Using GPS to lay out a field

[quicksandfarmer]

So you get up to 6 mile range with the radio system between base and rover? That is great.

I haven't been able to test the range of the radio system but I doubt it's that far, I wouldn't be surprised if it was only a few hundred yards. The base has to be within six miles of the rover in order for the DGPS to be accurate.

 

[dodge man]

With a true VRS system (virtual reference station) the bases do not have to be close, although the closer they are the accuracy is better. With a single base the errors start to get larger the farther you get away from the base. Maybe 10 to 15 miles is the practical limit on a single base.

 

[dodge man]

I looked at the spec sheet and didn’t see anything listed for the radio. Typical is 1 or 2 watts. Even a 1 watt will probably go a mile. The higher you get the radio antenna the further the range. When we setup our 35 watt radio we often get the antenna 20 feet in the air. You need a license for this radio.

I noticed your unit does track Russian and Chinese satellites which helps for a quicker fix and allows for more obstructions.

 

[defranks]

Very interesting thread. I've been looking for an economical GPS that I can use to find my property corners. I know about where they are, but the survey lists one corner as having a pin, which I cannot find with a metal detector, and another as being a "stone". I found a painted stone using my old Garmin GPS, but I'd really like to have more accurate placement.

If I were to buy this U-Blox kit, will that give me everything I need to make it work?

(Couldn't link the URL, but a kit is available from Digi-Key, C94-M8P-2-10)

It looks like it has two of everything and comes pre-configured, but requiring some software downloads. The manual mentions "putty", and I have no clue what this, but I'm sure an internet search would turn it up.

Looks like the price may have come down, as this kit is $400 and includes two of everything, including ground planes.

 

[quicksandfarmer]

Very interesting thread. I've been looking for an economical GPS that I can use to find my property corners. I know about where they are, but the survey lists one corner as having a pin, which I cannot find with a metal detector, and another as being a "stone". I found a painted stone using my old Garmin GPS, but I'd really like to have more accurate placement.

If I were to buy this U-Blox kit, will that give me everything I need to make it work?

(Couldn't link the URL, but a kit is available from Digi-Key, C94-M8P-2-10)

It looks like it has two of everything and comes pre-configured, but requiring some software downloads. The manual mentions "putty", and I have no clue what this, but I'm sure an internet search would turn it up.

Looks like the price may have come down, as this kit is $400 and includes two of everything, including ground planes.

That's the exact kit I'm using. ****. I paid $800 from the U-Blox website for that same exact kit! (I actually paid $1200 because I dropped one of the boards and broke it and had to replace it.) I found that the ground planes in the kit weren't enough to give good results, I got better results putting the receiver on the roof of my car and then settled on using 18" pizza pans.

With that kit and a laptop you can get your location accurately, the limit is going to be how accurately you place the base unit.

 

[quicksandfarmer]

The manual mentions "putty", and I have no clue what this, but I'm sure an internet search would turn it up.

A long-winded explanation:

In 1874 Emile Baudot invented the teletype, which consisted of a pair of machines connected by wires where pushing a key on one machine caused a letter to be printed on the other. (The "Baud" used to describe modem speeds is named in honor of Emile Baudot.) When computers were developed it was quickly realized that it would be handy to have a way to get information into and out of them, and since teletypes already existed they were repurposed to connect to computers. When I first used a computer, in the 1970's, I would type on a teletype. When video screens and electronic keyboards were introduced it was easiest just to use the existing teletype interface so in the early days they were called electronic teletypes.

Over time the electronic teletypes got replaced with keyboards and monitors that connected directly to the computer. However, the teletype interface was still ubiquitous, so it was handy for connecting peripherals like printers and modems. As the interface became more general purpose it became known as the "serial interface." If you had a computer that didn't have an actual teletype, but wanted to configure one of those serial devices, it was handy to have a program on your computer that emulated the teletype. The most popular of those was named "TTY," short for teletype.

About 20 years ago the USB interface came along. Since the serial interface was so common at the time USB was made to be backwards compatible. GPS devices use the serial interface, although newer ones will only have a USB port.

So when you connect that DGPS device to your laptop or smartphone, it's essentially using the same interface that Emile Baudot created in 1874.

End of history lesson. The point of all that is you can connect to your GPS device using a TTY program, or "terminal emulator." I seem to recall that the kit came with one, it's probably the "putty" they're talking about. With a TTY you can communicate with the chip like you're using a teletype, you type commands and it sends back responses. The kit also comes with configuration software. It also comes with mapping software that takes the output from the chip and displays it on the screen. I only used the Windows versions, I don't know if there are other ones. When I started out with this I would connect the rover unit to the USB port on my laptop and walk around until the battery died.

 

[aczlan]

Very interesting thread. I've been looking for an economical GPS that I can use to find my property corners. I know about where they are, but the survey lists one corner as having a pin, which I cannot find with a metal detector, and another as being a "stone". I found a painted stone using my old Garmin GPS, but I'd really like to have more accurate placement.

If I were to buy this U-Blox kit, will that give me everything I need to make it work?

(Couldn't link the URL, but a kit is available from Digi-Key, C94-M8P-2-10)

It looks like it has two of everything and comes pre-configured, but requiring some software downloads. The manual mentions "putty", and I have no clue what this, but I'm sure an internet search would turn it up.

Looks like the price may have come down, as this kit is $400 and includes two of everything, including ground planes.

Putty is a windows program that gives you a text-based interface to talk to hardware of some kind.
Free and very easy to find online.

Aaron Z

 

[dodge man]

Getting a GPS system like you are looking at is probably not going to help you find your corners. Do you have coordinates for them? Probably not. Most surveyors work in state plane coordinates and the OP sounds like he works in lats and longs. I’m not sure if the OP has the ability to stake point or not? Say I’m surveying your property and find a corner. If the next corner is 500 feet away, i stake the first corner and walk roughly the correct direction until I’m 500 feet away. This narrows down the search area. I’m not sure if that’s possible with this type of system.

Long story short there is not a magic list of coordinates for property corners so GPS isn’t a magic box.

 

[s219]

Very interesting thread. I've been looking for an economical GPS that I can use to find my property corners. I know about where they are, but the survey lists one corner as having a pin, which I cannot find with a metal detector, and another as being a "stone". I found a painted stone using my old Garmin GPS, but I'd really like to have more accurate placement.

If I were to buy this U-Blox kit, will that give me everything I need to make it work?

(Couldn't link the URL, but a kit is available from Digi-Key, C94-M8P-2-10)

It looks like it has two of everything and comes pre-configured, but requiring some software downloads. The manual mentions "putty", and I have no clue what this, but I'm sure an internet search would turn it up.

Looks like the price may have come down, as this kit is $400 and includes two of everything, including ground planes.

How accurate do you need to be? How big is the property? Do you have clear line of sight to the sky? Can you see one corner from another? I have a hard time believing you need centimeter accuracy DGPS just to ballpark some corners. What I have done in the past is to combine standard GPS information with property line bearings to triangulate a corner. It always puts me within 6 inches of the pin.

 

[defranks]

I have a good idea where my corners are. My 20 acre, nearly square parcel is bounded on two sides by two intersecting roads, so the exact corner there is unimportant... the practical boundaries on those two sides are the two roads. One boundary is a state wildlife area, and it's roughly marked with paint on a line of trees. The two corners that interest me have been surveyed. One is supposed to have a pin, but I was unable to find it. The other is a "stone", and sure enough, there's a painted stone along the property line I share with the state, right where my GPS said it should be, within the error of the GPS.
There's a property marker across the road from the corner with the missing pin, but it's not got a surveyor's cap on it, it's a painted "T" post, but I believe it's pretty close based on my GPS and measuring from corner at the intersection of the roads.
I think, but am not certain, that my boundaries are recorded with lat and long coordinates. I'll have to dig out the document to be sure. Three of the corners are on roads, so I have a pretty good view straight up, but there are trees on both sides. That fourth (the painted stone) corner is in the woods, but my handheld GPS has reception there.
Thank you all for the input! It's much appreciated. I may just buy that kit to have it, I'm a ham radio operator, fly model airplanes, and bought a hand-held GPS WAY back when they first became generally available and were WAY too expensive. In other words, I like my gadgets.