--- title: GPS Hidden Messages - Computerphile | daily.dev description: A researcher at UCL investigated hidden 'text message' fields in GPS signals that are undocumented and ignored by standard receivers. Using a software-defined... canonical: https://daily.dev/posts/gps-hidden-messages---computerphile-ssmrovadt twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: GPS Hidden Messages - Computerphile | daily.dev og:description: A researcher at UCL investigated hidden 'text message' fields in GPS signals that are undocumented and ignored by standard receivers. Using a software-defined... og:url: https://daily.dev/posts/gps-hidden-messages---computerphile-ssmrovadt og:image: https://api.daily.dev/og/posts/sSMrOvAdt.png og:image:alt: GPS Hidden Messages - Computerphile og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # GPS Hidden Messages - Computerphile **[Computerphile](https://daily.dev/sources/computerphile)** · 19 min read · 4 upvotes · 0 comments ## Summary A researcher at UCL investigated hidden 'text message' fields in GPS signals that are undocumented and ignored by standard receivers. Using a software-defined receiver and a GPS message archive dating back to 2007, they applied entropy analysis and cumulative sum statistical tests to detect patterns in the seemingly random data. A dramatic change occurred on May 26, 2011 — all satellites briefly broadcast a repeating 1010 pattern (technically a spec violation) before switching to faster-rotating messages. This timing correlates with the publicly announced launch of the US military's over-the-air GPS rekeying system, leading to the hypothesis that these hidden messages are the mechanism for distributing encrypted keys to authorized military GPS receivers. No decryption was achieved; the analysis is purely traffic analysis based on metadata patterns. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Schneier on Security](https://daily.dev/posts/schneier-on-security-a0hqg0sfd) · Schneier on Security · 0 upvotes · 0 comments - [Spy Tech: The GPS Numbers Station](https://daily.dev/posts/spy-tech-the-gps-numbers-station-gudc6dsze) · Hackaday · 1 upvotes · 0 comments --- Tags: [#cryptography](https://daily.dev/tags/cryptography), [#signal-processing](https://daily.dev/tags/signal-processing) [View this post on daily.dev](https://daily.dev/posts/gps-hidden-messages---computerphile-ssmrovadt) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"GPS Hidden Messages - Computerphile","url":"https://daily.dev/posts/gps-hidden-messages---computerphile-ssmrovadt","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/gps-hidden-messages---computerphile-ssmrovadt"},"datePublished":"2026-07-16T14:53:56.696Z","dateModified":"2026-07-16T20:21:11.258Z","description":"A researcher at UCL investigated hidden 'text message' fields in GPS signals that are undocumented and ignored by standard receivers. Using a software-defined...","image":"https://i.ytimg.com/vi/2Q6OvYjOJi0/sddefault.jpg","thumbnailUrl":"https://i.ytimg.com/vi/2Q6OvYjOJi0/sddefault.jpg","isAccessibleForFree":true,"articleSection":"Computerphile","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"Computerphile","logo":"https://media.daily.dev/image/upload/s--hZFFIKfd--/f_auto/v1712315606/logos/computerphile","url":"https://daily.dev/sources/computerphile"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/gps-hidden-messages---computerphile-ssmrovadt","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":4},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"cryptography,signal-processing","timeRequired":"PT19M","video":{"@type":"VideoObject","name":"GPS Hidden Messages - Computerphile","description":"A researcher at UCL investigated hidden 'text message' fields in GPS signals that are undocumented and ignored by standard receivers. Using a software-defined...","thumbnailUrl":"https://i.ytimg.com/vi/2Q6OvYjOJi0/sddefault.jpg","uploadDate":"2026-07-16T14:53:56.696Z","duration":"PT19M","url":"https://api.daily.dev/r/sSMrOvAdt","embedUrl":"https://www.youtube.com/embed/2Q6OvYjOJi0"}} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Computerphile","item":"https://daily.dev/sources/computerphile"},{"@type":"ListItem","position":3,"name":"GPS Hidden Messages - Computerphile"}]} ```