key in receiver. Really in principle not all that much different to many of the subsription services that's been availabe using GPS for the past 10 years. If one wants accuracy one simply has to pay for the privlidge regardless of it being GPS, Galileo or Glonass.

 

Cheers, Kerry.

Edited November 26, 2003 by Kerry.

[+TotemLake]

Let's not forget the major investment the FAA made and subsequent approval for airlines to depend on it. I would think that would be the point of no return from the days of SA.

[Kerry.]

Let's not forget the major investment the FAA made and subsequent approval for airlines to depend on it. I would think that would be the point of no return from the days of SA.

Lets just say that the FAA started the WAAS thing way before SA was discontinued and for several years since SA was discontinued WAAS really went no where. One can make many assumptions with the delay but one thing is certain WAAS so far has cost in the vicincity of close to 6 billion US and (just) covers the CONUS , GPS since day zero has cost around 12 billion and gives world global coverage.

 

What WADGPS type systems (such as WAAS) do and the portion of the planet they cover in relation to the improvement in accuracy per metre is quite staggering.

 

Well and truely in the (many many) millions per metre but then one has only to look at who drove the recent change in WAAS status for some insight in the politics and it certainly wasn't FAA.

 

Cheers, Kerry.

Edited November 27, 2003 by Kerry.

[+Doc-Dean]

......aren't they likely to do it after the first GPS-based terror attack, or are we enough of a critical mass by now? I somehow doubt it!

The terrorists aren't up to the task of creating GPS Guided munitions. (Heck, the USA doesn't have it perfected). They use people-guided munitions, and unintelligent rockets, and so forth.

 

A lot of commercial companies and emergency services now depend on GPS. It is here to stay IMHO.

Or perhaps it should be called "unintelligent" people-guided munitions.

 

 

[Dan Vull]

There are a couple of world wide DGPS providers on the market, RACAL, Omni-Star just to name a couple. They both offer sub-meter corrections but OS offer a decimeter package. The cost of units is prohibitive except for GIS Survey types. Coverage is planet wide or so they say. There are ways to stay on top of the politics of GPS, GPS World is a magazine that shows up once in a while and I'm sure the USDOT and FAA have sites and then there is always NAVSTARS home page.