Has anybody tested their Apple watch against a published NGS point?
I was reading the specs and was pretty impressed.
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Made with aerospace-grade titanium for the perfect balance between weight, ruggedness, and corrosion resistance. Case designed with raised edges to protect the flat sapphire front crystal from edge impacts. Super rugged to withstand the elements.
Features
- L1 and L5 GPS, GLONASS, Galileo, QZSS, and BeiDou "
How long before we can use them as a virtual base station for survey grade results??
no L2 or L2c?
why not????
I don't know... maybe chip availability, cost or size??
Isn't L5 more robust than L2C? Better signal design and higher power/bandwidth?
Probably provides the most bang for their buck.
@rover83 L5 vs L2C. Lots of mis information on these. L5 was designed specifically for emergencies on the gps constellation for people who fly ambulance firemen police etc etc. L2c was designed for civilian use and to be how do i say this a little louder and more clear than our older L2 signal. Now manufacturers do many things outside of that design so some are using parts of the L5 band because of its robustness to aid in the canopy etc. L5 is really what aids us more than anything on getting into the trees and hostile environments. If you want you can test this. Not all satellites gps have the L5. Yet determine which ones do and which ones do not and observe the snrs rms values at a point with and without the L5 being in the constellation. Not all sats gps have L2c yet either. We still have some old birds floating around. I have not done this test only through a controlled environment of reading these years ago when it was still being developed fyi. So I might be off it has been a bit since i wore a different hat.
I use trimble so i read more on it in recent work. Take for instance the t04 file trimble is doing spectrum read. Which they probably have bounds set which allows it to hear everything in a certain range then the firmware can isolate what frequencies and messages it needs. All of the data is in the t04 file even bleed overs that are not necessarily gps signals fyi. This is not a bad approach at all. I believe javad does something a little similar but they allow a little more isolation and focus which is why they did so well in canopies before others could. Trimble had to play a little catch up with javad. Or it was just a business decision who knows. As they say no secrets anywhere really. L5 also if used correctly helps to detect multipath and such much better if the firmware or algorithms are set and it can for example cross ck the other signals better. The more satellites help one of the biggest reasons is time we can use a partial good signal from a different satellite to solve for time and throw out anything else. So the faster processor have allowed this to happen. Time is what gets us our accuracy hands down. If we could tote a cesium and rubidium along with us and could perform clock stearing in realtme we would not even have to post process or do rtk. Our absolute position would be golden. Rtk kinda approaches the clock biases of our reciever clocks and the satellite clocks. Which some have different clocks. All of this for gps is monitored and corrected for daily weekly monthly and yearly. The clocks on satellites themselves and at the monitor stations. Tied to usno
FWIW. Living in a newly developed area there aren’t any NGS points with horizontal control nearby. I have not searched for any to test the watch.
That said, even with the multiple constellations used there remains the issue of the accuracy of an unaugmented point positioning solution. Without use of precise ephemerides, SV positions are not accurate enough for high-accuracy positioning, unresolved clock errors remain, tropo and iono errors remain.
Looking at the display on my watch shows five decimal place latitudes and four decimal place longitudes. I don’t know why different levels are used. The displayed values translated to DMS indicate decimeter level results. My unit shows heights as approximate with the display showing values to the nearest foot.
Overall, I am only about 60% satisfied with the watch. It replaced a Fitbit fitness tracker that did not require much in the way of interaction.
Shortly after buying the watch on a trip to Honolulu in March I hiked to the top of Diamondhead. Somehow the watch failed to log the segment from the park entrance to the top. It did keep track of my depth while snorkeling. It has a nifty feature to purge water from the watch. Sometimes I have to purge water after a shower.
BTW, it is still required to reserve a spot to enter the park.Cost for hikers is $5 plus taxes and fees. Last year’s trip, I walked from my Waikiki hotel to the park only to be turned away as I did not have a reservation.
@geeoddmike Yes, of course those issues are critical.
I think I was interested as the watch now has it's own GPS chips, and isn't just getting location data from a linked iphone.
Thanks for the Hawaii info, I'll pass that along to my daughter. She's there for 3 months for work!
It took me fifteen years to finally make it to Hawaii for work. Like most old timers, I recall the “old days” and lament the changes. Especially the astronomical increases in housing prices and horrible traffic.
I expect you daughter will enjoy her stay. Hawaiian Airlines does have $49 fares between Islands. The other Islands provide a much mellower experience.
I try to visit the Islands yearly, missing the Covid years and when traveling overseas. I try to keep track of my increasing decrepitude by comparing my times climbing Diamond Head. I’m glad the stairway is no longer the only way to the top.
For me Hanauma Bay is another must see on Oahu. Reservations are also required. See: https://hanaumabaystatepark.com/frequently-asked-questions/#1618023625287-43ac6360-1d6d Note that if she has a Hawaii driving license or military ID entrance is free.
Excuse the lengthy reminiscences…
Seems you would need some sort of external antenna either hardwired or maybe bluetooth for better precision???
I think the new iPhone Pro's have the same GNSS specs? Maybe external antenna connected via cable?
As for hitting a NGS monument. Well i don’t have a Apple Watch but I imagine its on wgs84 not nad 83. So irtf positions would be closer. Depending on where you are. Now it is autonomous but I would bet that since many cell towers are positioned or supposed to be positioned in the usa on nad 83 they also use those and some biases to pull it somewhere in between the two. But I would imagine it also matches google earth or apple’s version of there maps ok. As they rely heavily on the maps vs the position which creates another issue. I know i had a crew chief that has some hunter app with boundaries on it and we hit literally on a few property corners once the size of his phone. Now same parcel it was off 20 feet on the rest. But hey we were having fun. I believe some day and hate to say this but if the survey work is done correctly and the county or city uses the information correctly then someone someday will be able to walk to there property corners and be spot on. Now that’s only to the fixed monuments of course as streams rivers etc will change overtime if that is the boundary. We as surveyors being historically the king of measurements is being taken over through technology. And those who came before us that took pride and discipline in doing it right. Its those who have laid that foundation that technology could be built to do what is being done today. I mean the gps constellation was designed and launched and working under those who used slide rules and understood the math and science we are using today. Yes we can now get to a few centimeters absolute accuracy anywhere in the world relative to almost any datum in very little time. We can achieve relative accuracy to less than that in minutes. I mean those before us where some very smart cookies. Yall in the plss states. Some of those ranges and townships and sections are amazingly the very distance we measure today and directions. Yes some are off 50ft but some are off for measuring issues and some are off for incompetence or greed or whatever laziness. But i can remember tying down some original corners in Colorado that were so tight that i was amazed that they pulled a chain and i was using fast static gps and not much difference. Not enough to even get worked up about. I am loving and hating a particular job i am on now. All boundaries that have little to do with measuring or math. I mean we are retracing almost purely on deeds that had no measurable statements and whats left boils almost down to possession evidence and parole evidence. Someone who started in land surveying then to geodetic surveying now back to this. It makes me happier than a puppy with two peters lol. I am loving it so much. I am sure the bean counters above me do not enjoy my delight but this is what land surveying is all about. Good thing i am semi retired because i will be fired if all i did was these lol.
This website has some really interesting stuff. I'm enjoying it.
Image copied from the PDF file version published by the University of New Brunswick, Canada as Lecture Note 58. Print version published in 1986. Dr Ben Remondi used this as his text in a course I took in the mid-1990s. Still a good reference.
Wells, D. E., N. Beck, D. Delikaraoglou, A. Kleusberg, E. J. Krakiwsky, G. Lachapelle, R. B. Langley, M. Nakiboglu, K. P. Schwarz, J. M. Tranquilla, and P. Vanicek (1986). Guide to GPS Positioning. Department of Geodesy and Geomatics Engineering Lecture Note No. 58, University of New Bnmswick(sic), Fredericton, New Brunswick, Canada, 291 pp.
From the same reference:
@geeoddmike Love it! That's awesome and heavy! 55 pounds ?
Looking at the display on my watch shows five decimal place latitudes and four decimal place longitudes.
I have an Apple Watch 5 and through the "compass" complication both Lat/Long are displayed to 5 places. I haven't a clue as to which constellation it uses.
Waiting for the Apple 10 watch (2025) which is predicted to have blood pressure reading capabilities.
