【正文】 案的結(jié)果。用戶可以跟上錄音過程和簡單地識別任何問題從文本信息中顯示的窗口。在應(yīng)用算法始于計算正弦適合和相應(yīng)的噪聲功率 PN0 頻率 fn0 立足 fsamplingsf = fsignal /()高于其估計和 fsampling 由給定的 fsignal 通過采樣頻率偏移三藩市 1。 “ 插件 ” 獨(dú)立 ?聲卡。一些結(jié)果在一個取樣頻率的 千赫是列在表 1 和表 2 以及在圖 4 和圖 5。同時 ， a / d 轉(zhuǎn)換器輸入范圍的偏移量。第一次試驗 ,結(jié)果表明一個非常低素質(zhì)的聲音并導(dǎo)致射來的錄音機(jī)部分取消任何下一步的測試。 (c)詳細(xì)的典型譜的 16 位模式實(shí)施的聲音在筆記本宏碁 TravelMate 射來的 212TX (測試頻率采樣頻率 44100 赫茲 )。第三依賴測試信號頻率的聲音 PCI64 射來的 本科畢業(yè)設(shè)計（論文）外文翻譯 10 圖 8。測試相同的牌在不同的機(jī)器帶來的只有微不足道的差異超過 點(diǎn)達(dá)到 resultsnot。 不同聲卡的測試結(jié)果都表明了從測量的角度上看音質(zhì)較差。 全文通過 CrossRef 帕斯 | |觀點(diǎn)被記錄在斯高帕斯 (0). [5] m . Pokorny》 ,第五卷 ,j . Roztocil、抑 Haasz 由 ADmodules 測試信號失真。n aliga ,and Linus Michaeli 1 [Author vitae] Department of Electronics and Telemunications, Technical University of Ko ice, Park Komensk233。97 stereo codec. Table 3 and Fig. 7 illustrate some of them. Table 3. Results from ENOB testing of sound CODEC implemented in notebook Acer TravelMate 212TX 本科畢業(yè)設(shè)計（論文）外文翻譯 21 Fullsize table (1K) Fullsize image (47K) Fig. 7. (a) ENOB dependence on test signal frequency for the 8 (*) and 16 ()bit mono modes of sound blaster implemented in notebook Acer TravelMate 212TX. (b) Typical spectrum for the 16bit mode of sound blaster implemented in notebook Acer TravelMate 212TX (test frequency 本科畢業(yè)設(shè)計（論文）外文翻譯 22 kHz, sampling frequency 44,100 Hz). (c) Detail of typical spectrum for the 16bit mode of sound blaster implemented in notebook Acer TravelMate 212TX (test frequency kHz, sampling frequency 44,100 Hz). View Within Article The achieved results indicate, likewise herein before, a bad quality of audio input in the tested notebook especially in the 16bit mode. Moreover, the strange spectrum shown in Fig. 7b and c implies an idea that the real sampling frequency in the sound codec is different from the set one or that the digital filter in the sigma–delta ADC does not work correctly. The last example is the ―standalone‖ plugin board Sound Blaster PCI64 by Creative Technology [15]. Some achieved results are shown in Table 4 and Fig. 8 and Fig. 9. In parison with previous sound blasters, this card proved lightly better metrological parameters. Table 4. ENOB dependence on the test signal frequency of Sound Blaster PCI64 Fullsize table (1K) View Within Article 本科畢業(yè)設(shè)計（論文）外文翻譯 23 Fullsize image (28K) Fig. 8. (a) ENOB dependence on test signal frequency for the 8 (*) and 16 ()bit mono modes of Sound Blaster PCI 64. (b) Typical spectrum in the 16bit mode of Sound Blaster PCI64 (test frequency 211 Hz, sampling frequency 44,100 Hz). View Within Article Fullsize image (41K) 本科畢業(yè)設(shè)計（論文）外文翻譯 24 Fig. 9. Distortion observed at Sound Blaster PCI64 for input signal meeting the full scale of audio input (input frequency 21 Hz, sampling frequency 44,100 Hz). View Within Article The sound card in the 8bit mode seems to be very close to the ideal one—the results of more than 8 bits are caused by the parison of the real quantisation noise with the ideal, whose normalised power is simplified, in most standards, to be 1/12. However, the maximum achieved value of ENOB in the 16bit mode was only slightly more than 12 bits, which is still far away from the declared 16bit resolution. Moreover, if the input signal meets nearly the full scale of tested audio input, a significant nonlinear distortion was observed in the recorded data (see Fig. 9). Testing the same card in different PCs brought only negligible differences in the achieved results—not more than bit and typically only about bit. This fact indicates that the main influence on the metrological parameters of sound card has the card design and not the disturbance of other PC ponents. 6. Conclusions The developed software was applied and tested in the assessment of a few sound cards. It seems to be a very useful tool—it enables measurement and acquisition of many plex parameters of sound cards in a relatively short time. Developed software employment by PC retailers can lead to the improvement of quality and confidence of offered PC ponents. The software will also be used in the educational process of teaching electronic measurement and data acquisition systems at the Technical University of Ko ice as a demonstration virtual instrument for the explanation and demonstration of standard ADC test methods. The achieved results from the executed tests of various sound cards indicate a generally low quality of their audio inputs from the metrological point of view. This fact is especially evident in the 16bit mode. The standalone plugin sound cards seem to be a bit better (by 1–2 bits) than the sound cards integrated on motherboards. Disturbing effects caused by other ponents inside PC seem to have much less influence on metrological parameters of the sound cards than the sound card design. All these facts restrict sound card application only on simple systems where the needed resolution is not higher than 10–12 bits. Moreover, there are big differences between the metrological parameters of the various sound cards. References 1. IEEE Std. 10571994, Standard for Digitizing Waveform Recorders. 2. IEEE Std. 1241, Draft ver. VS022500. 3. DYNAD, Draft ver. , 20xx. 4. P. Arpaia, F. Cennamo and P. Daponte , Metrological characterisation of analogtodigital converters—a state of the art. In: Proceedings of the Third International Conference on Advanced A/D and D/A Conversion Techniques and their Applications (Conf. Publ. no. 466) (1999), pp. 134–144. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (0) 5. M. Pokorny, J. Roztocil and V. Haasz , Suppression of test signal distortion by ADmodules. In: Dynamic Testing, Proceedings of IMEKO TC4 Symposium ISSDMI 39。 Waveform recorder test。 [8] 一、《 Kollar 馬庫斯 ,正弦波的 ADC 的手段測試國際比較。種種事實(shí)都表明聲卡只能用在不超過 10