Wikipedia:Reference desk/Archives/Computing/2015 October 13

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October 13

Funny noise

There's a noise that I have always associated with mobile phones affecting other electronic equipment. Of course I never managed to record it, so I could never get confirmation.

Wikipedia to the rescue! The noise occurred in the WikiConference USA video/livestream for day 1 at c. 1:15:01-1:15:10.

Anyone know definitively what it is?

All the best: Rich Farmbrough, 00:04, 13 October 2015 (UTC).

Here's a link cued to the spot where the interference occurs: WikiConference USA 2015 - 1:14:50. I just call it "cell phone interference". If you want to know the meaning behind the sounds, I did a Google search for "cell phone interference" and found a Slashdot comment that explains a little bit:

• "GSM is a TDMA (Time Division Multiple Access) system. This means a single physical channel is divided up in time for multiple people to share. A single physical channel is just a frequency range, such as 890-890.2 MHz. Each physical channel is divided up in time into what are called timeslots. Timeslots are grouped by 8's into what are called frames. Each timeslot lasts 0.577ms, and a frame is 4.615ms. When your phone is communicating with the base it is assigned a single timeslot in each frame. This means it is transmitting ON off off off off off off off ON off off... and the ON's are spaced 4.615ms apart (the frame duration). 1/4.615ms gives you 216.7Hz, which means that if (when?) it is picked up by other electronics, it is most definitely in the audio band and you will hear it. [...] when you hear the interference before receiving a call/SMS, this is what is happening 1) one or more base stations broadcast "hey you" to the geographic region where your phone is (your phone is always listening for this) 2) your phone contacts a specific base station requesting a channel (AUDIBLE) 3) the base station responds, assigning a channel 4) your phone goes to that channel, authenticates, etc. (AUDIBLE) 5) phone finally rings / SMS is sent"

--Bavi H (talk) 01:28, 13 October 2015 (UTC)

Thanks that's very helpful. The characteristic pattern (Da- dah-dah Da- dah-dah Da) presumably reflects this protocol. Maybe I'll put ferrite beads on all the mobiles.. . no wait...

All the best: Rich Farmbrough, 17:50, 13 October 2015 (UTC).

• By the way, thank you: I used to hear that fairly often while playing music from my computer, and I supposed it was because the speakers are oldish. —Tamfang (talk) 20:04, 14 October 2015 (UTC)

viewing a file pulled from github

hello,

Let's say I have a GitHub repository containing only one file, helloWorld.txt. I have created a new git repository in my local computer inside some folder "test" and pulled the above mentioned GitHub repository. Where is the helloWorld.txt file located now? How can I open it with notepad and edit it? Thanks! 212.179.21.194 (talk) 08:52, 13 October 2015 (UTC)

How did you create the git repository locally?--Phil Holmes (talk) 09:06, 13 October 2015 (UTC)

with the "git init" command. 212.179.21.194 (talk) 09:22, 13 October 2015 (UTC)

When I'm creating a local repository as a copy of a remote, I've always used "git clone". Please try that.--Phil Holmes (talk) 11:54, 13 October 2015 (UTC)

Note that line endings for text files differ between Windows and Unix (which includes OS X). Notepad is a very rudimentary program that only understands Windows line endings; if the file is from a Unix system, it will mash the whole file onto one line. This is one thing that frequently trips up people on Windows systems who are new to programming. If you're going to do any serious programming you're going to want to use a serious text editor (i.e., not Notepad) anyway. You could give our comparison of text editors a look, and/or ask people you know for recommendations. --71.119.131.184 (talk) 06:11, 14 October 2015 (UTC)

Followup: I guess I should have mentioned IDEs, which a lot of people consider different from "text editors", though the line is kind of blurry when you consider editors like emacs or vim. --71.119.131.184 (talk) 06:19, 14 October 2015 (UTC)

Thanks you for the answer, but I think I didn't clarify my question well. I work in windows, and I just want to understand where are the files pulled from GitHub stored. 31.154.144.146 (talk) 16:41, 14 October 2015 (UTC)

'git init' starts an empty repository [1]. You can set a target dir to copy template info from, but it will not copy the actual files. I agree that you probably want 'git clone'. SemanticMantis (talk) 18:26, 14 October 2015 (UTC)