USB Digital Accelerometer FAQs

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Information for specifications of the 333D01 can be found on the Specifications page.

The 333D01 is a plug and play USB digital accelerometer. Instead of outputting a voltage or current signal proportional to acceleration, it outputs digital samples.

By directly outputting digital samples from the sensor over USB, you bypass the need for a separate acquisition system, cables and adaptors, or specialized software. Because the 333D01 USB digital accelerometer appears as a USB microphone to the audio driver, any software that works with sound recording via USB (USB microphones, headsets) will work with the USB digital accelerometer.

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All you need to do is attach the sensor to the vibrating test surface of interest via the ¼ -28 mounting threads (or adhesive), plug the sensor into a computer or mobile device (via USB On-The-Go) USB port, open your data capture software of choice, and you’re ready to go!

The easiest way is with a temporary adhesive such as cyanoacrylate for smooth surfaces and “dental cement” for rough surfaces. Take care not to fill the stud mount hole by either filling it with wax or putty or using a stud mounted adhesive mounting base. *For more tips, an overview of mounting techniques can be found here.

The 333D01 has a ¼-28 thread in the center. Mounting studs and adhesive mounting bases can be purchased from a variety of vendors, for example PCB. Multiple thread adaptors are available to attach to other screw threads via mounting studs. Magnetic mounts are also available. Refer to the online sensor manual section on mounting for more details and best mounting practices.

After plugging the sensor into a computer or mobile device, simply select the 333D01 in the software’s interface and hit the record or capture button. You can also specify a specific sample rate or bit depth. The software should detect the 333D01’s capabilities from the device itself.

The 333D01 sends a stream of audio formatted data. The software you choose will need to have saving capabilities to store the data after capture. Typically, this will be in an audio format such as a .WAV file or an application specific format.

For general purpose use, a sample rate of 48000Hz will work for most applications. For specific frequency measurements, make sure the sample rate is at least twice the maximum expected frequency. For low frequency ( < 20 Hz) applications the 8000 Hz rate is ideal.

The device is a single vibration sensing axis and the same signal can be found on both channels. Channel A is suitable for measurements up to ±20 g full scale while Channel B is the same signal scaled ±10 g full scale.

Because the sensor identifies as a USB audio device, multiple sensors can be active simultaneously though they WILL NOT BE synchronized. To use more sensors, simply plug in multiple USB hubs. The limit for the maximum number of USB device attached to a computer is 128, according to the USB specification.

The 333D01 USB digital accelerometer supports standard audio sampling rates – 48 kHz, 44.1 kHz, 32 kHz, 22.05 kHz, 16 kHz, 11.025 kHz, and 8 kHz.

The 333D01 has 24-bit resolution, but can also output 16-bit resolution samples. This is selectable in audio driver software.

The 333D01 has a flat response from 2-8000 Hz within ±5% deviation of the calibrated sensitivity at reference frequency.

The 333D01 is within ±5% deviation from 100Hz down to 2 Hz. The -3 dB limit is typically 0.75 Hz.

The 333D01 is within ±5% deviation from 100 Hz up to 8000 Hz. The +3 dB limit is typically 15 kHz.

The 333D01 can nominally measure up to 20 g (196 m/s²) of acceleration through Channel A. Channel B is the same signal scaled to nominally measure up to 10 g (98 m/s²) of acceleration.

The maximum useable frequency depends on the select sample rate – cutoff occurs at ½ of the sample rate. For example, if the sample rate is 8 kHz, you can accurately measure and analyze frequencies up to 4 kHz.

Yes, for storing self-identifying information and calibration information. It cannot store vibration data.  It is similar in concept to the IEEE 1451.4 TEDS (Transducer Electronic Data Sheet) standard.

The 333D01 weighs 131 grams (4.62 oz), cable not included.

USB 2.0 full speed, using audio class device protocols.

The integrated cable is 2.9 m (9.6 ft).

The cable for the sensor is integrated into a sealed housing.  It is not removable.

The 333D01 can operate between -10° C and 70° C (14° F to 158° F).

The sensor is not susceptible to static electricity generated and conveyed through the human body.  The design has been tested as part of susceptibility in CE mark testing.

USB type A

The sensor operates off of the 5V USB bus and consumes less than 50 mA.

The 333D01 has been tested for and is compliant with CE mark standards.

The 333D01 comes with both a calibration certificate and calibration data stored in its internal memory. Software can access this internal data by reading the USB Serial Number descriptor. 333D01 optimized software can perform this task automatically, directly translating the sensor output to engineering units.  See the Software Page for a list of supporting software and features.

36750 counts / (m/s²) (Channel A) and 71974 counts / (m/s²) (Channel B)

Simply plug the 333D01 USB cable into a USB On-The-Go (OTG) adaptor cable.

Simply plug the 333D01’s integrated USB cable into any USB port.

Yes, you can use one or multiple USB extender cables or USB hubs. The maximum length able to be reached is 10km using Fiber Optic cabling, 100m using Copper, and, roughly, 5m using a passive(just wires) extender cable.

Windows® 7 and 8 offers full compatibility with the 333D01. Windows® XP is compatible, though limited to 16-bit resolution with standard Windows audio drivers.

Yes – the 333D01 is compatible with both Android phones and tablets, through the use of a USB OTG cable.

The 333D01 works with Macintosh operating systems and iOS mobile platform. For iOS devices with a lightning connector, Apple’s Lightning to USB Camera Adapter can be used.

Yes – on this site there are examples of MATLAB® scripts, as well as LabView® and LabWindows® applications that interact with the 333D01.

The base MATLAB® package can read data from the sensor using Windows® DirectSound drivers. However, more functionality can be obtained with the DSP Toolbox using the dsp.AudioRecorder object.

Sometimes when first plugging in the sensor, the device information is not properly transmitted. If unplugging and replugging the sensor does not fix the problem, you can try restarting the computer. If that does not resolve the problem, uninstall the device through the Device Manager window (may require a restart).

If you are using Windows built-in drivers, make sure that the correct sample rate is selected in the Windows Recording Devices interface. This should match the sample setting in your software application.

The raw data coming from the sensor is a 16-bit or 24-bit sample (depending on software settings), sent a byte at a time. Depending on the application this may be displayed as a digital count from -223 to +223 (leading bit is a sign bit) or represented as a full scale value (FSV). To convert from FSV to digital counts, multiply the full scale value by 223 or 215 for 24-bit samples and 16-bit samples, respectively. To convert from a digital count to engineering units of m/s2, divide the digital count value by the calibration value for the channel in question. To convert from m/s2 to g, divide by 9.80665.

If the clipping is in Channel B, the input acceleration being measured has likely reached it the Channel B maximum measurement range (normally 10 g). Switching to Channel A should solve the problem.  If clipping is still present , the acceleration measured is likely beyond the max range of 20 g and cannot be accurately measured by this device.

Default Windows sound drivers do not permit 24-bit samples below 44100 Hz sample rates. However, using another sound driver such as ASIO will allow full use of the sensor’s bit depth and sample rate capabilities.

The 333D01 is rated up to 7000 g of shock without damage. Your sensor should still work – however if you are concerned about performance impacts, you can have your sensor recalibrated by a regional instrument calibration lab or by www.digiducer.com. Email us at info@digiducer.com for details.

ASIO stands for Audio Stream Input and Output. (ASIO is a low latency, high fidelity interface directly between software and the sound card, or in this case the 333D01 hardware. A free implementation can be found in ASIO4All.)

ASIO allows you to utilize the full features of the sensor by bypassing Windows restrictions and directly accessing the hardware. Specifically, it allows you to choose any combination of bit depth and sample rate supported by the 333D01.

Though you can operate with the standard Windows DirectSound drivers, it requires you to match the sample rate chosen in software with the sample rate listed in the Windows Recording Devices interface. If these sample rates do not match, Windows resamples incoming data which will corrupt the integrity of the data. In addition, Windows DirectSound only permits the use of 24-bit samples with 44.1kHz and 48kHz sample rates. The sensor itself allows any of its 7 available sample rates to be used with either 24-bit or 16-bit resolution.