Wireless Data

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.