The SLMX4, a radar-based sensor that is replacing the Xethru


PRICE: $425.00


The SLMX4 is a low-power, yet powerful computing system with an array of other sensing technologies and multiple communication options. SLMX4 has an antenna set designed directly into the PCB stack for ease and miniaturization, without the need for cumbersome connectors and cables.

Common applications include presence detection, proximity sensing, occupancy sensing, respiration monitoring (replacing the Xethru respiration sensor), sleep monitoring, and HVAC control. Modules can be combined to create sensing arrays for people tracking and foot-traffic flow.

A server-based firmware for MATLAB integration and rapid algorithm development is also available.  It boasts an ARM M7 MCU with room to grow for augmented features and applications. All documentation can be found on its companion Github page: SLMX4-Github 

Firmware Options

  • X4 SoC Transceiver
    • CF = 7.29 GHz
    • BW = 1.4 GHz
  • Differential planar antenna embedded in the PCB
    • 3-5 dBi over frequency
  • NXP i.MX RT1060 Cortex-M7 Crossover MCU
    • 3020 CoreMark/1284 DMIPS @ 600 MHz
    • Real-time, low-latency response as low as 20 ns
    • 1MB On-Chip SRAM
  • 1.8V Power Distribution System, i.e. very low power
    • High efficiency switching regulator(s)
    • USB Type-C connector
  • 16 MB NOR Flash 
  • 8 MB SDRAM

Firmware Options


Sensing capabilities:
    • Presence detection
    • Respiration (+/- 1 RPM)
    • Movement detection (including type of movement)
    • Range: 5 meters
    • Optional peripheral sensors:
      • ALS
      • Temp
      • Humidity
  • Environment Sensing
  • Communications
    • WiFi + BLE
    • USB
  • Visual Indicators
    • RGB LED
    • Red + Green LEDs


ParameterDescription MinMaxUnits
Power120 mA @ 5V (via micro-USB cable) (continuous, duty cycled for low power)0.6 watts
Temperature Range085C
Size60 x 18 Height (including USB connector)mm
InterfacesUSB, Wi-Fi, BT