What are SDHC Cards

SDHC (Secure Digital High-Capacity) cards are flash memory cards with a minimum capacity of 4GB (gigabytes). SDHC cards provide removable memory for compatible digital devices including cameras, camcorders, PDAs, MP3 players and more. Secure Digital refers to a specific format within the flash card market. SDHC cards are designed for devices that are compatible with the SDHC 2.00 specification. Products designed exclusively to support previous SD specifications 1.0 and 1.1 will not be able to utilize SDHC cards.

The growing demand for high-capacity flash memory springs partially from the increasing use of high-definition video and high-resolution digital photography. SDHC cards meet the challenge of these demanding products not only by providing ample storage but also by introducing a new feature: classifications of data transfer speed (DTS). Consumers can get the best performance value out of their digital products by using flash memory cards that support the device's highest standards for data transfer speed. The SDHC specification 2.00 calls for cards to be classified according to the minimal sustained DTS as follows:

1. Class 2: minimum sustained DTS of 2MB/sec
2. Class 4: minimum sustained DTS of 4MB/sec
3. Class 6: minimum sustained DTS of 6MB/sec

SDHC cards are classified to guarantee a specific sustained DTS. This potentially saves consumers money, as flash cards are priced not only according to capacity, but also to speed. For example, if a product's maximum DTS is 2MB/sec, dishing out extra cash for Class 4 or Class 6 SDHC cards would be a waste of money. Conversely, devices that can utilize the 4MB/sec or 6MB/sec DTR will perform significantly better with Class 4 or Class 6 SDHC cards, respectively.

Secure Digital was forced to create a new specification for SDHC cards when the previous specification topped out at a capacity of 2GB. This occurred previously when SD cards hit the 512MB wall. The new 2.00 specification should last a bit longer, as it allows SDHC cards to reach a maximum capacity of 32GB. Secure Digital is so-named because of its ability to protect copyright content through digital rights management or DRM. Because of this, it is a favored flash memory format in the audiovisual industry. 

SDHC cards are about the size of a postage stamp. Insiders expect them to be available through several different manufacturers by summer 2006, and prices will vary. Before purchasing, be sure your device is compatible. There are several card formats available on the market, and devices are proprietary. If a device manual does not list SDHC cards, or state it is "SD specification 2.00 compatible," the device cannot utilize these cards.

What is a Wireless TV Router

A wireless TV router is a device that allows a television signal to be broadcast to other areas of the home without cables. This will allow viewing in a number of different ways, depending on the type of home equipment. For example, the wireless TV router could send a signal to a computer or a video projector for use on a large screen.

The technology behind wireless TV routers is still in the process of being fully developed. However, Apple has announced its intentions to manufacture a product known as iTV. This is essentially a wireless TV router that will allow users to download movies from a system, such as iTunes™ and then play those movies on a standard or high-definition television set. While this can be done now, it requires connecting a computer by wires to the TV set.

Another technology in development is known as WHDI, or wireless home digital interface. A number of companies are responsible for developing this technology. They include: Sony, AMIMON, Hitachi, Motorola, Samsung and Sharp. Together, these companies are setting a standard for a new type of wireless TV router that will cater specifically to high-definition applications.

The demand for a fully functional wireless TV router is growing. With TVs becoming flatter and lighter, the locations where they can be placed continues to expand. However, unsightly wires make some locations impractical, or unattractive, without a great deal of additional work, such as running wires behind walls.

Further, with more TVs in more rooms of the home, it may take a lot of extra cable to fully outfit each set. With a wireless TV router, the hardware setup would become as simple as plugging the router in and making sure each television was connected. However, before this happens, there are still some obstacles to overcome.

As with any new technology, standardization will be a big key in order to get such products on the market in an affordable and acceptable form. For those waiting for such technology, it should be encouraging that WHDI has so many industry leaders working on a product together. This helps with standardization.

Another obstacle will be existing televisions, which are not outfitted to receive wireless signals such as the kind that will be utilized by a wireless TV router. In order to take advantage of such technology, users will either have to replace television sets with sets that can receive those signals, or buy an adapter for existing televisions. So even after buying the wireless TV router, there is likely to be some additional expense.

What Is the Difference Between Mbps and MBps

MBps is an abbreviation for Megabytes per second, whereas Mbps is an abbreviation for megabits per second. Eight megabits equal one Megabyte. These abbreviations are commonly used to specify how much data can be transferred per second between two points. In some cases, mbps is used as an abbreviation for megabits per second; however, the lowercase m technically means "milli" not "mega," so it doesn't really mean the same thing.

To put megabits and Megabytes in perspective, let's back up for just a moment. One bit of data is a single "on" or "off" digit, a one or zero. It takes eight bits to represent a single character, or one byte of data.

1. 8 bits = 1 byte
2. 1000 bytes = 8 kilobits (kb) = 1 Kilobyte (KB)
3. 1000 Kilobytes (KB) = 8 megabits (Mb) = 1 Megabyte (MB)

As a point of possible confusion it should be mentioned that there are two different systems for calculating multiples of data: the decimal system as noted above, and the binary system. 

According to the binary system, used in relation to computer storage and memory, it takes not 1000 bytes to equal a KB, but 1024 bytes. This is because the binary system is base 2, and 2¹⁰ = 1024. Technically, the designations in this case are Kibibyte (KiB) and Mebibyte (MiB), but these haven't caught on in the public sector, leading many uses of "MB" to mean 1024 kilobytes, and others to mean 1000 kilobytes. When considering MBps, however, the decimal system applies, as the reference is to data transfer rates and not data storage.

Data transfer rates are quite handy for gauging performance levels of various hardware devices. Everything from USB and Firewire® ports to memory card readers and mobile devices are associated with corresponding transfer rates, often measured in megabits or Megabytes per second. 

We must also translate speed to value when considering Internet service plans, advertised by download and upload speeds expressed in kilobits per second (kbps) or megabits per second. For example, a typical Digital Subscriber Line (DSL) plan might have an upper transfer limit of 1,500 kbps, which can also be expressed as 1.5 Mbps. A cable plan might be advertised with speeds up to 5,000 kbps or 5 Mbps; and fiber optic Internet can reach speeds of 50 Mbps or more. 

The wireless G network (802.11g) has a maximum transfer rate of 54 Mbps, making it much faster than all but the fastest fiber optic Internet plans. Thankfully, going wireless won’t slow your surfing. The more current wireless N standard (802.11n) can’t speed up your Internet connection, but will allow faster data transfer rates between local networked computers of up to 100 Mbps, or about twice the data transfer rate of G networks.

As if the abbreviations aren't close enough to cause confusion, it doesn’t help that they are often expressed in the wrong case. When in doubt look for translations such as the kilobit or Kilobyte equivalent, or simply ask someone if the specification is indeed megabits per second or Megabytes per second.