I started by explaining a little bit about radio waves generally. “There are radio signals that are very low frequency, with a long wavelength, as well as those that are very high frequency.”

“What do you mean? What are radio signals?”

“Radio signals are like waves in water,” I said. My wife, the science teacher, quickly brought up a picture of the electromagnetic spectrum as an illustration. “There are tiny, ultra-high-frequency gamma rays and x-rays, as well as light waves in the middle and lower frequency radio waves.”

“So there are radio waves all around us right now?”

“Radio signals are like light, only in a color you can’t see,” I explained. “Every radio device sends it signals out in all directions, hoping an antenna will pick them up. And the spectrum of all these frequencies is divided up into segments like television channels.”

Big mistake: My TiVo-raised kids have no idea what a television channel is. But they had some idea about radio stations and could understand that different frequencies could contain different information.

So I transitioned into a discussion of congestion. “The phone and the computer are like flashlights, but it’s hard to see a flashlight in a bright room. If the room has blue lights, and you turn on a red flashlight, it will be obvious. But a blue one would be almost invisible!”

“So why is 5 GHz Wi-Fi so much faster than our old network,” asked the kids.

“There are 2 reasons,” I answered. “First, the 2.4 GHz spectrum used by regular Wi-Fi is really crowded, with lots of devices sharing it. Even telephones, cameras, and microwave ovens use that frequency! Second, 5 GHz has a lot more space for everyone to share, so much that you can even use wider channels.”

“Why don’t they just make more space for regular 2.4 GHz Wi-Fi?”

“They can’t! There’s just too many other people using radio signals around there, and they can’t move them around. The same thing happened in 900 MHz, and it might eventually happen in 5 GHz, too,” I explained. “It’s important that someone regulate who uses what frequency or it would be chaos. Imagine if anyone could drive in any direction anywhere on the highway!”

“It would be pretty cool to be able to see radio waves,” one of the kids commented.

“You can,” I answered. “A friend of mine makes a little device you plug into the computer, and it allows you to see all the signals in the 2.4 GHz and 5 GHz bands. It’s used by Wi-Fi engineers to plan networks. My friend gave me one, if you’d like to see it!”

I grabbed my laptop and Wi-Spy DBx card, started VMware Fusion, and launched MetaGeek’s Chanalyzer application. In a few minutes, I had a screen full of signals in the 2.4 GHz range. Although we live in a quiet suburb with large lawns, there were dozens of devices sharing that paltry spectrum.

This is why we can't have nice things...

I then switched over to the 5 GHz band. After a moment, we saw our first 5 GHz signal. Then we saw some more, all clustered around channel 100. A quick option click on the Wi-Fi icon in the menu bar showed us that the Ruckus access point was indeed using channel 100. The only signal in the entire 5 GHz band was our own access point!

5 GHz is like a beautiful, open highway

After a while, we did see some others stray signals in the 5 GHz band. But Chanalyzer gave a wonderful visual demonstration of the contention in 2.4 GHz and the wide open spaces in 5 GHz.

I was even able to demonstrate the wider channels used by the Ruckus access point and my MacBook Pro. The kids walked away with a better understanding of electromagnetic waves, radio devices, and the rules that govern their use. Special thanks to Tech Field Day sponsors, Ruckus Wireless and MetaGeek for making this little demonstration possible!

Disclaimer: Ruckus Wireless and MetaGeek gave me the products mentioned in this post free of charge as part of Tech Field Day. I still may have had this conversation without them, but I wouldn’t have had such exciting visuals!

© sfoskett for Stephen Foskett, Pack Rat, 2012. | Teaching Science with Wi-Fi (Thanks, Ruckus and MetaGeek!)
This post was categorized as Apple, Ask a Pack Rat, Personal, Terabyte home. Each of my categories has its own feed if you'd like to filter out or focus on posts like this.

Tech Field Day events are all about the people, so I’m really looking forward to getting together with so many great folks from the Wi-Fi arena. Once again, Jennifer Huber helped organize the event, and Marcus Burton, Andrew von Nagy, Tom Hollingsworth, Rocky Gregory, Sam Clements, and Chris Lyttle will return to the event. They’re joined by newcomers, Daniel Cybulskie and Blake Krone, and 3 more “players to be named later”.

Returning presenting sponsors include AeroHive Networks and MetaGeek, and they are joined by Aruba Networks, Ekahau, Meraki, and Ruckus Wireless. One more sponsor will be named shortly.

Watch this space for more information about Wireless Field Day 2!

© sfoskett for Stephen Foskett, Pack Rat, 2011. | Wireless Field Day 2 – Silicon Valley
This post was categorized as Personal. Each of my categories has its own feed if you'd like to filter out or focus on posts like this.

As was the case with our OpenFlow Symposium in October, the public will be invited to attend the Wi-Fi Mobility Symposium in January. Free tickets will be posted at EventBrite, and will be announced on this very page! The event will also be streamed live over the Internet if you are unable to attend in person.

This post is really something of a placeholder at this point, and I will be updating it with information as the event approaches.

© sfoskett for Stephen Foskett, Pack Rat, 2011. | Wi-Fi Mobility Symposium – San Jose, CA
This post was categorized as Personal. Each of my categories has its own feed if you'd like to filter out or focus on posts like this.

Apple boasts that their AirPort Extreme base station is "5x faster" but which devices can connect?

Apple is not always quick to support new technologies, but they threw their weight behind 802.11n Wi-Fi as soon as hardware was available. They upgraded their access points, laptop and desktop computers beginning in 2006, though support importable devices lagged. But the capabilities of 802.11n devices varies widely, and today’s Apple devices are no exception.

802.11n Capability Refresh

Routers like this Cisco E4200 can hit 450 Mb/s data rate!

As I discussed in detail last week, there are four main technology enhancements to 802.11n: MIMO and multi-streaming, 40 MHz channels, 5 GHz radio spectrum, and various packet enhancements. Each of these is optional for 802.11n devices, and Apple has picked a subset to support.

Basic 802.11n devices operate in the same 2.4 GHz radio channels as earlier Wi-Fi technologies. Many also lack the multiple radios and amplifiers required for multi-stream performance, and Apple only supports 40 MHz channels in the 5 GHz range. This means that simple devices are limited to a data rate of 72.2 Mb per second. These compromises are often made to conserve power or due to physical space constraints, so portable devices like the iPhone lack the performance of full-fledged computers.

Most desktop and laptop implementations of 802.11n include radios capable of either 2.4 GHz or 5 GHz operation, and many offer two or three antennas for MIMO and multi-streaming. From 2006, Apple has offered 802.11 draft-n wireless cards in their laptop and desktop line, and all of these boast dual stream, dual frequency radios. Beginning in 2011, Apple has introduced ultra high-performance Wi-Fi offering three spatial streams and up to 450 Mb per second data rate.

When it comes to access points, Apple has aggressively moved toward 802.11n but lacks many of the features found on competitive products. The Apple AirPort line of Wi-Fi access points currently includes both the AirPort Express, with selectable frequency and dual stream support, as well as the AirPort Extreme, which supports both frequencies concurrently as well as triple stream performance. But Apple does not allow multi-streaming or 40 MHz channels in the 2.4 GHz frequency range on any device in their AirPort line.

Apple 802.11n Wi-Fi Device Capabilities

You might also want to read Which iPad is the Best Choice? and Decision Point: Comparing the 2011 MacBook Pro Models

To try to alleviate the confusion around which devices support what 802.11n features, I created the following table. Generally speaking, any Apple access point, laptop or desktop built since 2006 includes selectable 2.4 or 5 GHz support and at least dual stream capabilities. Every Apple TV also includes 802.11n Wi-Fi right out of the box. On the portable device side, both iPad generations, the iPhone 4, and the latest iPod Touch support 802.11n, though performance is limited.

Apple Devices with Limited 802.11n Support

I love my AirPort Express, but it's limited to two streams and either 2.4 or 5 GHz

Apple’s portable devices sacrifice performance for efficiency when it comes to Wi-Fi. The iPhone 4, 3rd generation iPod Touch, iPad, and Apple TV each have just one Wi-Fi antenna, so they are limited to single stream performance. The iPhone 4, iPod Touch, and first-generation iPad also lack 5 GHz radio compatibility, though the second-generation iPad and Apple TV do include it. This means that households with these popular devices cannot use 5 GHz-only networks, making the dual-band AirPort Extreme more attractive as a base station than the switchable AirPort Express.

Unsupported Apple Devices

Many readers will find that they own devices that do not support 802.11n at all, forcing them to maintain backward compatibility when deploying new Wi-Fi routers. Some very recent devices, including the iPhone 3G S and previous and the first three generations of iPod Touch, require 802.11g to connect. On the computer side of things, pre-2006 MacBook, MacBook Pro, and iMac computers lack 802.11n compatibility. But the Mac Mini is the real standout: It didn’t include 802.11n until the Core 2 Duo refresh in early 2009.

Stephen’s Stance

Apple's 5th-generation AirPort Extreme can hit 450 Mb/s data rate in combination with the 2011 MacBook Pro and iMac

It is nice to see Apple out in front with a technology like 802.11n, considering their reluctance to support Blu-Ray and USB 3.0. Although expensive, the AirPort Extreme and 2011 MacBook Pro and iMac sport top-of-the-line specs and high performance Wi-Fi. But the lack of 5 GHz support across the board means many users will stick to the crowded 2.4 GHz spectrum, limiting performance. And I’m sure owners of recent but unsupported devices (the older iPhone, iPod Touch, and Mac Mini) will be disappointed to have to stick to 802.11g.

© sfoskett for Stephen Foskett, Pack Rat, 2011. | Which Apple Devices Support 802.11n Wi-Fi?
This post was categorized as Apple, Everything, Personal, Terabyte home. Each of my categories has its own feed if you'd like to filter out or focus on posts like this.

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Subscribe to my Google Reader feed or follow me on Twitter to see these in real-time.

© sfoskett for Stephen Foskett, Pack Rat, 2011. | Back From the Pile: Interesting Links, July 8, 2011
This post was categorized as Everything. Each of my categories has its own feed if you'd like to filter out or focus on posts like this.

The Out-of-Box Experience

For more information on the Eye-Fi card line-up, see Introducing the Eye-Fi X2 Card and What Are The True Eye-Fi X2 802.11n Wi-Fi Capabilities?

The Eye-Fi Center application uses Adobe Air and has lots of tiny, fiddly buttons

The Eye-Fi comes in a pleasing package, and includes a USB SD card reader along with the SD card itself. I was happy to find Mac and Windows software pre-loaded on the card – just insert it and you are ready to install and configure the Eye-Fi Helper and Eye-Fi Center software.

Before it is useful, the Eye-Fi card must be configured in Eye-Fi Center. This includes associating it with an online Eye-Fi View account as well as any photo-sharing services you might want. The software uses Adobe Air, and the user interface is neither Windows nor Mac-like. It uses lots of tiny fiddly icons, menus, and tabs, and I found it difficult to understand what was going on at times.

"Failed to initialize the Eye-Fi card" is an all-too-common error message. Eject it and try again...

Annoyingly, the Eye-Fi Center frequently refuses to recognize my card when I insert it directly into the SD slot on my MacBook Pro. The card functions fine (iPhoto can see it and import), but the Eye-Fi Helper reports no card attached and Eye-Fi Center won’t allow it to be configured. This caused initial frustration for me, and continues to annoy. Eye-Fi blames the MacBook Pro slot for “powering down” and recommends their USB reader.

You can only configure networks your laptop can currently access, so you will see this screen often...

Adding a known Wi-Fi network requires the computer to be in range and connected, a serious limitation. I was unable to configure the Wi-Fi for my home and work LAN since I was on a trip, and it’s a hassle to move the card to the computer when I happen to be on-site. Why not let me program networks arbitrarily, perhaps in an “Advanced” menu?

Configuring Direct Mode

Configuring Direct Mode and setting up the iOS app are much more difficult tasks than expected, even for an advanced computer user. You must enable Direct Mode in Eye-Fi center with the card in the computer, then configure all devices (including the computer itself) to connect to the special network created by the card. Since it’s password protected, the Eye-Fi instructions call for a multi-step process of copying and pasting the password.

It would have been much easier if there was a way to disable the password entirely. It’s not much of a security risk – Direct Mode is only active when the card is powered on and has photos to transfer, and its weak Wi-Fi signal is limited to short range only. I would also like to be able to customize the SSID: Perhaps something without the word, “Eye-Fi” in it?

Since Direct Mode is an ad-hoc network, some operating systems (including, apparently, Mac OS X and iOS) occasionally refuse to automatically connect. When this happens, one must manually select the Eye-Fi network when a transfer is to be made. And I found that the iPhone sometimes refused to download photos in Direct Mode, even when everything appeared to be set up correctly.

Direct Mode can only connect to a single device at a time. I was testing with an iPhone, iPad, and MacBook pro and had to tell the Eye-Fi software to switch devices frequently. When you do switch, however, it re-uploads photos to the new client software, creating duplicates if online photo sharing is enabled!

A Slow and Draining Experience

When initially configured, the Eye-Fi card will upload all photos to the online service, any configured sharing sites, and any connected devices. This takes quite a while for a 14 megapixel camera.

In the case of my NEX-5, each image is about 6 MB. Each took 10 to 20 seconds to upload using my Virgin MiFi, with an inexplicable delay before and after. I tend to shoot a lot of photos at events like Tech Field Day, and the Eye-Fi/MiFi combination simply could not keep up with my demands.

I would take a few photos and then set the camera aside, leaving it on so the Eye-Fi could transfer. Contrary to Eye-Fi’s claims, this rapidly drained the (normally strong) battery in the NEX and proved unsatisfying in terms of usability.

Put simply, over the course of three days of use, my photos were never where I wanted them when I wanted them there. They would eventually upload to Flickr, but by then I was on to the next presentation or location. I couldn’t wait for the card: By day 3 I was frequently removing the Eye-Fi and using it as an ordinary SD card.

Tuning the Eye-Fi Experience

One reason my photos were so slow to upload was the sheer volume of data to be transferred. I took hundreds of photos over the course of two days, 598 to be exact. Uploading 3 GB of data over a MiFi just isn’t practical; even a standard broadband connection would have had difficulty with this kind of load.

This is a perennial complaint about the Eye-Fi, and something the company really can’t solve. Images keep getting bigger and cameras just keep getting faster. The new “wireless n” radio in the X2 series of cards is severely limited in terms of performance and does little to help.

I can think of two solutions, neither of which exploit the full potential of the Eye-Fi card:

1. “Wireless card reader” – Disable all online services and rely on Direct Mode for wireless connection to a computer, iPhone, or iPad.
2. “Selective transfer” – Configure the Eye-Fi to selectively upload only the best photos, skipping the local computer.

In both cases, many of the vaunted features of the card are ignored. Neither uses the Eye-Fi View online service, for example, and Endless Memory and the Eye-Fi Center application are skipped. But these options function, which is really the point, after all.

Stephen’s Stance

I simply cannot recommend any Eye-Fi card, even the fancy new X2 line, to average camera users. Even enthusiasts like me would be wise to curb their enthusiasm. Most features barely work in practice, and the device frequently failed to perform.

I found myself pulling the Eye-Fi card from the camera and transferring photos like any old SD card. Only Direct Mode shows any promise, and it was annoyingly inconsistent, but I did come up with two workable use cases. All in all, I’m deeply disappointed.

© sfoskett for Stephen Foskett, Pack Rat, 2011. | Hands-On Review: The Eye-Fi Connect X2 Card
This post was categorized as Apple, Personal, Terabyte home. Each of my categories has its own feed if you'd like to filter out or focus on posts like this.

The Eye-Fi X2 card packs a 200 MHz ARM CPU and limited Marvell 802.11b/g/n Wi-Fi chipset

My experience with the Eye-Fi connected SD camera card has been frustrating, but I wasn’t sure how much blame the company deserved. Uploading massive 14 megapixel photos is going to be slow over a 3G connection using any device, after all. But how fast could the Eye-Fi go on a really great wireless LAN? The company is skimpy with technical specs, but I did manage to figure out just what the Eye-Fi X2 series of cards are capable of in terms of CPU and Wi-Fi performance.

Eye-Fi claims that the X2 card line is capable of “Class 6” read and write speed inside a camera. Class 6 means 6 MB/s, and one might think this is the maximum throughput for the card. Considering that my camera can shoot seven frames per second at 14 megapixels (each image being about 6 MB in size), the Eye-Fi could not handle heavy-duty use when set to transfer all images immediately even if this was the real-world performance one could expect.

This only gets worse when one considers the Eye-Fi Pro X2 card with its RAW image compatibility. My Sony NEX-5 shoots 15 MB RAW images, about three times the size of a “fine” JPEG. This means it would take three times longer to transfer each image, a truly frustrating experience even with the fastest network.

What’s Inside?

Eye-Fi (the company) would rather that we focus on the capabilities of their card rather than its technical components. But any self-respecting geek is going to want to know what makes it tick! I’d rather not cut open my card to get a peek at the chips inside, but Eye-Fi released some official details about the components used in the X2 series of cards, and a quick Google search revealed all that I needed to know.

An official company blog post includes a cutaway image of the inside of the card as well as details about the new X2 chipset. According to Eye-Fi themselves, the X2 line includes a new engine called “Arcturus” which includes a 200 MHz ARM926 processor core. The 926 is part of the 32-bit ARM9 RISC family and includes a digital signal processor, Java acceleration, and local cache. This is not a bad chip, considering the ultra small form factor of the Eye-Fi card.

So the card has enough CPU juice to handle reasonable performance requirements, but what about the Wi-Fi chipset? Eye-Fi doesn’t say too much about the capabilities of the X2 card line, except to boast of their newfound 802.11n compatibility. But the markings on the Wi-Fi chip are clearly visible in Eye-Fi’s official photographs, and a quick search reveals very limited capabilities.

Eye-Fi Wi-Fi

You might want to refer to my 802.11n Overview

The Eye-Fi card uses a Marvell 88W8786 integrated system-on-chip WLAN controller. This is an early 802.11n chip with few features:

• The radio is capable of 2.4 GHz transmissions only, so it is incompatible with 5 GHz 802.11n networks
• Like many portable devices, a single transmit and receive antenna is used so MIMO performance gains are restricted
• The datasheet lists 20/40 MHz coexistence, so it must support 40 MHz channels on 2.4 GHz, a feature that is highly unlikely to be used given the limited number of channels there

In short, the Eye-Fi X2 card is “802.11n in name only” and does not support most of the advanced performance features users might expect. Theoretical data rate with 40 MHz channels is limited to 150 Mb/s, and throughput with 20 MB/s channels tops out at 75 Mb/s, with much less in the real world.

Stephen’s Stance

My own experience shows that the Eye-Fi X2 card takes 3 to 5 seconds to transfer a 6 MB image to my laptop using direct mode. This translates into roughly 12 Mb/s, and represents a best case scenario for image transfer. This drastically reduces the value of the Eye-Fi card when used with high-resolution cameras. Which are exactly the kind of cameras that people might have who are willing to spend more than twice as much for a connected SD card!

Then there’s compatibility. The Eye-Fi card does not support 5 GHz-only 802.11n networks. This isn’t unique – neither does the iPhone 4! But it’s bound to disappoint and frustrate some customers. Products like this are the reason I decided to set my AirPort Express (an either/or base station in terms of radio bands) to use 2.4 GHz even though it is “N-only”.

© sfoskett for Stephen Foskett, Pack Rat, 2011. | What Are The True Eye-Fi X2 802.11n Wi-Fi Capabilities?
This post was categorized as Apple, Personal. Each of my categories has its own feed if you'd like to filter out or focus on posts like this.

What does this logo really mean? It depends on the product...

Consumers and businesses love wireless networking, but the latest version of 802.11 “Wi-Fi” will leave many scratching their heads. With a confusing array of optional features, most of which are disabled by default for compatibility, today’s 802.11n products will not deliver the performance gains promised by vendors and expected by consumers. Let’s take a look at the key components of “Wi-Fi n” and consider what is included and what is not.

A Little Wireless History

Also see Jennifer Huber’s post, The History of Wireless Part One

802.11n is the fifth major revision to the 802.11 wireless Ethernet spec marketed popularly as Wi-Fi. I have been interested and involved since the very start, implementing a dead-end Raylink FHSS 802.11 network in the 1990′s, and skipping 5 GHz 802.11a before deploying 2.4 GHz 802.11b and faster 802.11g networks. Today, I use a mix of 802.11b and new 802.11n devices in both the 2.4 and 5 GHz bands.

Each of these upgrades saw a major performance boost, and each also saw broader adoption by consumers and businesses. Basic 802.11 was a revelation in mobility in the 1990′s but 2 Mb/s couldn’t support real work. After its ratification in 1999, many corporations deployed 802.11a at 5 GHz to avoid the crowded 2.4 GHz band and boost theoretical performance all they way to 54 Mb/s. At the same time, consumers began snapping up standardized 802.11b “Wi-Fi” devices, despite the crowded confines of the 2.4 GHz band and mediocre 11 Mb/s performance.

Introduced mid-decade, 802.11g would become the catalyst for a wireless networking revolution. It matched 802.11a with 54 Mb/s peak performance but was compatible with 802.11b in the 2.4 GHz band. And “wireless g” was widely implemented from consumer and business devices to public hotspots. Home deployment of mixed 802.11b/g access points is common, with an easy majority of broadband Internet subscribers sharing their connection as I do, using a single Wi-Fi router.

But my home office network is nowhere near as advanced as the corporate wireless LANs that are the workplaces of my friends from Wireless Field Day. Most are rapidly adopting 802.11n and deploying its performance-enhancing features. They use “mesh” access points for mobility and deploy wireless controllers to coordinate the network. And they sniff the airwaves for interference and rogue devices.

Four Key Enhancements in 802.11n

802.11n was designed to unify the Wi-Fi world and bring new levels of performance. It includes both 2.4 and 5 GHz radio spectrum as well as multi-stream “MIMO” radio capability, wider channels, and frame aggregation. 802.11n is even backward-compatible with 802.11 a, b, and g networks.

802.11n is a package of enhancements, most of which are optional

The 802.11n specification adds the following four key areas of improvement:

1. Frames and symbols are tuned for better performance. This includes aggregation, which reduces the overhead of data transmission by combining multiple MAC Service Data Units (MSDUs) or MAC Protocol Data Units (MPDUs). Another optional enhancement is a shorter guard interval between symbols.
2. Some 802.11g devices included multiple antennas, but true multi-antenna and multi-radio MIMO capability is new in 802.11n. “Wi-Fi n” can combine multiple data streams in the same channel to double, triple or even quadruple throughput using spatial division multiplexing (SDM), but most devices use just one or two radios, blunting the performance benefit. Space-time block coding (STBC) is another option to improve MIMO performance.
3. 802.11n is compatible with both the 2.4 GHz band common to consumer Wi-Fi devices and the 5 GHz 802.11a band. When operating at higher frequency, “wireless n” has more channels to choose from and will experience less interference from Bluetooth, portable phones, baby monitors, and other scourges of the 2.4 GHz range. But many 802.11n devices do not operate by default at 5 GHz, and some lack this capability entirely.
4. 802.11n can also use wide 40 MHz slices of spectrum, doubling performance but potentially interfering with previous 802.11 devices that used just 20 MHz at a time. This potential for incompatibility has greatly restricted implementation of this feature in the 2.4 GHz band, and such devices are required to support coexistence mechanisms. A new “green-field mode” is optional for high-throughput (HT) networks.

It is difficult to be all things to all people, so the standards bodies made many of the advanced features of 802.11n optional. This means that many “wireless n” products do not support performance-enhanzing features like multi-streaming and 5 GHz operation. In fact, many popular devices offer little more than basic 802.11n compatibility.

Even more troubling, most consumer-grade access points disable the features they do support in the name of compatibility. Buy a brand-new “Wi-Fi n” router and it probably won’t use the 5 GHz band or 40 MHz channels, and is unlikely to contain more than two radios for MIMO and SDM to exploit. Both the device and access point must support each feature to reach maximum performance.

The Current State of 802.11n

802.11n MIMO capability is specified in "axb:c" notation, as seen here

Today, many 802.11n access points support both 2.4 and 5 GHz, sometimes with a single radio but often with two. Some also include two or three antennas and can support two or three spatial streams. Properly configured, these access points can reach 300 Mb/s in throughput, but are often limited to 72 Mb/s in their out-of-box state. Many vendors specify a default configuration with 20 MHz channels and 2.4 GHz for compatibility with “wireless g” devices.

Some consumer access points (and most business ones) can be configured for full 802.11n performance in the 5 GHz band while at the same time maintaining an 802.11b/g network at 2.4 GHz. These are known as “concurrent” or “simultaneous”, as opposed to “selectable” dual-band products that only support one or the other frequency range. These offer the best of both worlds, pushing Wireless-N performance without sacrificing “wireless g” clients. But this requires the expense of multiple radios and more-complicated software.

Client devices are flexible and limited at the same time. Cost, space, and power constraints mean many devices do not support 5 GHz frequencies and multiple spatial streams. But those that do will often “fall forward” to improve performance when paired with an appropriate access point.

The latest MacBook Pro, for example, includes a 3×3:3 radio and can hit 450 Mb/s if a capable access point is available. But most PCs and tablets have just one or two radios, and some are restricted to 2.4 GHz as well. Mobile devices like my own iPhone 4 and Eye-Fi camera card are severely limited, with 802.11n included mainly for compatibility rather than performance. The iPhone 4 and Eye-Fi card are 2.4 GHz-only and 1×1:1, the iPad 2 is 2.4 or 5 GHz but still 1×1:1, and the AirPort Express I use is dual-band 2×2:2.

Stephen’s Stance

Buyers of 802.11n wireless network equipment should not assume they will see a great benefit right out of the box. Most will have to enable by hand a high-performance configuration including wide channels and 5 GHz operation. And some client devices may never reach the levels of performance expected by consumers due to hardware limitations.

It is disappointing that enhanced performance is disabled by default. But perhaps this will change as 802.11n-compatible client devices become more common.

© sfoskett for Stephen Foskett, Pack Rat, 2011. | Not All 802.11n Networks Are Alike
This post was categorized as Apple, Computer History, Features, Personal, Terabyte home. Each of my categories has its own feed if you'd like to filter out or focus on posts like this.

The Eye-Fi promises simple connectivity for digital cameras, but does it really work?

One reason the smartphones like the iPhone are gaining ground on purpose-built cameras is their instant connectivity: Take a photo and you can immediately share it on Twitter, Flickr, Facebook, or other popular sites. Wouldn’t it be great if your SLR or digital camera could do the same? This is the promise of the Eye-Fi card: It adds Wi-Fi connectivity to most popular cameras, enabling you to transfer photos directly to your laptop or the Internet. If only it worked.

Introducing the Eye-Fi

The Eye-Fi card is a marvel of engineering. Now in its second iteration (X2), the Eye-Fi is a standard SD card with a built-in Wi-Fi radio and smarts to handle connecting and transferring images. It’s really amazing to think that that tiny card has a whole computer with Wi-Fi inside it!

Check out my follow-on post to see just what lurks inside the Eye-Fi X2!

But the Eye-Fi is more than a card. It’s also an online service (Eye-Fi View), software application for Windows or Mac (Eye-Fi Center), and app for iOS or Android that enables photo sharing. The card is useless without these applications and services.

The Eye-Fi card is compatible with most cameras that take SD media, and many (including my Sony NEX-5) have special support for the card. My NEX includes an on-screen icon showing card status, and will keep the camera powered on while images are being transferred.

The X2 Generation

Last year, Eye-Fi upgraded the hardware in their Eye-Fi lineup. These new X2 cards are a huge upgrade, as you will soon see, and were enough to finally push me off the fence and buy one. I purchased a Connect X2 card at Wal Mart, which sells them for a reasonable $39, as does Amazon.

Earlier Eye-Fi cards required a known Wi-Fi network to do anything at all, limiting their usefulness. But the new X2 series (including the Connect X2 I purchased) has a “Direct Mode” capability, allowing the card to act as a limited hotspot to transfer photos to a laptop, tablet, or phone when no network is in range.

Eye-Fi Features and Services

All Eye-Fi X2 cards offer the same features and services – for a price. Even my lowly Connect X2 can be upgraded to match the Pro X2′s geotagging and public Wi-Fi support. The only really Pro-exclusive feature is RAW file transfer. But none of these added features is actually worth that much, as you will see. I recommend the base Connect X2.

Eye-Fi inexplicably leaves the Geo X2 off their comparison table. And they’re not exactly generous with the information. So here’s my own Eye-Fi comparison table, and I’ve included about the nicest regular SD card I could find.

	Patriot 32 GB SDHC	Eye-Fi Connect X2	Eye-Fi Geo X2	Eye-Fi Mobile X2	Eye-Fi Pro X2
Speed	Class 10 (10 MB/s)	Class 6 (6 MB/s)
Connectivity	SD Reader	SD Reader, 802.11 b/g/n Wi-Fi with Direct Mode
Capacity	32 GB	4 GB		8 GB
RAW compatibility	Manual import only				Yes
Sharing	Manual	Automatic to Flickr, Facebook, etc
Geotagging	No	$29.99 option	Yes	$29.99 option	Yes
Hotspot Access	No	$29.99 per year			First year free, then $29.99 per year
List Price	$84.99	$49.99	$69.95	$79.99	$106.99
Street Price	$50	$40	$70	$72	$90
Price With Geo	N/A	$70	$70	$102	$90

Direct Mode

This is the real killer feature of the Eye-Fi X2 line. When the card isn’t in range of a known Wi-Fi hotspot (and has photos to transfer) it will create its own ad-hoc network for local devices. Once connected to this network, laptops, tablets, and phones can transfer photos at Wi-Fi speed directly from the card.

I’ll write more about it in a follow-on post, but suffice to say that Direct Mode is the only feature worth paying for and it’s included free on all Eye-Fi X2 cards!

Geotagging

Geotagging seems like an awesome add-on for a digital camera, and it is surprising more don’t already include it. Sites like Flickr and applications like iPhoto make great use of location tagging, and the iPhone automatically tags all photos.

But the Eye-Fi has two major strikes against it when it comes to geotagging, and these combine to reduce the value of this feature:

1. The Eye-Fi cards don’t have a GPS receiver, so they have to triangulate location based on nearby Wi-Fi access points. This gives innacurate location data at the best of times and is completely worthless off the beaten path.
2. The Eye-Fi doesn’t tag photos when they are taken but rather when they are transferred by the Eye-Fi software. This means that any images imported directly off the card won’t have geotags.

The limited functionality of Eye-Fi geotagging means it’s simply not worth paying extra for. There goes the $69 Geo X2 from Apple, as well as the $29 upgrade for Connect X2 users.

Hotspot Support

Basic Eye-Fi models only recognize hotspots you program them for, but the top model can access a wide range of public hotspots automatically. This is also available as an extra-charge item, priced at $29.99 per year.

Hotspot access was very valuable in earlier Eye-Fi models, since there was no way to transfer photos without them. But the X2 cards, with their Direct Mode, offer a better alternative at no cost. It’s definitely not worth buying a Pro X2 card for hotspot access, since it only includes one year of service.

SDHC Class 6 and Wireless-N Speed

The Eye-Fi X2 features two performance and compatibility improvements over previous models:

1. SDHC Class 6 compatibility means the card can now keep up with today’s fast shooting and megapixel-heavy cameras. This is more important for HD video, but some cameras (like my NEX) can tax Class 4 (40 MB/s) cards in speed shooting modes, and Class 6 (6 MB/s) might not even be enough. In fact, I did encounter some “cannot write” errors when using the Eye-Fi card, and I attribute this to the card still not being fast enough!
2. The new X2 cards support Wi-Fi “N” networks. This is more about compatibility than performance, since the card can’t transfer fast enough to tax a “G” network anyway. But folks like me who have “N-only” networks at home appreciate it, however.

Neiter of these features are deal-breakers, and neither adds much to the Eye-Fi experience. But both are welcome updates and keep the cards from becoming obsolete in today’s world.

Which Eye-Fi Card Is Best?

Normally, I have to waffle a bit when recommending a purchase. After all, some people might need to drive a Ferrari, right? But the Eye-Fi is a special case, and a single answer will do:

If you decide to buy an Eye-Fi card, get the cheapest Connect X2 model and don’t bother with any upgrades.

Seriously. The added features in the upscale Eye-Fi cards are worthless in real-world usage. Don’t buy them.

1. Stepping up to 8 GB of capacity isn’t all that valuable in a connected card, and this is some seriously expensive capacity
2. Eye-Fi geotagging is just about worthless, so put it out of your mind and don’t be tempted
3. Public hotspot usage will just be frustrating, and Direct Mode allows the card to function without it

In my next post, I will discuss my real-world experience with the Eye-Fi card, and end with a disappointing recommendation.

© sfoskett for Stephen Foskett, Pack Rat, 2011. | Introducing the Eye-Fi X2 Card
This post was categorized as Apple, Personal, Terabyte home. Each of my categories has its own feed if you'd like to filter out or focus on posts like this.

AirDrop enables direct file sharing over Wi-Fi

As computers get easier to use, once-”magical” features like Wi-Fi and Bluetooth begin showing usability issues. Although every modern computer operating system includes the ability to share files locally, it is usually a major hassle setting things up. Apple intends to remedy this situation with AirDrop, a Wi-Fi-based local filesharing protocol built into Mac OS X “Lion”. How exactly does AirDrop work? Let’s take a look.

Wi-Fi Tricks

Wi-Fi is no simple technology. Modern Wi-Fi radio chipsets include multiple transmitters, receivers, and antennas. These are normally used to boost throughput for a single link, but it’s possible to do much more with these radios.

A little-known feature in Microsoft Windows is Wi-Fi virtualization, allowing certain Wi-Fi chips to act as both a client and a base station at the same time. In this way, a Windows 7 machine can simultaneously access a Wi-Fi network and share that network with multiple clients.

Another new trick for Wi-Fi is “Wi-Fi Direct”, a short range communication protocol that functions similarly to Bluetooth but uses Wi-Fi hardware instead. The first Wi-Fi Direct hardware is just beginning to appear in early 2011, in the form of chipsets from the major vendors as well as a mouse from HP and a card from Eye-Fi.

Introducing AirDrop

Apple’s AirDrop is functionally similar to a hybrid between Wi-Fi direct and Wi-Fi virtualization, but it is a proprietary Apple protocol. AirDrop allows two computers (running Mac OS X “Lion” on compatible hardware) to transfer files in a friendly, no-configuration-required mechanism direct from Finder.

AirDrop will prove useful in business and classroom settings where one must quickly and easily move files between computers. A teacher could open AirDrop and collect assignments from students or pass out new materials, and collaborators in a conference room or airport could quickly exchange information.

AirDrop Concerns

The AirDrop interface itself seems fairly robust and secure, with no permanent connections or authentication. AirDrop is only active when one clicks on the icon in Finder, and every file transfer requires permission on both the sending and receiving systems. AirDrop connections are firewalled, and it automatically encrypts all transactions using TLS, so snooping is not much of a concern either.

AirDrop support is limited to Mac OS X “Lion”, and requires modern Wi-Fi hardware from Atheros or Broadcomm. Most recent machines include capable hardware, but the early Broadcomm BCM4321 found in the early 2009 Mac Mini is not supported. And AirDrop does not use Wi-Fi Direct, being a proprietary protocol developed by Apple. This makes it unlikely that it will spread beyond the Macintosh computer range.

Apple has not indicated that AirDrop will spread to iOS devices like the iPhone and iPad, but it seems a logical and useful addition. But these devices have a very basic Wi-Fi implementation, lacking multiple spatial streams. If they do not support AirDrop and Wi-Fi simultaneously, Apple may still enable it as an either/or option.

Stephen’s Stance

Apple has aggressively moved to eliminate “superfluous” peripherals and connections, wiping out the floppy and now selling a number of machines without optical drives. AirDrop continues this progression, attacking the prime use case for USB flash drives.

One can imagine an exciting use case for this technology, but it is disappointingly limited to recent Macs running the latest operating system. It would certainly be more consumer friendly if Apple had decided to leverage Wi-Fi Direct and expanded support to PCs and iOS devices. Sadly, the only likely expansion of AirDrop is to the iPad and iPhone.

© sfoskett for Stephen Foskett, Pack Rat, 2011. | Snooping on AirDrop in Apple’s Mac OS X 10.7 “Lion”
This post was categorized as Apple, Everything, Personal, Terabyte home. Each of my categories has its own feed if you'd like to filter out or focus on posts like this.