Like the good Mr. Nolton I used both in the Army (67-70, 656 Engineers Germany).?ÿ The MRA 1 was retired not long after I arrived.?ÿ Being my introduction to EDM I thought they were awesome.?ÿ They were somewhat more susceptible to uncertainties in temp and pressure and just like GPS they could create some strange multipath effects when shooting low over a body of water.?ÿ Years later when the first GPS satellites went up and we were working out many of the early kinks at NGS, it dawned on they're just Tellurometers in space although moving a bit faster then we did in the Army.
If I recall correctly the units we used were like this set
source: https://images.app.goo.gl/vM3mMu1omq4Ewmg89
they were quite simple to use, we only needed a short session to demonstrate.
My longest EDMI "shot" was with a Cubic Electro-Tape DM-20 in the Spring of 1983 (also my last observation with those units).
Porcupine USGS PID MR0680 in Utah (me)
to Session Mtn ET USGS PID MR0861 in Wyoming (my little brother)
206,872 feet (39.2 miles).
We made several other shots that day, but that one was the last one, and the longest.
Pushing the envelope for those units (sorry, not pictures that day).
I still have some blank "calculation forms" for that equipment (somewhere).
Loyal
1976. Laying out a triangulation control network for the City of Helena, Montana. NGS came in with their Telurometers to set the baselines for us. Didn't get to run the instrument, but got to drive the old Willies Jeep to the top of Mount Helena with the cargo load in the back. Had to pack that beast the last 100 yards. That was plenty far enough.
Well I got hold of a pristine HP3805A last year. Picked off 10,000 ft like it was nothing. Which well beyond the 1 mi brochure range. And it checks out on the CBL better than brochure too. And, it??s no worse than shagging a T2. ?ÿ
@jbstahlFellow Surveyor friend of mine used one. He said they referred to it as the MRA C__k sucker. He had two strokes this past week and is in the hospital. When I mentioned this article he got a twinkle in his eyes.
Didn't you have to add a constant over 6500 feet and add a correction to the output of a 3805? That was the one you just aimed and pushed the button wasn't it?
Ah, you are informed. In the manual it simply state ??near or beyond 2Km it does not function correctly?.
however, there was a hand written instruction sheet in the case re: over 2Km, subtract 0.220 m. And it was written that 1999.999 is good, 2000.001 is subtract 22 cm. I didn??t test the exact boundary of the 22 cm bug.?ÿ
I did compare a 2.2Km range and subtracting 0.220 appeared to be exactly the right thing to do.
the more nagging issue is the hardwired 28 mm mirror offset. And I have an array of Wild 70 mm, and a good old AGA triple 28 mm. Nightmare.
The mirror offset is only in the manual. And no HP instruction on exceeding 2Km.
Fortunately, it??s now only for demo, and more relevant: chain calibration only. And it is a fine standard for chain cal.?ÿ
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I used one doing aerial photography control. The first time I shot over 6000 feet it gave me a reading of 200 feet or so, which I obviously knew was wrong. Called HP and they gave me the magic number to add and the correction numbers. I don't think it was in the manual. We only used HP glass. It would shoot over two miles to a triple prism.
the document that was hand written only indicated 0.22 m error. And at 3100 m (10,300 m) it was off by the expected 0.22 m.
I have the giant rectangular Wild glass, which is not a problem but for the 70 v 28 mm offset. Not hard to keep track of.
I??m just pleased that I have a nice example. And the bonus hand written note on 2Km fix.
i like the cal sticker ?ÿ
gotta admit, it??s easy to use
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