Breakout board uses HB100 doppler motion sensor


limpkin has been working on a dev board for the HB100 microwave sensor. He developed a breakout board that allows the module to operate as a motion sensor. “I’m sure you’re quite familiar with the Doppler effect: you send an RF signal at a given frequency to a target, and if this object/person is moving the reflected signal’s frequency will be shifted. The HB100 outputs a low level voltage (few uV) whose frequency represents the speed at which an object is moving towards or away from the sensor. The output can be very noisy, so in addition to amplifying the signal, we need to filter out frequencies that don’t match what we expect from ordinary objects.” His design uses op amps and supporting discrete components to accomplish this.

You can find project schematic, KICAD files and all details on Limpkin’s Blog.

Via the contact form.

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Comments

  1. Drone says:

    When I saw this my memory was jogged… These HB100 modules seem to come from a company called AgilSense, a division of ST Electronics (Satcom & Sensor Systems) in Singapore. I’m familiar with ST Electronics as my company uses their Agilis Satcom products in real-life.

    I see at my post-time the ebay Rover pulled up a sale page for one HB100 module for $13.19 USD out of the U.S.

    From the AgilSense site the HB100 operates at 10.525 GHz with an EIRP of 20 dBm max. 15 dBm typical, 12 dBm minimum, a 30-40 mA current consumption and a Doppler pulse frequency in the 2KHz range. This is a 5V only device. The site says the HB100 is, “Human detection of at least 15m away. Suitable for use in USA and Canada. There are other versions, seemingly with different frequencies and EIRP compliant with different countries.

    15 meters is pretty good. Compare that with an IR passive proximity sensor. Plus the way it works lends itself to detecting whether an object is moving toward (ingress) or away (egress) relative to the sensor. This sensor is not useful for “static” distance measurement, only for measurement of object motion relative to the sensor position. The azimuth -3dB beamwidth is 80 degrees while the elevation beamwidth is 40 degrees. You might be able to rotate the sensor 90 degrees to swap azimuth and elevation, but if you do so perhaps expect less sensitivity due more thermal noise pick-up from the ground or floor.

    This is a typical microwave “Radar Gun” like component. There are simply patch antennas, a DRO oscillator, and a single on-module mixer that does direct-conversion to baseband. From the picture of the digital output it looks like the raw output is sliced to 0-5VDC, so you get a varying frequeny output square wave signal to work with.

    The backpack board article linked to in this post uses simple analog filtering of the mixer output. If you want to take it to the next level interface the output to a micro-controller GPIO pin assigned to a timer-counter then apply some simple DSP. This may dramatically improve the response time (don’t forget a Nyquist filter, if needed in your implementation of-course).

    At X-band, this module should do well in a properly designed weatherized enclosure. I wonder if it could be used for a rainfall detector/measurement device. Hmmm…

    How about taking the baseband output after filtering and putting it into the sound input of a PC and then use a sound card SDR application like GNU-Radio. Bat motion-detector maybe?

    What if you take two of these modules and point them at each other? X-band communications link? Try modulating Vcc to shift (or on-off key) the DRO.

    Or maybe don’t point them at each other but point them at different angles in space? Maybe doing that will allow (with post-processing) to determine the 2D position of objects. Three modules may yield 3D. Maybe two modules with one rotated 90 degrees relative from the other can yield both 2D and 3D information due to differing beamwidths?

    Point this at a rotating object and measure RPM?

    How about using this as a radio altimeter for a drone, a quad-copter perhaps. It may allow smooth landings when GPS resolution is too bad and your nine-degrees of freedom sensor system drifts. Better than a cranky barometer MEMS chip.

    Boost the output with a MMIC as an X-band test source. Modulate VCC with a PRBS to make a cheap noise source for X-band filter measurement using a second device as a detector?

    Too bad they didn’t incorporate a quadrature local oscillator with quadrature mixer baseband output in this module. Doing so would really lend itself to I/Q SDR applications. But I think this device is primarily targeting non infrared proximity sensors for automated door openers.

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