GHZ

GHZ or GHz may refer to:

ISM band

The industrial, scientific and medical (ISM) radio bands are radio bands (portions of the radio spectrum) reserved internationally for the use of radio frequency (RF) energy for industrial, scientific and medical purposes other than telecommunications. Examples of applications in these bands include radio-frequency process heating, microwave ovens, and medical diathermy machines. The powerful emissions of these devices can create electromagnetic interference and disrupt radio communication using the same frequency, so these devices were limited to certain bands of frequencies. In general, communications equipment operating in these bands must tolerate any interference generated by ISM applications, and users have no regulatory protection from ISM device operation.

Despite the intent of the original allocations, and because there are multiple allocations, in recent years the fastest-growing uses of these bands have been for short-range, low power communications systems. Cordless phones, Bluetooth devices, near field communication (NFC) devices, and wireless computer networks all use frequencies allocated to low power communications as well as ISM, although these low power emitters are not considered ISM.

Hertz

The hertz (symbol Hz) is the unit of frequency in the International System of Units (SI) and is defined as one cycle per second. It is named for Heinrich Rudolf Hertz, the first person to provide conclusive proof of the existence of electromagnetic waves.

One of the unit's most common uses is in the description of sine waves and musical tones, particularly those used in radio and other audio-related applications. It is also used to describe the speeds at which computers and other electronics are driven.

Definition

The hertz is equivalent to cycles per second. In defining the second, the International Committee for Weights and Measures declared that "the standard to be employed is the transition between the hyperfine levels F = 4, M =  0 and F = 3, M = 0 of the ground state 2S_1/2 of the cesium 133 atom, unperturbed by external fields, and that the frequency of this transition is assigned the value 9 192 631 770 hertz" thereby effectively defining the hertz and the second simultaneously.