# Frequently Asked Questions

* **Is it absolutely necessary to have two boards; one rover and one base?**

The RTK technology requires a stationary receiver to allow exact calculation of the rover module. To achieve this, you need **two receivers**, one to act as the base module, and another as the rover module, **whatever the use case is**.

* **Do the Drotek F9P modules have built-in batteries? Do they need an external power supply?**

The [DP0601 module](https://store-drotek.com/891-rtk-zed-f9p-gnss.html), as well as the [Sirius F9P Rover](https://store-drotek.com/911-sirius-rtk-gnss-rover-f9p.html), do **not** have built-in batteries. This means you have to supply power to these boards in order to have them working. You can supply them with power from USB port (except for the Sirius RTK module which doesn't have one), for instance with a power bank for smartphones or a computer. The necessary power supply is **5V** so make sure to not oversupply them.\
The Sirius F9P Base contains built-in batteries for autonomy.&#x20;

* **Are the Drotek F9P RTK modules compatible with other brands' telemetry kits?**

The Drotek F9P RTK modules are compatible with most telemetry kits. In fact, they are compatible with approximately any device that has a serial port using the **UART** protocol.

* **Can the F9P modules be used without an autopilot?**

The use of an autopilot is not obligatory, even though some of the modules are built specifically for this purpose. Using an autopilot provides a MAVLink in which can be encapsulated the RTK data, and an automatic process that will configure the modules almost entirely automatically. Using the RTK modules without an autopilot will require you to configure the modules in order to be able to communicate with the telemetry boards correctly. You can find more on configuring the F9P RTK modules by following [this link](https://drotek.gitbook.io/rtk-f9p-positioning-solutions/how-to-get-started/zed-f9p-rtk-configuration).

* **What's the most efficient Survey-in time? How long does it take to reach 1 m accuracy? 50 cm accuracy? 10 cm accuracy?**

There is no best survey-in time, as its duration will mainly depend on what accuracy you want to reach. This setting can be set up with either Mission Planner or QGroundControl, as well as the U-Center software in case you don't use an autopilot. Keep in mind that having an efficient survey-in will require having the base set in the most building-free space and a clear sky-view. The time necessary to reach a 1-meter accuracy for the base positioning is approximately 10 minutes. Reaching 50 cm and below accuracy will require a much longer period of time, roughly an hour, or more.

In order to get the most accurate position for your base, you can use known reference locations in order to have an accurate position. You should be able to find such places by looking for your national _geodesy_ institute (i.e. it is the [IGN](http://geodesie.ign.fr/index.php?page=points_geodesiques) for France). For the USA for instance, you should find information following [this link](https://www.ngs.noaa.gov/).

* **Can multiple rover modules be used with a single base module?**

In order to use multiple rover modules with a single base, you have to choose between using a **special telemetry firmware** that will allow multipoint communication (more information can be found [here](http://ardupilot.org/copter/docs/common-telemetry-landingpage.html)), or using the TCP/IP protocol to stream the RTK data from the base module. You can find more information on the configuring of the Ublox chip and its TCP/IP features by following [this link](https://www.u-blox.com/en/product/neo-m8p-series).

* **Is it possible to have multiple bases to increase accuracy?**

It is virtually **impossible** to use multiple base modules for a normal RTK setup, as it would not increase the accuracy, and require a much more complex setup.

* **Are Drotek F9P modules compatible with other brands RTK modules? (i.e. Drotek rover module with other brand base module)**

It is possible to use a Drotek receiver as the rover module, and another brand's RTK receiver as the base module, but this requires to ensure that the data received by the Drotek RTK module contains **RTCM 3** messages.

* **What is the difference between serial ports UART1 and UART2?**&#x20;

UART1 sends RTCM and NMEA messages.\
Regardless of the inputs for the protocols In and Out via:\
ucenter > Configuration View > Protocols (PRTs), UART2 does not send NMEA messages.  \
\
**"**&#x42;e aware that the communication links Tx (Transmitter) Rx (Receiver) are reversed on the GNSS modules for the UART2 pins".&#x20;

* **How to ensure the RTCM messages are enabled at the base station to achieve a successful "Fixed RTK" at the rover end?**&#x20;

u-center > View > Configuration View (Ctrl + F9) > MSG (Messages) > F5-05 RTCM3.3 1005 (for eg.) > Enable USB and the preferred UART.&#x20;

* **How to verify if the RTCM messages have successfully transferred to the Rover receiver?**

We can check the RTCM messages sent via the USB at the receiver on ucenter. \
ucenter > View > Message View (F9) > UBX > RXM (Receiver Manager) > RTCM (RTCM input status)\
Following is an example of the RTCM message view:

![](https://lh6.googleusercontent.com/CvFk04JoO_96H0pHfOFgboZ452R2lgcbuUtT_uyBT806s-14ySedSwGRgcJDU470a8UNcgvkLw_yEZVgHI-ZjFo6E09_l1Swq6HNbpdtgyProY7saBINdc1rI6CIUiCZnk8WaO7XqJoPYYxzUkasXg)

* **How to install the firmware completely in case of failure or bricked F9P GNSS module?** &#x20;

Sometimes the ublox chip doesn't completely support Windows 10, we must continuously attempt to upload the firmware until the upload is successful. Parameters that need to be followed: \
\
&#xNAN;_**Go to u-center 20.10**_ >> Tools > Firmware update

_**Firmware image**_ - UBX\_F9\_100\_HPG\_113\_ZED\_F9P.7e6e899c5597acddf2f5f2f70fdf5fbe \
\> ublox Firmware update 1.13\
\
&#xNAN;_**Baudrate**_ - 57600 to load and the file _**Send training sequence**_ - must be selected\
\
In case you are trying to recover a bricked GNSS F9P module, you can follow the following configurations.\
\
Then initiate the update individually with the following selections: \
\
&#xNAN;_**Use chip erase**_ - 460800 bps

_**Enter safeboot**_ before update - 115200 bps&#x20;

Once most of the update is completed, it ensures the recovery of the GNSS module.

* **Error with "USB not recognized" - Operating system being Windows 10**

Normally, this issue arises if the USB is unable to power and transfer data at the same time and secondly, if the Ublox Drivers are not, compatible with Windows 10.

The following steps will provide the solution:

```
1. Rebooting the computer and reinstalling the u-center software 
```

Restart the computer and try connecting the USB device again. \
If not disconnect the USB device, then uninstall the device software. After the name of the device is removed, remove the device from the computer and restart the computer. Then reinstall the software.&#x20;

```
2. Search for the specific driver in the device manager
```

Search on the computer for the ublox driver on Task Manager, then select the ublox driver and use the update driver option, and that could work.\
\
USB Drivers using Device manager:

Press Ctrl + Alt + Delete at the same time \
\- Select Device Manager from the list\
\- Find Universal Serial Bus controllers and expand the list \
\- Right-click Unknown Device \
\- Select Properties \
\- Select Drivers \
\- Click Update Driver \
\- Close Device Manager \
\- Restart your PC

* **How can one revert the GNSS F9P module back to its original configuration?**&#x20;

u-center > Configuration View (Ctrl+F9) > CFG (Configuration) > Choose "Revert to default configuration & select all the devices (0-BBR, 1-FLASH, 2-I2C-EEPROM, 4-SPI-FLASH) > Send&#x20;

or you can click the default configuration icon on the action toolbar.\


<figure><img src="https://3825805345-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-LYSZeu4HjB-NrVI4riL%2Fuploads%2FrGGYvv75sTkbioxntkv6%2Fdefault_config_ucenter_icon.png?alt=media&#x26;token=cd2a41c5-385f-4b9d-b884-0607d3577f6d" alt=""><figcaption></figcaption></figure>

* **Is the Sirius RTK Base F9P dual use? Can it be used as a rover station too?**&#x20;

Yes, the Sirius RTK Base F9P can be used as a rover station as well. It depends on the internal configuration of the u-blox chip. The configuration file can be changed \
It is a possibility to use the advantage of the built-in batteries on the Sirius RTK base F9P for autonomy purposes. This arrangement would allow the user to mount the battery-powered SIRIUS RTK Base F9P with its threaded mounting hole on mobile and fixed platforms of choice.&#x20;

* **How to configure a GNSS module with the Moving base configuration?**

You can configure the module with MSM7 RTCM messages instead of the MSM4 RTCM messages. The 1005 RTCM message is not required since it is solely for stationary use (standalone base station).\
This configuration will deliver the relative position of the rover with centimeter-level accuracy.  \
Also, ensure that the moving base station is not surveyed-In. It only requires the relevant RTCM changes in the u-center configuration.&#x20;

* **How to verify the relative length and relative heading information of a moving rover with respect to a moving base?**&#x20;

The relative length (baseline) and the relative heading (orientation relative to the true north) can be obtained via the u-center application. \
The values can be viewed on RELPOSNED registry from the rover. \
ucenter > Message View (F9) > UBX > NAV (Navigation) > RELPOSNED (Relative Position NED).

![](https://3825805345-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-LYSZeu4HjB-NrVI4riL%2Fuploads%2FRCmpH0vPRfz26PSheZX1%2FRELPOSNED_cropped.PNG?alt=media\&token=26f09459-6875-4f0c-be5a-1f4f0cbb61a9)

* **How can you integrate the internal and external compass on a SIRIUS RTK GNSS ROVER (F9P + RM3100) with the help of a Pixhawk3Pro autopilot?**

On QGroundControl (QGC), we can enable and disable the mag parameters with the following configuration:\
QGC > Vehicle Setup > Parameters > CAL\_MAG0\_ID/CAL\_MAG1\_ID

You may identify the MAG\_IDs by simply connecting the internal compass first (Pixhawk 3 Pro flight controller) to check for the ID. Then attach the external compass (SIRIUS RTK GNSS ROVER (F9P + RM3100). \
Once the IDs are identified, one can calibrate the external compass with respect to the orientation of the autopilot. You may check on the 'Set Orientations' topic on the Px4 guide: https://docs.qgroundcontrol.com/master/en/SetupView/sensors\_px4.html

* **Does the integrated antenna include SAW filters for damping interfering signals?**&#x20;

Yes, there are 2 extra SAW filters in our dual-band ceramic patch antenna (that is used on the Sirius Base and Rover).

* **Why is it important to place a metal plate below the antenna receiving the signals?**&#x20;

A metal ground plane is mostly important for short ranges between the base and the rover. The ground plane has the advantage to better attract the signals to the antenna; it has the ability to improve signal acquisition. However, the metal plate is not mandatory to achieve direct line-of-sight signals. A clear view of the sky to the antennas with the base station placed at a higher altitude could do the trick.

* **Why do we prefer F9P GNSS modules to M8P GNSS modules?**&#x20;

F9P uses both L1 and L2 frequency bands resolving RTK FIXED within seconds compared to minutes on the L1-only based M8P''. M8P does not support Galileo constellations. It is normal that it would take more time to achieve an RTK fix when configured for the first time of the Survey-In. \
F9P GNSS modules are configured with the MSM4 messages for standalone or MSM7 messages for moving base along with the 1230 messages. It also requires the addition of 4072 messages.&#x20;

* **How can one integrate the ZED-F9P GNSS modules for Bluetooth functionality?**&#x20;

Firstly, one could purchase the bluetooth HC-05-6 pin module. Use the UART1 from the gnss module to connect to the BT module. The cables can be directly soldered to the BT module to ensure a firm connection.\
\
GNSS module --> BT module\
5V      -->     VCC\
GND   -->     GND\
Tx       -->     Rx\
Rx       -->     Tx

You need to set the baudrate of the BT module on UART1 (u-center configuration). One must download the Arduino program with some changes to the software to execute the configuration. Now you should be able to connect to the BT module (HC-05, password: 1234) and receive NMEA messages.

Then, one must follow the instructions for AT command settings. Search for Bluetooth AT Commands Settings (HC05 HC06) - Arduino Project Hub

* **Is there a way to extract the rover information from the base station?**

Yes, maybe you can try to use a 2-way radio receiver connected to the rover station.&#x20;

* **Can one extend the cable antenna? What would be the signal loss?**&#x20;

We use a 1m long cable that has a significantly lower power loss compared to longer cables. It is said that depending on the extension, it could lose between 20% to 50% of the original signal. \
LMR-400 SMA cable has the lowest signal loss in its class due to its double shielding. To calculate the cable loss, we could use the cable loss mode on an antenna analyzer. To improve voltage regulation in a circuit, you can increase the cross-sectional size of the conductors. This is done to lower the overall resistance of the cable length.
