Ronni Grapenthin - Notes
New Mexico Tech
Dept. of Earth &
801 Leroy Place
Taking on a position as assistant professor gave me the wonderful start-up money we're so keen on to get our operations started. Ironically spending that money turned out to be much more of a time sink than I anticipated and a lot of that time went into purchases related to campaign GPS equipment. While UNAVCO has a plethora of information on this stuff in their knowledge-base, it doesn't quite tell you what and where to buy. Since a few friends, who recently also scored faculty posts, asked exactly this question, I will follow Matt Might's advice on low-cost academic blogging and respond to public. Plus, this forces me to finally put all the information that's distributed over file system and a large number of emails in one place. A good deal of this information comes from collaborators and, of course, the fantastic engineers at UNAVCO.
The 3 components of a survey setup that I detail below are:
If you haven't done a GNSS/GPS survey yet, read UNAVCO's campaign handbook.
Note that all prices given here are guidelines. Obviously they can change and you should get your quotes directly from vendors yourself once you're ready to do the purchasing.
If you intend to establish new benchmarks, epoxy the Bevis pin into solid bedrock. These can be installed with a battery powered drill (e.g., Bosch RH328VC-36K 36V SDS-plus Rotary Hammer) and a 1/2 inch drill bit (e.g., Bosch HC2087 S4L SDS-Plus Shank Bit 1/2 by 16 by 18-Inch) and require epoxy. One pin cost me about $17 in the machine shop. Precision Design & Machine should be able to make these for you if you don't have access to a machine shop; or try to find another one on the web.
If the substrate is not solid bedrock (and you're interested in processes that don't relate to tectonics / require sub-cm precision), try the FENO Spike. This might be useful for hydro-geodetic surveys.
If you require a solid monument in unstable substrate, you probably want a shallow or deep drill brace monument, a concrete pillar or something similar. The idea is to anchor deeply and create stability that way. It's best to get in touch with UNAVCO to sort out what your options are given stability requirements.
You have a number of options, but I will focus on fixed-height spike mount and tripod setups. Simply, because that's what I use.
The spike mounts have to be machined and the recent version that UNAVCO designed is pretty sweet, so here are their details/ specs. The UAF specifications, which have a long history and McMaster Carr part numbers, are basically an earlier model of the UNAVCO setup. I had these machined in the R&ED machine shop at New Mexico Tech; including labor and parts they came out to cost about $775.
If you don't have a machine shop on campus, UNAVCO seems to use Precision Design & Machine, who have the specs for their
latest design on file. I don't know how expensive their production is (friend told me $585/spike mount, so you might
want to inquire with them.) :
Cases for the spike mounts are advisable. I am having mine made by Apocalypse Design, Fairbanks, Alaska. They have a pattern from UAF (make sure it's the one that has an 0.5-1 inch added to all sides, the original is a tight fit; ~$150/ea, I'll post a photo once I have them.).
This requires a significant number of items, here we go (for all of this it's worthwhile to shop around! You can simply enter the item description into Google Shopping.:
Note that this follows the setup the UNAVCO Polar Group has developed. I used this at Erebus and liked it. It's not necessarily the smallest / most lightweight setup, keep that in mind! Again, get in touch with UNAVCO if you need to customize your design, or play with the components yourself. You will need: receiver + antenna, battery, a pelican case to protect your receiver (they do float in glacial outburst floods!), foam inserts to keep everything in place during transport / flood, and optionally solar panel & charge controller.
I bought Trimble NetR9 receivers through UNAVCOs group purchase program; the price for a receiver with a Zephyr Geodetic 2 antenna two years ago was $4,200 (GPS tracking only, GLONASS enabled was $1500 more per receiver). However, since then UNAVCO has chosen Septentrio as the preferred vendor and I don't know what the current prices. However, UNAVCO provides a list with vendor contacts that provide special pricing for UNAVCO members.
I ordered my Pelican 1600 cases from B&H Photo Video for $140/ea and had my foam inserts made by:
Accurate Gasket & Stamping
2780 S. Raritan St.
Englewood, CO 80110
Phone: (303) 339-1240
Refer to the "NetR8/NetRS GPS Foam Case Insert" and call them for a quote, which depends on number made. The quote I got was $152/ea. and plan for 3-4 weeks of production.
Another vendor is:
425 S 48th Street Suite 114
Tempe, AZ 85281
Phone: (800) 345-1498.
They also sell the cases and ship the foam in them (handy!) Some quotes are (get your own, they change!):
NetR9 Cushion Top - C#011148
NetR9 Cushion Bottom - C#011149
Pelican 1600 Empty
I went with rechargeable lead-acid batteries. We'll see how it goes. Two of these, connected in parallel, go into 1 pelican case. I got Schuhmacher SEM-1562A-CA battery chargers and used the ring connectors that come with this as permanent connectors in the campaign box.
Just cut up the one that comes with the NetR9, which requires a fairly expensive limo connector. Connect that to the batteries. Get some quick connect power connectors and maybe some of these terminal blocks for connecting things (I am not good at soldering.)
I am right now trying to get these, and we'll see how it turns out. The internal cables are mounted to the receiver box, and provide connectors to the outside. The external cables are then connected to the box. If well done, no water/snow etc. will get into the box! You need:
Other things you might need:
rg <at> nmt <dot> edu | Created: 2016/06/18 | Last modified: August 08 2016 20:21.