ATB precision Analog
+ digital Audio Analyser
The Measurement program
The measurement program is a Windows program easy to
learn and to handle.For each measurement there is a
special program with ist own settings. The user has not
to think about what settings he needs for a special
measurement, he only calls up the measurement. If the
user has done the measurement before, the program knows
all settings and he can start the measurement at once.
With the windows program it is easy to create a
documentation via the clipboard. To use the data for a
calculation program there is a ASCI data sheet.In future
there will come following measurements:
- 2-Channel FFT
- Room Akoustic program
- 32 Band True RMS Analyser
- Quality Control test program with thresholds and
Rub and Buzz
The Measurements of the ATB precision
The Windows 95/98 and NT
Program included following measurements:
Impulse Response
Optitest
The Optitest
is a very fast and comfortable SPL measurement. The
stimulus for this measure is on a audio CD. For
automotive measurement the CD player plays the signal.
The measurement could be done without having trouble by
connecting the signal to the systems input. The
measurement time is 1/3 sec. The frequency range is from
20Hz to 24kHz. The measures are averaging for a room
correction or near field measurement.
Room
correction measurement
Frequency
range in the car
blue = one measure,
read
= room correction measurement
The
acoustical measurement of a Automotive Sound System is
not easy . In the interior of a car there are many
interferences in the sound field.
Each position for the microphone shows a different SPL
plot.. There is only one way to get a SPL measurement
with corresponding to the sound. During the measurement
the microphone is placed at several positions in the
area of the drivers head.. These
measures are averaging to get the real SPL plot.
Near field measurement
Near field
measurement: blue
= bass, green = mid,
red = room corrected
mid- high
light green
= bass reflex port, black = averaging from bass, mid and
bass port
For the bass
the former shown measurement does not work. To get a
measurement without interferences for low frequencies,
there is the near field measurement. But this
measurement had normally an error caused by the near
field effect. The near field effect makes a drop in the
SPL plot. Another error is the pressure from the bass
reflex port which is neglected by the normal
measurement. The near field measurement of the optitest
was done with several microphone positions in the range
from the woofer to the reflecting port. These measures
averaging for the real SPL plot. After the optitest
there are the room correction plot and the near field
plot. To get the plot for the frequency range from 20Hz
to 24kHz the plots are stick together in the Combine
menu.
2-Channel Oscilloscope
with FFT
Analyser
The
oscilloscope program works like a 2-channel storage
oscilloscope. The max. sample rate is 100kHz. The
dynamic range is > 100dB. In the continues mode it
works like an analogue oscilloscope. For speakers
there is the step function measurement.
Frequenzanalyser
The
oscilloscope is also for the FFT analyser. It is for
distortion measurement, especially Intermodulation
Distortion. For the IMD measurement there is a generator
signal with two sine-sweeps with the frequency ratio of
2:3.
The
Generator of the ATB is like an analogue one, because
the converting rate is 4MHz and the resolution 20bit.
There are
following signals:
Sine, Triangle, Rectangle, Pulse, Envelope,
IMD and several Multiton signals.
Magnitude Response
This
measurement is a sine sweep measure. It is for the test
of electronic components. There is a plot for magnitude
and phase. The scale is in dBU or dBV. The frequency range
is from 1Hz to 50Hz.
Impedance
Response
This
measurement is a sine sweep measure. It is for the
speaker test. The speaker is only to connect to the box
for the test. The measurement is also for the phase. The
ranges are 25W,
50W,
150W
and 2kW.
The frequency range is from 1Hz to 50Hz. There is a menu
for calibration the resistor of the connecting wire.
SPL Response
This
measurement is a sine sweep measure. The sound pressure
is measured with an Amplifier output
voltage from 2.8V for 8W
or 2V for 4W
speaker. The distance from speaker to microphone is 1m.
The measurement is also for the phase. The frequency
range is from 1Hz to 50kHz. There is
a menu for the microphone sensitivity and a help menu
for distance. Another help menu is a volt meter to test
the amplifier output.
FFT
Measurements
This
Measurement is a 4-FFT with a special noise. It is for
anechoic speaker measurement. There is also a
measurement with reference or correction
curve in the program. An other part of the program shows
an 1/3 octave plot. The scale is in SPL. The measurement
is a 4-fold FFT, this means that the frequency range
from 18Hz........24kHz is divided into 4 ranges to adapt
the linear frequency distribution of the FFT to the
logarithmic distribution of the plot. For each range
there is set an adaptive time window which depresses the
room reflections to the minimum. For setting the time
windows there is the help menu distance.
Cumulative
Spectrum Decay
(Waterfall)
This
measurement is a Cosinus-Burst measure. The measurement
shows the time behaviour with front and back slope. The
time axis is in periods. This measurement is near to the
well known TEF measurement, but easier to handle. There
are not the normal problems with time windows, because
the only setting is the distance from speaker to the
microphone. The frequency range is from
20Hz........30kHz and the resolution up to 60dB. The
waterfall display is able to rotate to have a front,
back or top view or something between.
Distortion
This
measurement is a sine sweep measure. It is for the test
of electronical or acoustical items. There are two
measures for THD up to K8 and K2, K3. The frequency
range is from 1Hz to 16kHz and the
scale from 1% to 100%. For 1kHz The distortion is <
0.01%.
Thiele-Small
measurement
The speaker
parameter measurement is a sine sweep measurement which
is very precise in comparison to the FFT measurement.
The automatical calculation with curve fitting
algorithmus gives very realistic parameters. There are
the weight and box measurement. For
the impedance measurement there are two currents to
switch, for small and large speakers. For the RDC
measurment there is a help function
MLS
Measurement
The stimulus
for the MLS measurement is Maximum Length Sequence.
The Impulse
Response Measure is for the room acoustic. The
resolution is 32k points. For the Impulse Response there
are some standard data files for calculation with extern
program.
Polar Plots
The Polar
Plots measurement is FFT measurement
with 1/3 octave display. In the program there is to set
the frequency range, the angle step and the display in
quarter, halve or full circle. There is also a turntable
drive.
Real Time Analyser
The real
Time Analyser has a resolution of 1/3 octave. It is for
noise measurements. There is a weighting of A,B and C.
The display mode is impulse, fast and slow. The levels
LA, LmA and LeqA are shown by meters. There is
also a meter for the NF voltage to measure the noise
ratio from amplifier and other electronical items
Dynamic
Measurement
The Dynamic
Measurement is an additional program. The stimulus for
the measurement is a sine halve wave. It is to test the
impulse behaviour of acoustical and
electrical items. This test is very important to measure
the sound.
More
information are at the web side
www.Dynamic-Measurement.de
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