Being a actuality who enjoys spending time in the acreage application RTK and DGPS, I followed up on my cavalcade aftermost month, “Sources of Public, Real-time, High-Precision Corrections,” with a cruise to the acreage to assay the NGS CORS Alive service. About a ages ago, I fabricated a cruise to Colorado to appear the Amplitude Acclimate Branch in Boulder, stop by the SPAR appointment in Colorado Springs, and appointment with some of my colleagues in the Denver area.
When I acclimatized in Denver, my plan was to accommodated Tim Smith (GPS Coordinator for the U.S. National Park Service) and biking to the Bakerville GPS assay armpit in the Rocky Mountains, which was at about ~11,000 anxiety in elevation. My absorbed was to assay the CORS Alive and PBO real-time alive that I discussed aftermost ages to bigger accept the accurateness and believability of those services.
I acclimatized at the Denver airport aboriginal on a Monday attainable to bedrock and aeon into the Rockies with some high-precision GNSS equipment. As it angry out, I was denied. In Colorado, the acclimate is dynamic. It was bound aspersing back I acclimatized in Denver. Snow was absolutely in my approaching for the aing few days. Tim fabricated the accommodation that we shouldn’t travel to Bakerville. The acumen for Tim’s trepidation wasn’t necessarily due to the acclimate in Bakerville, but rather that the I-70 Interstate ability about-face into a parking lot and we’d be ashore in cartage for a few hours. Fair enough. The advancement plan was to do some bounded testing in the parking lot adjoining to Tim’s appointment in Denver.
Tim arrive Mel Philbrook to accompany us. Mel is a adept GNSS technologist who works for the bounded Trimble dealer. He brought an SUV abounding of Trimble GNSS equipment, including one of the new R10 GNSS units as able-bodied as a GeoXH handheld with an alien antenna.
Mel additionally had an Intuicom RTK Bridge in the block of his SUV that facilitated the altered sources of RTK advertence abstracts we could use. He could about-face from CORS Alive to the bounded VRS via NTRIP to UHF at the cast of a switch, sending corrections to both the R10 and the GeoXH. I was decidedly absorbed in seeing how the units performed application CORS Streaming, which is/was a chargeless RTK account (single baseline) that was in beta assay phase. In Oregon, I don’t accept admission to CORS Alive because the alone CORS Alive abject west of the Mississippi River is in Boulder, Colorado. The abject is TMGO (Table Mountain CORS).
The baseline ambit from TMGO to our breadth was about 55 km. The R10 was advertisement a accumbent attention of about 4 cm. Not bad for a 55-km baseline. I didn’t analyze the after-effects to a assay mark (shame on me, but accumulate account because I get to that) so I’m dupe the R10’s attention estimate. Tim said he’s run the assay afore application a GeoXH and a best baseline and saw sub 10-cm accumbent precision. It’s not what the archetypal actuality application abbreviate baseline or RTK arrangement is acclimatized to, but for the high-precision GIS user who’s mapping utility, transportation, and infrastructure, that’s appealing abuse good.
Tim, Mel and I spent an hour or so messing about with the accessories afore packing it up. Not a absolute authentic study, but it accepted that CORS Alive was attainable via NTRIP and analytic accurate.
In the meantime, the snow wasn’t letting up. This is the appearance as I was abrogation Tim’s appointment to arch to Boulder for the Amplitude Acclimate Workshop:
I wasn’t accomplished with my CORS Alive testing yet. My acquaintance at Tim’s appointment gave me abundant aplomb to admeasure time afterwards in the anniversary to conduct a added abundant assay afterwards the Amplitude Acclimate Workshop. Hopefully, the acclimate would abet (call me a capricious acreage guy).
Space Acclimate Workshop
Every April, NOAA’s Amplitude Acclimate Prediction Center in Boulder hosts the Amplitude Acclimate Branch (SWW), a acquisition that has acquired into the arch appointment in the U.S. for amplitude weather-related topics. It attracts attendees, experts and speakers from all over the world. The altercation isn’t centered on GNSS, but GNSS absolutely is a affair that is discussed. This year’s axial affair was the electric ability grid. You can appearance the SWW affairs here.
Believe it or not, this ages (May 2013) was the predicted “solar maximum” for the accepted solar aeon (Solar Aeon 24, an 11-year cycle). However, Solar Aeon 24 has been accidentally weak. See the afterward accelerate presented by Doug Bisecker of the Amplitude Acclimate Prediction Center. Doug is the Chairman of the Solar Aeon 24 Prediction Panel. His question, “Is there any adventitious we can still deliver some respectability?” speaks volumes about the adversity in admiration amplitude weather.
From the above, you can see the absolute cardinal of sun atom accident has been decidedly beneath than predicted. Although sun spots aren’t what account GNSS receivers to accept problems, sun spots can announce the bulk of solar activity, which can be accompanying to geomagnetic storms. Geomagnetic storms afflict the ionosphere and are the contest that account the best problems for GNSS receivers. Looking at the top blueprint above, you can see the aberration in activity amid the aftermost solar best (peaked in aboriginal 2002) and today. The aberration is acutely significant.
Does this beggarly we, the high-precision GNSS users, get a chargeless canyon on Solar Aeon 24?
Not at all.
Historically speaking, the best acute geomagnetic storms (e.g., Oct/Nov 2002) accept occurred afterwards the solar best so our acuteness to this affair should be agog for the aing two years. Furthermore, there are orders of consequence added high-precision GNSS receivers actuality acclimated than anytime before, and in mission-critical applications such as auto-steer in apparatus ascendancy (agriculture, construction, etc.). Best GNSS high-precision users today haven’t accomplished the furnishings of an acute geomagnetic storm. For a abbreviate album on the furnishings of solar activity on GNSS/GPS, you ability appetite to booty a attending at this commodity I wrote in 2008 as able-bodied Richard Langley’s 2011 Innovation cavalcade “GNSS and the Ionosphere.” In accession to the content, they both accommodate some admired links to accordant articles.
In band with a ambition of the workshop, a console of GNSS professionals looked at issues that users face as they go about their business at solar max. The console was “Global Aeronautics Accessory Arrangement (GNSS) Services: Analysis Bare to Fill Operational Gaps.” Joe Kunches (SWPC) chastened the console that included Dr. Geoff Crowley (Astra), Dr. Anthea Coster (MIT), Capt. Steven Miller (USAF) and myself. We accent attention GNSS, accessory aeronautics for bartering aerodynamics (ADS-B), and accepted assignment to bigger accept the errors the ionosphere imposes on user activities.
Something abroad I abstruse at the appointment was how boxy ionospheric blaze is on GNSS receivers in Brazil. I feel for those users. Back I mentioned I was traveling to Chile for an RTK project, the scientists said it is worse in Chile than the U.S., but still not as bad as Brazil. I’ll be absolute absorbed to acquaintance how altered it is than the U.S. (or added genitalia of the apple breadth I’ve traveled).
I accumulate a appealing aing eye on amplitude acclimate and in acquaintance with NOAA’s Amplitude Acclimate Prediction Center. Back I apprehend of a amplitude acclimate accident that may affect high-precision GNSS/GPS receivers, I accelerate out a Tweet with the hashtag #SolarActivity. You can chase me on Twitter at https://twitter.com/GPSGIS_Eric.
From Amplitude Acclimate Back to Bounded Weather
As the anniversary progressed during the Amplitude Acclimate Workshop, the snow continued. Boulder looked like Christmas in April.
I absolutely capital to absorb some added time in the acreage to assay the accurateness of the NGS’s CORS Alive account and I was active out of time. In adjustment to achieve the assay the way I wanted, I bare to acquisition a bounded NGS assay mark that was empiric application GPS. I arrested out the NGS assay mark database and got lucky. There was one (PID = KK2060) amid on a angle point parking breadth off of Highway 36 on the way from my auberge to the Amplitude Acclimate Workshop. I couldn’t accept asked for a bigger or added acceptable assay mark location. I was planning to use a Bluetooth GNSS receiver so I could absolutely aggregate abstracts while sitting in my car.
On Thursday morning, Mother Nature austere her skies for me so I collection to the angle point. Remember, there’s a brace of anxiety of snow on the ground, so I was absolutely acquisitive to see some affectionate of copse lathe that would get me aing to the assay mark (no, I didn’t preload the KK2060 coords in my GPS L). Fortunately, a copse pale was a the assay mark. However, I didn’t accept a advertise or a metal detector so it was either application my easily to advertise and chase beneath two anxiety of snow for the mark, or…thanks to the rental car company, the car came with a healthy-sized windshield scraper. Afterwards 15 account of digging in the snow with a windshield scraper, I begin KK2060. I’m abiding to the bodies anchored on the angle adequate the view; I looked absolute apprehensive application a windshield scraper to dig a aperture in the snow. I wouldn’t accept been afraid if a accompaniment trooper had apparent up.
My final claiming was…no tripod or tribrach. I biking ablaze and didn’t appetite to backpack a set and, of course, I forgot to ask Tim if I could borrow a set. It’s never a acceptable abstraction to set a GNSS antenna anon on the ground, but the antenna was baby (<3” in diameter) and I did accept a 5” bore arena even with about a 1” post. I was able to abode it over the assay mark with reasonable confidence.
As I mentioned before, I was application a Bluetooth GNSS receiver (GPS L1/L2, GLONASS), the SXBlue III GNSS.
To aggregate the data, I was application an SXPad handheld with an AT&T SIM agenda for the Internet connection. For data-collection software, I acclimated VisualGPSce, a chargeless GPS data-collection affairs that collects and displays raw NMEA data. Although it doesn’t affectation abundant digits of attention for the accumbent position, it accomplishes the simple assignment of accession NMEA-formatted abstracts afterwards applying any transformation so I get the raw NMEA-formatted abstracts from the receiver. It additionally displays some advantageous advice such as PDOP, RTK indicator and elevation.
The aftermost allotment of data-collection software I acclimated was a chargeless NTRIP applicant software accounting by the SXBlue bodies alleged SXBlue RTN. I bare an NTRIP applicant software to admission the CORS Alive arise point. The software manages the IP address, anchorage and login/pwd of the CORS Alive system.
Logging into the NGS CORS Alive armpit was painless, and aural a few abnormal I had an RTK FIXed position from the GNSS receiver, all from the abundance of my rental car, acknowledgment to all-embracing Bluetooth. I calm ~45 account of NMEA abstracts (1-Hz abstracts rate) afterwards interruption.
When I alternate to the office, I began the activity of comparing the after-effects from CORS Alive to the NGS assay mark coordinate. I arrested with NGS and they appear that CORS Alive is referenced to the ITRF00 (epoch 1997.0) datum. The KK2060 alike is appear in NAD83/2011 (epoch 2010.0). I bare to accommodate the accomplishment aberration afore assuming any assay so I acclimated the NGS HTDP (Horizontal Time Dependent Positioning) online apparatus to achieve this.
Finally, I acclimated NMEA Analyzer (custom-built software for assuming statistical assay on GNSS NMEA abstracts to NSSDA accumbent accurateness standards) to account accurateness (not precision) ethics of the data. I set up the NMEA Analyzer software to about baddest 200 epochs out of the ~2,700 calm to abate any bent due to clarification or added receiver “tricks”. Afterward are the accumbent results:
Not bad for an antenna sitting on the arena and an 18-km baseline application a $6,000 GNSS receiver and a chargeless RTK abject station. Folks, this is the administration that GNSS technology is heading. The connected admeasurement of high-precision GNSS basement (RTK networks, real-time PPP, etc.) and the falling prices of RTK GNSS receivers will badly access the availability of high-precision technology to those who ahead could not allow to accomplish the investment.
I didn’t get a adventitious to assay the PBO real-time alive while I was in Colorado, but auspiciously there are abounding PBO real-time stations that I can assay from the abundance of my home appointment actuality in Oregon. In fact, there are so abounding in Oregon and Washington that I can assay abounding altered baseline distances to accept what accurateness users can expect. Attending for my assay after-effects on that ancient this summer.
National Geodetic Assay (NGS) Suffering
Only a anniversary afterwards I did my acreage assay of NGS’ CORS Alive arrangement in Colorado, NGS appear it was shutting bottomward the CORS Alive account able April 26. On April 23, NGS issued the afterward apprehension by email:
The National Geodetic Survey’s ancestor Real Time GNSS Abstracts Account (Streaming CORS) will be discontinued able April 26, 2013. The ancestor was alien a few years ago as a baby analysis activity to barometer absorption and acceptance as able-bodied as assay a affidavit of abstraction with the RTCM communities. However, due to low acceptance of this ancestor account and agents limitations aural the National Geodetic Survey, we accept absitively to abandon the prototype. There were abounding accidental factors that advance to this accommodation but the afterward contempo alternation of contest has had a cogent appulse on activity abutment and operations:
If you accept any questions or comments to share, amuse acquaintance Neil Weston at 301-713-3191 or by email – [email protected]
I anticipate the activity was premature. Hardly anyone knew about the CORS Alive account and it was alone deployed in a baby cardinal of locations, which was not abundant to awning a cogent geographic breadth or above busline areas.
Nonetheless, I anticipate this activity credibility to bigger problems at the NGS. To all of us in the U.S. (and those in added countries), the NGS has been a amazing antecedent of GNSS abstruse expertise, articles and services. The botheration is that they are accident ability at a faster amount than they are gaining. Just in the accomplished few months, Dave Doyle and Bill Henning accept both retired. Those two were a big allotment of the NGS user association beat “boots on the ground” effort.
Furthermore, as the apprehension indicates, NGS’s alone “real-time expert” (Bill Henning) is now retired. That’s a problem. As real-time, high-precision GNSS is accepting absorption bound in industries above analysis and engineering, the assets for NGS to abutment this trend should additionally expand, not contract. On the added hand, the use of GNSS post-processing is not increasing, yet NGS has endless of assets allocated to abutment post-processing. As technology trends shift, assets charge to be redistributed in alignment with those trends.
The Approaching of NDGPS Open for Accessible Comment
The U.S. NDGPS affairs is on the chopping block again. However, this time it’s abundant added serious. The aftermost time this affair apparent was in 2007 back allotment for some of the NDGPS sites was actuality threatened. At that time, alone some of the civil sites were adverse decommissioning. The U.S. Coast Guard DGPS allotment of NDGPS was safe and funded.
However, that’s not the case this time. Even the U.S. Coast Guard is starting to catechism the amount of the DGPS arrangement it created and has been application for added than 15 years. The FAA’s WAAS (Wide Breadth Augmentation System) has accurate to be a applicable another to NDGPS and is acclimated by bags of action mariners and bartering abyssal pilot associations beyond the U.S., as able-bodied as high-precision users in GIS and surveying/engineering. To added complicate the issue, the use of GLONASS is not accurate by NDGPS. Like what we’ve apparent in high-precision surveying/engineering receivers, GLONASS is acceptable an important affection in receivers acclimated by bartering mariners who accept to accord with area and structures that impede accessory visibility. Even admitting WAAS doesn’t abutment GLONASS, some newer GNSS receivers are able to accommodate GLONASS abstracts into the WAAS solution, added accretion the amount of WAAS over NDGPS.
It’s acceptable that you aren’t an NDGPS user, but you ability still be afflicted if the NDGPS is decommissioned. There are a absolute of 86 NDGPS stations beyond the Continental U.S., Alaska and Hawaii. As able-bodied as actuality NDGPS arresting broadcasters, they are additionally allotment of the NGS CORS affairs that is acclimated by the NGS’s OPUS online post-processing service. If you are application OPUS or NGS CORS for post-processing, you ability be application NDGPS CORS abstracts and not apprehend it. Afterward is a map of all NDGPS stations in the U.S.:
If you’re absorbed in account an account from the U.S. Coast Guard and Department of Busline about the appeal for accessible animadversion and appointment a comment, bang here. To be considered, comments charge be submitted by July 15.
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