Fellow BeerLeggers (aka SurveyConnect Forum readers)
Last week I posted this:
OPUS - Understanding the Results (Land Surveying)
by Geezer @, OREGON
I did not understand why the results I got with the "X-90 OPUS" GPS unit did not agree with the coordinates I got from a 20k RTK unit.
First, I thank all that replied. I learned a lot, and am very grateful.
As in so many cases, the problem was my uneducated attempt to compare two things based on the assumption that they should be the same.
As was pointed out by several, but most pointedly by Ken Bays, Mark Silver, and others, there might have been a "datum shift" between the two observations. Indeed there was! The first results by the 20k unit, were observed in 2010. I adjusted those coordinates by the amount of shift in my area and the results were favorable. Not being satisfied with that, I re-observed the two points with the 20k unit.
WOW!!!! The re-observed results of the 20k unit was only 0.04' in Northing, and 0.03' in Easting from my "X-90 OPUS" 15 minute observation.
I am very impressed with the "X-90 OPUS" unit and agree totally with the write up given it in the recent edition of GPS World. 🙂 🙂 🙂
Again, thanx to all,
Geezer
Mr. Geezer: What is an X 90 OPUS unit? and did you compare vertical results? I'm sort of shopping for a low investment entry level GPS.....
I had breakfast with Mark last Saturday morning when he passed through town. We discussed the X-90 in great detail, and then played around with one out in the parking lot for awhile.
A VERY impressive unit that appears to be rugged and well constructed. Considering the beautiful padded case, a complete set of batteries, chargers, cables, etc., it's a STEAL.
We discussed maybe running some “real-world” tests in the near future, but more as an excuse to have a few beers in boonies, than to really prove anything we don't already know.
Here's a link to the GPS World article:
http://www.gpsworld.com/a-new-standard-for-l1l2-gps-static-receivers/
Here's a link to Mark's site:
Loyal
www.igage.com/out/ms/2lance/X90-OPUS.pdf?
If that doesn't get you there, google "X90-OPUS"
This unit is fantastic, for as much as what it does NOT do as for what it DOES do.
It DOES give you quality (at the cm level) positions from NGS OPUS
It DOES NOT break your bank account (I believe price is about $2500)
It DOES NOT require one to be a sophixticated compuyter guru (no offense to anyone who is)to operate it.
Although there are two buttons that you could push if you want to, I used one never pushed more than one - One button push to turn it on - and the same button push to turn it off.
It automatically stored, formatted the data in rinex format - ready for submittal to NGS OPUS.
You will do yourself a favor if you read the write up in GPS World.
I have no pony in the show, but I would highly recommend this unit.
Geezer
> I had breakfast with Mark last Saturday morning when he passed through town. We discussed the X-90 in great detail, and then played around with one out in the parking lot for awhile.
>
> A VERY impressive unit that appears to be rugged and well constructed. Considering the beautiful padded case, a complete set of batteries, chargers, cables, etc., it's a STEAL.
>
> We discussed maybe running some “real-world” tests in the near future, but more as an excuse to have a few beers in boonies, than to really prove anything we don't already know.
That's a fairly cool piece of equipment. I assume that a pair of them are capable of generating RINEX files that can be processed to give the vector between two stations, as well (if you have the post-processing software to do it) or is there something about the hardware design that prevents that?
Kent
It can (and will) generate a standard RINEX file, and for all practical (STATIC) purposes, is the same as any other GPS Receiver.
Two or three (or more) of these babies and you are in the NETWORK Business.
Loyal
Loyal
If it's just turn on and off can you input the station name and the antenna height when you do the observation so it's part of the obs file? I suppose that's not a deal killer but it's what I'm used to doing with my 4700's. Not a real big deal to keep that info in another device but having it in the file from the beginning is better. Maybe a smart phone app could be used for that purpose with a USB cable.
Kent
> It can (and will) generate a standard RINEX file, and for all practical (STATIC) purposes, is the same as any other GPS Receiver.
>
> Two or three (or more) of these babies and you are in the NETWORK Business.
Yeah, I'd want three for land surveying, one for a base and two for occupying pairs of control points at the same time. I'll be very interested to hear what your opinion is after seeing the hardware in action. I used my L1-only 4600LS units quite a bit without a DC/controller, so I know how simple it is just to keep a field book record of what was occupied when and enter that when the files are imported for post-processing.
Leon & Kent
I don't believe that you can INPUT Station, HI, etc. data into the unit in 'real-time.' When you export the binary file and create the RINEX file, you can enter a Station/Marker/whatever, Point Number, and/or edit the Height of the ARP if you are not using a standard 2 meter fixed height rod.
The unit defaults to 5 second epochs, but you can change that if you wish, and of course decimate the RINEX file to whatever you wish when you create it.
Loyal
Can I use it for PPK ?
Any reason I couldn't use one for PPK ?
Time to trade in the Leica 1200 for about ten of these units and a Wild T-0.
Can I use it for PPK ?
I would think you could use them for PPK base station but you would need a rover and controller.
Can I use it for PPK ?
I was thinking, turn it on and collect PPK, output a RINEX and have the post processing software extract points from the static intervals. Use the WSRN for base station data.
Can I use it for PPK ?
Yes/No, The X90-OPUS will work great as the base (as it was designed). There is another unit(a bit more in $, called the "X90+") that can be used for the PPK rover (has BT) with a data collector. You'd need your own or CHC's post processing software.
The iGage unit was designed to make OPUS work so easy that anybody can do it (and do it correctly). I really loved how the unit appears as a drive letter on your computer without having to install any software what so ever.
Thinking about large static observations to support aerial photogrammetry, could put 10 of these units out all at the same time for less cost than a single high-end RTK rover!