# HZ

The SI unit of frequency equal to one cycle per second.

## Related Terms

### HARMONIC

1. A sinusoidal quantity having a frequency that is an integral multiple of the frequency of a periodic quantity to which it is related. 2. A signal having a frequency which is an integral multiple of the fundamental frequency.

### INFRASONIC

Having a frequency below the audible range. Frequencies above the audible range are called ULTRASONIC.

### IN-BAND RACON

A racon which transmits in the marine radar frequency band. There are two types of in-band racons, swept-frequency racons and experimental fixed-frequency racons. The transmitter of the sweptfrequency racon sweeps through a range of frequencies within the band to insure that a radar receiver tuned to a particular frequency within the band will be able to detect the signal. The fixed-frequency racon transmits on

### NATURAL FREQUENCY

The lowest resonant frequency of a body or system.

### HERTZ

A unit in the metric system used to measure frequency in cycles per second. Its symbol is Hz.

### INFRARED

Having a frequency immediately beyond the red end of the visible spectrum; rays of longer wavelength than visible light, but shorter than radio waves.

### INTERMEDIATE FREQUENCY

In super heterodyne reception, the frequency which is derived by mixing the signalcarrying frequency with the local oscillator frequency. If there are more than one such mixing process, the successive intermediate frequencies are known as the first, second, etc. intermediate frequency.

### INTERROGATION

The transmission of a radio frequency pulse, or combination of pulses, intended to trigger a transponder or group of transponder.

### ISOCERAUNIC

Indicating or having equal frequency or intensity of thunderstorms

### ISOCHASM

A line connecting points having the same average frequency of auroras