paden cash, post: 389208, member: 20 wrote: ....I remember starting the processing (with an IBM 486) on files when I left the office at 6PM. If I was lucky it might be finished when I returned the next morning at 6AM. I do not miss those days at all.
386, 486, and then finally the 586 which was called the pentium. yes...and hit the process button before you go home. Find your errors, if there were any, and reprocess if necessary the end of the next day. And the pentium math module (double precision) that had a bug they had to fix. Gotten a bit higher-power computers since then.
I believe the first GPS that I saw was sitting on a CalTrans second order traverse point just North of my office on U.S. Highway 101. There was a tripod with a antenna more like today's antennas. There was a tent nearby with a soldier from Great Britain on loan to the Defense Mapping Agency and a large box with Lexie(sic) lights continually changing the position of the antenna. The large box was made by Magnavox. There were more of these receivers scattered about my county on State second order points and USC&GS points. It appeared that they were ground truthing their derived locations. The team was supported by helicopters and military vehicles. The Englishman was at that same site for several weeks.
Yep. Dr. Richard Collins and the macrometer. No code received. Interferometic measurement of the doppler shift of the GPS signal. The TI-4100s came out, $175k a box, single frequency. Then Charlie Trimble and Trimble 4000S when Javad was working for him. Those were the days, we knew the madness of insatiable quest for precise positioning was the future for the surveyor and public. Seems both like yesterday and a long time ago. Thanks for trip down memory lane, I feel older than dirt now. LOL
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If it was 1983 then it was probably the first. I had thought that the City of Pittsburgh was the first city wide GPS survey, but it was 1984. I remember the newspaper covered a news conference in Point Park about the "new space technology", but the problem was they called it satellite surveillance rather than satellite surveying.
I later worked for the company that did the 1984 Pittsburgh survey, I tried to get the 1984 data, but it had been backed up on VHS tapes (un-retrievable) using a VCR that a guy that worked there rigged up somehow. .
Tom Adams, post: 389182, member: 7285 wrote: I remember with the 4000SST's we always aimed them the same direction under the theory that we didn't know exactly where the phase center was, and if they were always the same directions as the others running @ the same time, any offset in the phase center would be the same so that their relative positions would cancel out that part of the error.
NGS still calibrates antennas with an antenna orientation in mind or I still point the "north" reference mark on my antennas north within a few degrees using a compass for ALL of my static work, not so much obviously for continuous kinematic such as road profile, etc. because it is pretty much impossible and for that work probably doesn't matter.
SHG
John Hamilton, post: 389100, member: 640 wrote: My first job out of college in 1986 was with Geo/Hydro, which was one of the first (or the first) GPS company, they started out using Macrometer V1000's (pictured in the first post) around 1984. Each day before the sessions we had to bring all of the units together and sync the clocks using either GOES time receiver or a Trimble 4000A. Then the 4000S came out, and we started using those for "lower order" surveys. The V1000 required a $3000/month subscription to get an ephemeris for processing, whereas the Trimble did not (but there was no software at first).
I remember processing the V1000 data, on a special computer, took a day or so to process a few baselines, manually fixing cycle slips.
"...manually fixing cycle slips."
No one who has not done such a thing can appreciate how much fun this was! GAWD!! Aspirin, Tylenol, alcohol!!!
Lee D, post: 389164, member: 7971 wrote: Were those Macrometers single or dual frequency? I remember the WM101 (WM was Wild - Magnavox) and WM102; the 102 was dual frequency.
The Macrometer Model V-1000 is a geodetic positioning instrument that uses the radio signals broadcast by the GPS satellites. The Macrometer is the only GPS user equipment commercially available that does not require any of the GPS codes. The Model V-1000 receives only the 19-cm wavelength signals from GPS although similar instruments, built for the U.S. Air Force Geophysics Laboratory, receive both the 19-and the 24-cm wavelengths. In this paper we summarize the results of two years of field testing of the V-1000. This instrument, observing four or five satellites fof a few hours, yields a point position accurate within several meters in each coordinate: latitude, longitude and ellipsoidal height. All three components of the relative position vector between a pair of points can be determined within 2 parts per million of the distance, given a similar schedule of observations. This accuracy has been obtained for intersite distances from one kilometer to several thousand kilometers.
Macrometer is a trademark of Aero Service Division, Western Geophysical Company of America
