It's a WM101 L1/L2 . It comes with a GPS antenna and battery pack and data is recorded onto the cassette tapes. Very heavy and solidly built.
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Interesting
Perhaps WM stands for Westinghouse Magnavox? Can't remember the history of equipment that clear, but WM-101 rings a bell. Probably a predecessor to the MX-1501, but I am pretty sure thats a USN Transit "Doppler" satellite receiver. Keyboard and interface looks the same as 1501.
Wild Magnovox, eventually I think Wild (or Leica) bought the commercial GPS unit of Magnavox.
Oh, yeah, I forgot about the 4000ST.?ÿ
My experience with the WM101 (which came after the Magnavox 1501 by the way) was that I was tired of using an external computer to collect data with a Trimble 4000. The first few months after we started using the receivers it was setup to write the data to a floppy drive (laptop had dual floppy drives, no hard drive) at the end of the session. So if the computer lost power, the entire session was lost. After many complaints from us, they modified the software so that it would write to the floppy every 5 minutes.?ÿ
Anyway, the WM101 had a cassette drive, so I rented a pair to do a job. Field work went well, but the processing software gave me a seemingly good solution (good statistics) that was off by one wavelength (19 cm, i.e. solved the wrong integers). I told the rep that I was OK with false negatives in processing baselines, but absolutely could not accept that it was giving me a false positive. Once Trimble heard that we were considering the WM101, they flew me and my boss out to Sunnyvale to show us the new receiver with onboard memory. That was in 1987, been using Trimble ever since. One problem I remember with the original WM101's was that if you had it in a vehicle, and the vehicle was running during the session, the vibrations from the vehicle could affect the oscillator in the receiver. So we would take it out of the vehicle and lay it on the ground during the session.?ÿ
Also, I disagree that the Macrometer V1000 was doppler only, it collected phase data but treated it as noise, it could not decode the signal, we had to use an external ephemeris ($3000/month downloaded over a 300 baud modem) and synchronize the onboard clocks everyday using an external time receiver (GOES receiver at first, then a Trimble 4000). Every day before and after the session we had to get all of the receivers together and synchronize them. Also, the receiver had to be powered up all of the time between sessions, using batteries and an inverter and plugging in at the hotel.?ÿ
Processing of V1000 data consisted of manually fixing cycle slips by looking at graphs of the pseudoranges and the phases. I remember the advertising slogan was "15 mm over 15 km in 15 minutes". In reality, hours were typically needed to get a good solution. And there weren't very many hours of 4 SV coverage. I can remember planning sessions where it would drop down to 3 SV's and we would extend the session to make up for that.?ÿ
Mine was a Trimble 4000 system, I don't remember the letters that went after the number 4000 though.?ÿ No ability to do static work and it did not have on the fly initialization.?ÿ Not having OTF initialization really sucked.
1997 - Trimble 4000SSi for static and RTK. Then all of the Trimble units up to the current.?ÿ Worked with the first Topcon Hipers and Leica GS15s at two companies, but it's been Trimble for a majority of the time.
1990 Trimble 4000ST, 1994 Leica 200, 1996 Leica 300 (my 1st RTK units and ran a ton of RTK with them), 2001 Leica 500's and 2007 Leica 1200's and still running those.
SHG
I have had both Trimble and Leica give false "good results", but not since early 2000's that I know of! I think it was semi common amoung all the brands earlier, I would hope these days very little of that gets through the software. I guess that is why redundant measurements are still good, only way to really know!
SHG
I recall working with Geodimeter RTK equipment in 1998 in Naperville Illinois.?ÿ Maybe it was a different manufacturer with the Geodimeter name??ÿ
Then in Florida introduced to some really clunky Leica RTK software.?ÿ ugh, everyone here seems to love Leica for some reason.?ÿ
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Lots of static work with Trimble 4000's and still love the 4700 design and use.?ÿ?ÿ
