Low Frequency Detector vs Vibration Usage & Stats

"Low Frequency Detector" is a new acoustic measurement tool for detecting the low frequency sound that is hard to hear in the normal situation. The human ear is insensitive enough to become a low frequency. If you may be exposed to the noise of neighboring constructions and factories without noticing, you may have a feeling bad and a sense of oppression. In this case, you can check what type of low frequency noise exists by simple operation of this app. In general, the low frequency sound is a sound wave with 1 Hz to 100 Hz. By depending on its frequency component and sound level, it is different the degree of influence on the human body and the noise sensation. This app also allows you to examine the frequency component of the low frequency sounds by 1/3 octave band analysis and FFT analysis. Features: - Low frequency power level measurement less than 100Hz (LF Level): Flat characteristic, Updating indication of measurement period 1 sec. - Power level measurement in the audible band (Leq): Flat characteristic, Updating indication of measurement period 200ms. - 1/3 octave band analysis (OCT) - FFT analysis (FFT) - Time course graph (TIME) - Snapshot (Snap) on the measurement display screen. - Report function (Report): Analysis report of a peak LF Level with TIME, OCT and FFT. - Measurement time : up to 60 sec. Functions: The measurement analysis is performed in the following step. Be sure to set the measurement conditions in Step-1 once before starting the sound measurement. 1) Calibration (Calibrate): A reference signal (1kHz sine wave) is output to determine the reference noise level for the low frequency component. If the volume level of iPhone is set to about 20-50%, the calibration will automatically adjust it to the optimum volume level for the reference signal. 2) Measurement (Measure) : Analyze a power level of low frequency sound. - LF Level (dB): Low frequency power level less than 100Hz. - Leq (dB): Sound power level with the frequency weight characteristic Z (Flat) of the audible band. 3) Measurement display: It can select either 1/3 octave band frequency analysis, FFT analysis or Time course graph. They are updated in real time. 4) Report: Measurement result report. It is effective when measuring for 10 seconds or more. # Time course graph : TIME - Low frequency (LF) Level (dB): Time course graph with peak level noise level judgment (RED-very noisy, YELLOW-noisy, GREEN-normal) at the peak level. - LF max (dB) : maximum dB value of low frequency. # Frequency response graph : OCT, FFT - OCT Band LF max (dB): maximum dB value in 1/3 octave band at LF max observation. - Max Level Frequency (Hz): peak frequency at LF max observation. Notes: - The sound measurement of the low frequency range is a level difference with respect to the reference signal (1kHz sine wave), which indicates the relative power level. - The reference signal is output during calibration and sound level measurement. - Do not change the volume level of iPhone after the calibration. - White line in the OCT and FFT modes indicates frequency characteristics in frequency weight correction of G characteristics. - Since iPhone's built-in microphone has a lower sensitivity on the very low frequency range, it is not recommended to measure a huge volume sound near a very loud noise source. - Since it takes a while for the observation value to stabilize immediately after the start of measurement, the maximum value is calculated from about 2 seconds later. - In the case high power of 1kHz component is included in the measured noise source, the precision of measured value by this app largely decreases. - Sudden noise or impulsive sounds are not low frequency noises in general. - The previous calibration information can be maintained internally. - The analysis results may vary due to individual differences in iPhone devices. - The authorization to access built-in microphone and Photos will be confirmed by iOS system at first boot.

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Vibration

Vibration is a true vibration spectrum analyzer using the built in accelerometers and gyroscope inside the iPod Touch and the iPhone and starting with version 3.x it can sample the built in microphone and the Digiducer professional quality external USB accelerometer. It acquires and displays time series data, optionally removes DC bias, applies a Hamming window and performs an FFT on each channel to produce frequency spectra. The 3-channel accelerometer has a sensitivity of approximately 0.02g and a range of ±2g making the iPhone and iPod Touch sensitive enough to analyze the vibration of most moving machinery. In many applications Vibration can be an excellent portable alternative to a commercial spectrum analyzer. In predictive maintenance applications Vibration can help identify bearing defects, shaft misalignment, imbalance, and structural resonant frequencies. Vibration is also useful for monitoring the acceleration of part and material handling equipment. The software is flexible and easy to use. It was written to emulate the familiar oscilloscope based spectrum analyzer. Sample rate and sample delay are easily adjustable and the user can select the length of the data acquisition and the vertical scale used for the display. Once the settings are configured simply press the sample button on the device or on your Apple Watch. When a test is complete the resulting data can be emailed to your desktop computer for documentation purposes. Features: • Sample the built in accelerometer or gyroscope, the internal Microphone or the professional Digiducer USB products including the 333D01, 333D04, 633A01 and 435B39. Additional Digiducer accelerometer features can be enabled via in-app purchase. • Adjustable sample rate from 10Hz to 100Hz for the internal sensors and 1 kHz to 48 kHz for the internal microphone and the Digiducer accelerometer (with in-app purchase) • Trigger sampling and review settings using the Apple Watch companion app. • Auto repeat and auto save allow data to be taken over extremely long periods of time. • Selectable data length from 256 to 4096 samples • Variable start delay from 0 to 20 seconds • Adjustable vertical scale for time series data • DC Remove option to get rid of the gravity vector • Switchable Hamming window for frequency analysis • Frequency data plotted as Linear-Linear, Log-Log, Log-Linear and Linear-Log • Computes rms and peak levels for each channel and for all three channels combined • Document your results by taking screen snapshots and syncing them to your computer or sending a CSV formatted email with the time and frequency data to your computer or saving data locally and downloading the data with iTunes • Turn on and off individual frequency plots • Calibrate the internal accelerometers and examine and edit the calibration data • Optional sounds to mark the start and stop of data acquisition • Data inspectors and zoom • Triggering off one or more accelerometer channels or microphone input. • Frequency data averaging and peak hold. Further development and additional features are planned. Please use the email links in the program to request new features and report any problems.