One common confusion relates to the variety of wireless networking options available and what the available options are. Pretty all of today's wireless networking technologies are call 802.11x where x is a letter. The first six characters are not that important, and while the final letter is vitally important. The common technologies are 802.11A, 802.11B, 802.11G, 802.11N. The differences between these technologies are substantial.

First, you should be aware that all performance specifications provided by any of these standards are woefully overstated. Generally you will see substantially less bandwidth than promised by the standard. That said, here are the various standards and performance and radio frequency used:

1. 802.11A - 54 Mb/sec, 5 GHz
2. 802.11B - 11 Mb/sec, 2.4 GHz
3. 802.11G - 54 Mb/sec, 2.4 GHz
4. 802.11N - 540 Mb/sec, 2.4 or 5 GHz

The first thing that you should notice is the frequency differences between the standards. The first standards were A and B and they differed by both bandwidth and frequency. At the time, there was a question about which would prevail given the performance trade off. The G standard was released to solve the performance issues of B and leverage 2.4 GHz. The future standard is N which will bring an entirely new level of performance.

The other issue is that initially wireless cards only worked with A or G and not both. At the time there was a big question about which of the two technologies would prevail. Today there are cards that can do both frequencies, but it does not really matter since the 2.4 GHz technologies prevailed and A is seen infrequently.

As you look at the above performance numbers, you should always remember that they are overstated. I just ran some specific tests to illustrate. (Note all tests were running using the iPerf utility and each performance run was completed twice.)

	Performance Spec	Actual
802.11G 20 Feet	54 Mb/sec	16.5 Mb/sec
802.11G 2 Feet	54 Mb/sec	20.6 Mb/sec
100 Base-T (wired	100 Mb/sec	93.7 Mb/sec

As you can see, the wireless standards underperformed their specs. It is also interesting to compare them to wired which is spec'd at approximately 2x the performance of wireless. Yet even with that spec, we saw performance that was almost 5x faster than wireless. A very big difference.

What should I buy?
The industry has standardized on 2.4 GHz technologies and so must customers are buying 802.11G wireless devices today. This is the safe choice and is recommended.

Should I buy 802.11N since faster is usually better?
The clear answer here is no. The issue is that the N standard has not been ratified by the standards thus it is unclear if N products shipping today will be compatible with the final standard. Thus if you purchase a unit today you not only pay a premium, but you run the risk of your hardware becoming obsolete and not supporting the standard. This particularly important since in the future it is likely that this technology will be embedded in laptops.

If I have 802.11B is vitally important that I upgrade to G?
The typical answer is no unless you have very bandwidth intensive applications. I find B/G wireless to be more than adequate for every day use. The only issue is transferring large files. I sometimes copy photos across the network and notice a major performance degradation with wireless. (I use G and B would likely be even more painfully slow.) If you are working with large files over the network, you are better off sticking with wired than trying to use any of the wireless standards. I would consider upgrading to N once the standard is ratified as that technology looks like it will bring new levels of wireless performance that were previously unattainable.

One of my colleagues is in the process of buying a Digital Rebel XT. This is my current favorite camera. I am sure that my colleague will ask about what format of picture to take. Well Steve, this is for you.

There are couple of different formats that you can take with the Digital Rebel XT and equivalent Digital SLR cameras. Their are typically two different formats that you can take, JPEG or RAW. Pretty much all cameras take JPEG and RAW is something quite different. Read on for more information.

JPEG -- This is the standard format used by most digital cameras. JPEG is a lossy format meaning that when the picture is taken and the camera creates the JPEG some of the image data will irreparably lost. This may not seem like a big deal but if you then edit the JPEG and then re-save it, you lose more detail. Thus every time you edit a JPEG and re-save the image as a JPEG the quality will degrade.

There is a an upside to JPEG which is that it is the most commonly used and understood format and can be viewed in any standard web browser. The other element is that the resulting file sizes are smaller than alternatives because of the lossy nature of the algorithm.

Summary
Pros: Well understood and easily viewable, small file size
Cons: Reduced image quality, image degradation when editing

RAW -- This format is a lower level format. When you a take a picture, the sensor in the camera captures the image on its sensor and the sensor outputs the image information. In a JPEG environment, that output is then processed in camera and turned into a JPEG. The RAW file contains all of the raw from the sensor with no processing. Thus it contains all of the possible image data from the sensor and is the highest resolution image possible from the sensor.

Also because the image has not been processed inside the camera, you can fix common image problems much more easily. An example of this is improper white balance which often occurs with digital cameras. The result is that the colors in a picture are skewed and you may see a bluish tint. This is easily fixed with RAW images and is more difficult to treat with JPEG.

The downside of RAW is that it is a proprietary format for each camera manufacturer. Thus if you shoot a RAW photo and send the RAW picture to someone, it is unlikely that person will be able to view the file. This means that some element of post-processing will be required with all RAW images to convert them to a more common image format such as JPEG.

Summary
Pros: Highest resolution image, improved image editing ability
Cons: Proprietary format, larger file size than JPEG

Recommendation:
For the average photographer JPEG is adequate. However, if you are looking for the best image quality you should look at RAW. The Digital Rebel XT also has the ability to simultaneously take RAW and JPEG. This potentially overcomes the weeks of RAW, but results in more than 2x the required storage space for each picture which is problematic IMO.

I generally find shooting RAW to be the preferred method. I always take RAW and then perform a batch conversion of all RAW photos to JPEGs using Photoshop. This way I always have RAW and JPEG version of all pictures. I prefer to perform the conversion on my computer to minimize the amount of space required on my CF Card.

In today's home theater environments, quality audio is paramount. In the old days, you could connect your tape deck or CD player via simple red and white analogue component cables. These are still used today for many sources, but there are better alternatives.

Each RCA cable represents a channel of audio and so the red and white cables represent left and right audio channels. This works fine for simple two channel audio. The problem is that home theater audio has between 6 and 8 channels. In theory, you could still have six separate audio component cables, but this gets complex rapidly. The first DVD player I had included a built in AC-3 decoder and had six separate RCA output channels.

The other solution work, but is not efficient. Imagine if you had multiple AC-3 components like a DVD player, cable box and videogame system. Now you would need 18 cables (6x3) which is very complex and inefficient. A solution to this problem is another technology called an optical digital audio cable or more commonly known as a toslink cable. Here is a picture of a toslink cable courtesy of Monoprice which is a very inexpensive place to purchase these cables.

These are high bandwidth optical cables that and can provide all 6 or 8 channels through one cable. This with a Toslink cable, you can replace all six RCA connectors and cables with one one Toslink. This is the most common cable type used today. In fact my Comcast cable box has a Toslink as does my XBox and DVD player.

The other alternative to the Toslink in another cable type called digital Coax. This cable is interesting because it combines the benefits of multi-channel Toslink and with convenience of RCA connections. Basically this connection type includes what looks like a traditional RCA connector and traditional RCA cable. The different is that while you plug in standard RCA cables, the actual signal sent across the cable is digital allow for 6 or 8 channels over one cable. In many respects this is the best of both worlds, by allowing Toslink density without the need for a special cable. Unfortunately, in my experience these types of connections are less common and instead Toslink has become the standard. Note that like Toslink the signal is binary and so a cable will either work or not. I say this because many vendors will try to sell you high priced cables for this. Do not be fooled, they maybe helpful if you are running long distances, but these provide limited value in most environments. In my setup, I am just using an extra RCA cable that I had hanging around and it works perfectly.

What does this mean to me?

The answer is that you should be aware of the important of Toslink or Digital Coax cables and make sure that any receiver you purchase has a full complement of these.

I previously posted an article on HDMI vs DVI video cabling. During that post, I highlighted the difference between the two technologies. They are the best connection methodology since they are all digital. If you must use an analogue connection then you should use component. These connection methodology splits the signal up into three separate channels, red, blue and green. It does support HD and so is the best analogue option if you cannot do DVI or HDMI.

There are a number of companies promoting IP Telephony based solutions. A classic example of this is Vonage. The question I get asked is what is it and should I use it? The answer is that it depends.

The first basic answer is that IP telephony basically uses your Internet connection for phone calls. Thus if you make a call, your call does not use a phone line in your house, but rather uses your Internet connection.

Before we get into the details about which is better, we need to review the background. A traditional telephone network is switched in nature. What this means is that when you call someone, you have two dedicated connections (listen and talk) between the two people on the phone. This connection is created based off of the phone number and then is broken when you hang up. IP, the protocol used by the Internet is different. In an IP environment, data is sent in the form of packets. Thus a voice is broken into many small packets and these packets are sent over the Internet and reconstructed at the destination. The thing to be aware of is that these can travel different routes to the destination and so the order they arrive may not be the same as they were send. (e.g. A,B,C could arrive in another order e.g. A,C,B)

What does the above really mean?

Benefits of IP Telephony:

1. Cost - These services tend to be substantially less expensive than traditional telephony.
2. Portability - With these services you are identified by a unique ID to the carrier. This idea is not geographic sensitive so you could connect your device in California and still receive calls at your 617 number
3. Features - IP telephony based systems often offer more advanced functionality than traditional telephony such as web-based voicemail

Negatives of IP

1. Reliability - THis is not to say that the service providers are not reliable, but rather is a testament to Internet connections. Generally broadband networks are built much less reliably than telephone networks. For example, if your power goes off, your phones will still works and your Internet connection typically won't. Ask your self, which goes out more, Internet service or phone service? Remember the IP telephony will only be as reliable as your Internet connection.
2. ence on Internet Connection - Since the phone is based off of your Internet connection, it will be impacted by the utilization of your connection. If you download/upload large files or perform any other action that requires a substantial amount of Internet bandwidth, your phone will be negatively impacted
3. Sound Quality - This has improved dramatically over the years and is probably pretty close; however remember since IP Telephony is not using switched network, voice quality will vary depending on network utilization or Internet traffic problems.
4. 911 Service - This was an early problem with IP Telephony since it is no longer affiliated with a physical location. You should check with your carrier to ensure that 911 services work properly. In some cases dialing 911 will not work properly which is a very bad thing.
5. Service - If you have a problem you will likely have to work with your IP telephony provider and your high speed Internet provider. The problem here is that the service I have found from my Internet Provider (my cable company) is not nearly as good as that from my telephone company. The last time I had an Internet outage, it took them a week to get here and fix it. If I had IP telephony, I would have been out of service for that time. My telephone company is much more responsive.

Which would I choose? In my neighborhood, Internet connectivity is not reliable. To me reliability relates not just to my house maintaining signal, but also the network as a whole. It is not uncommon for us to lose cable signal for short periods of time every few weeks. This is not a major problem for TV, but is not acceptable for our telephones. We also lose power now and again which of course also causes problems with the Internet while our phones still work.

My general recommendation is that IP telephony is a great option for an extra phone line, but I would not recommend it for the primary house phone. There are just too many issues around support and reliability.