{"id":4836,"date":"2019-06-03T01:00:57","date_gmt":"2019-06-02T22:00:57","guid":{"rendered":"http:\/\/www.ufukonen.com\/tr\/?p=4836"},"modified":"2021-05-04T20:49:32","modified_gmt":"2021-05-04T17:49:32","slug":"mikrofonlar-signal-to-noise-ratio","status":"publish","type":"post","link":"https:\/\/www.ufukonen.com\/tr\/mikrofonlar-signal-to-noise-ratio.html","title":{"rendered":"Mikrofonlar ve Signal-to-Noise Ratio"},"content":{"rendered":"

Bir \u00f6nceki hafta mikrofonlar\u0131n kendi dip g\u00fcr\u00fclt\u00fcleri ile ilgili “Mikrofonlar ve Equivalent Noise Level<\/a>” ba\u015fl\u0131kl\u0131 bir yaz\u0131 yazm\u0131\u015f, ‘self noise’ olarak da bilinen bu g\u00fcr\u00fclt\u00fclerin neden olu\u015ftu\u011funu ve nas\u0131l \u00f6l\u00e7\u00fcld\u00fc\u011f\u00fcn\u00fc anlatm\u0131\u015ft\u0131m.<\/p>\n

Equivalent noise level ya da self noise seviyesi genelde A-weighting dengesi kullan\u0131larak \u00f6l\u00e7\u00fcl\u00fcyor ve dB SPL cinsinden ifade ediliyor. Bu sebepten dolay\u0131 de\u011ferler \u00e7o\u011fu zaman dB(A) olarak yaz\u0131l\u0131yor. \u00d6l\u00e7\u00fcm i\u00e7in kullan\u0131lan di\u011fer bir denge de, CCIR-weighting olarak da bilinen, ITU-weighting dengesi. De\u011ferlerin Neumann taraf\u0131ndan yap\u0131lm\u0131\u015f s\u0131n\u0131fland\u0131rmas\u0131na g\u00f6z atmak i\u00e7in buraya t\u0131klayabilirsiniz<\/a>.<\/p>\n

Signal-to-Noise Ratio (S\/N Ratio)<\/h3>\n

Mikrofonlar\u0131n g\u00fcr\u00fclt\u00fc seviyelerini ifade etmenin bir di\u011fer yolu ise signal-to-noise ratio (S\/N Ratio), T\u00fcrk\u00e7e kar\u015f\u0131l\u0131\u011f\u0131 ile sinyalin g\u00fcr\u00fclt\u00fcye olan oran\u0131d\u0131r.<\/p>\n

Signal-to-noise ratio, dB cinsinden ifade ediliyor.<\/p>\n

Hesab\u0131 \u00e7ok kolay… Bir mikrofonun sinyalinin g\u00fcr\u00fclt\u00fcye olan oran\u0131n\u0131 bulmak i\u00e7in referans ses bas\u0131n\u00e7 seviyesinden, mikrofonun dip g\u00fcr\u00fclt\u00fc seviyesini (equivalent noise level \/ self noise) \u00e7\u0131kartmak yetiyor.<\/p>\n

Peki, referans ses bas\u0131n\u00e7 seviyesi nedir?<\/p>\n

Referans ses bas\u0131n\u00e7 seviyesi olarak 94 dB SPL al\u0131n\u0131yor. Bunu sebebi ise 1 Pascal’\u0131n 94 dB SPL’e e\u015fit olmas\u0131.<\/p>\n

Bu durumda form\u00fcl a\u015fa\u011f\u0131daki gibi oluyor:<\/p>\n

Signal-to-noise (RMS, A-weighted) = 94 dB SPL – self noise dB<\/strong><\/p>\n

Sinyalin G\u00fcr\u00fclt\u00fcye Oran\u0131 ve Dinamik Alan<\/h3>\n

Sinyalin g\u00fcr\u00fclt\u00fcye oran\u0131 ile dinamik alan kavramlar\u0131n\u0131n birbirleri ile kar\u0131\u015ft\u0131r\u0131lmamas\u0131 \u00e7ok \u00f6nemlidir.<\/p>\n

“Headroom Nedir ve Neden \u00d6nemlidir?<\/a>” ba\u015fl\u0131kl\u0131 yaz\u0131mda detayl\u0131ca anlatm\u0131\u015ft\u0131m; dinamik alan, sinyalde g\u00fcr\u00fclt\u00fc e\u015fi\u011fi ile bozulma (distortion) noktas\u0131 aras\u0131nda kalan aland\u0131r. Daha basit bir anlat\u0131mla, dinamik alan, sinyalde m\u00fcmk\u00fcn olan en d\u00fc\u015f\u00fck ve en y\u00fcksek seviyeler aras\u0131ndaki farkt\u0131r. Yaz\u0131y\u0131 okumak i\u00e7in buraya t\u0131klay\u0131n\u0131z.<\/p>\n

\u00d6rnek De\u011ferler<\/h3>\n

\u00d6rnek olarak Neumann TLM 103 cardioid condenser mikrofonun teknik \u00f6zelliklerini inceleyelim.<\/p>\n

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Neumann TLM 103<\/p><\/div>\n

Equivalent noise level, A-Weighting olarak 7 dB olarak verilmi\u015f. Signal-to-noise ratio ise yine A-weighting olarak 87 dB olarak verilmi\u015f.<\/p>\n

Bu de\u011ferleri form\u00fcle koyup kar\u015f\u0131la\u015ft\u0131ral\u0131m:<\/p>\n

Signal-to-noise (RMS, A-weighted) = 94 dB SPL – 7 dB(A) = 87 dB<\/p>\n

Form\u00fcl ve verilen de\u011ferler birbirleri ile uyu\u015fuyor.<\/p>\n

Self Noise, S\/N Ratio ve Polar Pattern<\/h3>\n

Mikrofonun dip g\u00fcr\u00fclt\u00fc seviyesi, dolay\u0131s\u0131 ile S\/N Ratio, mikrofonun polar pattern ve kaps\u00fcl\u00fc ile de alakal\u0131d\u0131r.<\/p>\n

\u00d6rnek olarak Shure KSM44A multi-pattern condenser mikrofonun teknik \u00f6zelliklerine bakal\u0131m.<\/p>\n

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Shure KSM44A<\/p><\/div>\n

Verilen equivalent noise level de\u011ferleri a\u015fa\u011f\u0131daki gibidir:<\/p>\n