CMX7364
RTCM SC135 Compliant RTK Wireless Modem
CMX7364
RTCM SC135 Compliant RTK Wireless Modem
Real Time Kinematics (RTK) is a method of providing high precision location information using differential GPS. Using a fixed base station that transmits both position and GNSS radio link information, it allows remote units, often referred to as rovers, to correct their own GNSS location with enhanced accuracy, down to the centimeter level. The radio link needs to provide a high quality of service (QoS) as real time communication is required and be able to operate over large geographic areas in applications such as precision agriculture and mining.
The 7364 FI-8 is a Function Image™ that runs on CML’s CMX7364 Multi-mode High Performance Wireless Data Modem, realizing a wireless modem compliant with the RTCM SC135 standard. The solution has been developed to simplify modem operation, automating many aspects of data frame construction such that the user simply inputs the data to be transmitted from the host processor over C-BUS, an SPI like serial interface. The modem will then assemble data for over air transmission automatically inserting Preamble, Frame Sync pattern, Frame Type symbols, CRCs and adding the appropriate FEC schemes to the header and data payloads for each frame type. RTCM SC135 Frame Type 0 (without FEC) and Frame Type 1 (with FEC) are supported. Transmissions may be variable length (up to 8440 bytes). The modem then generates 4-FSK with a RRC alpha 0.2 plus optional sinc filter modulated signals, suitable for I/Q or 2-point VCO modulation. The modem also has a transmit sequencer that controls power amplifier ramping to avoid spurious emission. In reception, following frame synchronization and data extraction the modem performs error correction before presenting the received data to the host.
The credit card sized small form factor of the evaluation platform is due to the highly integrated nature of the CML IC solutions and its software defined architecture allows support of multiple channel bandwidths (12.5/25/50kHz) and modulation types with a single hardware design. There are two versions of the design available; the DE9941A-375 optimised for operation in the 350 – 450 MHz band and the DE9941A-435 optimised for operation in the 400 – 470 MHz band.
The board can be used to demonstrate receive and transmit performance with multi-level QAM, FSK and GMSK type modulation. Using the on-board ARM host controller, a full transceiver can be demonstrated interfacing to a host PC via USB, with scripts available to set up the board as a transceiver, as well as running BER tests and operation in transmit mode only.
Devices are available through our Distributor Network.
Function Image 8.x can be downloaded from the CML Micro Technical Portal.
Features of the CMX7364 RTCM SC135 Compliant RTK Wireless Modem include:
- Provides a communication link with data formatting meeting RTCM SC135 requirements
- Supports 12.5kHz and 25kHz RF channel spacing
- 4-FSK modulation 4800 and 9600 ksymbols/s
- Formatted data blocks may be of variable length (up to 8440 bytes) with 16-bit CRCs for error detection, with Hamming code or Reed Solomon (RS) coding for error correction.
- Two frame sync detectors
- Automatic frame sync detect
- Rx carrier frequency correction Tx and Rx: ‘direct connect’ to zero IF transceiver
- Digital IF filter reconfigures for multiple RF channel spacings (Rx)
- Deviation control without manual trim (Tx) I/Q trims
- Receive signal quality measurement
- SPI-compatible serial bus interface
- Read/Write 128-byte FIFOs and data buffers streamline transfers and relax host service latency
- Multi-formatted asynchronous data transfer
- Unformatted synchronous data transfer
Applications the CMX7364 RTCM SC135 Compliant RTK Wireless Modem can be used for:
- Real Time Kinematics
- Precision agriculture
- Construction
- Mining
Power Supply Requirements for the CMX7364 RTCM SC135 Compliant RTK Wireless Modem:
- 4.5 V
RTCM GUI Application for Windows PCs.
A PC based GUI application for the DE9941A-375 and DE9941A-435 that runs on Windows 10. Only a 64-bit version is available.
DE9941A-RTCM-SC135-GUI. Version 1.03
Arm firmware file
This image file must be programmed into the DE9941A for it to communicate with the RTCM GUI App.
DE9941A_RTCM_F03.01.04.bin. Version F03.01.04
PE0003 firmware file
This image file is to restore operation of the DE9941A for non RTCM scripts (CMX764 FI 1, 2, 4).
DE9941A-SCRIPT_F02.01.00.bin. Version F02.01.00
DE9941A Bootloader
This image is for older versions of the DE9941A and upgrades their bootloader to work with the RTCM application. This should only be required if you receive an error when trying to connect to the RTCM GUI Application.
DE9914A-BOOTLOADER_F01.01.00.bin. Version F01.01.00
USB driver
This driver is only suitable for Windows PC running 64-bit OS.
This can be downloaded from the PE0003 Product page
Visual C redistributable runtime libraries
This runtime library may be needed to use the RTCM GUI Application. You will only need this if the RTCM GUI fails to start and Windows reports that the Visual C runtimes are required.
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