{"id":16622,"date":"2025-06-11T16:51:53","date_gmt":"2025-06-11T16:51:53","guid":{"rendered":"https:\/\/gaviki.com\/blog\/?p=16622"},"modified":"2025-06-11T16:51:57","modified_gmt":"2025-06-11T16:51:57","slug":"draw-the-autocorrelation-function-for-the-following-codes-1-0010111-2-0000000-find-which-code-has-a-better-correlation-function-and-why","status":"publish","type":"post","link":"https:\/\/gaviki.com\/blog\/draw-the-autocorrelation-function-for-the-following-codes-1-0010111-2-0000000-find-which-code-has-a-better-correlation-function-and-why\/","title":{"rendered":"Draw the autocorrelation function for the following codes: 1- 0010111 2- 0000000 Find which code has a better correlation function and why"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">Draw the autocorrelation function for the following codes: 1- 0010111 2- 0000000 Find which code has a better correlation function and why.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-cyan-blue-color\"><strong>The correct answer and explanation is:<\/strong><\/mark><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">To find the <strong>autocorrelation function<\/strong> for the two binary codes and determine which has better autocorrelation properties, we follow these steps:<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Step 1: Convert binary to bipolar format<\/strong><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">We replace:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>0<\/code> \u2192 <code>-1<\/code><\/li>\n\n\n\n<li><code>1<\/code> \u2192 <code>+1<\/code><\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\">Code 1: 0010111 \u2192 Bipolar: -1 -1 +1 -1 +1 +1 +1<\/h4>\n\n\n\n<h4 class=\"wp-block-heading\">Code 2: 0000000 \u2192 Bipolar: -1 -1 -1 -1 -1 -1 -1<\/h4>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Step 2: Compute autocorrelation function (ACF)<\/strong><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">The autocorrelation function R(k)R(k) of a sequence x(n)x(n) is calculated as: R(k)=\u2211n=0N\u2212k\u22121x(n)\u22c5x(n+k)R(k) = \\sum_{n=0}^{N-k-1} x(n) \\cdot x(n+k)<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Where kk is the lag (0 to N-1).<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Let\u2019s compute the autocorrelation functions manually for both codes.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Code 1: ACF of 0010111 (bipolar)<\/strong><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Let x=[\u22121,\u22121,+1,\u22121,+1,+1,+1]x = [-1, -1, +1, -1, +1, +1, +1]<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>R(0)=(\u22121)2+(\u22121)2+12+(\u22121)2+12+12+12=7R(0) = (-1)^2 + (-1)^2 + 1^2 + (-1)^2 + 1^2 + 1^2 + 1^2 = 7<\/li>\n\n\n\n<li>R(1)=(\u22121)(\u22121)+(\u22121)(1)+(1)(\u22121)+(\u22121)(1)+(1)(1)+(1)(1)=1R(1) = (-1)(-1) + (-1)(1) + (1)(-1) + (-1)(1) + (1)(1) + (1)(1) = 1<\/li>\n\n\n\n<li>R(2)=(\u22121)(1)+(\u22121)(\u22121)+(1)(1)+(\u22121)(1)+(1)(1)=1R(2) = (-1)(1) + (-1)(-1) + (1)(1) + (-1)(1) + (1)(1) = 1<\/li>\n\n\n\n<li>R(3)=(\u22121)(\u22121)+(\u22121)(1)+(1)(1)+(\u22121)(1)=2R(3) = (-1)(-1) + (-1)(1) + (1)(1) + (-1)(1) = 2<\/li>\n\n\n\n<li>R(4)=(\u22121)(1)+(\u22121)(1)+(1)(1)=\u22121R(4) = (-1)(1) + (-1)(1) + (1)(1) = -1<\/li>\n\n\n\n<li>R(5)=(\u22121)(1)+(\u22121)(1)=\u22122R(5) = (-1)(1) + (-1)(1) = -2<\/li>\n\n\n\n<li>R(6)=(\u22121)(1)=\u22121R(6) = (-1)(1) = -1<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">So, ACF = [<strong>7, 1, 1, 2, -1, -2, -1<\/strong>]<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Code 2: ACF of 0000000 (bipolar)<\/strong><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Let x=[\u22121,\u22121,\u22121,\u22121,\u22121,\u22121,\u22121]x = [-1, -1, -1, -1, -1, -1, -1]<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>R(0)=7R(0) = 7<\/li>\n\n\n\n<li>R(1)=(\u22121)2+(\u22121)2+&#8230;=6R(1) = (-1)^2 + (-1)^2 + &#8230; = 6<\/li>\n\n\n\n<li>R(2)=5R(2) = 5<\/li>\n\n\n\n<li>&#8230;<\/li>\n\n\n\n<li>R(6)=1R(6) = 1<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">So, ACF = [<strong>7, 6, 5, 4, 3, 2, 1<\/strong>]<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Analysis &amp; Conclusion (300 Words)<\/strong><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Autocorrelation is a measure of how well a signal matches a shifted version of itself. A good autocorrelation function for communication systems has a <strong>sharp peak at lag 0<\/strong> and <strong>low values (ideally zero)<\/strong> elsewhere. This property helps in distinguishing the signal from noise and in detecting signal timing accurately.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">From the results above:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Code 1<\/strong> has an ACF of: [<strong>7, 1, 1, 2, -1, -2, -1<\/strong>]<\/li>\n\n\n\n<li><strong>Code 2<\/strong> has an ACF of: [<strong>7, 6, 5, 4, 3, 2, 1<\/strong>]<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">While both codes have the same peak value at lag 0 (which is expected, as this represents total signal energy), Code 1 shows <strong>much lower side-lobes<\/strong>, and some values are even <strong>negative<\/strong> or <strong>close to zero<\/strong>. These lower values away from the peak (lag 0) mean that Code 1 exhibits <strong>better autocorrelation properties<\/strong>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">In contrast, Code 2 is a constant sequence (all zeros), leading to high correlation at every lag. This uniformity makes it poor for signal detection because it lacks uniqueness \u2014 the receiver cannot easily distinguish the start of the code, increasing the risk of synchronization errors.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Thus, <strong>Code 1 is better<\/strong>, as it has a distinct, narrow peak and relatively low off-peak values \u2014 ideal for minimizing cross-talk and ensuring accurate detection in digital communication systems like CDMA and spread-spectrum.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<p class=\"wp-block-paragraph\">\u2705 <strong>Correct Answer<\/strong>: <strong>Code 1 (0010111)<\/strong> has a better correlation function because it has lower off-peak autocorrelation values, which improves signal detection and synchronization.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Draw the autocorrelation function for the following codes: 1- 0010111 2- 0000000 Find which code has a better correlation function and why. The correct answer and explanation is: To find the autocorrelation function for the two binary codes and determine which has better autocorrelation properties, we follow these steps: Step 1: Convert binary to bipolar [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-16622","post","type-post","status-publish","format-standard","hentry","category-quiz-questions"],"_links":{"self":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts\/16622","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/comments?post=16622"}],"version-history":[{"count":1,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts\/16622\/revisions"}],"predecessor-version":[{"id":16623,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts\/16622\/revisions\/16623"}],"wp:attachment":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/media?parent=16622"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/categories?post=16622"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/tags?post=16622"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}