RTK Facet L-Band

GPS/GNSS Enclosed Products
1

Want to verify how to turn my Facet L Band into a base station. It looks like i need another piece of hardware? Can I set other devices to receive the correction data? Do those devices need RTK chips?

2

The RTK product line has a variety of ways to transmit the correction data including:

Also note, the L-Band can enter what’s called Assisted Base (https://docs.sparkfun.com/SparkFun_RTK_ … isted-base).

You may be thinking of how the Facet can transmit the correction data directly to a Rover without connecting to an NTRIP Caster (such as rtk2go). That is possible but requires an external radio such as the LoRaSerial(https://www.sparkfun.com/products/20029) or a telemetry radio (https://www.sparkfun.com/products/19032) connected to the RADIO port of the Facet.

3

When in base station mode how large of an area can it cover and how many devices can it send correction data to at the same time?

4

The corrections from a base station are generally good up to ~20km away. If your rover is further away from the base than that, the RTK Fix accuracy begins to degrade, I’ve heard about 1cm per 10km distance.

A base station generally pushes data to a caster. From that caster, a large number (100s+) of rovers can connect and obtain the corrections from that caster source (they are called mount points).

5

The devices receiving the correction data must have RTK GPS Chips correct? In my scenario i would want to give correction data to vehicles moving around in a radius of about 5 miles. Could be upwards of 400 devices at a time but usually the number would be less than 100. In a scenario with closer to 400 devices would i use two Base Stations? Is there another device that is best used as a base station?

6

The devices receiving the correction data must have RTK GPS Chips correct?

Yes. The ZED-F9P is the current front runner for lowest cost with the highest capabilities (IMO).

In a scenario with closer to 400 devices would i use two Base Stations?

You don’t need more than one base to handle many rovers. Some basic googling did not give me a concrete answer on the number of simultaneous clients to an NTRIP server, but it’s got to be in the thousands. Snip claims ‘unlimited’ (https://www.use-snip.com/feature-matrix/). It all depends on the server running the Caster. rtk2go, Emlid, and other free services will likely limit the number of client connections, but this is (likely) not a limit of the caster but the company’s want to avoid misuse of their service. If you setup your own caster, I suspect you could easily handle 1k+ rovers. Checkout Snip (https://www.use-snip.com/feature-matrix/) for more info.

7

How does the Base station communicate the correction data? Is it through cellular?

8

Can you tell us a bit more about your plans? Using an L-Band for a base is a bit odd. If you need a temporary base, the Facet L-Band may make sense. If your setup is more permanent, the RTK Reference Station (https://www.sparkfun.com/products/22429) with Ethernet/WiFi is a much better way to go.

If you plan to use the Facet L-Band, the RTK product line has a variety of ways to transmit the correction data including:

If it were me, I would use a Reference Station if I have permanent housing/power. If it’s temporary, I would use the Facet L-Band with a cell phone acting as a hot spot: the L-Band connects to the hot spot WiFi and sends it’s corrections to the caster.

9

We have two use cases.

  1. We need a good device for surveying areas. Mapping out specific items and getting the details right.

  2. We would want a base station. The station would be permanent. Minimum of 4 years in one spot providing correction data to specific devices on vehicles in a 5-7 square mile area. 50 to 500 devices within that area. It is possible to speak to a Sparkfun Sales Rep or anything?

10

Sparkfun Sales Rep or anything?

We don’t currently have a dedicated RTK sales rep but we are looking for one! (https://www.sparkfun.com/jobs/1035)

  1. We need a good device for surveying areas. Mapping out specific items and getting the details right.

The Facet L-Band should fit your needs well if your live in USA contiguous 48 or the EU.

  1. We would want a base station. The station would be permanent. Minimum of 4 years in one spot providing correction data to specific devices on vehicles in a 5-7 square mile area.

An RTK Reference Station is the most robust solution.

11

can you send a link to the Reference stations? Just to make sure I am looking at the right product.

12

Sorry, I should have done that: https://www.sparkfun.com/products/22429

13

The kit has everything you need except mounting hardware. We offer a few different mounting hardware bits, but it all depends on what type of roof and structure you have access to.

14

I have been using the device for trails. I thought it was showing the location of the device on the map but it appears it shows the phone I’m using to connect. Does that mean it is giving my phone correction data? Is there a different way I should be using it?

15

Check the quickstart guide here: https://docs.sparkfun.com/SparkFun_RTK_ … o/#android

You should see a green dot in SW Maps when RTK Fix is achieved.

16

So I have to do that every time. Got it. I still have a blue dot right now but three prongs next to the satellite

17

I have an L band key

18

I still have a blue dot right now but three prongs next to the satellite

A blue dot indicates RTK Float. The three prongs means you’re decrypting L-Band corrections successfully (https://docs.sparkfun.com/SparkFun_RTK_ … ys/#l-band). Depending on your GNSS reception, RTK fix can take a few minutes depending on how good the GNSS reception is. If there’s a lot of dense tree canopy or natural obstacles (ie, mountain walls, etc) then RTK Fix may not be possible.

19

So only a green dot means RTK fix. What does RTK float mean in terms of accuracy?

20

Also, do you have any base stations that use L1/L5 bands?