Best equipment value choice for documenting underground utilities on farm property

GPS/GNSS
1

Hi there.

I posted about my situation in the past, but am now trying to narrow down equipment. . .

I have a 225 acre property that has substantial existing water, electric and fiber optic lines that I want to ultimately map out. I am planning to lay down some existing lines in the near future and I want to document the line locations with RTK GPS equipment every x feet before filling in the trenches so that I will have precise horizontal and vertical location information that I can map out for the property. I also have plans to plat out a future RV park area with the same equipment.

I have been researching equipment and am trying to get to the point of purchasing. I have looked at the Sparkfun offerings and there are certainly multiple choices there. I have also looked elsewhere. Of the Sparkfun offerings, the Facet seems to hit the sweet spot as far as ease of use and value are concerned. I have tried to compare it to value products on Amazon and have found the E1 by Singular XYZ to be an apparently comparable product with the following differences. The E1 seems to have:

  • Longer battery life
  • Tilt compensation
  • Built in UHF radio
  • Included software
  • A price that is perhaps $200 more

Of these points, it seems like the tilt compensation would be a real nice addition. I know that the Torch has that but I’m not sure that I can justify paying such a premium for that unit, even though it sounds like a great solution for me. Because I don’t have phone service on parts of my property, it seems like I’m limited to using a base station with a UHS or LoRa connection to get the RTK fix. Having that built in to the unit is nice. As far as the included software is concerned, I’m not sure how it compares to the free SW Maps.

I don’t know how to judge the Facet or the E1 for their respective ability to get workable signals under tree canopy, but that would be important to me.

Can anyone provide guidance as to what is and is not important for the use cases that I mentioned as it relates to the Facet and competing products? I am a complete noob to all this so there will be a learning curve for me and ease of use is desired. I suspect that support through this forum would be better than what I could get through a company based in China so that is likely a win for the Facet. What else do I need to be consider? Feel free to steer me away from both of these products if there is a better value choice out there.

Thanks for any insight you can provide. I suspect that other people new to this world will benefit from what you have to say here.

2

I’d like to drill down a little deeper on that comment, because it has a big impact on your project.

As you know, it’s time to choose between a network rover (we call it RTN), or a Base/Rover Pair.

RTN requires internet service (typically Cellular), but it’s not in the same realm as what’s required for Voice Communications on a cellphone. I’ve logged many RTN positions when my iPhone has 1 or 0 “bars” of service, using a Facet, Torch, or PostCard connected to the iPhone over Bluetooth and SW Map’s NTRIP Client.

[Warning: Personal Opinion] Don’t get caught-up with tilt compensation. I turn it OFF (when available) for all the GNSS devices I’m responsible for. Hold the rod plumb with a bullseye bubble, and use an accurate Rod Height :slight_smile:

If you want to jump right in and get your feet wet, it’s hard not to justify a PostCard + antenna and finding out for sure if Cellular/NTRIP works on your property. It’s a ridiculously cheap way to get “hands-on” with L1/L2/L5 RTN….using the smartphone in your pocket + SW Maps freeware.

Or you could start with a $740 Facet, to figure out if NTRIP will serve you on your property before heading down the Local Base + Rover path. Since you mentioned tree canopy, it’s worth noting the PostCard uses L5 - the Facet does not.

Eventually you might take what you learned from the PostCard and transition into purchasing a finished product, or simply put the PostCard in an enclosure and proceed with data collection.

3

First of all, thanks for the reply.

So, is that to say that the Postcard + antenna should perform better in a tree canopy environment than a Facet?

From reading about the postcard, it looks like they recommend the “Portability Shield” to facilitate taking it into the field. So the postcard plus portability shield plus an antenna is all that is needed, provided that you can get correction data via the net? We don’t have free correction data here in TN that I am aware of, so it seems like a base station should be in my future, regardless, but this is perhaps a good way to get started.

Why do you prefer to deactivate the tilt feature. To a newbie, it seems like that would greatly simplify things.

David

4

Na, I’m not ready to say that. I can say that I’ve had a postcard outperform a Facet under canopy in a couple of side-by-side tests using the same correction source at “almost” the same time. Other users have reported the opposite. There are so many factors in generating a RTK solution.

The only factual statement is the PostCard has the benefit of the L5 band, which “can” penetrate tree canopy better due to the wavelength. But in the RTK game of inches, we shouldn’t expect much, in terms of absolute accuracy, under tree canopy anyway. You have to be mindful of multipath. Just know that you shouldn’t trust an elevation under tree canopy.

Really, the main benefit here is you get an on-board battery charger with the shield, IMHO. You’ll be Bluetooth connected to the PostCard anyway, and have access to the same metrics displayed on the OLED screen of the shield. Once you step away from a network rover, the shield has more importance.

Performing GIS data collection, there are times that you need to adjust the rod height.

Many times you need to set the antenna directly on the asset, and need an effective 0’ rod height, but still need to account for the Electrical Phase Center (some distance above the mechanical phase center + it’s height above ARP). You can’t really do that “on-the-fly” if the instrument is performing tilt compensation, unless your data collector is hardware specific.

I’ve found that it’s best to simplify the field workflow. You’re dealing with mosquitoes, hot, cold, people asking questions, cell phone ringing, snakes, dogs, the boogeyman, etc. Plumb the rod and take the shot……takes about 3 seconds. The only thing I want my tech’s doing is temporarily changing the Rod Height when required, and be sure to change it back :slight_smile:

Many people love Tilt Compensation and swear by it, that’s why I tagged my comment with [Warning: Personal Opinion]. But if I can’t trust myself or someone working for me to hold the Rod straight - then RTK isn’t something I/they should be doing.

2 Likes
5

Hi David,

I won’t provide a suggestion as to what equipment you should use but your task of mapping underground utilities is something I do regularly in my line of work. I thought it would be good for you to hear how a Surveyor would go about this type of work. I understand you want to do this cheap but I will provide a general sense of what it might cost for a professional to accomplish this effort.

First off, we would subcontract a underground locator to perform paint/marking out the utilities. They normally cost around $3,000 to $10,000 for a property ranging in size of 5 acres or less. Their efforts require a technician to use a couple of different methods of searching the utilities such as ground penetrating radar and electromagnetic locators to name a few. After they are finished marking up the site, they will go and collect their markings with GPS/GNSS receiver. I don’t know how accurate their equipment is because we dont use their data, but they do provide a nice overhead map with the different colored utility lines to get a sense of the approximate locations. Keep in mind, the technicians sometimes mark out the approximate depths of utility ever so often because their instruments can measure for it. But when they come by to collect the marking with a GPS shot, they don’t include the vertical elevation information. So the map is for horizontal position only. I’m sure you could pay even more to get them to provide elevation info but they might sell you some more expensive methods to collect that information.

Now, where the surveyor comes in. We would perform a topographic survey. If any of your design goes across your property or near your property line, we would suggest a boundary survey too. In the process of collecting data, we would be mapping features and elevations to show where everything is within the scope of work. These surveys together run around $2,000 to $10,000 for a property ranging in size of 5 acres or less, similar to the underground locator costs. A map would be created showing the property lines, the above ground features and all underground locating markings. This map would still not show exactly where the lines are but if you needed to dig and locate a utility line, the map would be the most accurate way to find these lines. You would likely be within a foot of a line (horizontally) where the utility line is marked on the map. Vertical is still only approximate unless you pothole locations to expose the underground utility.

All that being said, this would the conventional way a Surveyor would collect data and provide you the information needed to make the best decisions. It is definitely not the cheapest and for what you need on your property with over 200 acres, this would get extremely expensive.

If you have any questions, dont hesitate to ask. I hope you find a solution to your project.

1 Like
6

@tSteffen04 - Welcome and thank you for this post! It is very educational for those of us who don’t know how the details get done.

7

@tSteffen04 - Thanks for your insight into the way this could all be professionally accomplished.

Regarding your mention of ground penetrating radar, we actually had such a service on the property. Between 2023 and 2024 we were fortunate to be in a geographical block that was selected or bid on (not exactly sure how that was determined) for running fiber optic Internet to our property as part of a federally funded rural initiative projects. When a block was accepted, they had to provide service to all homes within that area, regardless of the difficulty or cost effectiveness of doing so. In our case they ran several miles of fiber over power lines and underground to service about a dozen homes. This was despite the fact that Starlink was available at that point and a far more cost effect solution. Because our property had a private 6” main water line and a property wide fiber intranet that they didn’t want to hit when trenching for their fiber conduit, they contracted with a small company that provided ground penetrating radar service to locate what they could. I mentioned this in a previous post when I first started researching RTK GPS here on the forum, but here is a link to a video of the process for anyone interested. This particular video makes it look easier than it actually was in some places where there was greater ambiguity.

8

So, with the helpful suggestions here, I ordered a pair of Postcards, Portability Shields (even though not strictly necessary), and antenna-to-device cables (I already had the antennas), along with the LoRa Serial Kit to link them as a simple alternative to passing the correction data over the Internet.

After looking through what arrived in the mail today, I realized that the Portability Shield does not include the battery intended to fit between the two boards, or the headers to connect the boards. The receptionist at SparkFun suggested I reach out to the community to determine which products to purchase to round this equipment out. There are several batteries listed on the site but I’m not sure which one is intended to fit between the boards. Having not soldered components together before, I am equally unsure what header components I need. Based on the “Recommended Products” that are listed with the Portability Shield, I came up with the following:

Is this the best choice for battery: Lithium Ion Battery - 850mAh - SparkFun Electronics

Is this the needed header component: Break Away Headers - Straight - SparkFun Electronics

Is there anything else needed to complete this kit?

What about if I acquire a printed case for the boards? Is there anything else that I need in anticipation of that?

Thanks so much.

9

The Postcard with display on my desk is using ~200mA with an active antenna attached. So the 850mA will give you a few hours of run time. The 1250mAh a little more, but it does stick out a bit as shown is the pictures. You can always use an external battery bank if you need more.

Yep - those headers are what you need. That should be all you need.

A 3D printed case is left up to the end user because we don’t know what holes you need access to and the configuration you plan on using. Other users may have a good source or guidance on what worked for them.

image
image493Ă—393 59.2 KB

10

I have the Postcard with its portability shield and a 5000 mAh battery.
It lasts me a full day of work and has never run out completely. I recharge it to 30%.
3D printing is up to you. There should be someone in your area who works in 3D, and using the example on the Sparkfun website, you can make modifications to fit a larger battery.