Wikipedia:Reference desk/Archives/Computing/2011 November 6

= November 6 =

Variable signal quality in WLAN network
What happens when you have a variable wi-fi signal quality. Neither the hot-spot, nor the computer is moving. It goes from 80% down to 0% sometimes. 88.9.210.218 (talk) 01:05, 6 November 2011 (UTC)


 * Just a guess: interference from other transmitters (Wi-Fi and other kinds)? --173.49.15.58 (talk) 12:43, 6 November 2011 (UTC)
 * Wifi can also be affected by people moving around in the house (as they can diffract the signal in various ways, potentially leading to destructive interference). Interference from things like microwave ovens, cordless phones or even a malfunctioning ballast on a fluorescent light can also be a problem. As far as other wifi transmitters goes, you might want to try switching your wireless access point to a different channel, in case the neighbours' wifi is set to the same or an adjacent channel and is interfering. You can apparently use tools such as this web based one to check which channels are used by wifi transmitters within range of your computer (I can't test this out personally as Linux doesn't appear to be supported, and unless you run Linux yourself I doubt instructions on how to run iwlist would be much help to you). This page from Cisco deals in quite some detail with the subject of wireless interference, and although it is from the perspective of a company IT department a lot of the information is more generally relevant. If you continue to have problems that can't be solved by switching channels, or be pinned down to e.g. your cordless phone system or wireless burglar alarm, you might want to go for the slightly ugly solution of just increasing your signal strength near your computer by putting a wireless repeater in between your access point and the computer. Note that this will generally halve your throughput on the wireless network, but for most people this won't be a problem as the choke-point in most home networks is the speed of the internet connection, not the LAN speed.Equisetum (talk &#124; contributions) 18:46, 6 November 2011 (UTC)

Alphabetically sorting icons in Excel
I have some excel tables that each have a column with a rating, expressed with groups of the symbols ★ and ½. The problem is that when I sort by that column, Excel uses the order: ★, ★★, ★★★, ★★★★, ★★★★★, ★★★★½, ★★★½, ★★½, ★½, ½. This is not the order I would like, it should be ★, ★½, ★★. etc.. Is there a way to make Excel sort them in the right order? Are there similar symbols that would sort in the right order (I already know that it does the same thing if I replace ½ with ✫)? If I replaced the spmbols with numbers from 1-10, is there a way to make them apear as icons? I know that "Conditional Formating -> Icon sets" has icons, but none of the available sets have more than five icons. Thank you. --96.52.144.175 (talk) 01:37, 6 November 2011 (UTC)


 * In Excel 2010 or, I believe, 2007, select the area on the spreadsheet you want to sort, then click the "Data" tab, then click the "Sort" button, then choose the "Sort by" and "Sort on" items normally, and then under "Order", in the popup menu, choose "Custom List...". Then choose "NEW LIST", and in the "List Entries" field, type ★, ★½, ★★, all the way up to five stars.  You can see this is also how Excel figures out that March gets sorted before April.  Comet Tuttle (talk) 07:22, 6 November 2011 (UTC)


 * To answer your other question, the following formula (not very elegant, but that's Excel for you) will convert a number 1-10 in cell A1 into ½, ★, ★½, ★★, ..., ★★★★★:

=IF(A1>9,"★","")&IF(A1>7,"★","")&IF(A1>5,"★","")&IF(A1>3,"★","")&IF(A1>1,"★","")&IF(MOD(A1,2)=1,"½","")
 * Gandalf61 (talk) 11:23, 7 November 2011 (UTC)
 * ... or, more concisely:

=LEFT("★★★★★",A1/2)&IF(MOD(A1,2)=1,"½","")
 * Gandalf61 (talk)
 * To do the opposite, I think you could use:

=LEN(SUBSTITUTE(A1, "½",""))+((LEN(SUBSTITUTE(A1, "★","")*.5))
 * To convert the star/half system to numeric values. I haven't tried it, though. It assumes there is no other data in the cell but stars and halves. (Then you could sort by this column, obviously.) --Mr.98 (talk) 13:25, 7 November 2011 (UTC)

gmail - web browser only?
Can gmail be accessed only through a browser, or is there software I can download to access it? Bubba73 You talkin' to me? 02:45, 6 November 2011 (UTC)
 * You should be able to check it with any email program that you might have that allows POP3. Dismas |(talk) 02:48, 6 November 2011 (UTC)
 * Or IMAP. Shadowjams (talk) 05:43, 6 November 2011 (UTC)
 * Or the e-mail programs on iPads and other mobile phones and tablets that connect with GMail more directly. Comet Tuttle (talk) 07:24, 6 November 2011 (UTC)

iPod full - can't delete
My daughter's ipod (3rd gen) is full. She says that she can't delete things she doesn't need because they used to show an "x" in the corner to delete them, but now they don't. How can she get the "x" back, or how can she delete things she doesn't want? Bubba73 You talkin' to me? 02:47, 6 November 2011 (UTC)
 * She should be able to connect it to whatever computer she uses to sync it to and change the playlists, etc. via iTunes. Dismas |(talk) 02:50, 6 November 2011 (UTC)


 * Hold your finger on the icon for several seconds. The "X" will appear.  Comet Tuttle (talk) 07:25, 6 November 2011 (UTC)

I'm reading emails from a Hotmail user.
He's sending messages to a YahooGroup. His emails do not appear to carry his IP. Only Yahoo and Hotmail IPs are present in the header. Odd. 66.108.223.179 (talk) 06:02, 6 November 2011 (UTC)


 * Do you have a question for the Reference Desk? Comet Tuttle (talk) 07:26, 6 November 2011 (UTC)
 * An email header does not usually contain the originators IP address. Email spoofing is also easy enough to make ANY information in the header, including the originating address, not very reliable. Vespine (talk) 05:28, 7 November 2011 (UTC)
 * The first part isn't really correct. Many SMTP servers do add the IP address of the sender in the received: from portion. Many web mail providers do add the IP either in the same way or in some other header like X-Originating-IP. When Gmail started, they were notable for not doing so. A quick test confirms Hotmail still usually seems to (in X-Originating-IP) as does Yahoo mail (in Received). You're right that spoofing means the info needs to be considered with care but a careful analysis of the received: headers will usually give you a fair idea if those are genuine which will give you an idea if the X-Originating-IP or any other such header is likely to be genuine. Remember that while the sender can add whatever bullshit they want, they usually can't stop the intermediate servers adding their own info. Nil Einne (talk) 10:37, 7 November 2011 (UTC)
 * It's possible that Yahoo Groups removes IP addresses from incoming emails before reposting them to the rest of the group, in order to protect users' privacy. --Colapeninsula (talk) 12:00, 7 November 2011 (UTC)
 * It's possible. However at least in this public (you may need to be signed in to a Yahoo account but you don't need to subscribe to the group) archive  it looks like all the headers are preserved (minus things perceived as email addresses which have been hidden) so in that case it would seem suprising if subscribers receiving the emails wouldn't also receive the full headers. In case anyone is wondering, in the first example I think the sender's IP is in the X-Yahoo-Post-IP field, I believe the sender did not actually e-mail the group but sent a message via the Yahoo groups web interface. While in the second it appears to be the bottom most X-Received and I think was sent via email via the Yahoo mail web interface. It may be there is a configurable option or perhaps they do it for lists which require subscription to view the archives (or perhaps those which require moderator approval to subscribe). Also if you are receiving a digest version, it seems likely most of the headers will be removed (although I'd be surprised if any headers showing the IP are preserved.)
 * Of course it's impossible to predict what happened in this particular case, especially without the headers itself, which should not be posted here for privacy reasons. For example, while many SMTP servers do add the IP address, I'm sure not all do. Both Yahoo's SMTP in the form of username@IP in the received: and Hotmail's SMTP in the received: and the X-originating-IP seem to. Although because of Yahoo adding it in the form of username@IP, if you are looking at web archives which hide email addresses, it's likely to be interpreted as an email address and hidden, as in this example. (I actually found out what's likely the sender's IP even in that case as Yahoo allowed me to try to send an email which as I predicted was a quick failure.)
 * This is presuming the IP really didn't show and it's not simply the OP missed it, the headers can be rather confusing when long. (Also, I know certain web mail interfaces particularly Gmail can mislead people unfamiliar with headers in to thinking 'show details' shows all the headers whereas you need something like 'show original' or 'show full headers' to see all the headers, although if the OP is seeing some IP addresses they're probably seeing all the headers.) BTW, I found that Yahoo also adds X-originating-IP when it receives messages to their mail servers but when I tested an e-mail sent from Hotmail to Yahoo Mail (not groups) it did not remove the original Hotmail X-originating-IP, so both were present.
 * Nil Einne (talk) 07:20, 8 November 2011 (UTC)