ARTA 官网有手册下载, 手册有测试声卡质量的详细步骤, 照做即可. 下面是步骤说明.
2.1 Souncard testing
The easiest way to test the quality of the soundcard is in the Spectrum analyzer mode.
1. Make the loopback connection for the soundcard testing.
2. Click the menu Mode -> Spectrum Analyzer or click the toolbar icon SPA.
3. Click the menu Generator->Setup or click the toolbar icon . You will get the dialog box
shown in Fig. 2.1.
Figure 2.1 The dialog box for the signal generator setup
This dialog box has following controls:
Sine / square generator section:
Frequency - enters the frequency of sine signal in Hz.
Peak Level - chooses the output peak level re full scale peak level (0dB to -90dB).
RMS voltage - shows voltage value of line output channel (for calibrated system)
Dither Level - chooses: None, 16bit, 18bit or 20bit.
Two sine generator section allows the choice of three possible combinations of frequencies and magnitude
ratios:
Def1 - sets f1=13kHz, f2=14kHz, amplitude ratio 1:1.
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Def2 - sets f1=100Hz, f2=8kHz, amplitude ratio 1:4.
User - enters two sine frequencies and the amplitude ratio .
Note: the two sine signal has the peak level defined in the Sine generator section – Peak Level control.
Multitone and noise generator section:
Output volume - chooses the output level re full scale level in range 0dB to -50dB.
PN Pink cut off - enters the low frequency cut-off in Hz, for the periodic pink noise.
Multitone - chooses the type of multitone signal (Wideband, Speech range, ITU_T O.81, Low decade,
High decade, Sine+Square).
Note 1: PN (periodic noise) is a periodic, noise-like signal with a controlled spectrum level and a random phase.
The periodic noise and multitone belonging to the class of multisine signals (to be explained later).
Note 2: Jitter test signal is a sine signal with a frequency equal to 1/4 of the sampling rate, and with a LSB bit
toggled with a frequency equal to 1/192 of the sampling rate.
Note 3: Multitone test signals contain mix of sine signals with different amplitudes and phases. Their use will be
explained later.
Now choose parameters of sine generator:
Frequency: 1000Hz
Peak level: -3dB
Dither level: 16 bit.
4. Using the dialog bar choose:
Gen: Sine
Fs (Hz): 48000Hz (sampling frequency or sampling rate)
FFT: 16384 (number of samples in FFT analysis frame)
Wnd: Kaiser5 (signal window to suppress leakage in FFT analysis)
Avg: None (averaging of the signal)
The same parameters can be set up in a dialog box 'Spectrum Analysis Setup' shown in Fig. 2.2.
(you get it by clicking the menu Setup->Measurement) . By using this dialog box you set (1) the
preferred input channel, (2) averaging parameters and (3) the FFT resolution.
Figure 2.2 The spectrum analysis setup
This dialog box has following controls:
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Input channel section:
Combo box chooses left or right channel as active soundcard input channel.
Averaging section sets:
Type: None, Linear, Exponential or Peak Hold.
Max. averages: the maximum number of averages.
FFT resolution section sets:
FFT size: number of samples in FFT block (4096, 8192, 16384, 32768, 65536 and 131072),
Window: Uniform, Hanning, Blackman3, Blackman4, Kaiser5, Kaiser7 or Flat Top window.
Sampling rate: 8000, 11025, 16000, 22050, 32000, 44100, 48000, 88200 or 96000 Hz.
5. Choose: Input channel: Left.
6. Prepare the Windows sound mixer:
Enable the line-input channel
Mute the line-input channel in the output mixer.
Set the line-out volume for maximum output sensitivity.
Set the line-input volume near minimal input sensitivity.
7. By menu command Setup->Spectrum Scaling ( ), or by clicking right mouse button in graph
title area, you get the dialog box 'Spectrum scaling' (shown in Fig. 2.3). Use this dialog box to set (1)
the magnitude scaling, (2) the power weighting and (3) distortion measures.
Figure 2.3 The spectrum scaling
Scaling section:
Magnitude scaling: dBFS (dB re full scale),
dBV or SPL (sound pressure level),
PSD (power spectral density mode in dB V/√Hz).
Voltage units: dBV or dBu,
Pressure units: dB re 20uPa or
dB re 1Pa (valid only if microphone is connected and enabled).
Power section:
Power Weighting combo box - chooses: None, A, B or C filter for weighted signal power estimation.
Show RMS level - check to show the power level at the bottom of the graph.
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Distortion section:
THD - check to show total harmonic distortions (THD) in sine response testing.
THD+N - check to show total harmonic distortions + noise in sine response testing.
IMD - check to show intermodulation distortions (IMD) in two sine response testing,
or transient intermodulation distortion (DIM) in square+sine multitone testing.
Multitone TD+N - check to show total distortion + noise (TD+N) in multitone response testing.
Normalize with full power – check to get THD normalized with signal power including higher harmonics.
Low cut-off (Hz) combo box - sets low frequency cut-off in THD+N measurements.
2nd and 3rd order IMD – check to show 2nd and 3rd order IMD defined in SMPTE, DIN, CCIF and IEC
standards.
Frequency weighting – check to use frequency weighting (A,B,C) in THD+N and TD+N measurements.
8. Check following check boxes: THD, THD+N and Show RMS level .
9. Start recording by clicking the toolbar icon (or via menu Recorder->Run). You should get a
response like the one shown in Fig. 2.4. This figure can be obtained by the copy/paste operation (menu
Edit->Copy).
Slowly increase the volume of the line input channel (using the soundcard mixer) until you get
the peak level close to -3dB FS.
Figure 2.4 Spectrum of 1 kHz sine generator of the soundcard Terratec EWX 24/96 in loopback setup.
Signal window: Kaiser5, FFT size: 16384, Fs: 48000Hz.
The bottom of Fig. 2.4 shows the spectrum value at the cursor position (frequency and magnitude),
RMS level and distortions. The cursor is drawn as a thin line that can be moved by pressing left mouse
button or by pressing keyboard's left and right keys.
If you get THD+N lower than 0.1% you have a usable soundcard.
If you get THD+N lower than 0.01% you have a good soundcard.
Note: During the measurement you can use the control bar to change the averaging type, reset
averaging, change the sampling frequency, change the type of an excitation signal and an FFT size.
You can change any plot parameters (dynamic range, frequency range and axis) from dialog box
'Spectrum graph setup' (you get it by clicking the menu Setup-> Graph setup or by clicking right
mouse button in the plot area). The easiest way to adjust graph margins is by using Right Control bar.
Functions of bar buttons are explained in Figure 2.5.
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Figure 2.5 Control bar for graph margins setup (also used for Frequency Response windows)
Note: Useful shortcuts to change the top graph magnitude margin are "Up" and "Down" keys and the
mouse scroll wheel (they move the plot up and down).
2.1 Souncard testing
The easiest way to test the quality of the soundcard is in the Spectrum analyzer mode.
1. Make the loopback connection for the soundcard testing.
2. Click the menu Mode -> Spectrum Analyzer or click the toolbar icon SPA.
3. Click the menu Generator->Setup or click the toolbar icon . You will get the dialog box
shown in Fig. 2.1.
Figure 2.1 The dialog box for the signal generator setup
This dialog box has following controls:
Sine / square generator section:
Frequency - enters the frequency of sine signal in Hz.
Peak Level - chooses the output peak level re full scale peak level (0dB to -90dB).
RMS voltage - shows voltage value of line output channel (for calibrated system)
Dither Level - chooses: None, 16bit, 18bit or 20bit.
Two sine generator section allows the choice of three possible combinations of frequencies and magnitude
ratios:
Def1 - sets f1=13kHz, f2=14kHz, amplitude ratio 1:1.
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Def2 - sets f1=100Hz, f2=8kHz, amplitude ratio 1:4.
User - enters two sine frequencies and the amplitude ratio .
Note: the two sine signal has the peak level defined in the Sine generator section – Peak Level control.
Multitone and noise generator section:
Output volume - chooses the output level re full scale level in range 0dB to -50dB.
PN Pink cut off - enters the low frequency cut-off in Hz, for the periodic pink noise.
Multitone - chooses the type of multitone signal (Wideband, Speech range, ITU_T O.81, Low decade,
High decade, Sine+Square).
Note 1: PN (periodic noise) is a periodic, noise-like signal with a controlled spectrum level and a random phase.
The periodic noise and multitone belonging to the class of multisine signals (to be explained later).
Note 2: Jitter test signal is a sine signal with a frequency equal to 1/4 of the sampling rate, and with a LSB bit
toggled with a frequency equal to 1/192 of the sampling rate.
Note 3: Multitone test signals contain mix of sine signals with different amplitudes and phases. Their use will be
explained later.
Now choose parameters of sine generator:
Frequency: 1000Hz
Peak level: -3dB
Dither level: 16 bit.
4. Using the dialog bar choose:
Gen: Sine
Fs (Hz): 48000Hz (sampling frequency or sampling rate)
FFT: 16384 (number of samples in FFT analysis frame)
Wnd: Kaiser5 (signal window to suppress leakage in FFT analysis)
Avg: None (averaging of the signal)
The same parameters can be set up in a dialog box 'Spectrum Analysis Setup' shown in Fig. 2.2.
(you get it by clicking the menu Setup->Measurement) . By using this dialog box you set (1) the
preferred input channel, (2) averaging parameters and (3) the FFT resolution.
Figure 2.2 The spectrum analysis setup
This dialog box has following controls:
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Input channel section:
Combo box chooses left or right channel as active soundcard input channel.
Averaging section sets:
Type: None, Linear, Exponential or Peak Hold.
Max. averages: the maximum number of averages.
FFT resolution section sets:
FFT size: number of samples in FFT block (4096, 8192, 16384, 32768, 65536 and 131072),
Window: Uniform, Hanning, Blackman3, Blackman4, Kaiser5, Kaiser7 or Flat Top window.
Sampling rate: 8000, 11025, 16000, 22050, 32000, 44100, 48000, 88200 or 96000 Hz.
5. Choose: Input channel: Left.
6. Prepare the Windows sound mixer:
Enable the line-input channel
Mute the line-input channel in the output mixer.
Set the line-out volume for maximum output sensitivity.
Set the line-input volume near minimal input sensitivity.
7. By menu command Setup->Spectrum Scaling ( ), or by clicking right mouse button in graph
title area, you get the dialog box 'Spectrum scaling' (shown in Fig. 2.3). Use this dialog box to set (1)
the magnitude scaling, (2) the power weighting and (3) distortion measures.
Figure 2.3 The spectrum scaling
Scaling section:
Magnitude scaling: dBFS (dB re full scale),
dBV or SPL (sound pressure level),
PSD (power spectral density mode in dB V/√Hz).
Voltage units: dBV or dBu,
Pressure units: dB re 20uPa or
dB re 1Pa (valid only if microphone is connected and enabled).
Power section:
Power Weighting combo box - chooses: None, A, B or C filter for weighted signal power estimation.
Show RMS level - check to show the power level at the bottom of the graph.
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Distortion section:
THD - check to show total harmonic distortions (THD) in sine response testing.
THD+N - check to show total harmonic distortions + noise in sine response testing.
IMD - check to show intermodulation distortions (IMD) in two sine response testing,
or transient intermodulation distortion (DIM) in square+sine multitone testing.
Multitone TD+N - check to show total distortion + noise (TD+N) in multitone response testing.
Normalize with full power – check to get THD normalized with signal power including higher harmonics.
Low cut-off (Hz) combo box - sets low frequency cut-off in THD+N measurements.
2nd and 3rd order IMD – check to show 2nd and 3rd order IMD defined in SMPTE, DIN, CCIF and IEC
standards.
Frequency weighting – check to use frequency weighting (A,B,C) in THD+N and TD+N measurements.
8. Check following check boxes: THD, THD+N and Show RMS level .
9. Start recording by clicking the toolbar icon (or via menu Recorder->Run). You should get a
response like the one shown in Fig. 2.4. This figure can be obtained by the copy/paste operation (menu
Edit->Copy).
Slowly increase the volume of the line input channel (using the soundcard mixer) until you get
the peak level close to -3dB FS.
Figure 2.4 Spectrum of 1 kHz sine generator of the soundcard Terratec EWX 24/96 in loopback setup.
Signal window: Kaiser5, FFT size: 16384, Fs: 48000Hz.
The bottom of Fig. 2.4 shows the spectrum value at the cursor position (frequency and magnitude),
RMS level and distortions. The cursor is drawn as a thin line that can be moved by pressing left mouse
button or by pressing keyboard's left and right keys.
If you get THD+N lower than 0.1% you have a usable soundcard.
If you get THD+N lower than 0.01% you have a good soundcard.
Note: During the measurement you can use the control bar to change the averaging type, reset
averaging, change the sampling frequency, change the type of an excitation signal and an FFT size.
You can change any plot parameters (dynamic range, frequency range and axis) from dialog box
'Spectrum graph setup' (you get it by clicking the menu Setup-> Graph setup or by clicking right
mouse button in the plot area). The easiest way to adjust graph margins is by using Right Control bar.
Functions of bar buttons are explained in Figure 2.5.
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Figure 2.5 Control bar for graph margins setup (also used for Frequency Response windows)
Note: Useful shortcuts to change the top graph magnitude margin are "Up" and "Down" keys and the
mouse scroll wheel (they move the plot up and down).