The three systems studied produced signals as low as 90, 105 and 130 kilohertz
pulse was selected for underwater locator beacons on black boxes because there is nothing else in the sea that would naturally make that sound, said William Waldock, an expert on search and rescue who teaches accident investigation at Embry-Riddle Aeronautical University in Prescott, Arizona.
Sometimes they produce sounds at very low frequency, these sounds could be below 20 kilohertz
and sometime they produce sounds at very high frequency, which could more than 150 kilo hertz.
The radio frequency spectrum includes all frequencies between 3 kilohertz
(kHz) and 300 gigahertz (GHz).
According to the WHO, electric and magnetic fields in the frequency up to 100 kilohertz
can affect the nervous systems of people exposed at high levels, resulting in acute health effects such as nerve stimulation.
The Mosquito emits a whining sound at 18 kilohertz
that switches on and off four times a second for up to 20 minutes.
Using equipment designed to study the very high-pitched bleeps that bats make, scientists have found that the frog calls also include very high-pitched chirps that topped 20 kilohertz
(20,000 cycles per second)--sound frequencies that people can't hear.
His lyrical, informal prose is accompanied by scientific diagrams of pitches and notes--musical transcriptions written in kilohertz
rather than eighth notes.
Under the new advice they will now cover all the frequency ranges up to 300 kilohertz
produced by TV and radio transmissions,mobile telecommunications and the supply and use of electricity.
A maximum oscillator frequency up to 500 kilohertz
(kHz) allows the designer to benefit from smaller size magnetic components.
All H8/38004 MCUs provide an on-chip LCD controller, asynchronous event counter, 8-bit timer, 16-bit timer, 2-channel 10-bit pulse width modulation (PWM) timer, watchdog timer, 4-channel 10-bit A/D converter, serial communication interface, clock oscillator, 32 kilohertz
(KHz) sub-clock oscillator and interrupt controller.
Both models are designed to operate in a low-frequency range of 5 hertz to 32 kilohertz