Megahertz to Cycle per second

IBM needed a clock that could derive both the CPU timing and the NTSC color-burst frequency (3.579545 MHz) for the built-in composite video output. Multiplying the color-burst frequency by 4/3 gave 4.77 MHz — a convenient compromise that let one crystal oscillator serve two purposes. The weird number was pure engineering pragmatism, not performance targeting.

The 433.05–434.79 MHz range is an ISM (Industrial, Scientific, Medical) band that is license-free in most of Europe. Cheap remote-control key fobs, weather stations, garage door openers, and IoT sensors all crowd into it because you can legally transmit at low power without a radio license. In the US, the equivalent unlicensed band is 315 MHz, which is why European and American car key fobs are not interchangeable.

AM encodes audio by varying the wave's amplitude, which is vulnerable to electrical interference (lightning, motors). FM varies the frequency instead, making it inherently noise-resistant. FM also has a wider channel bandwidth (200 kHz vs. AM's 10 kHz), allowing it to carry the full 20–15,000 Hz audio spectrum in stereo. The MHz carrier frequency itself isn't what improves quality — it's the modulation method and bandwidth.

Intel and AMD marketed processors by clock speed — 500 MHz, 1 GHz, 2 GHz — implying faster was always better. By 2004, Intel's Pentium 4 hit 3.8 GHz but ran so hot and consumed so much power that performance-per-watt cratered. The industry pivoted to multi-core designs: instead of one core at 4 GHz, you got two or four cores at 2 GHz each, doing more total work with less heat. Raw megahertz stopped being a useful buying metric.

Bluetooth operates in the 2.4 GHz ISM band (2,400–2,483.5 MHz), which is reserved globally for unlicensed use. This avoids the need for regulatory approval in each country. The trade-off is sharing the band with Wi-Fi, microwaves, and baby monitors. Bluetooth mitigates interference by hopping between 79 channels 1,600 times per second — if one frequency is jammed, it has already moved on.

The General Conference on Weights and Measures wanted consistent named units honoring key physicists, paralleling the watt, volt, and ampere. "Cycles per second" was descriptive but wordy, and it didn't follow the pattern of one-word unit names. Heinrich Hertz — who proved electromagnetic waves exist — was the obvious namesake. The swap was official from 1960, though many engineers kept saying "cps" well into the 1970s.

In some vintage audio and ham radio communities, "cps" persists as nostalgic shorthand. More practically, it survives in teaching contexts where making the physical meaning explicit is helpful — telling a student that 440 cps means "440 complete vibrations each second" is more intuitive than "440 Hz" until they have internalised the unit. Officially, though, every standards body has switched to hertz.

Because people searching for "cycles per second to hertz" are usually reading an old textbook or datasheet that uses cps and want confirmation that it is a 1:1 equivalence — no multiplication needed. The conversion factor is exactly 1, but verifying that still saves someone a trip to the library or a forum post.

A 1950s oscilloscope might list its bandwidth as "DC to 5,000,000 cps." A radio receiver would specify "tuning range: 540 to 1,600 kc/s" (kilocycles per second). Turntable specs read "wow and flutter: 0.15% at 33⅓ cps." After 1960, "kc/s" became "kHz" and "Mc/s" became "MHz," but the underlying numbers stayed identical.

One cycle is one full oscillation — from peak to peak. One radian is about 1/6.28 of a full circle. So 1 cycle per second = 2π radians per second ≈ 6.283 rad/s. Engineers use radians per second in equations where angular measure matters (torque, rotational inertia), and cycles per second (hertz) when counting whole oscillations. Forgetting the 2π factor is one of the most common mistakes in physics homework.