You are viewing the RTK receiver setup guide. The settings each receiver in a Ditch Assist system needs, from the app or by hand. For wiring and mounting, use the matching install manual.
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RTK receiver setup for Ditch Assist®

Ditch Assist runs on the RTK GPS you already have: any receiver that sends standard NMEA messages over an RS-232 serial port. The first section lists what every receiver needs, with links to the step-by-step settings for common brands.

The rest of the guide sets up an Emlid Reach RS3 or RS4, in the Emlid Flow app (the receiver app), for each job in a Ditch Assist system: the RTK base on the tripod, the rover cabled to the control module or DIG™, and the Ditch Assist Lite rover that the tablet reads over Wi-Fi. For a Reach, the quickest way is to let the Ditch Assist app program it for you; the same settings are listed screen by screen, so you can set one by hand or check one.

Any RTK receiver

On the Full Automation Kit, the Guidance Only Kit and DIG, the receiver's position goes into the control module through the RTK GPS cable. Set the receiver to send:

  • NMEA 0183 on its RS-232 serial port
  • Baud rate 38,400
  • GGA and VTG at 5 Hz or faster (10 Hz works too)
  • Every other message off
  • Talker ID GP, not GN, if your receiver has the option

GGA carries the position and needs at least 5 Hz. VTG only carries speed and heading, so a receiver that sets a rate for each message can send it at 1 Hz, as the Reach settings below do. Where one rate covers every message, use 5 Hz. The receiver also needs an RTK fix, from your own base or a correction network, set up the way its maker describes.

Once it is connected, the control module's STATUS 2 light blinks each time it gets a valid position: about five blinks a second at 5 Hz. No blinking means no valid messages are arriving.

Step-by-step settings for common receivers are in the install manuals:

Ditch Assist Lite is the exception: it runs on an Emlid Reach RS3 or RS4, which the tablet reads over the receiver's own Wi-Fi. With another brand of receiver, the Guidance Only Kit gives the same guidance through the control module.

Emlid Reach RS3 and RS4 GPS receivers

Everything from here on is for an Emlid Reach RS3 or RS4: as the RTK base, as the Ditch Assist rover cabled to the control module or DIG, or as the Ditch Assist Lite rover.

At a glance

On an Emlid Reach RS3 or RS4, what each role needs. Set by hand, anything not listed stays as it is. When the Ditch Assist app programs a receiver, it also puts a few solver settings the receiver app no longer shows back to Emlid's defaults.

Swipe the table sideways to see all three roles.

Setting RTK baseOn the tripod. Sends corrections over LoRa radio. Ditch Assist roverCabled to the control module or DIG. Ditch Assist Lite roverOn the machine. The tablet reads it over Wi-Fi.
GNSS settingsGPS, GLONASS and Galileo on; BeiDou and QZSS off. Update rate 5 Hz, elevation mask 15, SNR mask 35. IMU (tilt sensor) off.
Position streaming 1OffSerial: RS-232, 38400, NMEATCP server: port 9001, NMEA
Position streaming 2OffBluetooth, NMEABluetooth, NMEA
NMEA messages—GGA 5 Hz and VTG 1 Hz on streaming 1 (GGA 1 Hz, VTG 1 Hz on Bluetooth); every other message off. Talker ID GP. Tilt compensation off.
Correction inputOffLoRa radio: the base's frequency, 18.23 kb/sLoRa radio from your base, or corrections over the receiver's mobile data (SIM)
Base output 1LoRa radio: your frequency, 18.23 kb/s. RS4 500 mW (1000 mW for more range), RS3 20 dBm.OffOff
Base output 2OffOffOff
Base settingsAverage SINGLE, 2:00 averaging timeNo changeNo change
RTCM3 messages1006 at 0.1 Hz; 1074, 1084, 1094 at 1 Hz; all others offNo changeNo change
Turn on with EXT powerNo changeOnNo change
Wi-FiNo changeNo changeHotspot: the tablet joins it
LoggingLeave it recording. The app's check flags a receiver with logging off.

Program it from the app

The Ditch Assist app can read a Reach RS3 or RS4, tell you which role it is set up for, and program any of the three roles for you.

  1. Join the tablet to the receiver's Wi-Fi hotspot. It is named after the receiver, for example Reach:C6:98, and the password is emlidreach unless someone changed it.
  2. In the Ditch Assist app, open Settings→Emlid Diagnostics (the button at the bottom of Settings).
  3. The app reads the receiver. If it already matches a role you get a green check with the role's name; otherwise it shows the closest role and which settings differ.
  4. Tap Configure and pick the role: Base, Rover (control module or DIG) or Lite Rover.
  5. Enter the LoRa frequency, between 902.000 and 928.000 MHz. Use the same frequency on the base and every rover. On an RS4 base, pick 500 or 1000 mW; an RS3 always goes out at 20 dBm, its maximum. Leave Send at 0.5 Hz instead of 1 Hz off unless the radio link has trouble.
  6. Tap Program receiver. The app writes one section at a time and reads each back before going on. If a section still won't take after three tries it stops and names it: finish that section by hand with the steps below.

Stop automatic grading before you program a receiver. If Ditch Assist Lite is running on that same receiver, programming it as a Lite Rover drops the connection for a few seconds. Programming it as a Base or Rover stops its position going out over Wi-Fi, so the app loses it as a GPS source.

If the radio can't carry all three constellations at 1 Hz, the app drops GLONASS, then Galileo, then GPS to 0.5 Hz until it fits, and tells you the rates it used.

The app also tells you if the receiver's firmware is older than the versions we have checked: update it in the receiver app first. If it says programming is disabled on this receiver or firmware, set the receiver up by hand with the steps below.

To change an RS4 base's radio power later, use the one-tap Switch base power on the check screen.

Set it up by hand

On a Reach, open the receiver app and connect to the receiver. It finds an RS3 or RS4 over Bluetooth.

  • Screens marked ↗ (GNSS settings, RTCM3 messages, NMEA settings) open only with the tablet on the receiver's Wi-Fi. The app offers to join it: tap Connect, and allow location access if it asks.
  • Picking an option in a list takes effect straight away. Editing screens need Save or Apply.
  • Work through the steps in order. The LoRa radio can only do one job at a time, so whatever was using it has to be switched off before you give it a new one.
  • The Ditch Assist app's check can still list a difference or two on a receiver set up by hand, such as base antenna height or settings the receiver app doesn't show. It runs the same. Tap Configure and Program receiver if you want the green check.
The tablet asks to connect to the receiver's Wi-Fi network, with Cancel and Connect buttons
The receiver app asks before it joins the receiver's Wi-Fi.

GNSS settings, every role

  1. Settings→GNSS settings

    • Elevation mask angle 15, SNR mask 35
    • GNSS systems: GPS, GLONASS, Galileo on; BeiDou and QZSS off
    • GNSS update rate 5 Hz

    Then Settings→IMU: Off. The receiver rides on the machine, so it reports the antenna position with no tilt correction.

    GNSS settings: elevation mask 15, SNR mask 35, GPS, GLONASS and Galileo ticked, update rate 5 Hz
    GNSS settings, the same on every receiver.

RTK base

The base sits on a tripod in one spot for the day, averages its position each time it is turned on, and sends corrections to the rovers over LoRa radio.

  1. Settings→Position streaming 1: Off. Then Position streaming 2: Off.

  2. Correction input: Off.

    The base makes corrections; it doesn't take them, so this frees the LoRa radio.

    Correction input list with Off selected

  3. Base output 1: Off. Then Settings→Base output 2: Off.

    With the radio off while you set the messages, the receiver doesn't refuse them for lack of air time. Base output 1 goes back on LoRa at the end.

  4. Base settings→Configure

    • Coordinates entry method Average SINGLE
    • Averaging time 2:00

    Tap Save. The base now averages its position for two minutes every time it is turned on. Antenna height doesn't matter for Ditch Assist; leave it as it is.

    Configure base: Average SINGLE, averaging time 2 minutes 0 seconds

  5. Base settings→RTCM3 messages

    • 1006 at 0.1 Hz (always on)
    • 1074 GPS, 1084 GLONASS and 1094 Galileo, each at 1 Hz
    • 1124 and 1230 off. Tap Show legacy messages and make sure 1004, 1008, 1012 and 1033 are off too.

    Tap Apply.

    RTCM3 messages: 1006 at 0.1 Hz, 1074, 1084 and 1094 ticked at 1 Hz, all other messages unticked

  6. Base output 1→LoRa radio: tap the pencil.

    • Frequency: pick a channel between 902.0 and 928.0 MHz. Every rover uses the same one.
    • Output power: RS4 500 mW (1000 mW when you need more range); RS3 20 dBm, its maximum.
    • Air data rate 18.23 kb/s. The slower rates are greyed out with these messages; that's expected.

    Tap Save, then pick LoRa radio in the list.

    LoRa radio settings: frequency 902.0 MHz, output power 500 mW, air data rate 18.23 kb/s
    RS4: power in milliwatts.
    Output power list from 6 to 20 dBm with 20 dBm selected
    RS3: power in dBm. Always 20 dBm.

  7. Check the receiver menu.

    It should read Correction input Off and Base output 1 LoRa radio, and Settings→Base output 2 should be Off.

    Receiver menu with correction input Off and base output 1 set to LoRa radio
    A finished base.
LoRa won't turn on?

The radio can't carry all three constellations at 1 Hz. Set 1084 (GLONASS) to 0.5 Hz and pick LoRa radio again. Still no? Set 1094 (Galileo) to 0.5 Hz, then 1074 (GPS).

Ditch Assist rover

For a receiver cabled to the Ditch Assist control module (Full Automation Kit and Guidance Only Kit), and for DIG.

  1. Settings→Position streaming 1→Serial: tap the pencil.

    • Port RS-232, baud rate 38400, format NMEA

    Open NMEA settings:

    • Tilt compensation for NMEA: Do not compensate receiver position
    • Talker ID GP
    • GGA 5 Hz and VTG 1 Hz; every other message off

    Tap Apply, then Save, then pick Serial in the list.

    GGA carries the position and needs at least 5 Hz. VTG only carries speed and heading, so 1 Hz is plenty.

    Serial output: port RS-232, baud rate 38400, format NMEA
    NMEA settings: no tilt compensation, talker ID GP, GGA at 5 Hz and VTG at 1 Hz ticked, all others unticked
    NMEA settings for the serial output.

  2. Settings→Position streaming 2→Bluetooth: tap the pencil.

    • Format NMEA. In NMEA settings: Do not compensate receiver position, talker ID GP, GGA 1 Hz, VTG 1 Hz, every other message off.

    Tap Apply, then Save, then pick Bluetooth in the list.

    Position streaming 2 with Bluetooth NMEA selected

  3. Base output 1: Off. Then Settings→Base output 2: Off.

    This frees the LoRa radio so the rover can listen on it.

  4. Correction input→LoRa radio: tap the pencil.

    • Frequency: the same as your base
    • Air data rate 18.23 kb/s

    Tap Save, then pick LoRa radio in the list. It reads Waiting for corrections until the base is on the air.

    Correction input with LoRa radio selected at 902.0 MHz and 18.23 kb/s, waiting for corrections

  5. Settings: turn on Turn on automatically when powered via EXT port.

    The receiver then switches on and off with the control module.

    Receiver settings: position streaming 1 Serial, position streaming 2 Bluetooth, and turn on automatically when powered via EXT port switched on
    A finished Ditch Assist rover.

Ditch Assist Lite rover

For a receiver on a machine with no control module. The tablet in the cab joins the receiver's own Wi-Fi and reads its position from there. Everything is the same as the Ditch Assist rover except position streaming 1, the EXT power switch and the Wi-Fi.

  1. Settings→Position streaming 1→TCP server: tap the pencil.

    • Port 9001, format NMEA
    • NMEA settings: no tilt compensation, talker ID GP, GGA 5 Hz, VTG 1 Hz, every other message off

    Tap Apply, then Save, then pick TCP server in the list.

    TCP server settings: port 9001, format NMEA
    Position streaming 1 with TCP server on port 9001, NMEA, selected

  2. Settings→Position streaming 2→Bluetooth: NMEA, GGA 1 Hz, VTG 1 Hz, as on the Ditch Assist rover.

  3. Base output 1: Off. Then Settings→Base output 2: Off.

  4. Correction input: from your own base, or over the receiver's mobile data.

    Programming the receiver from the app sets LoRa radio. If it takes corrections over mobile data, set that again afterwards; the app's check then lists Correction input as a difference, which is expected.

  5. Wi-Fi: leave it in Hotspot mode.

    Leave Turn on automatically when powered via EXT port as it is: the receiver runs on its own battery.

    Wi-Fi screen in hotspot mode, showing the network name, the password and Active
    The tablet joins this network.
    Receiver menu with correction input LoRa radio, base output 1 Off and Wi-Fi in hotspot mode
    A finished Ditch Assist Lite rover.
Corrections over mobile data

With no base, a Ditch Assist Lite rover can take RTK corrections over its own mobile connection. The tablet stays on the receiver's Wi-Fi, so the receiver has to reach the internet by itself, through a SIM card.

  1. Put a nano-SIM in the receiver.

    A data-only or IoT SIM with some prepaid credit is ideal. The receiver only sends and receives a small amount of correction data.

  2. Settings→Mobile data: turn Mobile data on.

    Enter the SIM's PIN if it asks for one. Most SIMs connect without APN details; if yours doesn't, enter your carrier's under APN settings. Some SIMs also need Data roaming on. Network bars appear next to the battery icon once it is connected.

  3. Pick the correction service under Correction input:

    • Emlid Corrections on a Reach RS4: sign in to an Emlid account in the receiver app's Profile tab, activate the subscription (every new receiver includes a free year), and choose Get corrections via Reach so the receiver gets them over its own SIM. This needs RS4 firmware 34.8 or later and Emlid Flow 15.7 or later. The service covers the US, the UK, much of continental Europe, Australia and New Zealand; it isn't available in Canada. Emlid's step-by-step guide: RTK over Emlid Corrections.
    • Another correction network (a state, provincial or commercial NTRIP service): choose NTRIP via Reach and add the service's address, port, mount point and login. This works on an RS3 or an RS4.
Reach RS3 and Emlid Corrections

An RS3 gets Emlid Corrections only through the receiver app running on a phone or tablet connected to it by Bluetooth, with the app left open. For Ditch Assist Lite on an RS3, use a base or an NTRIP network over the RS3's own mobile data instead.

Then, on the tablet

  1. Join the receiver's hotspot: Reach:XX:XX unless it was renamed, password emlidreach.

    If the tablet warns that the network has no internet, choose to stay connected. On a Samsung tablet, open Wi-Fi→Intelligent Wi-Fi and turn off Switch to better Wi-Fi networks, or the tablet leaves the hotspot every few minutes.

  2. In the Ditch Assist app: Settings→Mode→Ditch Assist Lite.

  3. Pick a workflow on the home screen, tap Emlid Reach, then Activate the first time.

    See Ditch Assist Lite for licensing and what the receiver needs on the machine.

Need a hand? Support has the common fixes, and the RTK GPS bundles page lists the receivers we supply.