# How does wi-fi on trains work? **URL:** \ **Category:** Factual Questions\ **Created:** [October 13, 2010, 12:56am UTC](https://boards.straightdope.com/t/how-does-wi-fi-on-trains-work/556943 "2010-10-13T00:56:46Z")\ **Posts on this page:** 15\ **Page:** 1
**Author:** ![NetTrekker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/nettrekker/32/2909_2.png) [@NetTrekker](https://boards.straightdope.com/u/NetTrekker)\ **Post date:** [October 13, 2010, 12:56am UTC](https://boards.straightdope.com/t/how-does-wi-fi-on-trains-work/556943/1 "2010-10-13T00:56:46Z")
Is it satellite-based or cellular service based? Wouldn’t the high speed of the train make it difficult to maintain a connection? Are high data rates possible as with DSL/cable, allowing video streaming, etc.? ---
**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\ **Post date:** [October 13, 2010, 1:01am UTC](https://boards.straightdope.com/t/how-does-wi-fi-on-trains-work/556943/2 "2010-10-13T01:01:36Z")
> **[About WiFi Rail](http://www.wifirail.net/pages/aboutus.html)** > > About WiFi Rail Here’s a start. ---
**Author:** ![Ludovic](https://avatars.discourse-cdn.com/v4/letter/l/7ab992/32.png) [@Ludovic](https://boards.straightdope.com/u/Ludovic)\ **Post date:** [October 13, 2010, 1:02am UTC](https://boards.straightdope.com/t/how-does-wi-fi-on-trains-work/556943/3 "2010-10-13T01:02:16Z")
The only catch is, it only works in websites that were written in Ruby on Rails…::::rimshot:::: ---
**Author:** ![NOLA\_Cajun](https://avatars.discourse-cdn.com/v4/letter/n/ea666f/32.png) [@NOLA\_Cajun](https://boards.straightdope.com/u/NOLA_Cajun)\ **Post date:** [October 13, 2010, 1:52am UTC](https://boards.straightdope.com/t/how-does-wi-fi-on-trains-work/556943/4 "2010-10-13T01:52:03Z")
I would imagine it’s probably like some of the boats I’ve worked on with a self tracking satellite system. Didn’t read the above link so don’t know if that’s what that is about or not. ---
**Author:** ![bump](https://avatars.discourse-cdn.com/v4/letter/b/7c8e57/32.png) [@bump](https://boards.straightdope.com/u/bump)\ **Post date:** [October 13, 2010, 2:18am UTC](https://boards.straightdope.com/t/how-does-wi-fi-on-trains-work/556943/5 "2010-10-13T02:18:44Z")
Well, the “wi-fi” itself is more than likely just a regular old 802.11 wireless network of some kind- if all the cars on the train are moving at the same speed, I don’t know why it wouldn’t work. As for the internet access, it’s likely satellite-based. ---
**Author:** ![Topologist](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/topologist/32/3208_2.png) [@Topologist](https://boards.straightdope.com/u/Topologist)\ **Post date:** [October 13, 2010, 2:37am UTC](https://boards.straightdope.com/t/how-does-wi-fi-on-trains-work/556943/6 "2010-10-13T02:37:47Z")
Amtrak’s onboard Wi-Fi service uses technology from Nomad Digital. According to their [press release](http://www.uknomad.com/press-amtrak-launch-passenger-wifi-on-acela-express-details-46.html), they’re aggregating 3G network signals to provide the service. Essentially, grabbing whatever and as many cell phone network signals as they can. ---
**Author:** ![NetTrekker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/nettrekker/32/2909_2.png) [@NetTrekker](https://boards.straightdope.com/u/NetTrekker)\ **Post date:** [October 13, 2010, 2:51am UTC](https://boards.straightdope.com/t/how-does-wi-fi-on-trains-work/556943/7 "2010-10-13T02:51:02Z")
> [@Ludovic](#): > > The only catch is, it only works in websites that were written in Ruby on Rails…::::rimshot:::: very punny ! 😃 ---
**Author:** ![GaryM](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/garym/32/241_2.png) [@GaryM](https://boards.straightdope.com/u/GaryM)\ **Post date:** [October 14, 2010, 4:07pm UTC](https://boards.straightdope.com/t/how-does-wi-fi-on-trains-work/556943/8 "2010-10-14T16:07:41Z")
And it will NOT work in Dark Territory. ---
**Author:** ![Bag\_of\_Mostly\_Water](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bag_of_mostly_water/32/1029_2.png) [@Bag\_of\_Mostly\_Water](https://boards.straightdope.com/u/Bag_of_Mostly_Water)\ **Post date:** [October 14, 2010, 4:20pm UTC](https://boards.straightdope.com/t/how-does-wi-fi-on-trains-work/556943/9 "2010-10-14T16:20:46Z")
I know at least one train WiFi network (CalTrain in the San Francisco Bay Area) used WiMAX base stations spaced about 15 miles apart along the rail line. Each train car picked up the WiMAX signal and converted it to WiFi within the car. I’m not sure how the WiMAX base stations were connected to the internet. ---
**Author:** ![Procrustus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/procrustus/32/2994_2.png) [@Procrustus](https://boards.straightdope.com/u/Procrustus)\ **Post date:** [October 14, 2010, 4:30pm UTC](https://boards.straightdope.com/t/how-does-wi-fi-on-trains-work/556943/10 "2010-10-14T16:30:53Z")
how about internet on airplanes? ---
**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\ **Post date:** [October 14, 2010, 4:46pm UTC](https://boards.straightdope.com/t/how-does-wi-fi-on-trains-work/556943/11 "2010-10-14T16:46:20Z")
[http://www.wlanbook.com/how-does-airplane-wifi-work/](http://www.wlanbook.com/how-does-airplane-wifi-work/) ---
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [October 14, 2010, 4:52pm UTC](https://boards.straightdope.com/t/how-does-wi-fi-on-trains-work/556943/12 "2010-10-14T16:52:29Z")
> [@Telemark](#): > > [http://www.wlanbook.com/how-does-airplane-wifi-work/](http://www.wlanbook.com/how-does-airplane-wifi-work/) Interesting. Can someone explain how having hundreds of ground-based transceivers cellphone-style for that concept is superior to a single geosynchronous satellite signal, or even a handful of non-geosync satelllites? ---
**Author:** ![robert\_columbia](https://avatars.discourse-cdn.com/v4/letter/r/e79b87/32.png) [@robert\_columbia](https://boards.straightdope.com/u/robert_columbia)\ **Post date:** [October 14, 2010, 5:32pm UTC](https://boards.straightdope.com/t/how-does-wi-fi-on-trains-work/556943/13 "2010-10-14T17:32:59Z")
> [@bump](#): > > Well, the “wi-fi” itself is more than likely just a regular old 802.11 wireless network of some kind- if all the cars on the train are moving at the same speed, I don’t know why it wouldn’t work. Right, because the wi-fi signals are travelling at light speed, which is much faster than the train, rending any frequency phase shift or timing problem into a triviality that probably can’t be reasonably detected by the equipment used. What could be a problem is if the uplink is cell tower based and the handoffs take X amount of time to process while the tranceiver is within range of both - the train might pass the sweet zone before the handoff is complete, causing a cutoff. ---
**Author:** ![Derleth](https://avatars.discourse-cdn.com/v4/letter/d/b9e5f3/32.png) [@Derleth](https://boards.straightdope.com/u/Derleth)\ **Post date:** [October 14, 2010, 6:02pm UTC](https://boards.straightdope.com/t/how-does-wi-fi-on-trains-work/556943/14 "2010-10-14T18:02:11Z")
> [@robert\_andrews](#): > > > [@bump](#): > > > > Well, the “wi-fi” itself is more than likely just a regular old 802.11 wireless network of some kind- if all the cars on the train are moving at the same speed, I don’t know why it wouldn’t work. > > Right, because the wi-fi signals are travelling at light speed, which is much faster than the train, rending any frequency phase shift or timing problem into a triviality that probably can’t be reasonably detected by the equipment used. Actually, unless someone moving relative to the train is using the train’s wifi, there shouldn’t be any Doppler shifting at all until the train begins to turn, speed up, slow down or, possibly, go up or down a grade. Think about this: The Earth is moving much, much faster than any train relative to the Sun. Do you worry about Doppler shifts when you’re getting your email at Starbucks? ---
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [October 15, 2010, 2:02pm UTC](https://boards.straightdope.com/t/how-does-wi-fi-on-trains-work/556943/15 "2010-10-15T14:02:43Z")
If the signal to the train or plane is coming from a satellite, especially a geosync one, the difference in relative speed is very little (the train isn’t moving towards or away from the sat much). The difference in speed between the wifi hotspot on the train and the end user is zero. So the movement is not a problem. I can see a problem if the train is fed by cell sites instead of satellite. If not well situated, handoff between towers could cause a signal to be lost briefly. Likewise, a handoff between non-gosync sats could do the same thing.