kHz (Kilohertz): Meaning & Facts

A kilohertz (kHz) is a unit of frequency measurement equal to 1,000 hertz or 1,000 cycles per second. It is commonly used to measure frequencies across many fields including audio, radio, computing, and telecommunications.

The hertz (Hz) is the standard unit of frequency measurement, representing one cycle per second. Adding the metric prefix “kilo-” to hertz denotes multiplication by 1,000, so 1 kHz represents 1,000 cycles per second. Understanding kHz gives insight into wave and signal frequencies across electronics, physics, and more.

Some key facts about the kilohertz unit:

• kHz measures the number of oscillations, cycles, or waves per second.
• 1 kHz = 1,000 Hz (hertz)
• High kHz indicates a high frequency, low kHz indicates a low frequency.
• The kilohertz range covers radio waves, sound waves, computer clocks, and more.
• kHz helps characterize frequencies and bandwidth for technologies using transmitting signals.

As an important metric unit, kilohertz has many applications spanning audio frequencies, radio frequencies, computing speeds, and telecommunication bandwidths. The specifics of these key uses of kHz will be explored in this article.

What is a Kilohertz?

A kilohertz (kHz) is a unit used to measure frequency, referring to the number of cycles per second of a periodic signal. One kilohertz is equal to 1,000 Hertz or 1,000 cycles per second.

The kilohertz is commonly used to express frequencies of digital devices and communications signals. For example:

• AM radio stations are assigned frequencies between 535 kHz and 1705 kHz
• FM radio stations transmit between 87.5 MHz and 108 MHz, or 87,500 to 108,000 kHz
• A standard computer clock speed of 3 GHz equals 3,000,000 kHz
• 4G LTE mobile networks use frequencies ranging from 600 MHz to 2.6 GHz, or 600,000 to 2,600,000 kHz

So in electronics and telecommunications, the kilohertz is a useful unit to precisely specify the rapid oscillations of alternating electric currents and electromagnetic waves for transmitters, circuits, processors and other devices.

Uses and Applications

Kilohertz measurements are commonly used to reference the frequencies found in radio broadcasting, television broadcasting, computing, mobile networks, audio systems, and other telecommunications applications. Some specific uses and applications of kHz include:

• Measuring audio frequencies – The human hearing range falls approximately between 20 Hz to 20 kHz. Audio equipment and signals are often measured in kHz or kHz ranges.
• Measuring radio frequencies – AM radio operates between 535 to 1605 kHz. Shortwave radio operates between 2.3 and 26.1 MHz, often referenced in kHz. VHF FM radio uses 88 to 108 MHz, also referenced in kHz.
• Computer clock speeds – Computer processor speeds are measured in megahertz (MHz) and gigahertz (GHz), which are multiples of kHz.
• Mobile networks – Cellular networks like 2G, 3G, 4G, and 5G use frequency ranges from 700 MHz to 2.5 GHz, referenced in kHz or MHz.
• Television broadcasting – Analog TV uses frequencies between 54 to 890 MHz, while digital TV uses frequencies between 170 to 700 MHz, both referenced in kHz.

Kilohertz measurements allow these systems to precisely define and regulate the frequencies used for transmission and reception across many telecommunications applications.

Measuring Audio Frequencies

kHz is commonly used to measure audio frequencies that are audible to the human ear. The generally accepted standard audible frequency range for humans is from 20 Hz to 20,000 Hz (20 kHz) (source). Lower frequencies around 20-200 Hz are perceived as bass sounds, while higher frequencies around 2,000-5,000 Hz are perceived as treble sounds.

Audio frequencies are measured in Hz or kHz to describe the number of sound wave cycles per second. A sound wave at 1 kHz means there are 1,000 cycles per second. The higher the kHz measurement, the higher pitched the sound.

Most adults can hear sounds up to around 16-18 kHz. Newborns can hear sounds up to 20 kHz, but high frequency hearing decreases with age. By age 55, most adults can only hear up to 12-15 kHz. Understanding the full human audio frequency range in kHz helps audio engineers optimize recordings for human hearing (source).

Measuring Radio Frequencies

AM radio signals typically operate in the frequency range of 535-1605 kilohertz (Radio Broadcast Signals). The AM radio band occupies frequencies between 535 kHz and 1705 kHz in the United States. Common frequencies include 540, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1220, 1250, 1300, 1350, 1400, 1450, 1500, 1550, and 1600 kHz.

FM radio stations are found in the VHF band from 88 to 108 MHz. This corresponds to frequencies from 88,000 kHz to 108,000 kHz (Why Do FM Frequencies End in an Odd Decimal?). FM frequencies are separated by 0.2 MHz (200 kHz) increments. Common FM radio frequencies include 88.1, 88.3, 88.5, 88.7, 88.9, 89.1, 89.3, 89.5, 89.7, 89.9, 90.1, 90.3, 90.5, 90.7, 90.9 MHz and continuing up to 107.9 MHz.

Computer Clock Speeds

The clock speed of a computer’s CPU is measured in hertz, which refers to clock cycles per second. Specifically, megahertz (MHz) or gigahertz (GHz) are used to describe CPU speeds.

A CPU’s clock cycle is the basic unit of time for the processor. Each tick moves the CPU one step forward in executing instructions. A 1 MHz CPU performs 1 million clock cycles per second. A 1 GHz CPU performs 1 billion cycles per second.

Higher clock speeds allow a CPU to perform more instructions per second, which generally leads to faster processing and responsiveness. However, clock speed alone is not the sole determinant of performance. Factors like architecture, cores, and cache also play a role.

Tools like HWiNFO64 and Ryzen Master can monitor CPU speeds in real-time. But the reported speeds may differ between tools based on how measurements are calculated. For example, HWiNFO64 factors in power states and CPU usage, while Ryzen Master shows a static default speed (according to this Reddit discussion).

Mobile Network Frequencies

Modern mobile networks like 4G and 5G rely on a range of radio frequencies measured in kilohertz to transmit voice calls and data. 4G networks typically operate between 700MHz to 2600MHz, which translates to frequencies between 700,000 kHz and 2,600,000 kHz.

5G networks utilize even higher frequency ranges, including mid-band frequencies from 2.5GHz to 3.7GHz (2,500,000 kHz to 3,700,000 kHz) as well as high-band millimeter wave frequencies between 24GHz to 40GHz (24,000,000 kHz to 40,000,000 kHz). The higher frequencies used by 5G allow for faster data speeds and lower latency compared to 4G LTE networks.

Using higher frequency signals in the kilohertz range allows these advanced mobile networks to transmit more data bandwidth. However, there is a tradeoff as higher frequencies do not travel as far and can be impeded by physical obstacles like buildings and walls. To compensate, 5G networks utilize smaller cell sites and more advanced radio techniques to provide consistent coverage.

Television Broadcasting

Television channels operate within designated frequency ranges that vary by region. In North America, TV broadcasting uses several frequency bands in the VHF and UHF ranges:

• 54-72 MHz (VHF channels 2-4)
• 76-88 MHz (VHF channels 5-6)
• 174-216 MHz (VHF channels 7-13)
• 470-608 MHz (UHF channels 14-36)
• 614-698 MHz (UHF channels 38-51; being reallocated for mobile broadband)

Most TV stations operate between 54-698 MHz, although some low-power stations use higher frequencies. Each standard 6 MHz TV channel is assigned a specific frequency number. For example, channel 2 operates between 54-60 MHz and channel 13 operates between 210-216 MHz in the VHF band. In the UHF band, channel 14 uses 470-476 MHz while channel 51 occupies 698-704 MHz.

The exact channel plan differs slightly between NTSC, ATSC, DVB-T, and ISDB-T standards. But in general, VHF wavelengths between 1-2 meters work better for long-distance over-the-air broadcasts, while the shorter UHF wavelengths under 1 meter are more susceptible to interference.

Source: https://en.wikipedia.org/wiki/Television_channel_frequencies

Other Applications

kHz measurement has some other notable usages beyond audio and radio frequencies:

In electronics, kHz is used to measure the clock speed of various computer components like the CPU, RAM, and GPU. Higher kHz generally indicates faster performance. For example, a 3 GHz CPU has a clock speed of 3000 MHz or 3 million kHz (Source).

In wireless technology, mobile networks like 2G, 3G, and 4G LTE rely on different frequency bands measured in kHz or MHz. For instance, most 4G LTE networks operate between 600-2600 MHz (Source).

Some scientific and medical devices use kHz frequencies for imaging, measurement, and treatment applications. For example, ultrasound imaging operates at 1-20 MHz, while MRI machines use RF pulses in the kHz to MHz range.

Overall, the kHz unit provides a standard way to quantify frequency across many technical and scientific fields beyond just audio reproduction.

Conclusion

Throughout this article, we have explored the meaning and uses of the kilohertz (kHz) unit of frequency. To summarize:

• A kilohertz represents one thousand cycles per second of a periodic phenomenon like sound or radio waves.
• Measuring frequencies in kilohertz allows us to quantify the audio frequencies of music, animal calls, etc. The normal human hearing range is 20 Hz to 20,000 Hz.
• Radio frequencies are also measured in kilohertz. Common radio bands range from hundreds of kilohertz to hundreds of megahertz.
• Computer processor speeds are benchmarked in gigahertz as a measure of their clock cycles per second.
• Mobile networks operate on various frequency bands in the kilohertz, megahertz, and gigahertz range.
• Analog television broadcasting used VHF and UHF channels from about 50 MHz to 1 GHz.

Being able to measure cycles per second in kilohertz has many important practical applications. It allows us to characterize and compare the frequencies used by various technologies and natural phenomena. Understanding these measurements also helps engineers choose appropriate frequencies when designing new systems and devices. The kilohertz is a vital unit for quantifying our technological soundscape.