Quick Start - RTK Torch

This quick start guide will get you started in 10 minutes or less. For the full product manual, please proceed to the Introduction.

Are you using Android or iOS?

Android

1. Download SW Maps. This may not be the GIS software you intend to do your data collection, but SW Maps is free and makes sure everything is working correctly out of the box.

   

   Download SW Maps for Android

2. Mount the hardware:

   • For RTK Torch: Attach the Torch to a 5/8" 11-TPI standard surveying pole or to a monopole using the included thread adapter if needed (Figure 1).

   

   Figure 1

3. Turn on the RTK Torch device by pressing the Power button for 3 to 4 seconds until a beep is heard and the two front LEDs illuminate (Figure 2).

   

   Figure 2

4. From your cell phone, open Bluetooth settings and pair it with a new device. You will see a list of available Bluetooth devices. Select the ‘Torch Rover-3AF1’. The '3AF1' is the last four digits of the device's MAC address and will vary depending on the device (Figure 3).

   

   Figure 3

5. Once paired, open SW Maps. Select ‘New Project’ and give your project a name like ‘RTK Project’.

6. Press the SW Maps icon in the top left corner of the home screen and select Bluetooth GNSS. You should see the ‘Torch Rover-3AF1’ in the list. Select it. Confirm that the Instrument Model is SparkFun RTK, then press the ‘Connect’ button in the bottom right corner (Figure 4). SW Maps will show a warning that the instrument height is 0m. That’s ok.

   

   Figure 4

7. Once connected, have a look at the Bluetooth LED on the RTK device. You should see the LED turn solid. You’re connected!

8. Now put the device outside with a clear view of the sky. GNSS doesn’t work indoors or near windows. Press the SW Maps icon in the top left corner of the home screen and select GNSS Status. Within about 30 seconds you should see 10 or more satellites in view (SIV) (Figure 5). More SIV is better. We regularly see 30 or more SIV. The horizontal positional accuracy (HPA) will start at around 10 meters and begin to decrease. The lower the HPA the more accurate your position. This accuracy is around 2m in normal mode.

   

   Figure 5

You can now use your RTK device to measure points with good (meter) accuracy. If you need extreme accuracy (down to 8mm) continue reading the RTK Crash Course.

iOS

The software options for Apple iOS are much more limited because Apple products do not support Bluetooth SPP. That's ok! The SparkFun RTK products support Bluetooth Low Energy (BLE) which does work with iOS.

1. Download SW Maps for iOS. This may not be the GIS software you intend to do your data collection, but SW Maps is free and makes sure everything is working correctly out of the box.

   

   Download SW Maps for iOS

2. Mount the hardware:

   • For RTK Torch: Attach the Torch to a 5/8" 11-TPI standard surveying pole or to a monopole using the included thread adapter (Figure 1).

   

   Figure 1

3. Turn on the RTK Torch device by pressing the Power button for 3 to 4 seconds until a beep is heard and the two front LEDs illuminate (Figure 2).

   

   Figure 2

4. Open SW Maps. Select ‘New Project’ and give your project a name like ‘RTK Project’.

5. Press the SW Maps icon in the top left corner of the home screen and select Bluetooth GNSS. You will need to agree to allow a Bluetooth connection. Set the Instrument Model to Generic NMEA (Bluetooth LE). Press 'Scan' and your RTK device should appear. Select it then press the ‘Connect’ button in the bottom left corner.

6. Once connected, have a look at the Bluetooth LED on the RTK device. You should see the LED turn solid. You’re connected!

7. Now put the device outside with a clear view of the sky. GNSS doesn’t work indoors or near windows. Press the SW Maps icon in the top left corner of the home screen and select GNSS Status. Within about 30 seconds you should see 10 or more satellites in view (SIV) (Figure 3). More SIV is better. We regularly see 30 or more SIV. The horizontal positional accuracy (HPA) will start at around 10 meters and begin to decrease. The lower the HPA the more accurate your position. This accuracy is around 2m in normal mode.

   

   Figure 3

You can now use your RTK device to measure points with good (meter) accuracy. If you need extreme accuracy (down to 8mm) continue reading the RTK Crash Course.

RTK Crash Course

To get millimeter accuracy we need to provide the RTK unit with correction values. See Corrections Sources for a breakdown of the options and the pros and cons of each. For this quickstart, we'll be showing how to use PointPerfect Flex for $15 a month.

Using PointPerfect Flex

• EVK:
• Facet mosaic:
• Postcard:
• Torch:
• TX2:

To get millimeter accuracy we need to provide the RTK unit with correction values. Corrections, often called RTCM, help the RTK unit refine its position calculations. There are multiple options for correction sources, but this tutorial focuses on PointPerfect. PointPerfect Flex over NTRIP is $15 per month and is an SSR based service meaning there are no base stations or 'dead-air' gaps in the coverage map. The PointPerfect Flex service is available for various areas of the globe including the Europe, the contiguous USA, Canada, Brazil regions, South Korea, and Australia regions, including up to 12 nautical miles (roughly 22 kilometers) off coastlines. See the coverage map for specifics.

PointPerfect Flex Coverage Map

Getting Access

PointPerfect Flex over NTRIP requires a set of user name, password, and mount point credentials. Please contact SparkFun to setup a monthly subscription.

An NTRIP Client is a small app that connects to the corrections server to get the corrections. Most GIS apps have an NTRIP Client built in.

Using NTRIP on a Phone

The easiest way is to use the service is with a cell phone. For this example, we'll use an Android phone with SW Maps but any GIS app with a built-in NTRIP Client (most do) can connect to PointPerfect.

In the above image, the phone is running the NTRIP Client and the corrections are downloaded from the internet using the phone's cellular connection. Those connections are sent over Bluetooth to the RTK device. The RTK device gets a high-precision solution and transmits the GPS location back to the phone over Bluetooth. The phone displays the location in an app allowing work to be done.

Above, in SW Maps select the NTRIP Client. This is the small cloud icon.

In the NTRIP Client detail window, enter the following information:

NTRIP Version: V1
NTRIP Server: ppntrip.services.u-blox.com
NTRIP Port: 2101
Mount Point: NEAR-RTCM
Username: (provided when service was set up)
Password: (provided when service was set up) 
Send NMEA GGA to Base Station: Please confirm this option is checked

The information can be copy/pasted from email or manually entered. Be careful to enter the data correctly. Once the credentials are entered, click Save and then Exit the NTRIP Client details window.

Next, turn on the RTK device and connect to it over Bluetooth by clicking on the receiver button (shown above).

Once connected, tap the NTRIP Client (cloud) icon again to open the menu. A list of clients will be shown, select the one you just entered and click 'Connect'.

Confirm that the Data Rate section shows more than 0 bytes per second over a few seconds. The number will bounce around, but every second a few hundred bytes of correction data should be downloaded and sent to the RTK device over Bluetooth. This indicates the NTRIP connection was successful.

Close the NTRIP Client window returning to the main app screen and proceed outdoors and get a clear view of the sky. Above we see a successful high-precision RTK Fix with 16mm horizontal accuracy. Now you can proceed with GIS work.

Above, if you get a 'Connection Failed' error it is likely that username or password was incorrect. Double check you credentials and try again.

No Cellular Coverage?

What if you don't have cellular connectivity? Corrections can be obtained over any internet connection. Starlink Roam or Eutelsat KONNECT can provide internet over satellite. Once WiFi is available at the job site the RTK device can be configured to connect to WiFi and get the corrections over its built-in NTRIP Client. See the NTRIP Client docs for more information.

Common Gotchas

• High-precision GNSS works best with a clear view of the sky; it does not work indoors or near a window. GNSS performance is generally not affected by clouds or storms. Trees and buildings can degrade performance but usually only in very thick canopies or very near tall building walls. GNSS reception is very possible in dense urban centers with skyscrapers but high-precision RTK may be impossible.

• The location reported by the RTK device is the location of the antenna element; it's not the location of the pointy end of the stick. Lat and Long are fairly easy to obtain but if you're capturing altitude be sure to do additional reading on ARPs (antenna reference points) and how to account for the antenna height in your data collection software. The Torch ARP is here.

  Note

  This rule does not apply when tilt compensation is activated. See the Tilt Compensation Menu for more information.

• An internet connection is required for most types of RTK. RTCM corrections can be transmitted over other types of connections (such as serial telemetry radios). See Correction Transport for more details.