# What else is X-band, other than speed radar and supermarket doors?

**URL:** <https://boards.straightdope.com/t/what-else-is-x-band-other-than-speed-radar-and-supermarket-doors/283213>\
**Category:** Factual Questions\
**Created:** [January 5, 2005, 4:30pm UTC](https://boards.straightdope.com/t/what-else-is-x-band-other-than-speed-radar-and-supermarket-doors/283213 "2005-01-05T16:30:37Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![SmackFu](https://avatars.discourse-cdn.com/v4/letter/s/53a042/32.png) [@SmackFu](https://boards.straightdope.com/u/SmackFu)\
**Post date:** [January 5, 2005, 4:30pm UTC](https://boards.straightdope.com/t/what-else-is-x-band-other-than-speed-radar-and-supermarket-doors/283213/1 "2005-01-05T16:30:37Z")

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In the parking lot at work, I get a very strong, 8 or 9 out of 9, X-Band signal on my new radar detector. It’s on a hilltop, but there are none of the usual suspects nearby that would give a false positive.

Any ideas?

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**Author:** ![Max\_Torque](https://avatars.discourse-cdn.com/v4/letter/m/e9bcb4/32.png) [@Max\_Torque](https://boards.straightdope.com/u/Max_Torque)\
**Post date:** [January 5, 2005, 5:11pm UTC](https://boards.straightdope.com/t/what-else-is-x-band-other-than-speed-radar-and-supermarket-doors/283213/2 "2005-01-05T17:11:30Z")

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The user manual for the Valentine One (which is what your new radar detector is, right?) lists “burglar alarms” as sharing the X-band frequency with door openers and speed radar. I believe some traffic signals also use X-band to detect when people are at the light so that it knows when a change is necessary (there’s at least one like that in my town).

However, just because you’re getting an 8 or 9 on the display doesn’t mean there are 8 or 9 _actual_ sources. Your detector may be reading bounces of strong signals off nearby buildings as additional sources.

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**Author:** ![Scruloose](https://avatars.discourse-cdn.com/v4/letter/s/e68b1a/32.png) [@Scruloose](https://boards.straightdope.com/u/Scruloose)\
**Post date:** [January 5, 2005, 6:26pm UTC](https://boards.straightdope.com/t/what-else-is-x-band-other-than-speed-radar-and-supermarket-doors/283213/3 "2005-01-05T18:26:04Z")

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Ships will (generally) carry S-band and X-band RADAR. You near a waterway?

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**Author:** ![bughunter](https://avatars.discourse-cdn.com/v4/letter/b/aeb1de/32.png) [@bughunter](https://boards.straightdope.com/u/bughunter)\
**Post date:** [January 5, 2005, 11:29pm UTC](https://boards.straightdope.com/t/what-else-is-x-band-other-than-speed-radar-and-supermarket-doors/283213/4 "2005-01-05T23:29:51Z")

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X-band Radar is between (roughly) 3GHz and 10GHz.

[Here is a frequency allocation chart](http://www.ntia.doc.gov/osmhome/allochrt.html) that covers the radio spectrum. If you look at the left half of the sixth row down, you see the X-band and a lot of radiolocation as well as fixed, mobile, and marine communications, and even some radioastronomy.

I have this printed out D-size on my office wall. It’s a great conversation piece. But you need an HP DesignJet or something similar to print it that big.