Bluetooth Gnss Apk

[Glynis Waughtal]

Lookingfor suggestions for an affordable external bluetooth GNSS receiver to use with Field Maps on an iPad with decent accuracy (sub 2-3 meter). Collecting ecological survey data and often working in remote locations (no service) under tree cover. What are the best options for under $2000?

See if the Bad Elf Flex Mini works for your case. All major GNSS supported and RTK available with external corrections and what the call their "extreme" mode. Works with Field Maps. They make good products and provide good support. bad-elf dot com.

While we recommend SW Maps for Android, there are a variety of 3rd party apps available for GIS and surveying. We will cover a few examples below that should give you an idea of how to get the incoming NMEA data over Bluetooth into the software of your choice.

From SW Map's main menu, select Bluetooth GNSS. This will display a list of available Bluetooth devices. Select the Rover or Base you just paired with. If you are taking height measurements (altitude) in addition to position (lat/long) be sure to enter the height of your antenna off the ground including any ARP offsets of your antenna (this should be printed on the side).

We need to send RTCM correction data from the phone back to the RTK device so that it can improve its fix accuracy. This is the amazing power of the SparkFun RTK products and SW Maps. Your phone can be the radio link! From the main SW Maps menu select NTRIP Client. Not there? Be sure the 'SparkFun RTK' instrument was automatically selected connecting. Disconnect and change the instrument to 'SparkFun RTK' to enable the NTRIP Connection option.

Once you have a full RTK fix you'll notice the location bubble in SW Maps turns green. Just for fun, rock your rover monopole back and forth on a fixed point. You'll see your location accurately reflected in SW Maps. Millimeter location precision is a truly staggering thing.

You will be shown a list of paired devices. Select the RTK device you'd like to connect to then click 'Connect'. The RTK device will connect and the MAC address shown on the RTK device OLED will change to the Bluetooth icon indicating a link is open.

What's an NTRIP Caster? In a nutshell, it's a server that is sending out correction data every second. There are thousands of sites around the globe that calculate the perturbations in the ionosphere and troposphere that decrease the accuracy of GNSS accuracy. Once the inaccuracies are known, correction values are encoded into data packets in the RTCM format. You, the user, don't need to know how to decode or deal with RTCM, you simply need to get RTCM from a source within 10km of your location into the RTK Express. The NTRIP client logs into the server (also known as the NTRIP caster) and grabs that data, every second, and sends it over Bluetooth to the RTK Express.

Don't have access to an NTRIP Caster? You can use a 2nd RTK product operating in Base mode to provide the correction data. Checkout Creating a Permanent Base. If you're the DIY sort, you can create your own low-cost base station using an ESP32 and a ZED-F9P breakout board. Check out How to Build a DIY GNSS Reference Station]( -to-build-a-diy-gnss-reference-station). If you'd just like a service, Syklark provides RTCM coverage for $49 a month (as of writing) and is extremely easy to set up and use. Remember, you can always use a 2nd RTK device in Base mode to provide RTCM correction data but it will be less accurate than a fixed position caster.

Click the Connect Bluetooth button, shown in red in the top right corner. The software will begin a connection to the RTK device. You'll see the MAC address on the RTK device changes to the Bluetooth icon indicating it's connected.

Note: If you are using a radio to connect Base to Rover, or if you are using the RTK Facet L-Band you do not need to set up NTRIP; the device will achieve RTK fixes and output extremely accurate location data by itself. But if L-Band corrections are not available, or you are not using a radio link, the NTRIP Client can provide corrections to this Rover.

If you selected 'DGPS' as the Model type, the RTK submenu will be shown. This is where you give the details about your NTRIP Caster such as your mount point, user name/pw, etc. For more information about creating your own NTRIP mount point please see Creating a Permanent Base

Survey Master by ComNam / SinoGNSS is an Android-based option. The download location can vary so google 'Survey Master ComNav Download' if the link above fails. Download the zip file, send the APK file to a phone and install the program.

If you are just getting started, use one of the default antenna types. If you are attempting to get sub-centimeter accuracy, enter the parameters of your antenna and add it. Above are the NGS-certified parameters for the TOP106 antenna.

Return to the 'Datalink type' window and select the Server you just entered. Re-enter the server address and port for your NTRIP Caster. Once complete, click on the down-pointing arrow. This will ping the Caster and obtain the mount point table. Select your mount point.

This software requires the RTK device to connect over TCP. Be sure you have a local WiFi network entered into the WiFi Config menu, have a TCP Client or Server enabled, and have noted the TCP port (it's 2947 by default).

Select NMEA network source. Enter the IP address and TCP port of the RTK device. The IP address can be found by opening a serial terminal while connected to WiFi (it is reported every few seconds). The TCP port is entered into the WiFi Config menu.

At this point, you will need to enable TCP Server mode on your RTK device from the WiFi Config menu. Once the RTK device is connected to local WiFi QGIS will be able to connect to the given IP address and TCP port.

Enter the IP address of your RTK device. This can be found by opening a serial connection to the device. The IP address will be displayed every few seconds. Enter the TCP port to use. By default an RTK device uses 2947.

Alternatively, a direct serial connection to the RTK device can be obtained. Use a USB cable to connect to the 'CONFIG UBLOX' port on RTK Surveyor/Express/Plus and the single USB C port on the RTK Facet/L-Band. Be sure you have the u-blox driver installed. Then select the appropriate COM port for the u-blox module. See Configure with Serial for more information.

First, configure the RTK device to output only NMEA messages. QField currently does not correctly parse other messages such as RAWX or RTCM so these will interfere with communication if they are enabled.

Select the Positioning Menu. Then, with your RTK device on and in normal mode (not AP Config) press the Scan button in the QField app to update the dropdown list of available Bluetooth devices. If your device is not detected, be sure you've paired your cellphone or laptop with Bluetooth.

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

Hopefully, these examples give you an idea of how to connect the RTK product line to most any GIS software. If there is other GIS software that you'd like to see configuration information about, please open an issue on the RTK Firmware repo and we'll add it.

In a nutshell, it's a server that is sending out correction data every second. There are thousands of sites around the globe that calculate the perturbations in the ionosphere and troposphere that decrease the accuracy of GNSS accuracy. Once the inaccuracies are known, correction values are encoded into data packets in the RTCM format. You, the user, don't need to know how to decode or deal with RTCM, you simply need to get RTCM from a source within 10km of your location into the RTK Express. The NTRIP client logs into the server (also known as the NTRIP caster) and grabs that data, every second, and sends it over Bluetooth to the RTK Express.

There are services available as well. Syklark provides RTCM coverage for $49 a month (as of writing) and is extremely easy to set up and use. Point One also offers RTK NTRIP service with a free 14 day trial and easy to use front end.

This is from memory, but it should get you close. If your struggling please give me a call at my office 708-482-8888 and i can get you going in 5 minutes or so. I should also add that this will only work if your touch screen is working and calibrated.

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