Now that the iPhone 4S tracks not only GPS satellites, but GLONASS satellites as well, I was thinking today.....What if Apple & AT&T decided to broadcast corrections on the cel network? I don't know the details of what's inside the iPhone, but is it possible that the iPhone (or your favorite flavor of smartphone) could become a high precision receiver? It's already connected to a network - If that network broadcasted corrections for various sources of GNSS errors, a device which now has an accuracy of 20 to 100 feet, might become one which has an accuracy of 1 to 5 feet? Or better?
You better believe it's possible, and probably likely.
I've heard Brent Jones say that some cell phone makers already hold the patents to technology that gets a cell phone position down to 2 cm accuracy.
Can't say his source and do not recall the manufacturer. But I trust that Brent believed it or he wouldn't have said it.
As for what that means to surveyors..... the future is coming at us really fast. Are we prepared for the changes we face? Unfortunately, I have to say most are not. (Right up to and possibly myself included.)
Larry P
Well, as one involved in the testing of the enhanced 911 systems then it's been much more accurate for several years over cell tower pinging and triangulation from towers. We tested a variety of phones during the testing process and got hits that were much closer to actual locations than our addressing system. (ani/ali).
Usually in the 5-10 meter range.
I have no idea of the phone technology with the GPS chips but I think this is about as good as it will get unless the smart phones push it and then perhaps submeter might be possible, for geocaching and such.
There would have to be a huge breakthrough in antenna design (not likely) to improve on that. I'm sure that most use the ribbon strip antennas.
As a computer and GPS recievers, it's probably not that much different than something like the handheld Trimble or Ashtech units designed for GIS data collection. Stream some corrections to it, setup a database, and you have a real-time GIS datacollector that would probably rival the main players for accuracy. Heck, someone could even write an app that stores points and logs the GPS data for post processing, which would probably give you meter level accuracy without streaming corrections, just not real-time accuracy.
In my opinion it's only a mater of time. I predict it will happen in less than 10 years. You will be able to use a cell phone or a similar sized device and you will be able to get centimeter accuracy.
What's Going to Happen When High-Accuracy GPS is Cheap?
Today’s GPS dual-frequency receivers (L1/L2) can achieve a high level of accuracy (1 cm) in a short period of time, as little as a few seconds. But, they are expensive. An entry-level GPS dual-frequency receiver is a few thousand U.S. dollars. The primary reason is because there is a limited number of companies that design GPS dual-frequency receivers for surveying, maybe a dozen or so. Why is there a limited number of manufacturers? The answer is because the original L2 was not an open signal. In the 1980s, some very smart engineers figured out how to utilize L2 (designed for military use only) in commercial receivers. When they developed those techniques, the companies were smart enough to patent them. There are so many patents in place that it makes it very difficult for a new designer to enter the traditional GPS dual-frequency market, whether it’s surveying, machine control, GIS, or whatever.
Unlike the original L2, L5 is an open signal. Its specification is published for anyone to use. No license fee. No receiver tax. Nothing.
Without any patent blocks, any company in the world is free to develop a GPS dual-frequency (L1/L5) receiver that would be just as accurate, and arguably more accurate, than today’s L1/L2 GPS dual-frequency receivers.
Looking back on the history of electronics, within and outside the GPS industry, we know that increased competition usually results in lower prices to the consumer and improved product quality.
Take, for example, GPS L1 receiver chips used in personal navigation devices and mobile phones. Those chips are available today for less than $3 each. Fifteen years ago, much less powerful GPS L1 receivers were $200 each and 10 times larger.
Mark my words: you will see a similar trend with high accuracy GPS dual-frequency receivers. GPS dual-frequency receivers will be sold at prices you can’t imagine today, allowing surveyors, engineers, contractors, GIS folks, biologists, ecologists, etc. (and an educated general public) to collect high-accuracy data (horizontal and vertical) very inexpensively.
The only thing holding this trend back is the availability of L5. It needs to be broadcast by about 24 GPS satellites. That’s going to happen somewhere between 2018 and 2020. Of course, GPS designers will be working on their receivers long before that.
Download your property data from Google Earth to your iPhone, wander around with the iPhone to your corners, then switch to the "metal detector" app that some have been talking about and bingo, DIY surveying.
Imagine how often we'll hear "You want $600 to do a survey that I can do with my iPhone in 15 minutes?"
Mine already gets within 2 meters
I think we're going to see a steady improvement in precision on the smartphone market, and the improvements aren't going to wait for L5, although when that too gets released, it will only add to the rate of improvement. To me, the fact that Apple has figured out how to use GLONASS means that their engineers are quite sophisticated. Of course, we know that for other reasons as well. I wouldn't be surprised if we saw a tremendous increase in precision, i.e. submeter capabilities, even in the next 2 years.
I believe I read an article in which Javad explained that the cost of the high precision receivers has everything to do with the number of users. As long as there are only 10,000 high precision receivers being sold each year to surveyors, agriculture, military, and construction, the cost per receiver is going to be high. However, the bargaining power of companies that provide hardware and service for hundreds of millions, if not soon billions, of smartphone users is tremendous. We will see rapid change.
I was at an Ashtech dealer meeting (or Thales Navigation or Magellan, whatever name they were going by at the time) and one of the Ashtech guys was talking about a friend of his sending him a message that they had successfully obtained a fixed solution between a pair of GPS equipped cell phones. And this was about five years ago. No telling what is being done now.
Don't forget to use your plumb bob app
http://appsamuck.com/day11.html
I am sure there is an app to download differentials.
If you got that, you should be able to get to 2 cm.
I remember, about 25 years, when the brothers, uncle, and
dad at Watts Instruments in Columbus, Ohio wrote an article
about using the Magellan to get down to 2 cm. They got
a call from Magellan asking what the heck they were doing.
They couldn't support high accuracy GPS. On course, about
two years later, Magellan came out with something called the
Pro Mark.
Hm, gotta figure out a polite way to communicate that $600 is way cheap compared to your expert witness rate when the adjoiner's attorney hires you ...
When technology has made everyone a technician, real knowledge and skills will be rarer and of greater value than ever.
I do agree with you, HB. Very few people complete their own deeds, wills, and taxes, even though we all possess pens and paper. It will again, as before, depend on educating the public.
I'd love to know about this app if it exists. The only real time networks that I know of in this area (western MA) are fee based and quite expensive. You can get the corrections but you gotta pay for them.
> Don't forget to use your plumb bob app
>> http://appsamuck.com/day11.htmlbr >
That is just crazyiness...I can remember when humans just held up an actual plumb bob, back in the olden days.
> In my opinion it's only a mater of time. I predict it will happen in less than 10 years. You will be able to use a cell phone or a similar sized device and you will be able to get centimeter accuracy.
I completely agree with you.
Great post Gavin.
By the way, is there an app which would allow for logging the GPS data as it is now received on the iPhone, and even to generate a RINEX file with that data? Can you create a RINEX file from pseudorange? data collected via consumer grade handheld device?
The market might not be as limited as you think. When people see performance in action they move toward it, but they might not know what they want in advance. I remember dismissing someone who 15 or so years ago had a device called a PalmPilot, and was describing how he used it for all sorts of things. A year or two later, I bought one, and liked it. Then I upgraded to the Treo, because it could do things that the Palm Pilot couldn't. Then the iPhone came along and I thought, hah, why do I need that, and then saw how it could be used, and so now I'm on an iPhone. My point is that the technology often leads the consumer to a new place. People didn't think they needed a car when they had horses that were perfectly acceptable, and then Henry Ford and others led the consumer to a new level.
The very idea that there are only a few people that care about high precision is probably a mistake. Virtually everybody cares about precision, at some level, admittedly some more than others. If you, as the consumer, could take your phone with a copy of a plan that displayed lat/long values for the monuments at each corner, and you could thereby find, and confirm, that your corner monuments exist (or, that they don't exist if that is the case), you have just completed at very little cost a task that you wouldn't have been able to do with such precision previously. Well, you could use a compass now, but it is a much harder thing to know whether you're at the point or not. High precision GPS capabilities in the phone would enable that sort of use by the consumer. A use that is admittedly scary for the land surveying community to bear, as it begs the question - what is the purpose of the land surveyor?
The question is, what is the average smart phone carrying consumer willing to pay for that technology? Fifty bucks? I bet alot of people would go for it at that price, if not more.
