ããžã¿ã«ä¿¡å·åŠçã«ãããããŒãªãšå€æã®åãæ¢æ±ããã®åçãå¿çšãäžççãªåœ±é¿ãçè§£ããŸãã
ããžã¿ã«ä¿¡å·åŠçã®è§£æïŒããŒãªãšå€æãžã®æ·±æã
ããžã¿ã«ä¿¡å·åŠçïŒDSPïŒã¯ãã¹ããŒããã©ã³ãå»ççšç»å蚺æè£ 眮ãããé«åºŠãªéä¿¡ã·ã¹ãã ãç§åŠæ©åšã«è³ããŸã§ãçŸä»£æè¡ã®åºç€ãšãªã£ãŠããŸããå€ãã®DSPã¢ããªã±ãŒã·ã§ã³ã®äžå¿ã«ã¯ãããŒãªãšå€æãšãã匷åãªæ°åŠçããŒã«ããããŸãããã®ããã°èšäºã§ã¯ãããŒãªãšå€æãè©³çŽ°ã«æ¢æ±ãããã®åçãå¿çšããããŠäžççãªåœ±é¿ã«ã€ããŠã®å æ¬çãªçè§£ãæäŸããŸãã
ããžã¿ã«ä¿¡å·åŠçãšã¯ïŒ
ããžã¿ã«ä¿¡å·åŠçã¯ãé³å£°ãæ åãã黿³¢ãã»ã³ãµãŒããŒã¿ã«è³ããŸã§ãããããä¿¡å·ãæ°åŠçãªææ³ãçšããŠæäœããããšãå«ã¿ãŸããé£ç¶æéä¿¡å·ãæ±ãã¢ããã°ä¿¡å·åŠçãšã¯ç°ãªããDSPã¯ãµã³ããªã³ã°ããéååãããããžã¿ã«ä¿¡å·ãæ±ããŸããããã«ãããããé«ãæè»æ§ã粟床ããããŠã¢ããã°é åã§ã¯å°é£ãŸãã¯äžå¯èœãªè€éãªæäœãå®è¡ããèœåãå¯èœã«ãªããŸãã
DSPã®äž»ãªå©ç¹ã¯æ¬¡ã®ãšããã§ãïŒ
- æè»æ§ïŒ DSPã¢ã«ãŽãªãºã ã¯ãœãããŠã§ã¢ãéããŠå®¹æã«å€æŽã»æŽæ°ã§ããå€åããèŠä»¶ã«é©å¿ã§ããŸãã
- ç²ŸåºŠïŒ ããžã¿ã«è¡šçŸã¯ãã€ãºãæå°éã«æããé«ç²ŸåºŠã®èšç®ãå¯èœã«ããŸãã
- å¹çæ§ïŒ DSPã®å®è£ ã¯ãã¢ããã°ã®å¯Ÿå¿ç©ãšæ¯èŒããŠããã°ãã°ããè¯ãæ§èœãšé»åå¹çãæäŸããŸãã
- åçŸæ§ïŒ ããžã¿ã«åŠçã¯ãè€æ°ã®ããã€ã¹ãç°å¢ã§äžè²«ããçµæãä¿èšŒããŸãã
ããŒãªãšå€æã®ç޹ä»
ããŒãªãšå€æïŒFTïŒã¯ããã©ã³ã¹ã®æ°åŠè ãžã£ã³ïŒããã£ã¹ãã»ãžã§ãŒãã»ããŒãªãšã«ã¡ãªãã§åä»ããããä¿¡å·ããã®æ§æåšæ³¢æ°ã«åè§£ããæ°åŠçããŒã«ã§ããããã«ãããä¿¡å·ã®æ¯å¹ ãæéã®é¢æ°ãšããŠèŠãæéé åãšãä¿¡å·ã®æ¯å¹ ãåšæ³¢æ°ã®é¢æ°ãšããŠèŠãåšæ³¢æ°é åãšãåãæ¿ããããšãã§ããŸãããã®å€æã¯ãããŸããŸãªå¿çšã«ãããŠä¿¡å·ãçè§£ãæäœããããã®åºæ¬ã§ãã
äžå¿çãªæŠå¿µ
ããŒãªãšå€æã®åºæ¬åçã¯ãã©ããªä¿¡å·ããç°ãªãåšæ³¢æ°ãæ¯å¹ ãäœçžãæã€æ£åŒŠæ³¢ïŒãµã€ã³æ³¢ãšã³ãµã€ã³æ³¢ïŒã®åãšããŠè¡šçŸã§ãããšããããšã§ããFTã¯ãå ã®ä¿¡å·ã«ååšããååšæ³¢æ°æåã®æ¯å¹ ãšäœçžãèšç®ããŸãã
æéé å vs. åšæ³¢æ°é åïŒ
- æéé åïŒ æéã«å¯Ÿããä¿¡å·ã®æ¯å¹ ã衚ããŸãããªã·ãã¹ã³ãŒãã§æ³¢åœ¢ãèŠãããé²é³ãããé³ãèŽããããããšãã«èŠããã®ã§ãã
- åšæ³¢æ°é åïŒ ä¿¡å·ã®åšæ³¢æ°æåã衚ããŸããä¿¡å·ã«ã©ã®åšæ³¢æ°ãååšãããã®åŒ·ãïŒæ¯å¹ ïŒãã©ã®çšåºŠãã瀺ããŸãã
ãã®èåŸã«ããæ°åŠïŒ
颿£ããŒãªãšå€æïŒDFTïŒã¯ãDSPã§äœ¿ãããããŒãªãšå€æã®äžè¬çãªããŒãžã§ã³ã§ããDFTã¯ãä¿¡å·ã®çééãµã³ãã«ã®æéã·ãŒã±ã³ã¹ããåšæ³¢æ°æåã衚ãå€ã®ã·ãŒã±ã³ã¹ã«å€æããŸããDFTã®åŒã¯æ¬¡ã®ãšããã§ãïŒ
X[k] = Σ [from n=0 to N-1] x[n] * e^(-j2Ïkn/N)
ããã§ïŒ
- X[k]ã¯kçªç®ã®åšæ³¢æ°æåã§ãã
- x[n]ã¯nçªç®ã®æéé åãµã³ãã«ã§ãã
- Nã¯ãµã³ãã«ã®ç·æ°ã§ãã
- jã¯èæ°åäœïŒâ-1ïŒã§ãã
é颿£ããŒãªãšå€æïŒIDFTïŒã¯ãä¿¡å·ãåšæ³¢æ°é åããæéé åã«æ»ãããã«äœ¿çšãããŸãã
x[n] = (1/N) * Σ [from k=0 to N-1] X[k] * e^(j2Ïkn/N)
é«éããŒãªãšå€æïŒFFTïŒïŒ
é«éããŒãªãšå€æïŒFFTïŒã¯ãDFTãèšç®ããããã®å¹ççãªã¢ã«ãŽãªãºã ã§ããèšç®ã®è€éããåçã«åæžãããªã¢ã«ã¿ã€ã ã®ä¿¡å·åŠçã¢ããªã±ãŒã·ã§ã³ã§å®çšçã«ããŸããFFTã¢ã«ãŽãªãºã ã¯DSPã«é©åœããããããä¿¡å·ã®ããé«éãªåŠçãå¯èœã«ããããåºç¯ãªå¿çšãå¯èœã«ããŸããã
ããŒãªãšå€æã®å¿çš
ããŒãªãšå€æãšãã®ããªãšãŒã·ã§ã³ã¯ãäžçäžã®ããŸããŸãªç£æ¥ãå¿çšã§åºã䜿çšãããŠããŸãã以äžã«ããã€ãã®äž»èŠãªäŸãæããŸãïŒ
1. ãªãŒãã£ãªåŠç
ã€ã³ã©ã€ãŒãŒã·ã§ã³ïŒ FTã«ããããªãŒãã£ãªãšã³ãžãã¢ã¯é²é³ãããé³ã®ç¹å®ã®åšæ³¢æ°åž¯åãç¹å®ã調æŽããããšãã§ããé³ã®ãã©ã³ã¹ãå¶åŸ¡ã§ããŸãã
ãã€ãºãªãã¯ã·ã§ã³ïŒ ãã€ãºãåšæ³¢æ°é åã§åé¢ããŠé€å»ãããªãŒãã£ãªé²é³ã®æç床ãåäžãããããšãã§ããŸãã
ãªãŒãã£ãªå§çž®ïŒ MP3ãAACãªã©ã®ãªãŒãã£ãªã³ãŒããã¯ã¯ãFTã䜿çšããŠãç¥èŠçã«ç¡é¢ä¿ãªåšæ³¢æ°æåãé€å»ããããšã§ãªãŒãã£ãªä¿¡å·ãåæã»å§çž®ãããªãŒãã£ãªå質ãç¶æããªãããã¡ã€ã«ãµã€ãºãåæžããŸããããã¯ãäžçäžã®ã¹ããªãŒãã³ã°ãµãŒãã¹ã«ãšã£ãŠäžå¯æ¬ ã§ãã
2. ç»ååŠç
ç»åãã£ã«ã¿ãªã³ã°ïŒ FTã¯ããŒãããã·ã£ãŒãåããšããžæ€åºãªã©ãç»åã«ããŸããŸãªãã£ã«ã¿ãªã³ã°æè¡ãé©çšããããã«äœ¿çšãããŸãããããã®æè¡ã¯ãå»çç»åãã³ã³ãã¥ãŒã¿ããžã§ã³ãåçæ®åœ±ã§åºã䜿çšãããŠããŸãã
ç»åå§çž®ïŒ JPEGç»åå§çž®ã¯ãFTã«é¢é£ãã倿ã§ãã颿£ã³ãµã€ã³å€æïŒDCTïŒãå©çšããŠãç»åãã¡ã€ã«ã®ãµã€ãºãåæžããŸããããã¯ããœãŒã·ã£ã«ã¡ãã£ã¢ãã©ãããã©ãŒã ããããã®åçãŸã§ãäžçäžã§ç»åãä¿åã»å ±æããããã«äžå¯æ¬ ã§ãã
å»çç»åïŒ MRIïŒç£æ°å ±é³Žç»åæ³ïŒãCTïŒã³ã³ãã¥ãŒã¿æå±€æ®åœ±ïŒãªã©ã®æè¡ã¯ãçããŒã¿ããç»åãåæ§æããããã«FTã«å€§ããäŸåããŠããŸãããããã®ç»åèšºææ³ã¯ãäžçäžã®èšºæãšæ²»çã«ãšã£ãŠæ¥µããŠéèŠã§ãã
3. 黿°éä¿¡
ä¿¡å·ã®åŸ©èª¿ãšå€èª¿ïŒ FTã¯ãã©ãžãªããã¬ããæºåž¯é»è©±ãããã¯ãŒã¯ãªã©ã®éä¿¡ã·ã¹ãã ã§å€èª¿ãããä¿¡å·ãéã¶æ å ±ãåæãæœåºããããã«äœ¿çšãããŸããå€èª¿æè¡ã¯ãäžçäžã®ããŒã¿äŒéã«ãšã£ãŠæ¥µããŠéèŠã§ãã
ãã£ãã«çåïŒ FTã¯ãéä¿¡ãã£ãã«ã«ãã£ãŠå°å ¥ãããæªã¿ãè£æ£ããããŒã¿äŒéã®ä¿¡é Œæ§ãåäžãããã®ã«åœ¹ç«ã¡ãŸããããã¯ãäžçäžã§å®å®ããã€ã³ã¿ãŒããããšé»è©±ãµãŒãã¹ãæäŸããããã«äžå¯æ¬ ã§ãã
ã¹ãã¯ãã«è§£æïŒ FTã¯ãä¿¡å·ã®åšæ³¢æ°ã¹ãã¯ãã«ãåæããããšãå¯èœã«ããç¡ç·åšæ³¢æ°ãç¹å®ã管çããããã«äœ¿çšãããŸããããã¯ãäžçäžã®ã¯ã€ã€ã¬ã¹éä¿¡ã«äžå¯æ¬ ã§ãã
4. ããŒã¿åæãšç§åŠç ç©¶
ã¹ãã¯ãã«åæïŒ ç§åŠè ã¯ãå°éæ³¢ã倩æããŒã¿ãéèæç³»åãªã©ãããŸããŸãªãœãŒã¹ããã®ããŒã¿ãåæããããã«FTã䜿çšãããã¿ãŒã³ããã¬ã³ããåšææ§ãç¹å®ããŸããããã¯ãäžçäžã®è€éãªçŸè±¡ãçè§£ããããã«äžå¯æ¬ ã§ãã
æ¯ååæïŒ ãšã³ãžãã¢ã¯ãæ©æ¢°ãæ§é ç©ã®æ¯åã®åšæ³¢æ°æåãåæããããã«FTã䜿çšããæœåšçãªåé¡ãç¹å®ããäºé²ä¿å šãå¯èœã«ããŸããããã¯ãäžçäžã®ç£æ¥ã§å®å šæ§ãšå¹çã確ä¿ããããã«éèŠã§ãã
å°éè§£æïŒ å°è³ªåŠè ã¯ãå°çã®æ§é ãçè§£ããå°éãäºæž¬ããããã«å°éããŒã¿ãåæããããã«FTãå©çšããŸããããã¯ãäžçäžã®çœå®³è»œæžãšé²çœæºåã«ãšã£ãŠæ¥µããŠéèŠã§ãã
5. ãã®ä»ã®å¿çš
- ã¬ãŒããŒãšãœããŒïŒ FTã¯ãã¬ãŒããŒããœããŒã·ã¹ãã ã§åå°ä¿¡å·ãåæããç©äœã®è·é¢ãéåºŠãæ¹åãæ±ºå®ããããã«äœ¿çšãããŸãã
- çç©å»å·¥åŠïŒ FTã¯ã蚺æç®çã§EEGïŒè³æ³¢ïŒãECGïŒå¿é»å³ïŒä¿¡å·ãåæãããªã©ãããŸããŸãªå¿çšã§äœ¿çšãããŸãã
- å¶åŸ¡ã·ã¹ãã ïŒ FTã¯ãã·ã¹ãã ã®åšæ³¢æ°å¿çãåæããã³ã³ãããŒã©ãŒãèšèšããããã«å¶åŸ¡ã·ã¹ãã ã§äœ¿çšãããŸãã
å®è·µçãªäŸ
ããŒãªãšå€æãããŸããŸãªæèã§ã©ã®ããã«äœ¿çšãããããããã€ãã®å®è·µçãªäŸãæ¢ã£ãŠã¿ãŸãããïŒ
1. ãªãŒãã£ãªé²é³ã®åæïŒäŸïŒã°ããŒãã«ãªé³æ¥œå¶äœïŒ
ãã€ãžã§ãªã¢ã®é³æ¥œãããã¥ãŒãµãŒãæ°ããã¢ããããŒãã®ãã©ãã¯ãå¶äœããŠãããšæ³åããŠã¿ãŠãã ããã圌ãã¯ãFFTã«å€§ããäŸåããŠãªãŒãã£ãªä¿¡å·ãèŠèŠåãæäœããããžã¿ã«ãªãŒãã£ãªã¯ãŒã¯ã¹ããŒã·ã§ã³ïŒDAWïŒã䜿çšããŸããFFTãé©çšããããšã§ããããã¥ãŒãµãŒã¯å楜åšïŒäŸïŒããŒã¹ã®ã¿ãŒããã©ã ãããŒã«ã«ïŒã®åšæ³¢æ°æåãèŠãããšãã§ããã€ã³ã©ã€ãŒãŒã·ã§ã³ã䜿çšããŠé³ã®ãã©ã³ã¹ã調æŽããŸããããã¯ãã©ã ã®ç¹å®ã®åšæ³¢æ°ãããŒã¹ãããŠãã³ããå¹ãããããããŒã«ã«ã®åšæ³¢æ°ãæžãããŠæ¯æŠé³ãæãããããããšãã§ããŸãããŸããéšå±ã®åé¿ãããã¯ã°ã©ãŠã³ãã®ãã é³ãªã©ã®äžèŠãªé³ãæå°éã«æããããã«ãã€ãºãªãã¯ã·ã§ã³ãé©çšããããšãã§ããŸããããã«ãããæ²ã®æç床ãåäžããå šäœçãªå質ãé«ãŸããäžçäžã®ããŸããŸãªãªã¹ãã³ã°ããã€ã¹ããã©ãããã©ãŒã ã§çŽ æŽããããµãŠã³ããä¿èšŒãããŸãã
2. å»çç»åïŒäŸïŒã€ã³ãã§ã®MRIã¹ãã£ã³ïŒ
ã€ã³ãã§ã¯ãå»åž«ã¯ããŸããŸãªç ç¶ã蚺æããããã«MRIè£ çœ®ãå©çšããŸããMRIã¯ããŒã¿ãçæããããã2DãŸãã¯3Dã®ããŒãªãšå€æã¢ã«ãŽãªãºã ã䜿çšããŠãäœã®å éšæ§é ã瀺ã詳现ãªç»åã«å€æãããŸããFTã«ãããç£æ°å ±é³Žä¿¡å·ããç»åãåæ§æããããšãã§ããå»åž«ã«è©³çŽ°ãªæ å ±ãæäŸããç æ°ã®æ©æèšºæãšå¹æçãªæ²»çèšç»ã®çå®ãå¯èœã«ããŸãã
3. 黿°éä¿¡ïŒäŸïŒãã©ãžã«ã®æºåž¯é»è©±ãããã¯ãŒã¯ïŒ
ãã©ãžã«ã®æºåž¯é»è©±ãããã¯ãŒã¯ã¯ãå¹ççãªããŒã¿äŒéã®ããã«ããŒãªãšå€æã«å€§ããäŸåããŠããŸããã¹ããŒããã©ã³ã§é»è©±ããããããã€ã³ã¿ãŒããããé²èЧããããããšãé³å£°ä¿¡å·ãããŒã¿ä¿¡å·ã¯é»æ³¢ã«å€æããããããã¯ãŒã¯ãä»ããŠéä¿¡ãããŸããåºå°å±ã¯FFTã䜿çšããŠåä¿¡ä¿¡å·ã埩調ããé³å£°æ å ±ãããŒã¿æ å ±ãæœåºããŸããä¿¡å·ã®åšæ³¢æ°ã¹ãã¯ãã«ãåæããããšã§ããããã¯ãŒã¯ã¯åž¯åå¹ ã®å²ãåœãŠãæé©åããå¹²æžãæžãããä¿¡é Œæ§ã®é«ãæ¥ç¶ãæäŸã§ããåºå€§ãªåœåå šäœããã³åœéæ¥ç¶ãšã®ã·ãŒã ã¬ã¹ãªéä¿¡ãä¿èšŒããŸãã
ããŒãªãšå€æã®å©ç¹ã𿬠ç¹
å©ç¹ïŒ
- åšæ³¢æ°é åã®æŽå¯ïŒ åšæ³¢æ°é åã§ä¿¡å·ãåæãã匷åãªæ¹æ³ãæäŸããé ãããæ å ±ãæããã«ããŸãã
- ä¿¡å·æäœïŒ ãã£ã«ã¿ãªã³ã°ãã€ã³ã©ã€ãŒãŒã·ã§ã³ãªã©ãæè»ã§æ£ç¢ºãªä¿¡å·æäœãå¯èœã«ããŸãã
- å¹ççãªå®è£ ïŒ FFTã¢ã«ãŽãªãºã ã«ãããFTã¯ãªã¢ã«ã¿ã€ã ã¢ããªã±ãŒã·ã§ã³ã§èšç®äžå¹ççã«ãªããŸãã
- å¹ åºãé©çšæ§ïŒ 倿§ãªç£æ¥ãå¿çšã§äœ¿çšãããŸãã
æ¬ ç¹ïŒ
- èšç®ã®è€éãïŒ FFTã¯è€éãã軜æžããŸãããéåžžã«å€§ããªä¿¡å·ã«å¯ŸããŠã¯äŸç¶ãšããŠèšç®éçŽçã«ãªãå¯èœæ§ããããŸãã
- æéæ å ±ã®æå€±ïŒ æšæºã®FTã¯ãåšæ³¢æ°æåã®ã¿ã€ãã³ã°ã«é¢ããæ å ±ãæäŸããŸããã
- ãšã€ãªã¢ã·ã³ã°ïŒ åšæ³¢æ°æ å ±ãæªããå¯èœæ§ã®ãããšã€ãªã¢ã·ã³ã°ãé¿ããããã«ããã€ãã¹ã-ã·ã£ãã³ã®ãµã³ããªã³ã°å®çãæ éã«èæ ®ããå¿ èŠããããŸãã
- çªé¢æ°ã®åœ±é¿ïŒ ä¿¡å·ã®æéã»ã°ã¡ã³ãã«FTãé©çšãããšãã¹ãã¯ãã«æŒããšããŠç¥ãããã¢ãŒãã£ãã¡ã¯ããçºçããå¯èœæ§ããããŸãã
åºç€ãè¶ ããŠïŒé«åºŠãªæŠå¿µ
åºæ¬çãªããŒãªãšå€æã¯åŒ·åãªããŒã«ã§ããããã®èœåãæ¡åŒµããããã€ãã®é«åºŠãªæŠå¿µããããŸãïŒ
1. çæéããŒãªãšå€æïŒSTFTïŒ
STFTã¯ãä¿¡å·ãçãã»ã°ã¡ã³ãã«åå²ããåã»ã°ã¡ã³ãã«FTãé©çšããããšã§ãæé-åšæ³¢æ°ã®ãã¬ãŒããªãã«å¯ŸåŠããŸããããã«ãããä¿¡å·ã®åšæ³¢æ°æåãæéãšãšãã«ã©ã®ããã«å€åããããåæã§ããŸããããã¯ã鳿¥œãé³å£°ã®ããã«åšæ³¢æ°æåãæéãšãšãã«å€åããéå®åžžä¿¡å·ãåæããããã«äžå¯æ¬ ã§ããäžçäžã®é³å£°èªèããªãŒãã£ãªåæãªã©ã®ã¢ããªã±ãŒã·ã§ã³ã§äœ¿çšãããŠããŸãã
2. ãŠã§ãŒãã¬ãã倿
ãŠã§ãŒãã¬ãã倿ã¯ãFTã®ä»£æ¿ææ®µãæäŸããŸãããŠã§ãŒãã¬ããã¯ãæéãšåšæ³¢æ°ã®äž¡æ¹ã§å±åšåããã颿°ã®ã»ããïŒãŠã§ãŒãã¬ããïŒã䜿çšããŸããããã«ãããéæž¡çãªç¹åŸŽãéå®åžžçãªç¹æ§ãæã€ä¿¡å·ã®ãã詳现ãªåæãå¯èœã«ãªããŸããããã¯ãç»åãã€ãºé€å»ãå°éè§£æãä¿¡å·å§çž®ãªã©ã®ã¢ããªã±ãŒã·ã§ã³ã§æçã§ãã
3. 颿£ã³ãµã€ã³å€æïŒDCTïŒ
ããŒãªãšå€æã«å¯æ¥ã«é¢é£ããDCTã¯ãJPEGãMPEG圢åŒãªã©ãç»åããããªã®å§çž®ã§åºã䜿çšãããŠããŸããããŒã¿ãåšæ³¢æ°é åã«å€æããéèŠæ§ã®äœãåšæ³¢æ°æåãç Žæ£ããããšã§å¹ççãªå§çž®ãå¯èœã«ããŸãããã®å§çž®ã¯ãäžçäžã®ãããªã¹ããªãŒãã³ã°ãããŒã¿ã¹ãã¬ãŒãžã«ãšã£ãŠæ¥µããŠéèŠã§ãã
äžçèŠæš¡ã§ã®åœ±é¿
ããŒãªãšå€æã¯äžçèŠæš¡ã§å€§ããªåœ±é¿ãäžããçŸä»£ç掻ã®å€ãã®åŽé¢ã«åœ±é¿ãåãŒããŠããŸãïŒ
- éä¿¡ãšæ¥ç¶æ§ïŒ FTã¯çŸä»£ã®éä¿¡ã·ã¹ãã ã«äžå¯æ¬ ã§ãããã©ãžãªããã¬ããã€ã³ã¿ãŒããããªã©ã®æè¡ãéããŠã°ããŒãã«ãªéä¿¡ãå¯èœã«ããŠããŸãã
- å»çã®é²æ©ïŒ å»çç»åããå»ç蚺æãŸã§ãFTã¯äžçäžã®éèŠãªå»çã®é²æ©ãä¿é²ããŠããŸãã
- çµæžæé·ïŒ FTãå«ãDSPæè¡ã¯ã倿§ãªã»ã¯ã¿ãŒã§ã€ãããŒã·ã§ã³ãšçµæžæé·ãæšé²ããŠããŸãã
- ãšã³ã¿ãŒãã€ã³ã¡ã³ããšã¡ãã£ã¢ïŒ FTã¯çŸä»£ã®ã¡ãã£ã¢å¶äœãæ¯ããã·ãŒã ã¬ã¹ãªãªãŒãã£ãªããã³ãããªã®ç·šéãšé ä¿¡ãå¯èœã«ããŠããŸãã
- ç§åŠççºèŠïŒ FTã¯ç§åŠç ç©¶ããã³åºç¯ãªããŒã¿ã»ããã®åæã«ãšã£ãŠè²ŽéãªããŒã«ã§ãã
ããŒãªãšå€æã®åºç¯ãªå¿çšã¯ãæè¡çæ¯èгã圢æããäžçäžã®äººã ã®ç掻ã®è³ªãåäžãããäžã§ã®ãã®åºæ¬çãªåœ¹å²ã瀺ããŠããŸãã
å®è·µçãªæŽå¯ãšãã¹ããã©ã¯ãã£ã¹
ããŒãªãšå€æã广çã«å©çšããããã«ããããã®æŽå¯ãšãã¹ããã©ã¯ãã£ã¹ãèæ ®ããŠãã ããïŒ
- é©åãªããŒã«ãéžæããïŒ èšç®ãªãœãŒã¹ãä¿¡å·ã®ç¹æ§ãæãŸããåæã®æ·±ããªã©ã®èŠå ãèæ ®ããŠãFTãå®è¡ããããã®é©åãªãœãããŠã§ã¢ãšããŒã«ãéžæããŸããSciPyïŒPythonïŒã®ãããªãªãŒãã³ãœãŒã¹ãªãã·ã§ã³ããMATLAB/Octaveã®ãããªå°éçãªDSPãœãããŠã§ã¢ããŸãã¯LabVIEWã®ãããªåçšãœãªã¥ãŒã·ã§ã³ã®å©çšå¯èœæ§ãæ€èšããŠãã ããã
- ä¿¡å·ã®ç¹æ§ãçè§£ããïŒ ãã€ãã¹ã-ã·ã£ãã³ã®ãµã³ããªã³ã°å®çã䜿çšããŠä¿¡å·ãæ£ç¢ºã«ãµã³ããªã³ã°ããŸããä¿¡å·ã®çš®é¡ïŒãªãŒãã£ãªãç»åãªã©ïŒãç¹æ§ïŒå®åžž vs. éå®åžžïŒãããã³äºæ³ãããåšæ³¢æ°ç¯å²ãªã©ã®ä¿¡å·ã®ç¹æ§ãçè§£ããŸãã
- çªé¢æ°ïŒ ã¹ãã¯ãã«æŒããæå°éã«æããããã«é©åãªçªé¢æ°ãéžæããŸãã
- çµæãè§£éããïŒ FTã®çµæãæ£ç¢ºã«è§£éããŸããåšæ³¢æ°ã¹ãã¯ãã«ã®èªã¿æ¹ããæéãšåšæ³¢æ°ã®é¢ä¿ãçè§£ããæ¹æ³ãåŠã³ãŸããä¿¡å·åŠçã¿ã¹ã¯ã«çµæã广çã«é©çšããæ¹æ³ãåŠã³ãŸãã
- ã³ãŒããæé©åããïŒ ã«ã¹ã¿ã DSPã³ãŒãã§äœæ¥ããŠããå Žåã¯ãç¹ã«å€§èŠæš¡ãªããŒã¿ã»ããããªã¢ã«ã¿ã€ã ã¢ããªã±ãŒã·ã§ã³ãæ±ãéã«ãå¹çã®ããã«ã³ãŒããæé©åããŸããäºåã«æ§ç¯ãããFFTå®è£ ãæäŸããæé©åãããã©ã€ãã©ãªã®äœ¿çšãæ€èšããŠãã ããã
- ææ°æ å ±ãå ¥æããïŒ DSPããã³é¢é£åéã®ææ°ã®é²æ©ã«ã€ããŠåžžã«æ å ±ãåŸãŠãããŸãããã®æ¥éã«é²åããåéã§ã¯ãç¶ç¶çãªåŠç¿ãäžå¯æ¬ ã§ãã
çµè«
ããŒãªãšå€æã¯ãããžã¿ã«ä¿¡å·åŠçã®äžçã«ãããŠåºæ¬çãã€éåžžã«æ±çšæ§ã®é«ãããŒã«ã§ãããªãŒãã£ãªå¶äœããå»çç»åãã°ããŒãã«ãªéä¿¡ã«è³ããŸã§ãçŸä»£äžçã圢äœãèšå€§ãªæè¡ã®åºç€ãšãªã£ãŠããŸãããã®ã¬ã€ãã§ã¯ãããŒãªãšå€æããã®å¿çšããããŠäžçäžã§ã®åœ±é¿ã«ã€ããŠè©³çŽ°ãªæŠèŠãæäŸããŸãããããŒãªãšå€æã®åçãçè§£ããããšã§ãäžçäžã®å°éå®¶ã¯ãã®èœåãããè¯ã掻çšããDSPã®é åã§é©æ°ãç¶ããããšãã§ããŸããåçã¯åãã§ãããããŒã«ãšæè¡ã¯é²åããæ¬¡äžä»£ã®ããã«ä¿¡å·ãšä¿¡å·åŠçãæ¢æ±ããããã®ç¡éã®å¯èœæ§ãæäŸããŸããDSPã®æ·±ããåŠã³ç¶ããæ¢æ±ãç¶ããããšãäžå¯æ¬ ã§ãã