Megahertz

A megahertz (MHz) is one million (10⁶) hertz, a measure of frequency.

Table of contents

1 Megahertz in radio
2 Megahertz in computing
3 See also

Megahertz in radio

When used in the context of radio, MHz refers to the number of oscillations of electromagnetic radiation. Severel parts of the radio spectrum fall into the MHz range:

LF (Low Frequency) 0.03 - 0.3 MHz
MF (Medium Frequency) 0.3-3 MHz
HF (High Frequency) 3-30 MHz
VHF (Very High Frequency) 30 - 300 MHz
UHF (Ultra High Frequency) 300 - 1000 MHz

A common alternative means of describing a radio frequency is using its wavelength, though since the adoption of the hertz as an SI unit, this is becoming rare. Wavelength varies inversely to frequency, i.e., high frequencies are associated with short wavelengths.

Megahertz in computing

Most CPUss made between 1974 and 2000 were labelled in terms of megahertz (though modern computers have processor speeds in the gigahertz (10⁹ hertz) range). The number of megahertz refers to the frequency of the CPU's master clock signal.

It is often assumed that if two CPUs have different "clock speeds", the one with the higher clock speed will be faster than the other. However, while clock speed is an important factor in overall performance, many other factors influence the performance of computers, and a better comparison is archived by using benchmarks.

For example, a RISC processor, which has very simple instructions that can be accomplished quickly, may run at a higher clock rate (at higher MHz) than a CISC processor with complex instructions. But because the CISC processor accomplishes more during each clock, it may be faster for any real-world application.