I have an opportunity to buy some used Sokkia GPS static heads. I have no idea how to price them. They are about 10 years old. I believe they are L1 frequencies only. I am thinking about $500-750 per head. Any Ideas?
I assume you mean the "Locus"-type L1 units.
That's a good price. We have seven of them and have found them to be rock-solid for control work.
Good units, I have 6, don't forget the software. Have heard that the internal batteries may be approaching their end of life, but have also heard the someone has found a way to open the case and replace them. I would not pay any more than $500 each today and if a package deal for 2 or more hold it at $350 each. If they have been used consistently the D cells probably have not caused any problems with corrosion, check the battery compartment very carefully for that.
jud
Sounds like you are talking about either Locus or Stratus. If it's Locus, they are very good and easy to use static units. You can download all the various version of Ashtech Software for free (L1 only) from their FTP site, but know that the Locus requires an IR reader that only works with a 9-pin serial port. You'll probably need a USB to serial adaptor. The Locus software was designed to work on Windows 95, and is a little tempramental with XP, but can be done, and I've never got it to work properly in Win7. There is a "patch" (also on the Ashtech FTP site) to make it the download work with XP. Good units though, as long as they continue to work.
What about the Stratus? Same issues? I looked at them a couple of weeks ago and the thing that makes me think they were stratus' is the fact that they used camcorder batteries you could hot swap.
The Stratus are a little newer and don't use an IR port, but they still require a 9-pin serial port for download, which worked fine on XP with a USB to serial adaptor. And yes, they do use little camcorder type batteries, but I'm not sure about hot swapping them. Never tried downloading Stratus on Win7, so I don't know if there are issues there. The problem with Stratus was that the Sokkia software (Spectrum) is terrible and not user friendly, and often yeilded bad results. I stopped using the Sokkia software, and converted the Stratus files to RINEX, then imported and continued to use the Ashtech software. I found on several occassions that data that would fail or yeild bad results with Spectrum would pass and yield good results in the Ashtech software, which made the extra steps of converting from Sokkia to Ashtech worth the hassle.
Sokkia has never been a big player in the GPS market and I think the quality of their processing software shows a half-hearted effort. But the GPS unit themselves were good and easy to use.
BTW, I forgot to meantion in my first post that the Ashtech software was the basis of the "Locus". The Locus as made by Ashtech and Sokkia just rebranded it. So the "Sokkia Locus" should download/process in the free Ashtech Software.
Anyway, If you get Stratus, make sure you get the Sokkia software and the 9-pin cable, because you will need it, even if it's just to download the units.
just FYI, I am using a serial adapter on Win 7 to download my R-8
Thank you all for your help. I think since they are Stratus's then I will offer him $500 per, and see if he takes it. One question I didn't ask, has anyone used these for OPUS work. I use OPUS at least as a verification to the software. Any thoughts?
I think OPUS requires a dual freq. receiver. Neither the Stratus or Locus were dual freq.
That was a good point, I checked on the antannae types accepted by OPUS and L1 Stratus is accepted. Couldn't screen capture it but here is the link.
http://www.ngs.noaa.gov/OPUS/index.jsp
here is the clip after all. 
L1 and OPUS
Hopefully someone with more knowledge of OPUS will chime in. It's always been my understanding that L1 only units can not resolve atmospheric condition corrections as well as L1-L2 units, and have a maximum vector length for survey grade results of about 7 miles under good conditions. I'm not sure what kind of results you would get if you loaded an L1 only file to OPUS, but I'd expect it would be a "float" solution (unless you had 3 or more CORS stations within miles of your site), good to a couple of feet, if it returned anything at all.
That said, the NGS included Sokkia Stratus for a reason, so maybe there is something I'm missing here.
L1 and OPUS
While there are a few "L1 only" antenna models in the NGS (and IGS) Antenna Calibration Files, OPUS (static or rapid static) does NOT accept OR process L1 only observations.
There has been "talk" over the years about an L1 version OPUS (OPIE as some called it), but I don't know whether or not the NGS is still pursuing it.
Loyal