# Blocking or interfering with a GPS signal **URL:** \ **Category:** Factual Questions\ **Created:** [June 28, 2013, 1:38pm UTC](https://boards.straightdope.com/t/blocking-or-interfering-with-a-gps-signal/662113 "2013-06-28T13:38:26Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![hlanelee](https://avatars.discourse-cdn.com/v4/letter/h/3bc359/32.png) [@hlanelee](https://boards.straightdope.com/u/hlanelee)\ **Post date:** [June 28, 2013, 1:38pm UTC](https://boards.straightdope.com/t/blocking-or-interfering-with-a-gps-signal/662113/1 "2013-06-28T13:38:26Z")
A few years ago I took a surveying class and we had an exercise on using a compass and counting paces to do preliminary work. There was some discussion about keeping track of the count over long distances and I showed the teacher how to make a pace counter with a piece of string and some beads. I told him that this was how the Army Rangers were taught to do dead reckoning. He asked why would they use a compass and string of beads when a GPS is so much better. I replied that a compass and pace counter was cheap and easy, could be used in the dark, was difficult to break, and was almost foolproof. I also added that I believed that a GPS transmitter was of low wattage and could be easily jammmed or interfered with, maybe with a local transmitter. Here’s my question, if I had a position that I wanted defend, could I block or otherwise make a GPS receiver useless within say a five mile diameter of my position? Any body miss me? ---
**Author:** ![Isilder](https://avatars.discourse-cdn.com/v4/letter/i/cc9497/32.png) [@Isilder](https://boards.straightdope.com/u/Isilder)\ **Post date:** [June 28, 2013, 1:47pm UTC](https://boards.straightdope.com/t/blocking-or-interfering-with-a-gps-signal/662113/2 "2013-06-28T13:47:21Z")
Newscientist has an article on that idea… it has been done by the USN. > **[GPS chaos: How a $30 box can jam your life](https://www.newscientist.com/article/dn20202-gps-chaos-how-a-30-box-can-jam-your-life/)** > > Signals from GPS satellites now help you to call your mother, power your home, and even land your plane – but a cheap plastic box can scramble it all ---
**Author:** ![UncleRojelio](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/unclerojelio/32/3160_2.png) [@UncleRojelio](https://boards.straightdope.com/u/UncleRojelio)\ **Post date:** [June 28, 2013, 1:51pm UTC](https://boards.straightdope.com/t/blocking-or-interfering-with-a-gps-signal/662113/3 "2013-06-28T13:51:39Z")
Almost any satellite signal can be [jammed](http://en.wikipedia.org/wiki/Satellite#Jamming) by a terrestrial source. GPS signals are often unintentionally jammed by toll booths and miscalibrated transmitters. Even when not deliberately jammed, GPS signals can be blocked by even heavy tree cover. GPS signals can even be [spoofed](http://en.wikipedia.org/wiki/GPS_spoofing#GPS_Spoofing). ---
**Author:** ![HipGnosis](https://avatars.discourse-cdn.com/v4/letter/h/76d3ee/32.png) [@HipGnosis](https://boards.straightdope.com/u/HipGnosis)\ **Post date:** [June 28, 2013, 4:11pm UTC](https://boards.straightdope.com/t/blocking-or-interfering-with-a-gps-signal/662113/4 "2013-06-28T16:11:10Z")
Sure, you can jam the GPS frequency, but your jammer transmitter can be locked onto and taken out in one ‘shot’. Besides, 5 miles isn’t going to protect you from technical weaponry. ---
**Author:** ![hlanelee](https://avatars.discourse-cdn.com/v4/letter/h/3bc359/32.png) [@hlanelee](https://boards.straightdope.com/u/hlanelee)\ **Post date:** [June 28, 2013, 5:17pm UTC](https://boards.straightdope.com/t/blocking-or-interfering-with-a-gps-signal/662113/5 "2013-06-28T17:17:40Z")
> [@HipGnosis](#): > > Sure, you can jam the GPS frequency, but your jammer transmitter can be locked onto and taken out in one ‘shot’. > Besides, 5 miles isn’t going to protect you from technical weaponry. Sometimes “blow everything up” is not the object and feet on the ground, old school is required.