From 39dc41346ce735b2643f0b057e65ff428a9aee91 Mon Sep 17 00:00:00 2001 From: Mark Marijnissen Date: Thu, 26 Feb 2015 12:57:33 +0100 Subject: [PATCH] update readme --- README.md | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/README.md b/README.md index 6e9ed36..393b992 100644 --- a/README.md +++ b/README.md @@ -6,8 +6,10 @@ See demo at http://lab.madebymark.nl/pitch-detector/example/. ## Examples -The **Y-Axis** is the auto-correlation score. The **X-Axis** is the frequency range, from high (22 +* The **Y-Axis** is the auto-correlation score. +* The **X-Axis** is the frequency range, from high (22 Khz) to low (83 Hz). +* The **Red bar** is the signal strength (RMS). The little dark red line is the minimal RMS. Detect best auto-correlation of all frequencies: @@ -152,6 +154,12 @@ If you know what you're looking or, set a frequency range. **Warning:** `minCorrelationIncrease` needs a large frequency range to detect a difference. The frequency range must be large enough to include both a low and high auto-correlation. +## Ideas to improve algorithm: + +* Draw an "optimal" auto-correlation shape, and calculate mean squared error (MSE) from measured auto-correlation score. When MSE is low enough, a pitch is detected. (or a combination of pitches!) +* Implement DTMF demodulation as example +* Learn a shape by recording auto-correlation scores of the perfect example. The resulting shape is the average of all recordes samples. Calculate standard deviation to see if the signal can be detected reliably. + ## Changelog ### 0.2.0 (26/02/2015)