Anyone got first-hand experience in heavy canopy environments with Topcon GPS with Vanguard/Fence technology? I am currently using Hiper Lite Plus receivers. They have worked very well over the last 8 years. But a receiver board has gone out in one of my units (approx $4000 installed) so it's time to make some hard decisions about upgrading. I think the GR5 and Hiper V with the Vanguard/Fence technology are probably better performers over the older Hiper Lites, but they would need to be a magic bullet for heavy canopy areas for the the extra $$ in my opinion.
I have no experience with the newest Topcon rtk. Having said that, I don't think there exists a system that works in heavy canopy. Then again, "heavy canopy" is subjective. I am impressed with the newer systems in moderate to light canopy. Receivers that can fix from GLONASS or a combination of GPS and GLONASS make a huge difference in my opinion.
I haven't used the GR5. So no direct answer here. However, we have both the Hyperlite+ and the GR3. I can tell you that I have little interest in using the Hypers, and use the GR3's all the time. This is purely anecdotal, but is true throughout our field crews.
Why is this? I think at least some of it comes from the lack of firmware support for the Hyperlites, while the GR3 still enjoy support. There are real changes that come from this.
And...cover is always iffy, and the results are always suspect, until confirmed, when using GNSS. I think that is a matter of physics, and while there will be mitigation of this, it will always be there to some degree. It is probable that "under cover" will someday be "survey grade", but I don't know that we are there yet.
We have used the GR5's for almost a year now. While care should always be used around any canopy or tall buildings this system seems to be the best that we have used regarding work around these areas.
I have used Hiper V and GR5 for past year, along with Hiper Lite + and Hiper XT for past 10 years.
I do see a difference in the time to get a fix, much faster in new antennas. In the woods, I notice a big difference also. Appears Topcon has changed the logarithm for a fix in canopy area where multipath may exist. In open hard woods with leaves on, an area where the older Hiper Lites/XTs will fix, the new models V/GR5 will NOT. They show only a float.
In my experience with the Vanguard/Fence Technology, if you get a fix in areas that are subject to multipath, the RTK results are a bit more reliable than they were in older Topcon gear.
LeeGreen.com
Is there a receiver that can fix a GLONASS only solution?
I was under the impression that some sats from the GPS constellation are required for fix.
GLONASS orbits are not known/tracked as well as GPS orbits; or so I have heard.
The ProMark 800 and Spectra Precision SP80 will supposedly do this. They are former Ashtech units that were bought by Trimble and rebranded as Spectra Precision. They claim that they can fix with only 4 sats of any combination of Glonass, GPS or Galileo. They also work with Survey Pro, so that's another plus for me. I'm going to pick up a new system this year and getting a demo of these is at the top of my list.