{"id":662,"date":"2015-03-25T09:20:22","date_gmt":"2015-03-25T14:20:22","guid":{"rendered":"http:\/\/test.pegasuslectures.com\/blog\/?p=662"},"modified":"2015-03-25T11:19:47","modified_gmt":"2015-03-25T16:19:47","slug":"quick-concepts-signal-to-noise-ratio","status":"publish","type":"post","link":"https:\/\/www.pegasuslectures.com\/blog\/index.php\/2015\/03\/25\/quick-concepts-signal-to-noise-ratio\/","title":{"rendered":"Quick Concepts: Signal-to-Noise Ratio"},"content":{"rendered":"

\"WeakThe concept of SIGNAL-TO-NOISE is foundational to understanding what represents a \u201cquality\u201d<\/strong> scan.\u00a0 Yet, I find it ironic that very little time is spent explaining why the ratio<\/span><\/strong> is more relevant than either signal strength or noise level.<\/p>\n

Consider the two extremes of:<\/p>\n

(1) Shouting across a crowded restaurant<\/p>\n

(2) Whispering in a public library<\/p>\n

Which situation represents a more \u201caudible\u201d environment ?<\/em><\/strong><\/p>\n

Your answer would involve an assessment of the strength or weakness of the signal (your voice) relative to<\/span><\/strong> the level of background noise\u2026.hence, a ratio<\/strong>.<\/p>\n

It is quite possible that the whisper in a library is more discernable than a shout across the crowded restaurant.<\/p>\n

 <\/p>\n

\"Shouting

Shouting Across a Crowded Restaurant<\/p><\/div>\n

\"Whispering

Whispering in a Public Library<\/p><\/div>\n

From this analogy, you can very quickly conclude:<\/p>\n

\n

Just because you have a large signal<\/span> doesn\u2019t mean you will have good signal-to-noise ratio\u00a0AND<\/strong> just because you have low noise<\/span>, doesn\u2019t mean you will have good SNR.<\/p>\n<\/blockquote>\n

For sonographers and ultrasound professionals, your job is to optimize signal-to-noise at all times.<\/strong>\u00a0 Making sure that the signal is large enough relative to the noise will give us good clinical or diagnostic data.<\/p>\n

In the video below, I discuss multiple strategies to improve SNR.<\/em> It is also important to note that increasing the receiver gain does NOT improve signal-to-noise ratio<\/span>.\u00a0 While many novice sonographers associate a brighter image with good (or better) SNR, what is more important than the brightness of the image is the contrast<\/strong> <\/span>between the signal and the noise levels. This will lead into a future discussion on \u201cApparent<\/strong>\u201d versus \u201cTrue<\/strong>\u201d SNR.<\/p>\n

This subject discussion intersects with a previous 2-part<\/a>, Quick Concepts<\/a> post on Transmit vs. Receive Gain<\/a>.<\/p>\n