Bruel & Kjaer 2250 FFT analyser and Tonal Assessment details, B&K 2250 FFT TA, BK 2250

Uses
FFT analysis of sound or vibration
Tone assessment in accordance with ISO 1996-2 [option]
Machinery troubleshooting
Product development
Quality control
Automotive component analysis

Features
Hand-held, single channel, FFT measurement
Analysis of sound or vibration
CCLD input for accelerometers
Wide dynamic range
Used for transient and continuous signals
Real-time operation (no data loss)
Up to 6400 lines. Resolution down to 16 mHz
Spans from 100 Hz to 20 kHz in a traditional 1-2-5 sequence + Zoom analysis
Linear and exponential averaging
Internal and external trigger
A-weighting in post-processing
Acceleration, velocity and displacement display
Measurements in SI (metric) and UK units
Unit scaling (RMS, Pwr, PSD, ESD, Peak, P-P)
Max spectrum hold
Compare spectrum to reference spectrum
Auto peak finding
Tone generator output
Signal recording
PC software for analysis, reporting and archiving

Tone Assessment Features
Tone assessment on hand-held analyzer
Measurement quality indicators on tone assessment

The BZ 7230 FFT Analysis Software is an application 'module' for the 2250 hand-held meter. The Fast Fourier Transform is a digital signal processing technique that converts a time record into a narrow band constant bandwidth filtered spectrum. Measurements are defined by specifying the frequency span and a number of lines (or filters).

FFT sound and vibration analysis is all about the details and the zoom facility allows you to focus on any part of the frequency range by specifying the centre frequency for the analysis span, resolutions down to 1/64 Hz are possible see the table for details.

Noise can be described as tonal if it contains a noticeable or discrete, continuous note. This may include noises such as hums, hiss, screeches, drones, etc., and any such subjective description is open to discussion and contradiction when reported.

ISO 1996-2 (2007) Annex C, "Objective method for assessing the audibility of tones in noise reference method", provides measurement procedures to be used to verify the audibility of tones and to quantify them. Although the methodology of any standard could be the subject of much discussion, the result of a test carried out in accordance with it, is not.

Automatically Configured for ISO 1996 Assessments
By its nature, making objective measurements to what is inherently a subjective response to a sound is difficult. Issues such as prominence, amplitude/frequency masking, and calculation of any tonal penalties makes the ISO 1996 assessments more than a simple FFT measurement.

BZ-7231 Tone Assessment Option for Type 2270 and 2250 Hand-held Analyzers running FFT Analysis Software BZ-7230, offers a quick and easy `in-the-field' objective assessment of tonal noise components, in compliance with ISO 1996 assessments. The facility to carry out the ISO Standard tone assessment on the analyzer with an immediate result offers objective feedback about whether you have `found the problem' or need to take further measurements.

In addition, the analyzer offers an easy way of setting up the FFT analysis to follow the ISO 1996-2 standard. When this option is selected, the analyzer automatically selects the appropriate measurement configuration. Simply press `start' and the measurement and analysis are in progress.

All the Details Available Instantly
On completion of the measurement, the calculation of tonal parameters for all the possible tonal candidates in the analysis takes only a few seconds, after which the following comprehensive list of results can be displayed on the spot:

Kt - the value added to the LAeq to give the tone-corrected rating level
Lta - the audibility of all tones found in the same critical band as the selected tone
Lpn - the Total level of the masking noise in the band containing the selected tone
Lpti - the Level of the selected tone
Lpt - the total Level of all tones in the critical band containing the prominent tone
Critical Band - the start and end of the critical band containing the selected tone

The LAeq and other broadband parameters are measured simultaneously by the hand-held analyzer and the tone corrected rating level can be calculated on the spot as shown in the typical FFT spectrum display above.

Manufacturer's Specifications

Gracey & Associates Hire Bruel & Kjaer 2250 FFT and Tone Assessment options

Gracey & Associates Hire

Bruel & Kjaer 2250 FFT and Tone Assessment options