Connecting to Wifi When You're Traveling

Almost time for a vacation?  Jim Hamm wants us to know about connecting to wifi and SNR (signal to noise ratio).  He informs us, "When traveling, I'm trying to connect to wifi access points in RV parks and motels with my computer, often with poor success. I may show a good RSSI (Received Signal Strength Indicator) but yet have a poor connection to the net. In other words, a strong wifi signal, but perhaps unable to connect to the internet. The problem may be too much 'noise' interfering with the signal. To determine this, you need to calculate the signal to noise ratio (SNR)." Jim goes on to explain, "In the RV park I'm presently in I have a very good SNR. The signal strength is -49 dBm and the noise level is -95 dBm -- a spread of 46, which is good. The minimum spread show be at least 20 dB. I'm using a wifi booster, the Engenius EOC 1650, which gives a lot of detail about all the various wifi signals that show up in the park. Even with this, the download speed is slow (that's all the vendor provides), but I can connect and use the internet okay. "Here is a review of the Engenius EOC 1650. It's available on Amazon. "There are other similar wifi boosters available, and some plug directly into a USB port on your computer. The Engenius booster requires electricity and plugs into your computer via an ethernet cable. "Following is an article explaining more about this. At the end are some links you might look at to help you get the SNR ratio,".Jim suggests. When performing a radio frequency (RF) site survey, it's important to define the range boundary of an access point based on signal-to-noise (SNR) ratio, which is the signal level (in dBm) minus the noise level (in dBm). For example, a signal level of -53dBm measured near an access point and typical noise level of -90dBm yields a SNR of 37dB, a healthy value for wireless LANs. Don't let the unit "dB" throw you -- it merely represents a difference in two logarithmic values, such as dBm. SNR Variance Impacts Performance The SNR of an access point signal, measured at the user device, decreases as range to the user increases because the applicable free space loss between the user and the access point reduces signal level. An increase in RF interference from microwave ovens and cordless phones, which increases the noise level, also decreases SNR. SNR directly impacts the performance of a wireless LAN connection. A higher SNR value means that the signal strength is stronger in relation to the noise levels, which allows higher data rates and fewer retransmissions -- all of which offers better throughput. Of course the opposite is also true. A lower SNR requires wireless LAN devices to operate at lower data rates, which decreases throughput. I recently ran user-oriented tests to determine the impacts of SNR values on the ability for a user to associate with an 802.11b/g access point and load a particular webpage. For various SNRs, here's what I found for the signal strength (found in the Windows radio status), association status, and performance when loading the  http://wireless-nets.com/staff.htm webpage from a wireless laptop. To ensure accurate comparisons, I cleared the laptop's cache before reloading the page: 40dB SNR = Excellent signal (5 bars); always associated; lightening fast. 25dB to 40dB SNR = Very good signal (3 - 4 bars); always associated; very fast. 15dB to 25dB SNR = Low signal (2 bars); always associated; usually fast. 10dB - 15dB SNR = very low signal (1 bar); mostly associated; mostly slow. 5dB to 10dB SNR = no signal; not associated; no go. These values seem consistent with testing I've done in the past, as well as what some of the vendors publish. SNR Recommendations Based on this testing, I recommend using around 20dB as the minimum SNR for defining the range boundary of each access point. That ensures a constant association with fairly good performance. Keep in mind that the corresponding level of performance only occurs at the boundary of each access point. Users associating with access points at closer range will have higher SNR and better performance. When measuring SNRs, be sure to use the same radio card and antenna as the users will have if possible. A variance in antenna gain between the survey equipment and user device will likely result in users having different SNR (and performance) than what you measured during the survey. Changes made in the facility, such as the addition of walls and movement of large boxes, will affect SNR too. Thus, it's generally a good idea to recheck the SNR from time-to-time, even after the network is operational. http://www.metageek.net/products/inssider/ http://istumbler.net/ (for Mac) http://www.softpedia.com/get/Network-Tools/Network-Monitoring/NetStumbler.shtml  (for PC)

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Format Both a Mac & a PC

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If you need to transfer files between a Mac and a PC, the only way to do that is by using either a USB flash drive or an external hard drive that is formatted with the exFAT format. You do need a blank flash drive or a blank external drive. Almost any new external drive you buy will have the correct format, but to be certain you should check the format with Get Info on the drive. To format a drive as exFat, open Disk Utility and click on the drive to be formatted in the left column. Then click on the "Erase" tab. In the window that pops up, choose "exFAT" for the Format option. Name the drive something that will remind you what the format and size is. Click "Erase". You can now use that drive on both a Mac and a PC - as long as the PC isn't running Windows XP (which doesn't support exFAT format).

The DOS format isn't supported on a Mac, so please don't use that.

What About Battery Backups?

        Have you wondered about those battery backups like Trip-Lite and APC?  John Carter has some information that will help solve the question.      
        John gets our attention here: "There’s nothing like a chit-chat between a disillusioned user and an expert to clear up misconceptions about something. This is the case regarding battery backups and why they sometimes do not last as long as the warranty. The conversation in this online thread at HardwareAnalysis.com about battery backups is really worth reading from top to bottom. You’ll find out why choosing the right battery backup for your electronic devices is essential and come away understanding why one with a two year warranty would fail long before its time or may last much longer. The expert also identifies several specs to consider aside from just the power rating. Naturally, the more demanding your needs are the more costly the battery backup will be."
        John goes on, "To figure out what size of battery backup is needed, total up the power consumption of all the devices you want to protect and buy a battery backup that can provide at least that much power.
        "For instance, the Tripp-Lite sold at Costco is rated at 500W. I use these units throughout my house to protect everything electronic: one in the bedroom for the entertainment system there, another in the living room for that entertainment system, and one each for the two computer systems in the study.
        "I doubt that any combination of components for a computer system would exceed 500W. However, a 21” iMac draws about 200W and hence dictates that a 300W battery backup (Tripp-Lite here or APC here) is the minimum to use."
        Here John concludes, "Also, depending on the number and type of components in an entertainment system the total power could exceed 500W (an A/V receiver rated at 100W per channel draws 500W total for a 5.1 speaker system at full volume) and warrant more than one battery backup device."

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Tips 'N Tricks Now on PMUG Site

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         There's a new page in the PMUG website called Tips 'N Tricks. The very first article submitted is by John Carter and the title is "Using One Time Machine Device for Two or More Apple Computers." Check it out! Go to www.pmug.us/  and click on the Benefits tab to see the drop-down menu, then click on Tips 'N Tricks. Enjoy!
        Then submit your own articles by sending an email to the website administrator.  Go to About Us and scroll down to Contact Us.

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How to Access Mac's Files on Your PC

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        John Carter writes, "This handy tip is shamelessly stolen from here and edited by me for Lion and Windows 7 users."

How to access a Mac’s files on your PC

        You've got both Macs and PC's on your home network, and you want to share files between them. Yesterday we ran down the steps for mounting a Windows shared folder on the Mac. Today the tides have turned.
       Read on for the details on how to read and write files to a shared Mac folder from your PC.
       Enable Windows sharing. First, on your Mac, in System Preferences, click on Sharing. Under Sharing, check the box for “File Sharing." When File Sharing is turned on, it will look like this:

       Take note of the text on that dialog that reads "Windows users can access shared folders on this computer, and administrators all volumes, at \192.168.0.10." Your address will be different, obviously, so write it down.
       The image above shows many more Shared Folders and Users than will be shown the first time. You need to add folders (click the + sign under Shared Folders) and select folders you want to share from the Finder window that pops up. Next, for each Shared Folder, add Users (click the + sign under Users) and select the permissions you want each user to have. The Users added must exist as a login on the Mac.
       Next, click on Options...   You should see this:

       If the first box is checked, other Macs will be able to see this Mac. If the second box is checked, other PCs will be able to see this Mac. For PC only access, only check the second box. If the top box is checked, you will see the following in the main window (even if the second box is also checked):

       The afp address shown is for Macs and is used only when just the top box is checked. If both boxes are checked or if only the second box is checked, replace afp with smb.
       Connect to your Mac from Windows. In Windows XP, from the Start menu, open the Run... dialog, and type the address you wrote down in the step above. Instead of the less-than-memorable IP address, you can use your computer's name, too. My Mac's name is nyx, so the sharing address I used is \nyxgina:

For Windows 7, type the IP address into the search bar:

       Or use the computer name: \Johns-MBPjcarter
       Windows will open a regular Explorer window that's peering in on your Mac user's home directory. If you have "show hidden files" enabled in Windows like I do, you'll see all of the Mac's hidden "dot" files and folders in the listing, like here:

And that's that! You're happily saving files to your Mac from your Windows PC. Isn't it nice when we all get along? Share your Mac and PC networking tips in the comments.— Gina Trapani

Questioning iCloud's Future

          What are the ramifications of iCloud, and what is its future?  David Passell found this and says, "Though this only appears to affect Mac users in Germany, it might be something to consider for iCloud's future. I personally do not like the idea of entrusting my data, etc. to some unknown agency. To me, iCloud reminds me of the time when workstations all were connected to some large central computer. Is this progress, or a way to control and make money, for someone, from your on-line activities?"

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Inside the Factory

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Jim Hamm sends this video of a visit inside a Foxconn factory where the iPad is manufactured.  He comments, "Very interesting to see what it is like to work there. When you see the crowded dorms, keep this in mind when you see the homes where the employees came from."For some reason all the criticism about working conditions in China's factories tend to focus on Apple's suppliers. I wonder where is the criticism about all the other computer, TV, etc., manufacturers that build and import products from China?"

Want a Different Start Page?

Want a start page that's different and handy to use?  Jim Hamm thinks you might.  Get background on modifying your start page and other tips and tricks here.  "Was interesting to click a few to just see what it was all about,"Jim explains.  What impressed me the most was viewing the archive which is up to date to "17.02.12" and reading that the writer is a 21 year old guy who's started blogging early in 2007.

New Approach to Introducing New OS

        An impressive one-on-one briefing given to John Gruber, of Daring Fireball, on Thursday by three top Apple men deserves special mention.  Jim Hamm sends us this article concerning Mountain Lion.  (If reading white print on dark background aggravates you remember to do Control + Option + Command with the number 8 key to toggle to an easier-to-read black print on light background.)

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MIT Offers Online Course

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        Of course, the word FREE catches our attention.  Jim Hamm knows that.  He sends this article and writes, "Here's an interesting concept being offered by MIT: a free online course. MIT acknowledges it can only accept and teach a very small amount of people that would like to attend there. This is a way to broaden MIT's exposure and expertise to the world. Will be interesting to see how this concept works out."
        Massachusetts Institute of Technology announces its first FREE course which begins March 5 and runs through June 8; see the interesting details.

iBook Update

        Here's the latest from Jim Hamm on the subject of iBook.  "One major advantage, in theory, of an ebook over a printed book is the ability to do updates electronically. Imagine how handy, and cost effective, this would be for text books for schools or on-the-job training manuals. Here's one writer's comments on his experience of updating a book he recently purchased from iBookstore.  
        "(A side note: the Scottsdale Library just notified me this same book is ready for me to pick up and read today. I'm looking forward to reading it). One responder to this article mentions an item I hadn't considered: how does one know which part, or parts, of the book has been changed?
        "What if, say, you have a big medical textbook and a notice comes out there are important changes to the book. How does one know where they are? Do you have to scan the whole book? Nah, that doesn't make sense. Do changes come out in red or bold or italicised?  An intriguing question, and one that surely has been addressed. I just haven't read about it yet."

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Mountain Lion Drops X11

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        "Apple is encouraging users to install and use XQuartz instead of X11," according to John Carter.  He continues, "In fact, X11 is not included in Mountain Lion. This article explains.
        "XQuartz is a community-supported version of the X11 windowing system for Mac OS-X 10.6.3 or later. Please visit http://xquartz.macosforge.org for more information.
        "I have been using XQuartz instead of X11 in Snow Leopard and Lion for some time. However, I am unable to delete X11 (even on Lion) because it claims to be required by the OS; it seems apparent that they are sharing some of the same files. Having both installed has not been a problem. I don’t know if X11 will be automatically deleted when I upgrade to Mountain Lion.
        "For anyone using GIMP, they must have either X11 or XQuartz installed. When XQuartz is running, the menu name is still X11, so unless you look for the version info you won’t know which one is running. Both X11 and XQuartz may be running at the same time, but launching one will not launch the other.
        Here’s what XQuartz looks like in the Dock:

And here’s what X11 looks like in the Dock:

It is not necessary to run Xquartz (or X11) all the time, but once it is launched (it will launch automatically when GIMP is launched), it stays running until you manually quit X11.

When launching either X11 or XQuartz, a terminal window will also launch, but this terminal is an X11 version of Terminal.

Here’s the title bar for the X11 terminal window:

And here’s the title bar for the Terminal window:  


If you have an X11 terminal window open, you really don’t need to also launch Terminal.
        John's closing words, "You can close the X11 terminal window if you don’t want to see it, but you should not close XQuartz (or X11) if you have GIMP or some other application open that requires X11. When launching GIMP, the X11 terminal window will also open. Closing the X11 terminal window will not close GIMP."

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Mountain Lion Makes RSS Changes in Mail

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          Changes?  Oh, yes.  Jim Hamm must be frowning as he sends us this: "Here are a couple of articles:   One and the other one, describing changes coming in Mountain Lion. I'm gonna miss the RSS feed into Mail, which I presently use quite a bit.  He quotes this part, "Look to the right, and you may notice Safari’s first major missing feature: RSS. It looks as though Really Simple Syndication was just not simple enough for Apple; the company has excised RSS entirely from Safari (and from Mail as well), leaving feed-parsing to external applications such as NetNewsWire or Reeder. If you have such a program installed and attempt to type in or click on a 'feed://' address, Safari will automatically punt you to your respective program;
otherwise, it displays an error."
        Jim has two comments,  "Darn! I liked having the RSS feed available in Mail. This is 'progress'?" However, he goes on to say, "A new feature in Mail is the ability to designate an email from a particular sender--such as 'Moi'--as a VIP...(grin)."

iPhone 4 Settlement Announced

        Jim Hamm informs us about the settlement, explaining "You might want to bookmark this site for future reference: www.iPhone4Settlement.com. It's not active yet, but later on it appears you will be able to get $15, or a bumper case, if you bought an iPhone 4. This will cost Apple a pretty penny, I suspect."
        He sends this link to MacDailyNews, also read about it here.