The Infiltec Model INFRA20 infrasound monitor is designed to record, display and analyze infrasound below the human hearing range in the 0.05 Hz to 20 Hz range. Infrasound is produced by wind turbines, helicopters, meteors, avalanches, volcanoes, large animals like elephants, etc. The INFRA20 is designed to provide infrasound monitoring for lab, home, school and field use in a compact, portable, and rugged package that is less expensive and easier to use than conventional designs. The INFRA20 does not require any power supply or assembly or enclosure or adustment; including alignment, damping, zeroing, etc. The INFRA20 works with the standard AmaSeis Windows based software, and with the new jAmaSeis software for Windows, Linux and Mac OS.

  • For laboratory, field, school, office, or home use to record and analyze infrasound. This infrasound monitor comes with a 15 ft (4m) serial cable, 15 ft (4m) of 1/8 inch ID plastic tubing, a USB-Serial adapter, and a CD contianing Windows software and software manual.
  • Detects infrasound in the 0.05 Hz to 20 Hz band that is generally inaudible to the human ear. Applications include monitoring wind turbines, machinery noise, building noise, elephants and other large animals, meteors, avalanches, volcanoes, earthquakes, cryptozoology studies of big foot and sasquatch, and paranormal investigations.
  • Requires an attached PC to log and display infrasound data, but other programs can run on PC while the infrasound data logging program is running. Works with Windows XP and above. The seismic data logging and analysis program AmaSeis is supplied on CD. Also runs with the new jAmaseis seismic software that runs on Windows, Linux and MAC OS.
  • The INFRA20 is not very sensitive to vibration or orientation, but it is very sensitive to temperature changes or altitude changes. Serial extension cables up to 100 ft can be used to connect it to the data logging PC.
  • The infrasound sensor is a differential pressure sensor with 1/8 inch ID tubing connection that is located on the side of the box that allows for tubing to be used to separate the monitor from the infrasound sensing location. The monitor is self adjusting, and never needs alignment, zeroing, leveling, or any other adjustments. No external power supply required. Setup takes minutes. Resolution is 0.001 Pascal (0.01 microbar). Range is ±25 Pascals. Sampling rate is 50 sps. Serial output data format is 9600bps, 8N1, 16 bit ASCII.

VIEW CURRENT INFRA-20 REAL-TIME INFRASOUND DATA IN 24 HOURS DISPLAY:
real-time display of INFRA20 infrasound monitor

This infrasound display is updated every 5 minutes and is generated by an INFRA-20 that runs 24/7 inside the Infiltec factory warehouse. The display was generated by the free AmaSeis seismic data logging/display software and the display updates are by Fling FTP software. You can set up a similar online display with your INFRA-20 using the same software.


Even though the INFRA-20 is inside a building, it can detect the infrasound outside the building. Each horizontal line covers 1 hour. Vertical axis is infrasound intensity.



  • The daily oval shaped infrasound peaks (about 3 minutes long) come from freight trains as they pass within about 100 meters several times per day.
  • The occasional rectangular infrasound peaks (about 2 minutes long) come from an unknown source, possibly a nearby factory.
  • The short infrasound spikes are often caused by doors in the factory being opened and closed.
  • Wind is the most common infrasound background noise, and it generally peaks during the daylight hours (11-24 UT hours). You can check the local weather and wind here to see if it is windy at the monitor location.
The hours on the vertical axis are in Universal/GMT time, +4 hours ahead of local USA EST. The data logging time base is corrected within milliseconds by the free program NetTime.

APPLICATIONS OF THE INFRA-20:

  • Wind turbine monitoring.
  • Animal monitoring, including elephants, hippos, rhinos, giraffes, tigers, alligators, certain birds, etc.
  • Earthquake and tsunami monitoring.
  • Bolide or detonating fireball meteor monitoring.
  • Volcano monitoring.
  • Avalanche monitoring.
  • Thunder, lightning and severe weather monitoring.
  • Sonic boom monitoring.
  • Explosion monitoring.
  • Aurora monitoring.
  • Alleged haunted site or ghost monitoring.
  • Rotating equipment monitoring.
  • Sick building analysis.
  • Environmental assessments.
  • Microbarom monitoring.
  • Helicopter monitoring.
  • Tornado monitoring.

  • FEATURES AND BENEFITS OF THE INFRA-20:

    • 10 second hardware setup! Take it out of the shipping box, plug it into your PC, and recording starts. (This assumes that AmaSeis software is installed and running)
    • Works with free AmaSeis seismic Windows software that provides data logging, 24 hour display, spectral analysis, bandpass filtering, etc.
    • No assembly ever required.
    • No damping adjustments ever required.
    • No external power supply ever required.
    • No leveling adjustments ever required.
    • No alignment ever required.
    • No adjustments for moving ever required, just pick it up and move it.
    • No adjustment of internal electronics (amplifier, filter, digitizer, power supply) ever required.
    • Practically indestructible to damage caused by shock, vibration, shipping & handling.
    • One enclosure contains everything: sensor, amplifier, filter, digitizer, power supply.
    • Metal enclosure shields electronics against noise from nearby electromagnetic interference.
    • High digital resolution (16 bits) keeps large and small infrasound events on scale.
    • Elliptic low-pass filter cutoff (8 pole) allows slow sampling output (50 sps) without aliasing.
    • Microprocessor firmware adjusts for component drift due to temperature changes, aging, etc.
    • Very low power (under 0.05 Watts) operation. Designed to operate continuously 24/7.
    • Connects to PC DB9 serial port, or a USB port through a USB-Serial DB9 adapter.
    • Works on Windows 98/XP/Vista/7/8/8.1 PC via AmaSeis logging data 24/7 in background. You can use your PC for other jobs while AmaSeis is running.

  • SPECIFICATIONS FOR THE INFRA-20

    • Performance: Resolution is 0.001 Pascals (0.01 microbar or 0.0075 millitorr) over the range of + or - 25 Pascals (250 microbars or 187.5 millitorr).
    • Mode of Operation: Microbarograph design with solid-state differential pressure sensor and high-pass pneumatic filter.
    • Output: Serial output formatted for AmaSeis seismic software, RS232 9600 baud N81 ASCII, 50 samples/second.
    • Frequency Pass-Band: 0.05 Hz to 20.0 Hz bandwidth digitized and stored on hard drive by AmaSeis at about 10 megabytes per 24 hours of operation.
    • Temperature Range 40 to 90 F (4 to 32 C) with no adjustments required. Internal firware automatically adjusts for drifts. Requires constant temperature during operation that can be provided by insulation such as a small lunchbox type cooler.
    • Housing: Diecast aluminum box encloses all electronics and sensor, 6.024x3.268x1.988 inches (153x83x50.5 mm). Shipping weight 2.2 lb (1 kg).
    • Computer Connection: 15 ft (4.5M) serial cable (up to 100 ft (30M) extension optional) connects to PC DB9 connector or USB-Serial DB9 adapter.
    • Adjustments: No leveling, alignment, damping, gain, zeroing, etc adjustments required.
    • Power Supply: No external power supply required, all power (under 0.05 Watts) is supplied by PC serial port through the serial cable connected to the PC.
    • Digital Processing: 16 bits voltage resolution from internal digitizer, 50 sample/second ASCII output, firmware adjusts for component drifts.
    • Lowpass Filter: Very steep analog 8 Pole elliptic filter with 20 Hz corner frequency for anti-aliasing.
    • Software: Windows PC based seismic data logging and analysis software AmaSeis or jAmaSeis  available online for free download. Includes spectral analysis and bandpass filtering functions.
    • Computer Requirements:PC running Windows (98/XP/V/7/8/8.1) can run AmaSeis in backgound while doing other tasks. Hard drive that can store 10 megabyte/day during 24/7 operation. DB9 serial port or USB-Serial adapter.

  • SAMPLE DETECTIONS BY AN INFRA-20 SYSTEM:

    • Here some INFRA-20 infrasound (0.01-20Hz) detections from the Washington, DC area where helicopters fly over several times daily:







  • UNDER DEVELOPMENT: A Portable Infrasound Generator .
    • Precise digital tuning within the 8 to 20 Hertz output in the Infrasound Range.
    • Controlled by a built-in variable frequency generator and driven by a powerful subwoofer amplifier
    • Powered by either house current 110-240 VAC or 12 VDC car battery
    • Portable by truck or van
    • Design follows Helmholtz resonator principles
    • Inexpensive compared to other speaker designs
    • Driven by powerful subwoofer speaker
    • Potential applications include: music augmentation, classroom/public demonstrations, evaluations of effects on people and animals, repelling birds, propagation studies, paranormal research, etc.
    Infrasound Generator INFRA-85G bult into the lid of a steel drumPicture of prototype during testing