Accuracy, price and support excellent… it reduce a lot work.

This product is wonderful at its price point. I tried the L-Band Correction and I marvel at the accuracy it can deliver without any base unit. No other GNSS receiver on the market that I know of delivers RTK correction via radio, internet, and L-band from a satellite and remains this affordable. Nonetheless, I hope the next gen of this product has an in-built sim card (LTE) as well as an in-built radio. What will even be more orgasmic is having this l-band RTK on survey drones and please add IOS support. I really hope the point-perfect coverage hits Africa.

It's veryaccurate, compact and easy to use. When will the IOS app become available? We can't use it to it's fullest potential until IOS is available!

This is meeting all the expectations that I had when I decided to purchase it. It gets accurate readings with in the 14 mm range. I don't have to set up base station to get those readings.

Everything worked as advertised! Had it set up in a few minutes. Just had to get it connected to a wifi network to download the keys. Once the keys was downloaded, it took about 1-2 minutes and the accuracy was down to an avg. ~14-16mm horizontal accuracy. The unit also supports several ways to extract the 4Hz positioning data using different protocols. Wonderful product!

Executive Summary: I bought the Facet L-Band GNSS receiver to see if it could be used on my projects, but it wasn't accurate enough vertically and the L-Band feature was useless. After three weeks, the device has stopped working. I can't recommend it to people who are looking for a survey grade GNSS receiver.

I want to preface this review by stating that I'm a registered professional engineer in the state of Virginia. Per Virginia code, P.E.s can practice land surveying if it is incidental to an engineering project. I work in land development and am looking into equipment options for future jobs and thought to give this a try and see what it can do. I've had the product for approximately three weeks now and here are my thoughts.

• Current Status of Device: It has stopped functioning. It's not powering on even after charging. As of right now, I have a $1,500 brick that I'm hoping to get a return on. I'll change my review to three stars if I can get a refund, but I'll update on that.

• Sparkfun Customer Service: The customer service is very lacking. I accidentally placed an order on the l-band facet ($1,500) versus the regular facet ($800). I immediately reached out via the customer service email, there is no customer service phoneline, and didn't get a response back until two days later after it had been charged. I thought, no worries I'll see what the l-band features do and decided to keep it.

• First Reception: This facet is essentially a plastic housing around the L1/L2 antenna, and computer boards. I'm not an electronics guy, I just know that there's a slot for usb-c, microSD, and the power button. The black cover is a rubbery cover that protects the device from dust and dirt, but is not seal tight. It takes about 10 minutes for someone to connect it to the wifi and get the keys for the l-band. I noticed that unlike other gnss receivers I've used, this was not waterproof so user beware.

• Horizontal Accuracy: I decided to go out and find a survey control monument in my City. I took the facet, a standard survey pole with a bubble (AdirPro from amazon), and my phone with SW-Maps. I used pointone RTCM service on the 14 day trial. I powered it on and walked to where I knew the monument was. Surprisingly, it was extremely accurate (At least in the horizontal. I did some other measurements, recorded the data in SW-Maps, and went back to the office for some post-processing. I found that the horizontal was accurately described. With rapid surveying for topo, I was averaging 20mm accuracy.

• RTK Fixes: I did notice that this receiver drops fixes a lot more than other receivers I've used. That was while using both the RTCM corrections and the L-band corrections.

• Instrument Height: I couldn't find anywhere in the documentation what the instrument height should be set at. They reference that the "L1 is here, L2 is there" but that doesn't tell me what I need to use to determine my instrument height. Other manufacturers say "Add X.XX' to your rod height" but there isn't anything here.

• Vertical Accuracy: This is where we go down the slippery slope. So, I decided another test to see if this could be used on my jobs is to confirm the vertical accuracy. Anyone working in my field knows that vertical accuracy is just as important as horizontal. So I went to two vertical control benchmarks in my City with established vertical elevations. These weren't local benchmarks but ones established by the City itself. In NAVD88, the elevations of the two controls were 12.66' and 13.93' respectively. A little math, that's a vertical delta of 1.27'. With that I went to the first one, set a control observation (30 observations with an RTK fix). I got an ellipsoidal height of -105.429 ft (converted from meters). I then found the GEOID18 height at the point found, which was -119.944 (NOAA GEOID18 based on lat/lon of the observed point). From the previous bullet, I couldn't find an exact height of the HI so I best determined it was 6.70' based on my pole at the mid point of the L1/L2 locations. I did the ortho calculation: Eh - Geoidh - Hi (https://www.ngs.noaa.gov/PUBS_LIB/gislis96.html) = -105.029 - - 119.944 - 6.7 = 8.215....Okay, maybe I messed something up? Per FieldGenius Android, the vertical deviation was 0.007' with 30 observations... Tell you what, let me check the delta from the ellips height of the two points and compare. luckily the established benchmarks are only 1000 feet away. Ellips1 = -105.029' and Ellips2 = -103.477'. Delta of the Ellips is 1.55' with a std of the second is 0.009'...So, delta of ellips (because they're so close, ellips delta approx= ortho delta) is 1.55', with deviations is 0.007'-0.009', versus 1.27' from the benchmarks. A difference of 0.28'. So there's a second check that I can't verify. I went ahead and checked some more benchmarks and I can't verify any of the vertical info. I can get accurate vertical control with other receivers, but I cannot with this Facet L-Band. For my work, I can't be that far off with vertical error.

• L-Band Feature: The L-Band is advertised essentially as being an option if you cannot get an RTK fix with a base station. All you need to do is connect to the wifi every 56 days so that the device can get encryption keys to use the L-Band service. Another note is that it's still a subscription service, it's just that users get the first year for free. So it's use case is for ares without celluar data or that can't use a base & rover setup. I initially used this feature but quickly found that the RTCM corrections via the NTRIP network I was on received a more accurate fix. L-band was averaging 60mm like it is advertised versus the 20mm from Additionally it was consistently faster at getting a fix. With that said, I personally found that the L-Band feature was pretty pointless for me. So, should you try the L-Band over the regular facet? You have to ask yourself the following questions: Are you going to have cellular service in the area? Yes, use a NTRIP. If no, can you use a temp base over an established point? If yes, use the base. If no, then look into the L-Band features.

• Base and Rover: I haven't used a temp base and rover setup with this, but in my experience I would use that in situations where I can't get celluar service.

• "Surveying" Capabilities: I think under the right circumstances, this can be used to determine horizontal improvements with accuracy. With a lot of work, more than what you need with other equipment, you could even close out boundaries. But I can't recommend this for anyone needing extreme vertical accuracy like what professionals need for land surveying or engineering projects.

• PPK Solutions: The description claims that there is a process for taking the PPP and converting it to data to perform a PPK solutions. However, it's convoluted and not straight forward. In base mode, the receiver records RAWX data, which is nice, but typical format for PPK solutions are RINEX. Let's say for example, you want to perform a static survey over a point to establish coordinates. In theory, you take the facet, set it up over a point perfectly ( I recommend tripod and tribrach ). You take a microsd, pop it in the facet, and turn it on base mode. Let it sit for at least 2 hours over the point and then take the data and process it through a PPK service like NOAA OPUS. However, you have to do an extra step and convert the RAWX to RINEX.

• App Options: Sparkfun's preferred app is SWMaps, which is good for simple applications and GIS, but it is not a good surveying app. It doesn't have stakeout or offset options, which I think is essential for surveying. My recommendation is FieldGenius (or trying to free 30day trial.) That app is more tailored for accurate surveying.

I wanted to do development on an Android phone interfacing with SparkFun RTK L-Band. Contacted Customer Support and they had no sample code interface. Would return unit if I could. Not useful to me.

Out of the box it's not doing what the manual and the youtube videos say. There's no instruction on how to connect to WiFi to get the keys and it's not connecting to WiFi to get the keys. The best I am seeing is 1.5ft horiz and vert accuracy. Not cool. Any suggestions on how to access the RTK correction keys would be greatly appreciated. Also, no 'car' icon when I select Rover mode. I have version 2.2 of the firmware and one menu item is 'mark' another is 'bubble' and neither appears to be documented anywhere.

The facet L band GNSS has been nothing more than an extremely expensive toy to this point. And most cases it is less accurate than my iPhone. I have a completely clear view of the sky and can only achieveWith any regularity 300 to 500 mm accuracy. The learning curve is rather steep, out of the box this unit is nowhere near ready go. It took two or three weeks researching through the forum to find a possible solution and even begin setting this up. Now I’m outside the return window and likely stuck with this lovely paperweight.

I wanted accurate property boundaries in order to build some non- permanent fences and clear trails. A professional survey for my 8 acres would have cost more than double what the SparkFun RTK Facet L-Band cost. It was easy to get the device up and running and paired with my iPhone. Works great when there’s an unobstructed view of the sky; takes longer in my woods (currently winter so no leaves); we’ll see how it works wince the canopies fill in. Regardless, the product has exceeded my expectations.