SNDR

The signal-to-noise and distortion ratio (SINAD) is a measure of the quality of a signal from a communications device, often defined as

:$$

\mathrm{SINAD} = 10\log_{10} \frac{P_\text{signal} + P_\text{noise} + P_\text{distortion}}{P_\text{noise} + P_\text{distortion}},

where $P$ is the average power of the signal, noise and distortion components. The noise power term can include both thermal noise and quantization noise. SINAD is usually expressed in dB and is quoted alongside the receiver RF sensitivity, to give a quantitative evaluation of the receiver sensitivity. Note that with this definition, unlike SNR, a SINAD reading can never be less than 1 (i.e. it is always positive when quoted in dB).

When calculating the distortion, it is common to exclude the DC components.{{citation |url=https://www.maximintegrated.com/en/design/technical-documents/tutorials/7/740.html |title=Tutorial 740 : Glossary of Frequently Used High-Speed Data Converter Terms |format=[https://pdfserv.maximintegrated.com/en/an/AN740.pdf PDF] |publisher=Maxim Integrated |date=2001-12-17 |access-date=2021-04-25}}

Due to widespread use, SINAD has collected several different definitions. SINAD is commonly defined as:

1. The ratio of (a) total received power, i.e., the signal to (b) the noise-plus-distortion power. This is modeled by the equation above.{{Cite web|url=https://www.electronics-notes.com/articles/radio/radio-receiver-sensitivity/what-is-sinad-signal-to-noise-and-distortion.php|title=What is SINAD {{!}} SINAD Measurements {{!}} Electronics Notes|website=electronics-notes.com|access-date=2019-03-24}}
2. The ratio of (a) the power of a test signal, i.e. a sine wave, to (b) the residual received power, i.e. noise-plus-distortion power. With this definition, it is possible to have a SINAD level less than one. This definition is used in the calculation of effective number of bits (ENOB) for DACs{{Cite journal|date=2012-02-01|title=IEEE Standard for Terminology and Test Methods of Digital-to-Analog Converter Devices|journal=IEEE STD 1658-2011|pages=1–126|doi=10.1109/IEEESTD.2012.6152113|isbn=978-0-7381-7147-0 }} and ADCs.{{Cite journal|date=2011-01-01|title=IEEE Standard for Terminology and Test Methods for Analog-to-Digital Converters|journal=IEEE STD 1241-2010 (Revision of IEEE STD 1241-2000)|pages=1–139|doi=10.1109/IEEESTD.2011.5692956|isbn=978-0-7381-6239-3 }}

Information on the relations between SINAD, ENOB, SNR, THD and SFDR can be found in the footnotes of this article.{{citation |url=https://www.analog.com/media/en/training-seminars/tutorials/MT-003.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://www.analog.com/media/en/training-seminars/tutorials/MT-003.pdf |archive-date=2022-10-09 |url-status=live |title=Understand SINAD, ENOB, SNR, THD, THD + N, and SFDR so You Don't Get Lost in the Noise Floor |last=Kester |first=Walt |publisher=Analog Devices, Inc. |date=October 2008 |access-date=2021-04-25 |others=MT-003}}

A typical example, quoted from a commercial hand held VHF or UHF radio, might be:

:Receiver sensitivity: 0.25 μV at 12 dB SINAD.

This is stating that the receiver will produce intelligible speech with a signal at its input as low as 0.25 μV. Radio receiver designers will test the product in a laboratory using a procedure, which is typically as follows:

• With no signal present on the input, the noise and distortion of the receiver are measured at a convenient level.
• A signal is applied to the input such that the output increases by 12 dB.
• The level of the signal needed to produce this is noted. In this case, it was found to be 0.25 microvolts.

According to the radio designer, intelligible speech can be detected 12 dB above the receiver's noise floor (noise and distortion). Regardless of the accuracy of this output power in regards to intelligible speech, having a standard output SINAD allows easy comparison between radio receiver input sensitivities. This 0.25 μV value is typical for VHF commercial radio, while 0.35 μV is probably more typical for UHF. In the real world, lower SINAD values (more noise) can still result in intelligible speech, but it is tiresome work to listen to a voice in that much noise.

Signal-to-noise and distortion ratio (SINADR{{cite journal | title=Evaluation of signal-to-noise and distortion ratio degradation in nonlinear systems | journal= IEEE Transactions on Microwave Theory and Techniques|date=March 2004 | volume=52 | issue=3 | pages=813–822 | doi=10.1109/TMTT.2004.823543 | issn=0018-9480| last1=Lavrador | first1=P.M. | last2=Borgesdecarvalho | first2=N. | last3=Pedro | first3=J.C. | bibcode=2004ITMTT..52..813L }}) is a measurement of the purity of a signal. SINADR is typically used in data converter specifications. SINADR is defined as:

:$$

\mathrm{SINADR} = \frac{P_\mathrm{signal}}{P_\mathrm{quantizationError} + P_\mathrm{randomNoise} + P_\mathrm{distortion}}

where $P$ is the average power of the signal, quantization error, random noise and distortion components. SINADR is usually expressed in dB. SINADR is a standard metric for analog-to-digital converter and digital-to-analog converter.

SINADR (in dB) is related to effective number of bits (ENOB) by the following equation:

:$$

\mathrm{SINADR} = ENOB\cdot 6.02 + 1.76

• Signal-to-noise ratio
• Total harmonic distortion (THD+N)

{{reflist}}

• [http://www.radio-electronics.com/info/rf-technology-design/rf-noise-sensitivity/sinad.php SINAD and SINAD measurements for radio receivers]

{{Noise}}

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Category:Noise (electronics)

Category:Error measures