PointPerfect L-band Configuration

Hardware Requirements and Prerequisites 

To use the PointPerfect L-band solution, you need two receivers:

1. a high-precision GNSS receiver
   Examples: ZED-F9P, ZED-F9R, NEO-F9P

2. an L-band GNSS correction receiver
   Examples:  NEO-D9S receiver from u-blox 

The correction receiver (NEO-D9S) receives encrypted PointPerfect L-band corrections from the L-band satellite and passes them to the F9 receiver.  The decryption of SPARTN messages happens within the F9 module using the current L-band dynamic keys.  

If you have not acquired the hardware to use L-band corrections, you can get started with both NEO-D9S and F9 receivers such as: 

• the C101-D9S (and user guide)

• the EVK -F9P  or C099-F9P  or similar application board from our vendor partners  

The NEO-D9S and F9 receivers must be connected via UART2 which is common practice and recommended for customer designs. (See jumper configuration example in C101-D9S user guide.)  UART1 or USB are the most convenient interfaces for monitoring and configuring both modules (i.e. when using u-center etc.)

You will need an antenna that supports specific frequencies, please refer to section 4.2 of the NEO-D9S Integration manual to determine the required frequency ranges. 

Along with the appropriate hardware devices mentioned above, PointPerfect L-band plans must be enabled on your thingstream domain to use the service. If you cannot select our PointPerfect L-band plans within your PointPerfect Location thing, please contact support@thingstream.io.   

L-band Receiver Configuration

The sections below describe how each receiver is configured. 

NEO-D9S configuration

NEO-D9S must be configured to receive SPARTN L-band correction data and forward these, encapsulated in UBX-RXM-PMP messages, to the F9 receiver via UART2.

L-band Configuration (D9S)

PointPerfect service-specific configuration for CFG-PMP keys (Point to multipoint configuration) must be implemented for your region (either US or EU) on the NEO-D9S receiver before it can receive PointPerfect correction data. 

Please contact us at support@thingstream.io to obtain the NEO-D9S PointPerfect L-band HEX (a decimal) configuration string of these keys for your specific region.

The HEX string can be loaded by:

• Extracting the HEX value from the file you receive

• Pasting this HEX value into the Custom field in u-center (View -> Message View -> Custom)

• Selecting the HEX Radio button

• Clicking the Send button at the bottom of the Message – CUSTOM window

Interface Configuration (D9S)

The UART2 interface of NEO-D9S needs to be configured to allow communication with the F9 receiver, using the following configuration items.  In u-center, use View -> Generation 9 Configuration View -> Advanced Configuration View.

Configuration item Value

• CFG-UART2OUTPROT-UBX 1 (true)

• CFG-UART2-BAUDRATE 38400

Also, confirm the CFG-MSGOUT-UBX_RXM_PMP_UART2 is set to 1 (by default is enabled).
This message enables UART2 of NEO-D9S to output UBX-RXM-PMP messages. 

Note:  The baud rate of 38400 is stated because it is the default setting for an F9 device.  You can make this higher, but make sure both devices (D9S and F9) have the same baud rate setting.

Functional Check (D9S)

Verify that NEO-D9S is operating correctly with these functional checks, most can be performed with u-center, see the Pointperfect Getting Started Guide for how to download it, and the u-center user guide for more information.

• Confirm your L-band antenna is connected, and placed in an open sky view to retrieve L-band messages with a direct line-of-sight to the geo-stationary satellite (typically south facing)

• Confirm communication has been established with the NEO-D9S (e.g., via u-center) through UART1 or USB. 

  • Use the Connect icon in the communication toolbar to connect to the corresponding COM port for your NEO-D9S

  • go to View, Packet Console to view incoming messages 

• Confirm the NEO-D9S firmware version is PMP 1.04

  • use View, Messages View, and open UBX-MON-VER 

• The L-band configuration item values have been verified.

  • use View, Messages View, open UBX-RXM-PMP 

The UBX-RXM-PMP message can be used to check the decoded correction data (the image below is for reference only)

It is important to check the UART2 communication to the F9.  In u-center, go to View, Messages View and find the UBX-MON-TXBUF message as shown in the image below.

F9 Receiver Configuration

Please confirm via the UBX-MON-VER message that the F9P has the latest firmware version.  

To use our L-Band service, the F9P device must be configured to receive and use the SPARTN L-band correction stream from the NEO-D9S in the form of a UBX-RXM-PMP message. 

L-band Configuration (F9)

The CFG-SPARTN-USE_SOURCE configuration key needs be set to LBAND:

Configuration item Value

• CFG-SPARTN-USE_SOURCE 1 - LBAND

This message value can be set using the View -> Generation 9 Configuration View -> Advanced Configuration View in u-center, please see the image below.

For more details regarding SPARTN source configuration, please refer to your product’s integration manual. 

Interface Configuration (F9)

The UBX protocol needs to be enabled on the ZED-F9P UART2 input (via View -> Generation 9 Configuration View -> Advanced Configuration View):

Configuration item Value

• CFG-UART2INPROT-UBX 1 (true)

PointPerfect Configuration (F9)

Below is a continuation of configuration steps from the PointPerfect Getting Started guide. 

You should already have:

1.      Created a PointPerfect location thing in your Thingstream domain account,

2.      Downloaded the JSON file from your Thingstream PointPerfect location thing and

3.      Downloaded/installed/opened u-center and connected to the port of your F9P device

The final step is to load the JSON configuration file using u-center.

NOTE:  The steps below are to connect your MQTT client and retrieve the dynamic keys provided in your plan to decrypt the SPARTN messages from L-band corrections using the NEO-D9S.  

Open the Receiver menu and select the MQTT Client item as shown in this screenshot.

In the dialog box shown below, click on the ellipsis (...) icon to browse your file system and select the correct JSON config file. 

Choose the Continental correction type.  Continental corrections are the only correction type applicable to our PointPerfect L-band corrections.

Select “Subscribe to key topic” to retrieve the dynamic keys from MQTT.  Optionally you can “Subscribe to AssistNow topic.” Do not select “Subscribe to data topic”, as your source of corrections will be via L-band.   

After clicking 'OK,' u-center will establish a connection with the PointPerfect MQTT service and receive your encryption keys.  You can check the MQTT connection status in the u-center's status bar. Clicking on the green connector icon will open the log, where you can monitor the dynamic key (and AssistNow) messages being received, as demonstrated below. 

At this point the F9P is receiving data from the PointPerfect service via L-band.  You can see the performance of the solution via u-center. Please refer to u-center [2] and F9 documentation (integration manuals) for more information on how to analyze the high-precision GNSS performance.  

Functional Check (F9)

Functional checks that are required to verify the F9 module is operating correctly with NEO-D9S:

• The user has established communication with the F9 module (e.g. via u-center 23.08 or later through UART1 or USB

• The F9 module has the latest FW version - find within each of our high-precision GNSS product pages under the documentation and resources section 

• The GNSS antenna has been plugged in and has a clear view of the open sky

• The L-band and keys configuration is completed for the F9 as described above.
  Enable and view the UBX-RXM-SPARTNKEY message to verify the L-band dynamic keys.

• The F9 UART2 has been connected to the NEO-D9S UART2.

• UBX-MON-COMMS messages can be enabled to verify that UBX messages (including UBX-RXM-PMP) are received on the F9 UART2:

• View the UBX-RXM-COR message to check the correction streams on the connected F9 as shown in the image below. 

If all these checks pass, the ZED-F9P receiver should get into RTK positioning fix. If you are not able to see any of the messages above, please contact support@thingstream.io for assistance.

L-band Dynamic Keys and Decryption

Decryption of SPARTN messages happens within the F9 module. The configured F9 device must subscribe to the key topic /pp/ubx/0236/Lb via MQTT to collect and transfer the L-band dynamic keys to the F9 receiver in UBX format. Please contact support@thingstream.io if you need help with getting the L-band keys to the F9 receiver.

Note: The keys are not stored in non-volatile memory and will be deleted on every module reset or restart. In such cases, the keys need to be passed to F9 again.

Encryption keys switch mid-month, and both current and next keys are always available in Thingstream.  The current dynamic key must be provided to the F9 to retain connectivity.  Host systems can manage dynamic keys, requiring connection every two months or less, based on the key cycle and acquisition date.

Reference Documentation

[1] ZED-F9P Integration manual, UBX-18010802
[2] u-center User guide, UBX-13005250
[3] u-blox F9 HPG 1.32 Interface description, UBX-22008968
[4] C099-F9P application board User guide, UBX- 18063024
[5] EVK-F9P-01 evaluation kit User guide, UBX-22038408  
[6] NEO-D9S Integration manual, UBX-19026111
[7] u-blox Knowledge Base – Services Support