SINAD

SINAD ( s ignal-to- i nterference ratio Including n oise a nd d istortion , as SND / ND hereinafter) is a measure of the transmission quality: higher SINAD value corresponds to a higher transmission quality.

SINAD describes the ratio of the total signal power , consisting of the useful signal , noise and distortion , to the sum of the interference signal , consisting of noise and distortion, of a low-frequency signal (e.g. at the output of a radio receiver ):

${\displaystyle \mathrm {SINAD} ={\frac {\mathrm {SND} }{\mathrm {ND} }}={\frac {P_{\mathrm {Signal} }+P_{\mathrm {Rauschen} }+P_{\mathrm {Verzerrungen} }}{P_{\mathrm {Rauschen} }+P_{\mathrm {Verzerrungen} }}}={\frac {P_{\mathrm {Signal} }}{P_{\mathrm {Rauschen} }+P_{\mathrm {Verzerrungen} }}}+1\geq 1}$

This ratio is usually expressed in the logarithmic auxiliary unit Bel .

In principle, the SINAD value cannot fall below 0 dB. If there is no useful signal, the numerator and denominator in the above equation are equal:

${\displaystyle P_{\mathrm {Signal} }=0\Rightarrow SINAD=1=0\,\mathrm {dB} }$

The SINAD measurement takes place e.g. B. Use in radio communication ( AM and FM ). With their help, further parameters of transmitters and receivers are measured, e.g. As the receiver sensitivity , the image frequency resistance, the intermodulation strength, etc.

To do this, however, the boundary conditions of the SINAD measurement must be specified more precisely than the above simple equation suggests:

• Frequency of the useful signal: 1000  Hz , 1020 Hz or another value.
• with or without psophometric evaluation (simulation of the frequency response of hearing ) z. B. according to A-rating or ITU-T O.41.
• Voltage measurement: effective value or quasi-peak value

SINAD values ​​measured with different boundary conditions are therefore not comparable with one another.

See also

• Effective number of bits (ENOB)
• Signal-to-noise ratio

literature

• Stefan Weinzierl (Ed.): Handbook of audio technology. Springer, Berlin et al. 2008, ISBN 978-3-540-34300-4 .
• ETSI EN 300 086-1 V1.3.1 (2008-09), Electromagnetic compatibility and Radio spectrum Matters (ERM); Land mobile service; Radio equipment with an internal or external RF connector intended primarily for analogue speech; Part 1: Technical characteristics and methods of measurement
• TIA-603-C, Land Mobile FM or PM Communications Equipment Measurement and Performance Standards, Telecommunications Industry Association, December 2004
• ITU-T O.41, Psophometer for use on telephone-type circuits, International Telecommunication Union, Telecommunication Standardization Sector, 1994
• Curt Rint (Ed.): Handbook for high frequency and electrical technicians. 13th revised edition. Volume 2. Hüthig and Pflaum, Heidelberg et al. 1981, ISBN 3-7785-0699-4 .