RockBLOCK Pro STL

RockBLOCK Pro is available with STL positioning. Satellite Time and Location® (Iridium STL®) - a Positioning, Navigation, and Timing (PNT) service that improves the resiliency and survivability of critical infrastructure when Global Positioning System (GPS) or Global Navigation Satellite System (GNSS) signals are absent or disrupted. This option requires hardware alterations, and as such is only available as an option at the point of purchase.

Configuration

Currently, STL positioning is supported by firmware versions 12.30 and 12.31.
When connecting via USB-C, the RockBLOCK Pro will show up as 3 devices - 2 Virtual Com Ports (VCP) and a mass storage device.
The HIGHER numbered VCP is a live updated status page. The LOWER numbered VCP is an AT command terminal.
If in doubt, your firmware version can be checked using the serial port status page, or by issuing the AT command AT+CGCV.
Configuration settings of the STL module are stored in the user.cfg file. This can be edited with a text editor and stored in JSON format, before dragging-and-dropping onto the RockBLOCK Pro mass storage device over USB. Alternatively the configuration can be read (AT+CFGR) and written AT+CFGW={<SinglelineJSONpayload>} using AT commands. A reboot is required for the new configuration to take effect.

Please also refer to our User Configuration Guide and Firmware and Config Update Process to learn more.

warning

Syntax and formatting are critical for JSON files. It is recommended for most users to use a text editor and upload the config file over USB. If a config file containing errors is uploaded, this will result in the RockBLOCK Pro reverting to its default configuration.

Position Configuration

Configuration of STL position is performed using the following section of the user.cfg file.
The upgrade process replaces the GNSS module with the STL module, hence some configuration elements for STL are still referred to as 'GNSS'.

"GNSS": {
    "Enabled": true,
    "nmeaForwardEnabled": false,
    "reportInterval": 0,
    "stlMode": "DYNAMIC",
    "stlSens": "MEDIUM"
  },

Configuration elements:

"Enabled":

• true - the STL module is enabled, and its position data made available to the Application.
• false - STL module is disabled.

"nmeaForwardEnabled":

• true - the STL position data is streamed out of the RockBLOCK Pro serial port in NMEA format, once per second.
• false - STL position streaming disabled.

"reportInterval":

• unsigned integer - the number of seconds between position reports being sent to Cloudloop.
• 0 - (zero) disables Cloudloop position upload.

"stlMode":

• DYNAMIC - Use when the device to be tracked is a moving object. Suitable for the vast majority of users.
• STATIC - Use ONLY when the device to be tracked is predominantly stationary.

"stlSens":

• HIGH - Maximum RF Preamp gain.
• MED - Medium RF Preamp gain.
• LOW - Minimum RF Preamp gain.

info

HIGH is not always the best setting to use - in circumstances where the signal strength is high, antenna gain is high, and / or RF cable loss is low, this can lead to signal distortion, and reduce the number of successfully processed position messages, resulting in a lower accuracy position.
Similarly, LOW preamp gain coupled with RF losses in signal strength can have the same effect.
This setting may need to be adjusted depending upon installation and geographical location.

Serial Port Configuration

When NMEA forwarding is enabled, the STL position data will be streamed over the RockBLOCK Pro's serial port.

Configuration of the Serial port is performed using the following section of the user.cfg file:

"Serial": {
    "Enabled": true,
    "mode": "RS232",
    "baud": 115200,
    "parity": "NONE",
    "bits": 8,
    "stop": 1
  },

Configuration elements:

"Enabled":

• true - the serial port is enabled.
• false - the serial port is disabled.

"mode":

• RS232 - Communication using RS-232 protocol. RECOMMENDED.
• RS4XX_HALF - Communication using RS-485 Half Duplex protocol.
• RS4XX_FULL - Communication using RS-422 / 485 Full Duplex protocol.

warning

There is a currently known bug with the RS4XX protocols, and as such, their use is not yet possible.

"baud":

• 4800, 9600, 19200, 38400, 57600, 115200, 230400

"parity":

• NONE

"bits":

• 8

"stop":

• 1, 2

Position Output

Once the above has been configured, the RockBLOCK Pro STL will output the position data in NMEA format. It will provide 3 strings per transmission. The messages transmitted are:

• GPGGA - Global Positioning System Fix Data - sent every second
• GPRMA - Recommended minimum specific Loran-C data - sent every second
• GPZDA - Date & Time - sent every five seconds

For example:

$GPGGA,084908.00,5052.732865,N,00115.509451,W,1,04,8.0,-12.4,M,,*30
$GPRMC,084908.00,A,5052.732865,N,00115.509451,W,0.2,-69.8,270625,,*36
$GPZDA,084908.00,27,06,2025,+00,00*46

GNSS data is also displayed on the RockBLOCK Pro's Status Page.
From the AT command terminal, the position data can be obtained via polling, using the AT+GNSS command.

info

A couple of the GGA parameters observed when using STL are different to those which may be expected from a traditional GNSS module.

Parameter	GNSS Expected	STL Expected	Notes
GGA Field 7	Satellites in view < 30 Higher is better	Satellites in view < 4 Higher is better	STL has fewer satellites in view to enable positioning.
GGA Field 8	HDOP 1 - 20 Lower is better	PFOM 1 - 9 Lower is better	Horizontal Dilution of Accuracy is replaced with Position Figure of Merit. It is still a measure of estimated positional accuracy, but with a different range than expected using HDOP. PFOM accuracy table is shown below.

PFOM table

Value	1	2	3	4	5	6	7	8	9
Estimated Position Error	< 25m	< 50m	< 75m	< 100m	< 200m	< 500	< 1000m	< 5000m	>= 5000m