BPSK wireless data modulator simplifies design for licensed frequency bands

The CMX7146 is a flexible data modulator from CML Microcircuits to simplify the design of transmit-only solutions using binary phase shift keying (BPSK) and differential BPSK modulation.

It generates baseband analogue in-phase and quadrature signals with programmable signal filtering. This in turn generates a signal ready for transmission and suitable for up-conversion to an RF carrier of the user’s choice.

The modulator is said by the company to provide extensive configuration in terms of data rates and modulation shaping, while enabling users to customise transmit frequencies and channel bandwidths using an external RF modulator. No extensive RF or DSP programming knowledge is required.

“We are seeing a lot of interest in satellite Internet of Things (IoT) applications that monitor very remote equipment and send relatively small messages,” said David Brooke, product manager for CML’s wireless voice and data products.

“For these kinds of functions, the new CMX7146 will give developers a quick and easy route to deploying a robust transmitter.”

BPSK is often used when durable, long-range communication is needed. It can be relatively simple to demodulate and extremely power efficient which suits it to satellite applications, marine search and rescue beacons and IoT transmitters.

The CMX7146 supports raw (bits in, modulation data out) and preloaded (messages in, modulation data out) transmissions and features a transmit trigger input to enable precisely timed data transfers.

A power amplifier ramping DAC can be used to control transmission bursts, which can be synchronised as part of the transmit sequence. To increase flexibility in sensor interfacing and IoT solutions, the CMX7146 integrates low power analogue to digital converters and four general purpose input/ouput interfaces.

The new device is based on CML’s FirmASIC technology, where device functionality is defined by a small configuration file that is loaded at power-up. This allows for future functionality upgrades provided by CML, such as alternative modulation schemes or over air protocols.

The new modulator complements CML’s existing range of wireless data modems aimed at applications in licensed frequency bands. In a typical system, the CMX7146 may be paired with CML’s CMX971 IQ modulator or CMX973 transceiver and a low-cost flash microcontroller that provides simple control functions as well as function image storage.

Such a solution supports transmit frequencies from 100MHz to 1000MHz, and higher frequency systems can be supported by using alternative up-converter solutions.

The CMX7146 operates from a single 3.3V supply and is provided in a 48 lead QFN package.


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