The 900 MHz ISM band is currently the most popular choice for "commodity" wireless transceivers, largely because of the ready availability of attractively priced products designed for cellular telephone use. These systems typically operate at very low data-rates, and often use relatively simple high-frequency electronics. Examples include wireless data modems, intrusion alarms, remote light switching, and remote meter reading. |
The most common transmitter architecture for this band is either a modulated VCO (e.g. FM) or a simple digital scheme with frequency shift keying (FSK) or bi-phase shift keying (BPSK) modulation. The commodity nature of these applications focuses the designer on functionality at a very economic price. High performance discrete transistors are the components of choice, plus a few cost-effective integrated circuits (ICs) for higher level functions. Solutions are commonly borrowed from the high volume cordless telephone and digital cellular telephone markets.
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