Upgrading LoRa Antenna

Why use a LoRa Antenna

Our testing of the Emlid Reach RS GNSS real-time kinematic (RTK) units continues.  The units deliver impressive results.  We find the units to be very accurate at a fraction of the cost of comparable or Survey grade RTK units.  When using two Reach RS units in the field you will need to configure the units to communicate RTCM3 correction data for RTK.   The simplest method is to use the built in LoRa radio to send and receive the correction messages between the base and rover.  Utilizing the LoRa radios for RTK corrections requires using the supplied LoRa antenna.


The supplied LoRa Antenna

Supplied LoRa antenna

The supplied LoRa antenna appears to be a directional antenna due to it having two flat sides.  Directional antennas are great an minimizing interference by radiating the signal in specific directions.  Focusing the signal ensures more of the signal power goes into the direction you.   The signal is narrow close to the antenna. The signal width gets wider as the signal travels further away.  This will be ideal for long distance base lines due to the limited interference with focused signal strength.   Emlid has post detailing the supplied antenna reaching a 19.2 km baseline.  19.2 km is nothing short of impressive, however it does require a clear line of sight.

Our LoRa Antenna use

We prefer to set up our Reach RS Base in the middle of the area we are working while using the base and rover configuration.  The ideal setup allows our base to be on a high point in the center of the land.  When set up in the center our rover will move around the base while collecting points.  Using this strategy we keep the baseline distance from one end to the other end of our project pretty consistent.  The directional antenna is great for hitting a long range baseline, however we rarely need our baseline greater than 100m.


Using an Omnidirectional LoRa Antenna

Reach RS units with omnidirectional LoRa antenna

An omnidirectional radiation pattern is ideal when the base is in the center.  Using an omnidirectional antenna provides a consistent LoRa signal in all directions around our base.  A donut like radiation pattern helps ensure we have optimal signal coverage around our base.  We purchased two different metal whip antennas with magnetic bases for our test.  The photos show the 5 db omnidirectional antennas we are using.  The magnetic base allows the base antenna to be placed on the roof of our vehicle which was about nine feet away from the base.  These antennas have a 10′ cable attached. The 10′ cable allows us to put some distance between the GNSS antenna and the LoRa antenna.


A side benefit?

Our signal noise appears to decrease when using the omnidirectional antenna away from the base. Private reference station networks from providers like Trimble or Topcon stations do not have LoRa antennas in close proximity to their stations.  They utilize computer network connections to transmit correction data.  This is more than likely to improve the GNSS reception and quality of the signal.  We need to continue testing this to document the existence of GNSS reception improvement while placing the LoRa away from the Reach RS.

omnidirectional LoRa antenna on car






Reach RS with SNIP NTRIP Caster

Setting up SNIP NTRIP Caster and Reach RS

I’ve seen a number of people at the Emlid forums asking about setting up NTRIP and how to utilize an NTRIP Caster with Reach and Reach RS.  Setting up your own NTRIP Caster using Reach RS is not that difficult, however you do need to make sure have the correct network infrastructure.  For this example we are going to us SNIP, a simple NTRIP Caster with a Free option for limited connections.  To follow this setup you will need two Reach RS units, one to be the base and one to be the rover . Running your own NTRIP Caster will require a publicly available IP address for the computer running the Caster and an internet connection for your Rover when in the field.  I typically run a hotspot from my iPhone for my Reach RS Rover for internet access.

Download SNIP from https://www.use-snip.com/download/ and install it.

The default install will set your caster to listen on localhost / We want to change that to the publically available IP.  For this example I am using an IP that is not public and all of my equipment is on my local network.


My Caster is going to run on IP using port 2101 so let’s change the IP. Click on the Caster and Clients tab then make sure the Caster is stopped.  If it is running, click Disconnect button so you can change the IP then enter the IP address.

Now that we have our Caster set up to run on the correct IP. Lets move on to setting up the a RAW TCP/IP port for input from the Base. Click on the Raw TCP/IP tab then click on Add New Port.

Enter a MountPt then click configure.

Enter your city/state, country and select the appropriate GNSS types, Carriers and set your Base lat and lon.

Our Raw TCP/IP port is now waiting for a connection from our Reach RS Base.

Next we need to configure our Reach RS Base to send its corrections output to the SNIP NTRIP Caster on the Raw TCP/IP port we configured using RTCM3. Your Base needs to have a network connection to your NTRIP Caster.  If your NTRIP Caster has a public IP you do not have to have your Base on the same physical network if your Base is on a network with an internet connection. Mine are on a local network in this example.

Enter the IP you gave your SNIP Caster, the port you set up for the Raw TCP/IP connection and the Mount Point. In this case its, 3000 and ReachRS then apply.

Once you hit apply you can go back to the SNIP application on the Raw TCP/IP tab and you should see it is now green indicating there is a connection and correction data from the base hitting the caster.

Go back over to the Caster and Clients tab and start up your NTRIP Caster by clicking the connect button.

We need to create a user on the Caster for our Reach RS Rover to subscribe to the corrections.  On the Caster and Clients tab click the Manage User Accounts button then add a user.

Now that we have an NTRIP Caster running with corrections from our Reach RS Base it is time to point our Reach RS Rover to get correction data from the SNIP NTRIP Caster.

You will need an internet connection for your Rover when you are in the field.  Mine is on a local network with my NTRIP Caster for this example.  Click on the Correction Input on your Reach RS Rover then turn on Base correction and select NTRIP.  We are going to enter the address, port, username, password and the mount port for our SNIP NTRIP Caster.  In my example that is, 2101, test, test and ReachRS.  Hit Apply and you should now be getting correction data from your Reach RS Base using the SNIP NTRIP Caster.

Note: I was not able to get the Rover using my SNIP NTRIP Caster without supplying a username and password in the Reach RS Rover.  I had anonymous enabled on the SNIP NTRIP Caster, but it would not work.  I could have missed something, but its a much better practice to limit your access than rather leaving it open.

Look at the Status of the Reach RS Rover and you should see it getting a differential now.

You should also see the an active connection on the Casters and Clients tab on SNIP.

If you do not have a publically exposed computer to run an NTRIP Caster then consider using the freely available community NTRIP Caster at http://RTK2go.com.  RTK2go runs SNIP as a free online caster with a few terms and conditions:

By sending your data stream to this Caster you affirm that:
a) You have the right to do so, and
b) You consent to allow others to freely use your data, and
c) The caster owner / operator shall be held harmless for any faults or loss – real or perceived.
The caster owner / operator (SCSC) reserves the right to remove or block any party for abuse.

If you do not have the infrastructure to host your own caster it can be a great solution for you.

Reach RS Accuracy Testing underway

Reach RS on tripod

How accurate is the Reach RS RTK GNSS Receiver?

I have been working on getting a good understanding of how to configure and use Reach RS for the past month working to a goal of comparing the Reach RS units vs L1 and L2 survey equipment from other manufactures. Ultimately I want to answer that question of how accurate is the Reach RS.   Today was the first time we have set up and tested the Reach RS unit for accuracy.  In essence today was the first real accuracy test of our Reach RS units.

We set up two units in a Base and Rover configuration using LoRa for correction.  We set the Base up to use an averaged single position using a 15 minute collection time.  Future testing will use 30 minutes for the averaged single position.  We want to use  a 45+ minute option for the average single position, however the current max is 30 minutes. Our rover is set up to get corrections from the base and set up over a known point. We utilized GPS, GLONAS & SBAS satellites on both base and rover. Once the base set the single solution position we turned on the rover. The rover began dialing in its location with a great AR values quickly. We let the rover get to 999.9 and stay for a couple minutes then turned everything off.

Examining the data

Back at the office we downloaded CORS data plus the base and rover logs. We post processed the base against the CORS then the rover against the solution position from our base.

A vertical datum conversion on the WGS84 ellipsoid gives us the NAVD88 heigh value. Conversion on the horizontal data to U.S. Survey feet, because thats what we work in. Comparing the post processed results we are ±0.111 Northing ±0.055 Easting and ±0.0570 Height from the coordinates on the survey monument.  I am very happy with our first test. We will continuing testing on a number of known points. The next phase of this will have us collecting the same locations with Reach RS and other units to compare both to the known points and to each other.

I will continue to share info as we progress with our testing. I also have a lot of notes for feature request that I need to post. :slight_smile: