Gigahertz, commonly abbreviated GHz, refers to frequencies in the range of billions of cycles per second. Giga is the standard multiplier for 1 billion and Hertz is the standard unit for measuring frequencies, expressed as cycles or occurrences per second. One GHz is equivalent to 1,000 megahertz (MHz).
Bluetooth® systems operate in the S-band, a spectrum from 2 to 4 GHz.
Most commonly, gigahertz is used to discuss computer performance or radio frequencies. In computers, it usually refers to the clock speed of the central processing unit ( CPU ); the faster the CPU clock can run, the faster, in general, the computer can process data and instructions. In 2000, Intel and Advanced Micro Devices reached a technical and marketing milestone by releasing the first CPUs to run at 1 GHz, and speeds have increased considerably since then.
In computers, the clock speed of the central processing unit is measured in GHz.
In radio communications, GHz is used to define bands of the electromagnetic spectrum, with different bands designated for different uses. The S-band, for example, is a spectrum band between 2 and 4 GHz. Common technologies such as Bluetooth®, wireless internet (WiFi™) and cordless phones operate in the S band. The L band, between 1 and 2 GHz, is used for satellite communications and global positioning systems, or GPS. Other notable bands include Ku and Ka, used by satellites as well as police radar weapons.
Cordless phones operate in the S band of the electromagnetic spectrum between 2 and 4 GHz.
Devices that transmit on or near the same band can interfere with each other. This is caused by the wave nature of radio waves; peaks in one wave can be offset by lows in the other wave, thus canceling out both waves. The closer the two signals are in frequency, the more pronounced the effect. Microwave ovens, for example, can interfere with Internet connections because they emit radiation at the same frequency as WiFi™ routers. Likewise, Bluetooth® and WiFi™ compete for the same frequencies and using them simultaneously can affect throughput.
The use of GHz frequencies for communications has been made possible by advances in semiconductor technologies. Before the widespread use of transistors and high-speed electronics, it was not practical to generate such high frequencies.
Communication satellites use the L-band between 1 and 2 GHz.