Wikipedia:Reference desk/Archives/Computing/2011 December 23

= December 23 =

Link quality, signal level in a wireless connection
What does it exactly mean? Why is the first x% and the second -xdBm? Why two variables, which appear to be the same? — Preceding unsigned comment added by 88.8.69.150 (talk) 00:06, 23 December 2011 (UTC)


 * These parameters could mean many things, depending on how the hardware, firmware, and software in your machine pre-process the data. However, the IEEE 802.11-2007 specification for PHY and MAC (...the most relevant specification for this question) defines the following (Section 4, Abbreviations and Acronyms):
 * SQ - signal quality (PN code correlation strength)
 * PN - pseudonoise (code sequence)
 * This is a quick way for a computer-system to determine how much useful power is getting from the transmitter to the receiver.
 * receiver input signal levels (802-11-14.6.15.1) - these are specified to be at least -20 dBm, or they don't count as valid signal (with some technicalities). This is a way to measure the total amount of power arriving at the receiver - from the intended transmitter and from any other source of RF noise, including other 802.11 devices.
 * The dBm is a unit used by RF engineers. It's a compromise between engineers who need to work in decibel (logarithmic scale), and engineers who need an absolute reference unit.  (Most uses of "decibel" are implicit comparison to some base signal level).  In the case of the dBm, it is "decibels, relative to milliwatts."
 * Section 19 of the spec details certain parameters that must be made available to services that interact with the 802.11 PHY; but I was not able to find a section in the 802.11 specification dictating which parameters should be plumbed up to the user-interface - this really is at the discretion of the implementer of your chip, card, system, and software. So, the GUI may be reporting any combination of specified measurements and calling it "signal level" or "link quality" in a sort of generic way.  Nimur (talk) 16:10, 23 December 2011 (UTC)

Hard drive
What is the correct model of internal hard drive for a mid-2010 model MacBook (7,1)? I think it's this one but I wanna make sure. Ten Pound Hammer • (What did I screw up now?) 05:23, 23 December 2011 (UTC)

problem with installation
whenever i want to install any program on my computer ,computer starts installing nano quest.for example when i have tried to install e-speaking software from net ,in spite of e-speaking nano quest is installed  — Preceding unsigned comment added by 119.152.60.24 (talk) 14:09, 23 December 2011 (UTC)
 * When asking for help with a bug, it is much more useful to describe the actions you took and the output you observed than to describe the goal you had and your beliefs about what the computer was trying to do. Looie496 (talk) 17:03, 23 December 2011 (UTC)