Doppler Radar Module (24 GHz) from Fujitsu to Monitor Heart Rate Without Contact
The 3-channel device is built to simplify the design of non-contact motion detection products.
Fujitsu Components America, Inc. has introduced the (PDF) FWM7RAZ01, a 3-channel, 24GHz Doppler radar sensor. Fujitsu claims that the new unit features a wide range of speed detection along with high interference tolerance.
Fujitsu’s FWM7RAZ01 3-channel, 24GHz Doppler radar sensor module. Image used courtesy of Fujitsu
The module and its accompanying evaluation kit are designed to facilitate the quick development of applications within the rapidly expanding universe of non-contact, movement sensing products. The module and evaluation kit aims to help designers without extensive expertise in high-frequency RF electronics to expedite results.
The FWM7RAZ01 supports I/Q output signals that range from 1Hz to 1MHz. This enables the device to wirelessly detect movement taking place at velocities ranging from 6 mm-per-second to 6 km-per-second. This detection can occur anywhere within a 30-meter radius.
While a Doppler Effect of 1MHz is unobservable in real-world applications, it can serve the purpose of detecting signal interference. The device will select a different channel to prevent signal overlap, thus avoiding misdetection.
The concept of I/Q signals is explained in more detail in Understanding I/Q Signals and Quadrature Modulation.
The module’s specific operating band is 24.075GHz to 24.175GHz in North America and 24.050GHz to 24.250GHz in East Asia.
Block diagram of the FWM7RAZ01. Image used courtesy of (PDF) Fujitsu
The operating voltage can range from 3.4VDC to 5.5VDC at 63mA, and the device draws 0.6mA when disabled. Effective radiated power (EIRP) ranges from 8dBm to 13dBm.
Human Vital Sign Monitoring and Other Applications
The Doppler radar sensor can read heart rates by focusing on one of the patient’s arteries, which vibrates ever so slightly in tandem with his or her heart rate. The sensitive module, in essence, counts those perturbations, averages them over time, and determines the heart rate.
Diagram of a traditional Doppler radar system using one transmit and two receive antennas. Image used courtesy of (PDF) Anders Høst-Madsen, Nicolas Petrochilos, Olga Boric-Lubecke, et al.
A similar methodology is used to determine the respiration rate of patients.
Other target applications for the FWM7RAZ01 include:
- Alerting health care workers if a patient has fallen
- Machine maintenance functions
- Mechanical movement detection
- Determining structural integrity
The FWM7RAZ01 24GHz Doppler radar sensor includes the 24GHz transceiver and the associated transmit and receive array antennas. An MCU, DAC, E2PROM, IF amplifier, and an LDO voltage regulator are also part of the module. The physical size of the device is 30mm x 44mm x 9.5mm.
The device has pin header terminals deployed on the back of the module, which will simplify integration. This final feature might be appreciated by those designers less familiar with high-frequency circuits.
Evaluation and Support Tools
Fujitsu offers FRM-ORCA-EVB1, an evaluation board for the FRM7RAZ series of Doppler radar sensors. The company also offers an evaluation board user manual to assist OEMs with FRM7RAZ and with the evaluation board.
Around the Industry
The NJR4265 series from New Japan Radio consists of four 24GHz microwave Doppler devices. They include an RF circuitry, antenna, IF amp, MCU, and a voltage regulator. The four separate devices vary slightly in output frequencies to accommodate the regulatory regimens of Europe, the United States, and Japan.
RFbeam Microwave GmbH's K-LC6 is a dual-channel Doppler radar module. A short-ranged device, it is most suited for gauging the motion of people and vehicles.