I know this belongs in another category, but the original Alaska post resides here. The discussion here is not to questions PLSS surveying techniques but GNSS surveying itself.
Alaska has in excess of 100 CORS sites, mostly in certain well developed areas. There are 8 rather large gaps in the balance of the state. In most states with a network of CORS the majority are state funded projects. From my quick observation 90% of the Alaska CORS sites are run by UNAVCO who are interested in tectonic movement. Of all those CORS, only 5 are GNSS capable (GPS and Glonass). One is operated by UNAVCO, 2 by Alaska DOT and 2 by a surveyors group. There are also 2 suitable Canadian GNSS CORS near the Alaskan border.
Alaska's problem with GPS surveying is not with the BLM but with Alaska itself. Alaska needs to step to the plate by funding CORS GNSS stations starting in the gaps and then replacing existing CORS with GNSS receivers and antennas.
What is required of the US is to update/replace pages (OPUS) and/or rsgps (OPUS-RS). This has to be fully GNSS capable, GPS (L1/L2/L5 plus WAAS ranging), Glonass, Galileo (plus EGNOS ranging), Compass as well as geosynchronous SBAS satellites. It is my understanding that all current WAAS satellites are broadcasting L1 & L5 signals. That means an L1/L5 ranging solution is possible, whether or not other L5 data is used.
This program could actually be an Alaska only CORS/OPUS-GNSS, which can later be fully US deployed.
Paul in PA
Paul in PA, post: 405813, member: 236 wrote: This program could actually be an Alaska only CORS/OPUS-GNSS, which can later be fully US
And Javad's DPOS as well.
N
Paul,
Thanks for the post. This is a very important topic. The Surveying and Professional GIS folks up here would agree 100% with your quick assessment. Our surveyors are the best in the business (personal bias - sorry) with making do with what they got.
I'll add to our "problem list". A geographical hindrance to line of sight to Geosynchronous augmentation so prevalent down in lower 48. Completely write us off for Omnistar and the like. Same for lack of cellular and RTN in the vast majority of AK. The one shining star... WAAS. WAAS has been our one augmentation where we got things right - due to our preponderance of aircraft. Given constraints with low horizon, we make up for that with our 7 WAAS Ground stations. I can reliably get 0.5 meter realtime with appropriate gear and proper datum shifting. - but again, all GS were put in with GPS only. Same with our PBO sites that make up the bulk of adopted CORS. Then, we had a fight with the US Coast Guard last November who wanted to pull 6 of our longest running NDGPS sites down for "lack of need". We temporarily won that battle when the user community from all facets of life (high speed ferries in SouthEast) prevented a loss of 14% of our network at the time. We still have not solved the matter you mentioned - support for the sites to even maintain them with the eventual trimming of site support from UNAVCO in 2018. No one has stepped up to the plate.
Anne Johnson's (AKDNR) arcgis online map was made to map this threatened CORS space around us. http://www.arcgis.com/home/webmap/viewer.html?webmap=f37ae9d2802349d5895441ee04ac0cc0
Joel
Joel,
One of the things I was thinking of last night for my every other Township GPSable monument was that an easement be created prior to transferring of 200' N, E, W & 400' S, that it be cleared and suitable for helicopter use and open up skyview in any forested areas.
Paul in PA
I would argue that this discussion should be decoupled with the other thread. Both are absolutely great discussions, but about different policy issues.
My issue in the other thread is the legal foundation of the boundaries themselves. Transitioning from evidence and law to a math foundation is short sighted.
On this issue, the State needs to fund what benefits the State. What is the compelling State interest in den sifting CORS? I'm certainly not saying one does not exist. I'm saying you need to articulate that need to the agencies and entities that can do something, then walk it through your legislature. That's how it gets done...
Paul in PA, post: 405841, member: 236 wrote: Joel,
One of the things I was thinking of last night for my every other Township GPSable monument was that an easement be created prior to transferring of 200' N, E, W & 400' S, that it be cleared and suitable for helicopter use and open up skyview in any forested areas.
Paul in PA
Not a bad idea in theory. However flying heavy equipment in and out can get expensive and a logistic nightmare.
The only real problem with using GPS for boundary work in Alaska is knowing which CORS are moving quickly and which are not. Maybe if you need higher accuracy you will have trouble with the lack of CORS, but who really cares if their property is shifted a couple of cm with respect to some distant reference point? No land owner I ever met.
