Sunday, October 14, 2018
Thursday, October 11, 2018
From: "OpenMV" <firstname.lastname@example.org>
Date: Oct 10, 2018 11:53 PM
Subject: OpenMV News
To: "John" <email@example.com>
Tuesday, October 9, 2018
Monday, September 24, 2018
Many applications require the detection of a few discrete sinusoids. The Goertzel filter is an IIR filter that uses the feedback to generate a very high Q bandpass filter where the coefficients are easily generated from the required centre frequency, according to the following equations. The most common configuration for using this technique is to measure the signal energy before and after the filter and to compare the two. If the energies are similar then the input signal is centred in the pass-band, if the output energy is significantly lower than the input energy then the signal is outside the pass band. The Goertzel algorithm is most commonly implemented as a second order recursive IIR filter, as shown below.
function Xk = goertzel_non_integer_k(x,k) % Computes an N-point DFT coefficient for a % real-valued input sequence 'x' where the center % frequency of the DFT bin is k/N radians/sample. % N is the length of the input sequence 'x'. % Positive-valued frequency index 'k' need not be % an integer but must be in the range of 0 –to- N-1. % [Richard Lyons, Oct. 2013] N = length(x); Alpha = 2*pi*k/N; Beta = 2*pi*k*(N-1)/N; % Precompute network coefficients Two_cos_Alpha = 2*cos(Alpha); a = cos(Beta); b = -sin(Beta); c = sin(Alpha)*sin(Beta) -cos(Alpha)*cos(Beta); d = sin(2*pi*k); % Init. delay line contents w1 = 0; w2 = 0; for n = 1:N % Start the N-sample feedback looping w0 = x(n) + Two_cos_Alpha*w1 -w2; % Delay line data shifting w2 = w1; w1 = w0; end Xk = w1*a + w2*c + j*(w1*b +w2*d);
Saturday, September 22, 2018
NaviPack makes any device smarter and easier to control. It uses the latest LiDAR technology and powerful APIs to create easy solutions for automated devices.
Wednesday, September 12, 2018
OpenCV3 - Keypoints in Computer Vision by Dr. Adrian Kaehler, Ph.D.
Learning OpenCV 3
Computer Vision in C++ with the OpenCV Libraryhttps://covers.oreillystatic.com/images/0636920044765/lrg.jpg