Vista WAAS Test w/USGS Benchmark (long)

[Kerry.]

quote:

---

Originally posted by fizzymagic:

In other words, you intentionally did a test of WAAS that was invalid. And you wanted to prove what?

 

Geez.

 

When I said that every test I knew of using WAAS showed improved accuracy, I assumed that people would understand that I meant every _valid_ test.

 

Your test is the intellectual equivalent of claiming a Ferrari is a worthless car because you tested in on a 4WD-only road and it got stuck.

---

 

Now I did spell out what this was all about, nothing to do with accuracy but all to do with EPE and knowing or not knowing and in that regard what better way to do that.

 

One other point was that wasn't mentioned was this was originally done in response to some rather deceptive advertising in pushing WAAS (and it's pin point accuracy) in areas that it was never going to work. You can talk about every_valid_test but some of the advertising hype I've seen (and questioned) is simply that advertising hype with no substance from manufacturers who should know better.

 

Now if Ferrari made claims they could do what a 4WD does then you'd obviously want to test that wouldn't you

 

Lets face it certain manufacturers were still comparing WAAS to SPS accuarcy pre Selective Availability almost 2 years after SA was set to zero but at least that's now been changed to the real world.

 

So for a standard SPS receiever with a CEP of 1.8m (< 6') what does 6 billion dollars worth of augmentation [WAAS) do for the average recreational user considering that 6 billion dollars only services a smallish part of the world compared to GPS proper.

 

There's starting to be a very fine line these days where reality begins and ends.

 

Cheers, Kerry.

 

I never get lost everybody keeps telling me where to go

[Kerry.]

quote:

---

Originally posted by fizzymagic:

In other words, you intentionally did a test of WAAS that was invalid. And you wanted to prove what?

 

Geez.

 

When I said that every test I knew of using WAAS showed improved accuracy, I assumed that people would understand that I meant every _valid_ test.

 

Your test is the intellectual equivalent of claiming a Ferrari is a worthless car because you tested in on a 4WD-only road and it got stuck.

---

 

Now I did spell out what this was all about, nothing to do with accuracy but all to do with EPE and knowing or not knowing and in that regard what better way to do that.

 

One other point was that wasn't mentioned was this was originally done in response to some rather deceptive advertising in pushing WAAS (and it's pin point accuracy) in areas that it was never going to work. You can talk about every_valid_test but some of the advertising hype I've seen (and questioned) is simply that advertising hype with no substance from manufacturers who should know better.

 

Now if Ferrari made claims they could do what a 4WD does then you'd obviously want to test that wouldn't you

 

Lets face it certain manufacturers were still comparing WAAS to SPS accuarcy pre Selective Availability almost 2 years after SA was set to zero but at least that's now been changed to the real world.

 

So for a standard SPS receiever with a CEP of 1.8m (< 6') what does 6 billion dollars worth of augmentation [WAAS) do for the average recreational user considering that 6 billion dollars only services a smallish part of the world compared to GPS proper.

 

There's starting to be a very fine line these days where reality begins and ends.

 

Cheers, Kerry.

 

I never get lost everybody keeps telling me where to go

[+EraSeek]

Here are a couple of comparisons that I had done in the past.

 

Benchmark 314' elevation,

GPS 328' 14' high

 

Benchmark 34'

GPS 22' 12' low

 

Benchmark 275'

GPS 257' 18' low

 

Benchmark 305'

GPS 279' 26' low

 

[+EraSeek]

Frankly I didn't get it either...doing a WAAS test outside of the WAAS area. Maybe the techincal stuff is blowing by me, but doing any test on any part of the system outside of it's limits makes no sense to my untrained brain. If you want to test it's EPE go next to a rock cliff or under a tree cover within the WAAS area.

 

At any rate, you've mentioned single frequency sats, and the coming duel fequency sats. I take it these duel frequency sats will function as a simple WAAS system, where the end unit will analyze the two signals, and determine error by how the two signals have been changed, much like how you can get different frequency waves passing through the Earth during and earthquake or a large blast and thereby see the internal structure of the Earth. Am I anywhere close? Or am I just embarassing myself?

[Kerry.]

EraSeek, I knew it wouldn't but the whole point was the advertising material suggested it would . The only way to argue with sales/marketing people when certain companies are paying their salary is to throw "facts" at them.

 

But for sure things are becoming much clearer these days but it's still interesting what the WAAS signal does to the navigation for those that might be on the fringe of useability. Up until recently there's simply been too much hype regarding WAAS, EGNOS and MSAS.

 

Testing EPE up against a cliff, obstructed data, no problem I can give you that too based on the following data

 

http://www.cqnet.com.au/~user/aitken/gps/gps_obs.htm

 

As for dual frequency your basically on the right line but no not really similar to WAAS as WAAS is a third party augmentation (and a dadgum expensive augmentation at that) like DGPS and others where as the second GPS frequency is part and parcel of the GPS system proper. With 2 frequencies one of the biggest errors in the atmospherics can be reduced based on the actual data instead of the current modelled atmospheric corrections that are used with standalone single freq receivers. With 2 frequencies then Wide Area Differential GPS (such as WAAS) goes up another level as well.

 

Elevation from GPS is really only a guide anyway at the vertical component is about 2.5 times less accurate than the horizontal and relies on internal geoid models which for a handheld is quite sparse and approximate to cover the entire world.

 

Cheers, Kerry.

 

I never get lost everybody keeps telling me where to go

[Kerry.]

EraSeek, I knew it wouldn't but the whole point was the advertising material suggested it would . The only way to argue with sales/marketing people when certain companies are paying their salary is to throw "facts" at them.

 

But for sure things are becoming much clearer these days but it's still interesting what the WAAS signal does to the navigation for those that might be on the fringe of useability. Up until recently there's simply been too much hype regarding WAAS, EGNOS and MSAS.

 

Testing EPE up against a cliff, obstructed data, no problem I can give you that too based on the following data

 

http://www.cqnet.com.au/~user/aitken/gps/gps_obs.htm

 

As for dual frequency your basically on the right line but no not really similar to WAAS as WAAS is a third party augmentation (and a dadgum expensive augmentation at that) like DGPS and others where as the second GPS frequency is part and parcel of the GPS system proper. With 2 frequencies one of the biggest errors in the atmospherics can be reduced based on the actual data instead of the current modelled atmospheric corrections that are used with standalone single freq receivers. With 2 frequencies then Wide Area Differential GPS (such as WAAS) goes up another level as well.

 

Elevation from GPS is really only a guide anyway at the vertical component is about 2.5 times less accurate than the horizontal and relies on internal geoid models which for a handheld is quite sparse and approximate to cover the entire world.

 

Cheers, Kerry.

 

I never get lost everybody keeps telling me where to go

[+Alan2]

quote:

---

Originally posted by Kerry:

EraSeek, I knew it wouldn't but the whole point was the advertising material suggested it would . The only way to argue with sales/marketing people when certain companies are paying their salary is to throw "facts" at them.

 

...

---

 

You just hit upon what Waas is all about Kerry. It's not about more accuracy. I have yet to see or read about how in a practical way for regular users of GPSr's that waas makes any real difference at all.

 

It's basically advertising hype to differentiate older product from new products and at least initially from mfr's that have it in their products vs those who don't.

 

After all, who would buy or want to keep "old" type equipment and not have all the latest features? This whole thing is about marketing and sales and perception.

 

Alan

[+Alan2]

quote:

---

Originally posted by Kerry:

EraSeek, I knew it wouldn't but the whole point was the advertising material suggested it would . The only way to argue with sales/marketing people when certain companies are paying their salary is to throw "facts" at them.

 

...

---

 

You just hit upon what Waas is all about Kerry. It's not about more accuracy. I have yet to see or read about how in a practical way for regular users of GPSr's that waas makes any real difference at all.

 

It's basically advertising hype to differentiate older product from new products and at least initially from mfr's that have it in their products vs those who don't.

 

After all, who would buy or want to keep "old" type equipment and not have all the latest features? This whole thing is about marketing and sales and perception.

 

Alan

[+EraSeek]

I guess I'm just not as jaded as you guys. Improvement is improvement. Why go to the moon? Was it worth the price? Look at the advancements to which it has led. Does it matter to me if I'm 40' off or 3' feet off? Not really, not usually. I've used my GPS in a whiteout before, didn't have WAAS with my 12, it led me out fine. Would it be better to be more precise? Sure. Why not? WAAS is a step along a path to precision. There will be many uses for that. For now, I'm just fascinated with the technology of it. It is an amazing tool, my GPS.

 

Perhaps I can share with you some text of a cache I have been hanging on to for a while but have not planted yet. It has to do with the wonder of atomic clocks. An integral part of the GPS system:

 

Cesium Pulse

 

In 1972 our official standard of time was changed. No longer is it measured by celestial positions but by 9,192,631,770 electromagnetic pulses per second of Cesium 133. A year is no longer 365.242199 days but 290,091,200,500,000,000 oscillations of Cs. Through history we strove to find an instrument capable of matching the accuracy of planetary motion and we have overshot the mark. The motion of the Earth and Sun has a much greater error (inconsistency) than our current Atomic Clock. The Atomic clock has an error of 1 sec in 6 million years. And the upcoming Mercury ion clock will have an error rate of 2 seconds since the beginning of time itself. It is not the accuracy but the dynamics of the Earth that we cannot match. The order of the universe uses a different definition of order than we. In 2005 NASA will launch the Primary Atomic Reference Clock in Space (PARCS). Where now master clocks across the globe are averaged together, PARCS will truly be the Primary timepiece of the world.

 

Why is this important to Geocachers? Navigation is distance and time! Each of the 24 satellites has2 to 4 atomic clocks on board. One nanosecond of error (one billionth of a second) equals 1 foot of error in a GPS. One reason for error in your GPS is the fact that your receiver’s clock cannot match the accuracy of the satellite’s atomic clock. Still, due to the technology you hold in your hand, your GPS display is accurate to about 1/10th of a second and it’s internal clock is accurate to within a few nanoseconds (satellites update your GPS to this accuracy every 12.5 mins). Consider the technological power you hold in your hand. Think about how it works.

 

In 1971 two scientists borrowed four atomic clocks from the Naval Observatory and flew them east and west around the globe. Comparing these atomic clocks with those left behind on the ground showed that those flying East experienced a slowing of time equal to 59 nanoseconds, and those flying west had time slow for them by 273 nanoseconds, the difference being caused by the fact that the Earth is rotating to the East.

 

[Kerry.]

EraSeek, just a quick one with the time or more imortantly the timing. The internal time in all receivers is basically just to tell the time.

 

The actual timing is one of the computed unknowns in the position solution. That why one needs a minimum of 3 sats for a 2D solution to calculate the 3 unknowns (XY & Time), similer with a 3D solution requires a min of 4 sats to calc XYZ & time.

 

Very simple soultion to a complex problem and certainly keeps the cost of receivers to a minimum.

 

Cheers, Kerry.

 

I never get lost everybody keeps telling me where to go

[Kerry.]

EraSeek, just a quick one with the time or more imortantly the timing. The internal time in all receivers is basically just to tell the time.

 

The actual timing is one of the computed unknowns in the position solution. That why one needs a minimum of 3 sats for a 2D solution to calculate the 3 unknowns (XY & Time), similer with a 3D solution requires a min of 4 sats to calc XYZ & time.

 

Very simple soultion to a complex problem and certainly keeps the cost of receivers to a minimum.

 

Cheers, Kerry.

 

I never get lost everybody keeps telling me where to go

[+apersson850]

Let's now leave the marketing people on their own for a while.

Isn't it really so, that part of the WAAS idea is to provide better integrity to the system? That is, quickly being able to determine that the system is operational as it should, or that it isn't, for some reason. The latter case could of course be fatal, to say the least, if used by an airplane for some kind of precision flying (like hitting a runway).

 

In the conditions and environments where caches usually are hidden, I doubt WAAS will increase real accuracy to that extent, that it will ruin this game. By always showing you exactly to the correct point, I mean. Maybe if they get some artificial intelligence into the units, to implement the "I think I know what the cache hider thought about" function...

 

Anders

[Kerry.]

Integrity, yes much more to do with integrity and safety-of-life type issues than purely accuarcy. It's all about "knowing" what the accuracy should be with appropriate warnings when outside limits.

 

I believe the current aviation guidelines in the U.S requires reception of warnings in 6 seconds or less (any pilots?). WAAS takes 5 seconds to process and broadcast the data from 27 ground stations so things are fairly tight.

 

Cheers, Kerry.

 

I never get lost everybody keeps telling me where to go

[Kerry.]

Integrity, yes much more to do with integrity and safety-of-life type issues than purely accuarcy. It's all about "knowing" what the accuracy should be with appropriate warnings when outside limits.

 

I believe the current aviation guidelines in the U.S requires reception of warnings in 6 seconds or less (any pilots?). WAAS takes 5 seconds to process and broadcast the data from 27 ground stations so things are fairly tight.

 

Cheers, Kerry.

 

I never get lost everybody keeps telling me where to go

[+BletchleyPark]

quote:

---

Originally posted by Prime Suspect:

Nowhere in your original message do I see any mention of how many satellites you had collected WAAS data on. On the few occasions where I've gotten WAAS data on all satellites I have a lock on, my "accuracy" reading is typically in the 5' to 10' range. Your double-digit readings lead me to believe that you never collected WAAS data on all the usable satellites.

---

 

Alas, I apologize. I did not record how many of the 8/9 satellites showed a "D" in the signal strength bars. Quite a blatant omission, I must admit . If my memory serves me correctly (a statistical probably that has been reduced substantially since the big 5-O) I did get "D"s on most (if not all) of the available satellites.

 

I feel compelled to retest with more samples and greater care to detail. Please let me know if there are other data that would be helpful to report from the test.

 

Again, my apologies.

 

BP

[+BletchleyPark]

quote:

---

Originally posted by Prime Suspect:

Nowhere in your original message do I see any mention of how many satellites you had collected WAAS data on. On the few occasions where I've gotten WAAS data on all satellites I have a lock on, my "accuracy" reading is typically in the 5' to 10' range. Your double-digit readings lead me to believe that you never collected WAAS data on all the usable satellites.

---

 

Alas, I apologize. I did not record how many of the 8/9 satellites showed a "D" in the signal strength bars. Quite a blatant omission, I must admit . If my memory serves me correctly (a statistical probably that has been reduced substantially since the big 5-O) I did get "D"s on most (if not all) of the available satellites.

 

I feel compelled to retest with more samples and greater care to detail. Please let me know if there are other data that would be helpful to report from the test.

 

Again, my apologies.

 

BP