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dBc (decibels relative to the carrier) is the power ratio of a signal to a carrier signal, expressed in decibels.For example, phase noise is expressed in dBc/Hz at a given frequency offset from the carrier. dBc can also be used as a measurement of Spurious-Free Dynamic Range between the desired signal and unwanted spurious outputs resulting from the use of signal converters such as a digital ...
Phase noise is sometimes also measured and expressed as a power obtained by integrating ℒ(f) over a certain range of offset frequencies. For example, the phase noise may be −40 dBc integrated over the range of 1 kHz to 100 kHz.
The decibel originates from methods used to quantify signal loss in telegraph and telephone circuits. Until the mid-1920s, the unit for loss was miles of standard cable (MSC). 1 MSC corresponded to the loss of power over one mile (approximately 1.6 km) of standard telephone cable at a frequency of 5000 radians per second (795.8 Hz), and matched closely the smallest attenuation detectable to a ...
The carrier-to-receiver noise density ratio is usually expressed in dB-Hz. The noise power density, N 0 = kT , is the receiver noise power per hertz , which can be written in terms of the Boltzmann constant k (in joules per kelvin ) and the noise temperature T (in kelvins).
Leeson's equation is an empirical expression that describes an oscillator's phase noise spectrum.. Leeson's expression [1] for single-sideband (SSB) phase noise in dBc/Hz (decibels relative to output level per hertz) and augmented for flicker noise: [2]
SFDR is usually measured in dBc (i.e. with respect to the carrier signal amplitude) or in dBFS (i.e. with respect to the ADC's full-scale range). Depending on the test condition, SFDR is observed within a pre-defined frequency window or from DC up to Nyquist frequency of the converter (ADC or DAC). [1]
The phrase "dB below full scale" has appeared in print since the 1950s, [27] [28] [29] and the term "dBFS" has been used since 1977. [30]Although the decibel (dB) is permitted for use alongside units of the International System of Units (SI), the dBFS is not.
Normal auditory systems can usually hear between 20 and 20,000 Hz. [2] When we measure sound, the measurement instrument takes the incoming auditory signal and analyzes it for these different features. Weighting filters in these instruments then filter out certain frequencies and decibel levels depending on the filter.