Dirt Talk: Can You Trust a Real-Time GPS Network?
June 2, 2009
Real-time GPS networks are rapidly proliferating across the country. Site Prep started reporting on this technology model back in 2007; today, the trend to use these networks for machine control applications appears to be growing.
Our current quick poll on is showing an increasing number of contractors subscribe to these networks, and one of our feature articles last month detailed the benefits of such a subscription (click to read From Farm to Fairground).
Last week I was surprised during a conversation I had with a very progressive contractor to find out that he wasn't interested in subscribing to a real-time network. He said, "It might be [useful] at some point, but I have to give up the control. If it goes down, what do I do?
His comment sparked my interest, and I wanted to open up this topic for more discussion. So, my question to users of real-time networks is: what has your experience been with this technology? What are the advantages? Disadvantages? If you currently subscribe to one of these networks in your region, has it gone down on you? Do you have a backup for this handling this situation? Do the advantages of subscribing to a real-time network outweigh the disadvantages?
And my question to nonusers is: why haven't you jumped on the bandwagon? Do you want to retain control of your base stations, or are you not interested in paying the subscription fees? What else plays a factor in your decision?
Please post your comments below to share your insights and continue this conversation.
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Kimberly Jensen, Editor
Comments (4)Post a Comment
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Title: GPS
By: Paul R.B. Lyons I of NYSDOT
Posted: June 10, 2009 9:48 AM
In surveying, we utilize software that
reveals the satilite positions.
Therefore, your scheduling rely's on when the satilite's are available.
With so many satilite's available,
the scheduling becomes a rare issue.
The contractor will only have problems when their might be bad weather. In that case, his/her workers would not
have a very productive day, anyway.
I would suggest that GPS sales force encourage contractor's that GPS can still remain an option for them. Yet,
not having it at all is a negative for their production abilities. They should put together a handbook on what to do when GPS is not available if this concern seems to be to troubling to them. My being educated in GPS has
only one thing that has kept me from having the equipment, and that is the cost. Understandably, the cost to pay for sales and production, weighs in on
the manufacturer cost. I have seen the recreational GPS equipment reach as low as $170.00. As more people buy the recreational GPS, for travel purposes (including the Automotive Industry per new car production), hopefully the average contractor won't be looking for reasons not to buy GPS for their equipment.
Thanks for including me in this
discussion.
Cordially yours,
Paul Robert Barnabus Lyons I
New York State- D.O.T. Main Office
50 Wolf Road POD 34
Albany, N.Y. 12232
Title: RTK RTN Usage
By: Frank Donk, PLS
Posted: June 10, 2009 11:27 AM
I'm a party chief with the California DOT - Caltrans. We use a RTN for nearly all of our RTK Surveying for topo and construction staking alike. One of the problems we use to have with using radio base station was haveing our signal blocked out by voice communications. We later went to cell modems which alleviated that but we found if you were working in an area that had no or limited cell phone coverage we would find ourselves daed in the water aond would have to get out the radio base station. WE now use a RTN and we haven't experienced any down time from our service (knock on wood). However we still have the coverage problem sometimes when we are out in rural areas with hills and limited coverage. There is also the cost factor. Being with a State Agency with many projects, we use it more than 50% of the time. If one were only using GPS for a small percentage of their jobs they would have to look at how they operate to see if they could use it more or change the way they do things to make it more cost effective.
Frank Donk, PLS
California Dept. of Transportation
Title: Contractors use of RTN
By: Matt Eklund
Posted: June 10, 2009 12:49 PM
It sounds like the contractor you talked to might be utilizing machine control widely, but not progressively. A "progressive" contractor would not preface an answer with a "what if it doesn't work" approach. Real Time Networks will become the norm for RTK survey and machine control. We have to keep in mind that it was only a few years ago that the only way one could access the internet was through a hard wire. Now, there are WAN and 802.11 hot spots everywhere. The new "notebook" is the "netbook". The same proliferation of RTN is happening right now. Trimble, Leica and Topcon all have services providing virtual bases through RTN. We have been using both single base line connections through IP and also RTN with no down time. The advantage of a RTN is that if a base goes down within the network, the system has redundancy in providing corrections so that the GPS user doesn't ever notice. I think there is no question that it is a proven solution for RTK survey. The question then becomes, "what are the road blocks to using it with machine control?" One has to consider the methods of connecting to RTN.
If connecting with cellular, one has to consider the cell signal of where they will be doing the work. If you are getting dropped calls on your phone, you more than likely will get them with the machine. If there is a spot onsite where cell reception is especially good, then one could set up a cell modem to rebroadcast via traditional site radios.
A connection can also be made by rebroadcasting RTK corrections via site radios from the internet connection at the site office.
With that said, even as reliable as it is, it would be irresponsible to rely solely on RTN for your RTK solution and backup plans, like using your rover as a base, have to be put in place to avoid machine down time in a production operation. In summary, I am confident that RTN will progress in such a way that it will be the norm for RTK survey and machine control.
Matt Eklund
GPS Program Manager
Sukut Construction, Santa Ana, CA
Title: RTK RTN Contractor Usage
By: Scott Masciantoni
Posted: June 10, 2009 1:57 PM
Ms. Jensen,
To add some insight, and hopefully answer your questions, I am a Professional Surveyor, I own and operate a professional surveying and mapping firm which provides all the conventional survey services, as well as, support all machine control applications. In addition, I am also the President of the RTKLink Corp., a regional Wide Area RTN, in the SE US, since 2001. We were, I believe, the first for profit RTN in the US with a subscription based business model. Typically in the beginning the majority of our RTN clients were surveyors. Over the last few years this has changed with the popularity of machine control, and precision agriculture, where we now are well diversified through the three.
In the business world, where time is money, accuracy and reliability are critical, and the referenced contractors' concerns are legitimate. I can not speak for others, but with respect to RTKLink, redundancy, in every aspect of the function of the RTN is critical. There are also portions of the equation such as base station telemetry and seminaton of the corrections through cellular telemetry, which are controlled by others; Over the years these landline data and wireless data services have been reliable, but there is no guarantee. As there is no guarantee that even with 100% redundancy in our hardware that there will not be a catastrophic failure. With that thought, there is no guarantee that local, contractor owned equipment will not experience a failure. Actual RTN performance and reliability has historically been good. As we also deal with the support end of the equation, a user support call is typically remedied in a matter of minutes, and more than 2/3 of the time is not a network related problem.
As for a backup plan, typically, most clients do not provide for a backup plan such as carrying a base station and radio. I also know that many firms do not own a base station setup and rely completely on the RTN.
The theoretical advantages of a RTN are easy to see; no local base to own, operate and maintain, no local project/survey control needed in the range of legacy methods such as UHF/VHF radio broadcast, and no personnel needed to man the local base station if not secure. The disadvantages are exactly what your contractor referred to, being, losing control, or more specifically, losing control at the time of a failure, and the recurring cellular and RTN subscription expenses if any. Finally, it is my opinion that the advantages far outweigh the disadvantages, again, because of the historical reliability and overall performance.
Sincerely,
Scott D. Masciantoni, PSM, President
Environmental & Construction Technologies, Inc./ RTKLink Corporation
President, FSMS Broward Chapter
email: president@browardfsms.com
http://www.fsms.org
ECT Contact Info:
911 NW 209 Ave.
Unit 103
Pembroke Pines, FL 33029
954-436-8660 Office
954-243-3516 Cell
954-436-8065 Fax
Email:Scott@EandCTech.com
www.eandctech.com
RTKLink Contact Info:
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Unit 103
Pembroke Pines, FL 33029
www.RTKLink.com
Email:smasciantoni@rtklink.com
1-800-579-7734 Toll Free