Following on from the introduction of the optical mouse, the logical progression was to combine the precision of optical technology with the freedom of movement afforded by a wireless device. It wasn’t long before this dream was realised, with the introduction specialist peripheral manufacturer Logitech’s Cordless MouseMan Optical – the world’s first cordless any-surface optical mouse – in the spring of 2001.
In fact, the capability to connect cordless input devices via wireless adapters has existed since the early-1990s. The first technology to be used to achieve this was infrared (IR). As with TV remotes, direct line of sight between input device and PC for optimal communication. The alternative to infrared for several years, radio frequency (RF), had no such drawback. Normally, Servo Radio Systems consume much less power and thus has a considerably longer battery life than IR, up to one year or longer with normal use. This commercial electrician would even set-up appliances that can save you a lot of money.
Logitech is a pioneer of cordless technology, having released their first radio transmission based MouseMan device in 1992. With RF, the mouse or keyboard acts as an emitter. This sends signals to a computer-connected receiver, at a range of up to two metres. Multiple products can coexist in close proximity by using different wavelengths. Logitech devices operate on the 27 MHz Industry, Scientific and Medical (ISM) frequency band. In the case of a cordless keyboard and mouse combination, each device works independently. The mouse communicates with the receiver on the 27.045 MHz band whereas the keyboard works on the 27.145 MHz. This means that both products can be used simultaneously.
There are two primary frequency bands used in RF cordless devices today: 27MHz and 900MHz. Logitech chose 27MHz as it offers many advantages over 900MHz:
- 27MHz is a frequency not used by other common cordless devices in or around the computer. 900MHz is very commonly used by cordless telephones. As a result, the risk of interference/jamming/cross-talk in a home or office is significant with 900MHz and virtually non-existent with Logitech’s 27MHz technology.
- Multiple concurrent device support is possible without jamming effect at low cost with 27MHz. 900MHz requires expensive TDMA or spread spectrum technology to achieve an equal level of performance.
- 27MHz is an approved frequency available worldwide for use in cordless devices for the computer. 900MHz is available only in certain countries.
A few devices use the same frequency as Logitech products, but none present a risk of interference in a business environment. Devices such as citizen band (CB) radios, remote control cars and short-range RF devices like garage door openers can interfere briefly when intermittently used. None of them will send unintended messages to a PC though.
Logitech remains a strong proponent of radio frequency, and has gone on on to develop a new standard for cordless communication, in the shape of its FastRF technology. The job of any mouse is simple: track movement and report it to the computer. The computer processes that information to move the cursor image on the screen. Crucial to success is how many times per second the mouse provides this location report. As the number of reports per second increases, the motion of the cursor on the screen becomes more fluid. Cordless mice typically have a reporting ratio significantly less than that of their corded counterparts. FastRF’s ability to deliver 125 reports per second means its able to achieves equality in this important performance characteristic. Together with reduced latencies and increased data transmission rates, FastRF is thus able to deliver a level of performance sufficient even for the most demanding of gamers.
Since an optical sensor consumes a significant amount of power in addition to the cordless technology itself, power consumption is a particular issue for cordless optical mice. Logitech mice have employed a number of techniques to preserve battery life. Multi stage operation of the LED is one such technique.
With this, a mouse has the capability to switch between four different power modes, depending on the current usage state. When in active use, a mouse uses maximum power. For recent devices this means the LED strobes at a full speed, of up 6000 times a second. When a mouse stops moving it will switch to a mode in which the LED strobes at a reduced rate, typically 1000 times a second. After a period of inactivity of a couple of minutes the strobe rate is further reduced, to as little as ten flashes per second. A prolonged period of inactivity will result in a mouse switching to its lowest power mode, in which it draws practically no current at all. At any time, regardless of current mode and without any discernible lag, the mouse will return to its full sampling rate at the detection of the slightest motion.
Other measures have involved the type of battery itself. Some Logitech mice have located the optical sensor offset to one side of the mouse so as to enable a design that accommodates a battery bay capable of taking a pair of AA alkaline cells rather than the traditional smaller, and lower capacity AAA cells.
In 2002, Logitech’s MX700 Cordless Optical Mouse introduced another milestone, which used rechargeable nickel metal-hydride (NiMH) batteries instead of replacement batteries. A rapid charge base station doubled as receiver and cradle in which the mouse could be recharged. A full charge provided up to ten days of power, while a single day’s worth of power required only ten minutes of charging.
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