docs: add ArduSimple RTK GPS simpleRTK 4 Optimum documentation

common/source/docs/common-ardusimple-rtk-gps-simplertk-4-optimum.rst

@@ -0,0 +1,65 @@
+.. _common-ardusimple-rtk-gps-simplertk-4-optimum:
+
+========================================================
+ArduSimple RTK GPS simpleRTK 4 Optimum (u-blox ZED-X20P)
+========================================================
+
+.. image:: ../../../images/ardusimple_simplertk_4_optimum_u-blox_zed-x20p.jpg
+    :target: ../_images/ardusimple_simplertk_4_optimum_u-blox_zed-x20p.jpg
+    :width: 450px
+
+simpleRTK 4 Optimum (u-blox ZED-X20P) is an allband GNSS/RTK receiver which provides centimeter accurate GNSS positioning and navigation for more accurate and reliable autonomous operations. 
+It supports all major satellite constellations and the L1, L2, L5, and L6 frequency bands, making it a great choice if you need reliable, high-accuracy positioning in challenging environments.  
+
+It provides:
+
+   -  Down to centimeter GPS accuracy
+   -  Up to 20 RTK position updates per second 
+   -  Allband: L1, L2, L5, and L6 support (Galileo HAS too)
+
+Where to Buy
+============
+
+- `ArduSimple simpleRTK 4 Pro (u-blox ZED-X20D) <https://www.ardusimple.com/product/simplertk4-optimum-zed-x20p/>`_
+
+Pin Map
+=======
+
+The system is connected to the autopilot via one of its UARTs.
+
+The JST-GH connector is following the Pixhawk standard:
+
+   -  1: 5V_IN
+   -  2: ZED-X20P UART1 RX (3.3V level)
+   -  3: ZED-X20P UART1 TX (3.3V level)
+   -  4: Timepulse output (3.3V level)
+   -  5: Event input (3.3V level)
+   -  6: GND
+
+.. image:: ../../../images/ardusimple_simplertk_4_optimum_u-blox_zed-x20p_pin.jpg
+    :target: ../_images/ardusimple_simplertk_4_optimum_u-blox_zed-x20p_pin.jpg
+    :width: 450px
+
+
+Wiring and Connections
+======================
+All ArduSimple GNSS models come with a JST GH 6-pin connector/cable that is compatible with the Pixhawk family and many other autopilots.
+
+XBee socket
+===========
+The onboard XBee socket can be used to expand functionality with `Plugin accessories <https://www.ardusimple.com/radio-links/>`_ (MR/LR radios, 2G/3G/4G modem, Bluetooth, WiFi, Ethernet, Dataloggers, RS232, Canbus, L-Band). 
+The cables/connectors may be modified to connect to other autopilot boards, using the Pin Map information provided above.
+
+ArduPilot integration
+=====================
+For normal GPS only operation, ArduPilot’s GPS parameter defaults will work for any serial port configured for ``SERIALx_PROTOCOL`` = 5.
+
+To achieve centimeter-level precision in positioning, RTK correction data must be sent to your drone in real time. There are two main methods for delivering this correction data:
+
+   -  Using NTRIP correction service:  If you are going to operate in areas with reliable internet connection and NTRIP service coverage, follow `Tutorial on sending NTRIP corrections to ArduPilot. <https://www.ardusimple.com/send-ntrip-corrections-to-ardupilot-with-missionplanner-qgroundcontrol-and-mavproxy/>`_  If you are not aware of NTRIP service provider in your area, we have prepared the `List of RTK correction service providers in your country. <https://www.ardusimple.com/rtk-correction-services-in-your-country/>`_ 
+   -  Using RTK corrections from a Base Station: if there is no internet access or NTRIP correction service available in your area, refer to ArduSimple’s `tutorial on sending RTK corrections from Base station to ArduPilot. <https://www.ardusimple.com/send-rtk-base-station-corrections-to-ardupilot-with-missionplanner-qgroundcontrol-and-mavproxy/>`_ 
+
+More information
+================
+   -  `User Guide: simpleRTK 4 Optimum <https://www.ardusimple.com/user-guide-simplertk4-optimum/>`_  
+   -  `How to configure u-blox ZED-X20 <https://www.ardusimple.com/how-to-configure-u-blox-zed-x20p/>`_ 

common/source/docs/common-positioning-landing-page.rst

@@ -63,6 +63,7 @@ These GPS can incorporate real time kinematic data, either internally generated
     ArduSimple RTK GPS simpleRTK2B Budget (u-blox ZED-F9P) <common-ardusimple-rtk-gps-simplertk2b-budget>
     ArduSimple RTK GPS simpleRTK3B Pro (Septentrio Mosaic-X5) <common-ardusimple-rtk-gps-simplertk3b-pro>
     ArduSimple RTK GPS simpleRTK3B Compass (Unicore UM982, Dual antenna heading) <common-ardusimple-rtk-gps-simplertk3b-compass>
+    ArduSimple RTK GPS simpleRTK 4 Optimum (u-blox ZED-X20P) <common-ardusimple-rtk-gps-simplertk-4-optimum>
     ARK MOSAIC-X5 RTK GPS <common-ark-mosaic-rtk-gps>
     ARK RTK Base <common-ark-rtk-base>
     ARK RTK F9P <common-ark-rtk-f9p-gps>