On a summer’s evening after a thunderstorm cleared the air and sun was getting low, I asked the crew a question “do you think we could measure to that glass we left on the far ridge a couple of days ago? "No way, that logging landing is a least 5 miles away and where would you point the instrument anyway?” Someone pointed out there was only a single prism on the tripod. Pondering this, I called the other crew on the radio and asked how long it would take them to get the truck up to the tripod, adds some prisms, get the truck behind the prism and point the headlights our way? In about 15 minutes I found a set of headlight took a sighting and hit measure. Ok, the EDM Leica DI2000 was good to about 5km ±3.5 miles using a triple prism. However, the number I was looking at on the readout was a lot more 34,856, I don't recall the 100ths. I could not bring myself to move for a few seconds as my mind tried to grasp the value. Then from behind me some said "do it again", I did and again 34,856, again 34,856, again 34,856 with the 100ths hanging right at ±0.15 feet. Reaching for the radio I asked “how many prisms did you use?” “Just the one” the radio answered.
The next day we traversed down to the highway, across the valley and to the top of far ridge and landing, closed the angle and called it a day. I could not wait to reduce the numbers and about halfway home I had it, raw distance closed 0.57 feet. "Stop for beer I am buying". Later I wrote the manufacturer of the EDM to tell what had happened. They called me up from Europe and said it was not possible. I think that what was said, my German is not that good.
That brings me to the question how far is far? Only direct line of sight by distance measure for the present, there is a huge number out there for triangulation, but more on that at future date.
Greg Spurlock, PLS
Spurlock & Associates
I believe they would call that "a fer peece" in the South.
probably qualifies as a "pretty fer peece".
I measured 3 miles to a triple on a clear day on the California Coast with a Leica 1102 total station. We put an orange vest on the tripod and all I could see was a tiny orange blur.
238,897 miles?
How about measuring to the Lunar Ranging Retro Reflector ( http://en.wikipedia.org/wiki/Lunar_Laser_Ranging_experiment)? I especially like the part where the beam is 4 miles wide, and only 1 out of 10^17 of photons is captured back on earth.
That's far!
We used to use an HP distance meter for long range measurements. We would run traverses to points with a piece of 5' pipe plumbed up with wires run through it. Then a painted orange 1 gallon ice cream bucket on the top of the pipe and mirrors set into the end of the pipe. 6 miiles was the longest I ever did.
Turned angles with a T2 then took it off and shot the distance with the HP.
6 miles was probably to 12 mirrors-not one.
Like the germans said-it's not possible!
Yet you did it; and to one mirror.
That might be a record for that kind of instrument.
I am wondering if the gun has a reflectorless mode which uses a laser diode.
Back in the day when HP came up with the 3820 they used a laser diode. A year or so later they introduced the HP-3808. I never had a distance it would not shoot, my longest with it was over 16 miles. in fact hard to find a line where you could see between that long. We did stack up a lot of triple prisms though, perhaps 3 or 6 triples because that is all we had. The generation before had Helium-Neon gas lasers in some models of EDM and would probably shoot pretty far.
Have a hard time believing a conventional total station going that far to a single. If course long distances relied on cool clear still air. I had a similar shock the first time I tested the 3808 and something like 93000 feet popped up in the display.
- jlw
I don't know about your crew, but on the crew I worked in, if I did this:
"I called the other crew on the radio and asked how long it would take them to get the truck up to the tripod, adds some prisms, get the truck behind the prism and point the headlights our way?"
and when I asked how many they used they said this:
“Just the one” the radio answered."
I'd be pretty sure they lied about it.
238,897 miles?
I've always been curious if that was at apogee or perigee and how wide was the beam at the source.
238k miles would actually be somewhere in between in think.
1.8 miles with a Topcon GTS-3B to 9 prisms, as I recall. It was a cold, clear day, and the gun struggled with the shot.
2.3 miles with an HP-3820A to a triple. That was mid-summer, overpass-to-overpass so the heat waves weren't too bad, but the gun didn't flinch at all.
Somewhere around 20k with a machine very similar to this...
18 miles using a Tellurometer CA-1000 with the big horn antennas.
I regularly did long distance when doing geodetic work with a T2 and AGA Geodimeter Model 8. Longest I did was 42km (26.1m). It was measured hilltop to hilltop at night to 1 bank of 16 prisms.
The K&E Rangemaster was a quicker instrument to use but it didn't have the range of the Model 8 particularly in the flat conditions of Western Australia.
Of it is all superseded by GPS these days.
Cheers
Graham
6.6 miles to a single prism? That's really far.
Right at 5 miles to a double prism using an AGA 76 once. Did not expect to get the shot but set up what we had left in the rig while on our way back to the instrument location, were winding angles and then shooting distance. The day was calm, overcast, cold 'about 30°' with powder snow on the ground. An exception, not the norm even if that AGA 76 was a good long distance EDM. It really shined when trying to find a target across the canyon and in shadow, get that laser to flash off of the prism once and all was found, with radios the set up crews could walk you in with that visible laser.
jud.
"Over there" is a fer peece, but "Over Yonder" is unmeasureable. At least in Mississippi. 😛