PIX4Dcatch RTK device with own-hosted RTK base station

PIX4Dcatch can be used with an RTK GNSS base stations to obtain RTK corrections. This is useful if there is no NTRIP coverage on the site, there is low-reliability 4G coverage, or subscribing to an extra NTRIP service is not an option.

Concept

An RTK base station is placed on a reference point with known coordinates. The corrections calculated by the base station are then transmitted to the PIX4Dcatch compatible RTK device with a real-time communication channel via the NTRIP protocol.

To set up an NTRIP service with an own-hosted base station, the following generic steps are needed.

1. Select a reference point close to the site with known coordinates. The coordinates of the point can either be known a-priori or calculated by other methods, e.g. PPP, long observations, etc.
2. Configure the base station to act as a base with the known reference in your preferred Coordinate Reference System.
3. Configure the RTK base station to connect to the internet using 4G or WiFi. For 4G you will need to install a SIM card with an active data plan in your base station.
4. Configure the NTRIP service to provide the corrections for PIX4Dcatch.

Configuring an Emlid base station

Emlid RS2, RS2+, RS3, and RS4 receivers are capable of acting directly as base stations and indirectly using the Emlid NTRIP caster service. These devices support both 4G and WiFi-based communication, which enables them to act as an NTRIP provider for PIX4Dcatch. Below we describe a simplified procedure for setup. More details are available on the Emlid public online documentation.

Configuring the Emlid NTRIP caster service

Emlid provides an NTRIP caster solution for free. This central service requires an internet connection for both the RTK base station and the RTK GNSS rover. Setting up the caster is a one-time setting that can be reused when needed.

Follow these steps to set up the caster:

1. Open a web browser and go to https://https://caster.emlid.com/app/mountpoints and sign in with your Emlid account.
2. Manage mount points in the My mount points section. It is safe to use the default settings. Please save the name of the mountpoint and the corresponding password; these values must be used to set up the base station.
3. My devices shows the credentials that have to be used by the RTK devices. Please save these values.

Setting up the base station

To set up an Emlid RS series receiver as a base station, the Emlid Flow app can be used. Emlid Flow is freely available in the App Store and the Google Store. The setup procedure is the same for all devices and can be done in the field.

Initial configuration before first time using.

Steps to complete on each site.

1. Connect the mobile phone to the RTK receiver via Bluetooth
2. Start the Emlid Flow app and connect the base station
3. Go to Base settings and define the base point coordinates and height offset. The following options are available. For more information please see the Emlid user documentation
   1. Manual entry - When you place the base over a known point
   2. Average SINGLE - The position of the base is calculated from a SINGLE solution over a pre-defined time period.
   3. Average FLOAT - The position of the base is calculated from a FLOAT solution over a pre-defined time period.
   4. Average FIX - The position of the base is calculated from a FIX solution over a pre-defined time period. In this case, the base station needs to be connected to another NTRIP service and acts as a device.
   5. RTCM3 messages - Select 10Hz
4. Go to Base output and select the NTRIP option.
5. Configure NTRIP access credentials. If Emlid's NTRIP caster is used, use the values from Emlid's NTRIP caster My mountpoints section; otherwise, use the default values to configure the credentials. IMAGE Definition of Emlid NTRIP caster credentials.
6. Save settings

Emlid base station using 4G

The 4G connection type requires the use of Emlid's NTRIP caster which simplifies the setting procedure.

1. Ensure the Emlid base station and PIX4Dcatch have a stable internet connection over the entire site.

Emlid base station using a local WIFi network

There are two ways to use WiFi for broadcasting NTRIP corrections. The simplest way is when a WiFi network exists on the site, and the WiFi has an uplink to the global internet.

Please consider the following:

• If there is no existing WiFi available, a new network has to be created. Emlid's receivers can create a WiFi hotspot. Please refer to Emlid's documentation. The network name will be like reach:XX:XX.
  Tip: When setting up a local network, ensure the WiFi has stable coverage for the entire scene.
• If there no global uplink is available, then Emlid's NTRIP caster cannot be used, and a local NTRIP service has to be provided.
  Tip: The RTK base station and the RTK device must be on the same WiFi network. Please ensure there is stable coverage at the reference point.

1. If there is no existing Wifi network, create a local WiFi network with the Emlid base station; through which the receiver will act as a hotspot.
2. If there is no connection to the internet, obtain the IP address of the base station. If the base station is acting as a hotspot, then it is most likely 192.168.1.1
3. Connect PIX4Dcatch to the WiFi network. If Emlid's hotspot is used, the network name is most likely labelled Local NTRIP.

Configure PIX4Dcatch to use the NTRIP service

Connect PIX4Dcatch to the RTK device, and for NTRIP settings, use the following values:

Use these values to set the NTRIP connection in PIX4Dcatch as indicated here.