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Trimble SPS85x Series GNSS Receivers - Product Review

Why you should be using the Trimble SPS855 series GNSS receivers

Trimble SPS85x series GNSS receiver with Zephyr and Zephyr Geodetic IIOver the last decade receiving RTK corrections through the internet has become a popular and cost effective way for land surveyors to deploy several rovers over multiple projects and jobsites.

Additionally, the FCC narrowband regulations in 2010 on the UHF band (450-470 Mhz), has taken a big hit on the distance a UHF radio will transmit. According to Trimble,narrow banded radios are estimated to transmit 1/3rd the distance of non-narrow band radios-not to mention the hassle of acquiring an FCC license.

And lets not forget base station theft. eBay and pawn shop shelf’s are riddled with Trimble base stations that were “found” on the side of the road.

Yes, it is easy to understand the benefits of network RTK corrections – and the Trimble SPS85x series (SPS850, SPS851, SPS852 and SPS855) are the best solution to the problem.

The Trimble SPS85x series receiver is a modular GNSS receiver with internal UHF or 900 Mhz radio. It can be used as either a base or rover (depending on options). It has an internal battery (10 to 12 hour), internal Bluetooth, internal user interface, and internal serial to Ethernet converter (simple internet setup) along with auto-base functionality, CMR, CMR+, CMRx and RTCM protocols. This receiver has everything! The SPS85x is so versatile and easy to set up.

The SPS85x is a modular receiver. It requires a separate GPS or GNSS antenna to receive satellite signals, preferably Trimble's Zephyr Geodetic Model II / III. This allows you to install the SPS85x receiver inside a jobsite trailer or vehicle – safe from the elements and thieves. These receivers also have a full-metal jacket and are totally sealed, so they can take some serious abuse and are IP67 rated waterproof.

Local Base:

Trimble SPS852 GNSS receiver on tripodAs we mentioned before- the SPS85x has an optional internal transmit and receive radio. The UHF radio offerings are: 410 to 430 Mhz, 430 to 450 Mhz, 450 to 470 Mhz. There is also a 900 Mhz version. These are 2 watt radios that can easily cover small sites. The distance a radio will transmit is always dependent on terrain, obstructions and radio antenna, and antenna height – but on average we received corrections around 1.5 miles away with either radio type. For longer distances – you can always add a high power external radio, like a Trimmark 3 or TDL450. For dual radio situations (900 and UHF) the SPS85x can transmit out of its internal radio – while also transmitting to an external one. This works great for sites where survey and construction crews are running different radio types e.g. Trimble survey (UHF) and Trimble Grade Control Systems (900 MHz).

The SPS85x has a front panel user interface that makes base station setup easy. The receiver can be set up with a Trimble data collector running, Trimble Survey Controller, Access or SCS900. There is also an auto-base feature that works great for machine control operators. The auto-base feature will remember its position parameters from the previous setup. It allows for 1 button (the power button) operation the next day.

Internet Base:

Trimble SPS852 GNSS Base Station as network RTKSending RTK corrections through the internet requires an internet connection for the base station and a cellular connection for the rovers that need to receive those corrections. The SPS85x was designed with the internet in mind. It is the easiest electronic device to set up on a network – that we have ever seen. Seriously – this thing was easier to set up than our wireless printer. It also has a web browser interface that allows you to access advanced futures like remote set up and remote troubleshooting – That’s right, you can access your base station from anywhere in the world – just open your browser and type in its IP address. Brilliant. Within 15 minutes, we had it transmitting RTK corrections over the internet….But wait – there’s more...

Another advantage of the SPS85x is that it can simultaneously transmit corrections over multiple ports, using multiple protocols. For example – you can send CMR+ corrections through the internet while sending RTCM corrections through the internal UHF radio – while also sending CMRx corrections through an external radio – or any combination of the sort. You can even have a 4th port sending via Bluetooth.

Another cool trick – two job sites – one base station:

Think about this scenario: You have multiple jobs that are close to each other, but out of radio range. The SPS85x can be located on one site, providing corrections locally – while sending corrections to the second site through the internet.

Note:Sending corrections through the internet enables your rover to receive those network corrections over nearly unlimited distances. This is not the same as a VRS solution. Keep in mind that the laws of physics which control RTK accuracy are still in play here and we don’t recommend using corrections when you are more than 20 miles from your base station. The Trimble R8 GNSS Model 3 receiver specs vertical kinematic survey accuracy at 20mm + 1ppm RMS. The longer the distance is between the rover and the base – the greater the vertical error. VRS solutions are more accurate at distances over 20 miles because they are able to model the atmospheric conditions and apply advanced corrections to your location based on multiple base stations that cover a large area.

Rover operation:

In a pinch, the SPS85x works as a rover too. It can be mounted to a survey pole, tucked away in a backpack, or mounted in a vehicle – perfect for daily quantity topo’s. The SPS receivers are optimized to work with Trimble’s SCS900 software, but it can also be used with Survey Controller software and Access ** Survey Controller requires and upgrade code – this code is usually free, but we are aware some dealerships will charge up to $250 for it.

Additional information:

SPS85x series receivers can range in price depending on the features installed. Here is what you need to know when buying one of these receivers:

SPS850 Extreme:

These were the original from back in 2005. They are 72 channel receivers that included GLONASS tracking and can be used as either a base or rover. They were offered multiple radio options: 900 Mhz, 410-430 Mhz, 430-450 Mhz, 450-470 Mhz There is also a non radio version. Optional upgrades include: L5 and data logging.


The SPS851 is the same receiver as the SPS850, except GLONASS tracking was optional (the SPS850 included the GLONASS option).


This is a 220 channel receiver that gets confusing because everything is an option – including the accuracy. From the factory this is a “dumb” or “blank” receiver. It has no options installed and will not do anything without them. Depending on the options purchased - the receiver can either be a base or a rover – or both. GLONASS is also an option, along with L5 and data logging. To ensure you are buying a RTK accuracy unit – make sure the RTK Precise option (base or rover) is installed. This option can also be purchased at anytime, but upgrades are not cheap. If you are looking at purchasing one of these receivers – please have your local dealership verify what options are currently installed. You can also check with us.


This is the most current version, released in 2011 with an amazing 440 channels! Trimbles datasheet shows that this receiver will also track COMPASS and Galileo constellations. The SPS855 also has a 900 Mhz option with one UHF option that covers the full 410 to 470 Mhz spectrum. Just like the SPS852, everything is an option with this receiver – so be cautious when purchasing.

SPS GNSS receivers are optimized to work with SCS900 software, but we have successfully tested and operated them with Access and Survey Controller ver 12.49.

Trimble SPS851, SPS852 GNSS Receiver Base Station

Trimble SPS852 GNSS

Trimble SPS850 through SPS855 look the same on the outside.  IP67 rated sealed receivers with internal batteries, yellow paint. Internal radio options and Bluetooth. 

Trimble Net R9 GNSS Receiver for VRS

Trimble NetR9

The Trimble NetR9 GNSS receiver looks the same as the SPS85x series but does not have the option of internal radio and cannot be used with Survey Controller software. The NetR9 was designed for office installations - not the field, but it is compatible with Access 2017, though we have not tested it as of yet.

Trimble Net RS GPS network base station

Trimble NetRS

The Trimble NetRs receiver was the first to go online, but was difficult to set up and was a GPS receiver only. Additionally the NetRS is not a field receiver and does not have an internal radio. This receiver has a Linux operating system.  Unless you are already familiar with these, our recommendation is to stay clear of the NetRS because of how difficult it is to get set up.

This article was written in 2016 and updated in April, 2020. We put forth our best efforts to ensure accuracy of information listed. Please use this information as an additional guide to help you make a decision.