Hello friends and merry christmas.?ÿ
I??m considering buying a new GPS system for RTK and post processing applications, I have two question,?ÿ
1) is GNSS really matters or just another term for GPS, I live in North Africa where only GPS and Glonass can be tracked.?ÿ
2) as an old user of Trimble receivers and software, I??m considering to buy the R8s system or Spectra??s SP60. I need advice from surveyors who had some experience with those receivers, especially under canopy.?ÿ
Any other advice in the subject is highly appreciated. Thanks?ÿ
1. GNSS is the umbrella term for all the different Satellites. GPS are just US satellites, Glonass are Russian Satellites. So you would be looking for GNSS receivers. If you could afford, you can try getting the option for Galileo in the future. But I would reccommend getting at least a dual frequency receiver rather than a single?ÿ frequency. I get better fixes with dual frequency.?ÿ
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Whether the trimble or Sp receivers work under canopy I am not sure. Maybe others could chime in. But recently some members did a Surveyors Field Test of the Javad and Trimble receivers and results were kinda surprising. Maybe you could see if it is useful for you.?ÿ
Thanks for uour replay, Actually my question was if GLONASS really matters in the results, today I made a test on few points with a Leica Viva GNSS, didnt notice any real effect after enabling or desabling glonass observation on post processing.?ÿ
Yes Glonass is essential if you want to work in marginal areas.
it is also essential to do at least two independent surveys of control you measure with RTK only. I've caught some weird errors on observations that looked just great statistically, particularly in the vertical.?ÿ
You may find trimble boards embedded in receivers of other brands (CHC,?ÿ there are other trimble?ÿ chameleons) , you will get same performance at half price.
Think of GLONASS as additional Satellites. Of course more is better, but how many channels does your receiver have. If you get the R8s which should have 440 channels you are set to go. However if you have the older ones with 72 channels then you will be limited to how many satellites you can track.?ÿ
In open areas, I find GPS is really all I need and GLONASS doesnt say made my solution residuals from 0.010m go to 0.001m . But it doesnt hurt to collect more on site. But in sketchy areas like urban areas, GLONASS have managed to get fixed solutions sometimes where GPS is unable to get a fix alone. Unfortunately, I do not do any work under canopy areas, so I cannot comment much on it.?ÿ
Having access to the additional satellites GLONASS provides makes a huge difference to the performance in marginal conditions such as under canopy. I would not consider spending money on any system which did not?ÿ have it.?ÿ?ÿ
You may find trimble boards embedded in receivers of other brands (CHC,?ÿ there are other trimble?ÿ chameleons) , you will get same performance at half price.
Hello Yuriy thanks for your replay, I'm not sure chinese manufacturers really make receivers that can last for years, I have few 5700 and even 4700 Trimble receivers, aged over 20 years, I think this is a point to consider when?ÿ buying a receiver.