signal-to-noise ratio


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ratio

 [ra´she-o] (L.)
an expression of the quantity of one substance or entity in relation to that of another; the relationship between two quantities expressed as the quotient of one divided by the other.
A/D ratio adult versus developmental toxicity ratio; the ratio between the toxic effects of a substance on adults (humans or animals, especially pregnant females) and such effects on developing embryos or fetuses.
A-G ratio (albumin-globulin ratio) the ratio of albumin to globulin in blood serum, plasma, cerebrospinal fluid, or urine.
arm ratio a figure expressing the relation of the length of the longer arm of a mitotic chromosome to that of the shorter arm.
benefit-risk ratio a determination of the potential of a research study for positive effects on patients compared to the risks of doing harm.
cardiothoracic ratio on a chest radiograph, the ratio of the transverse diameter of the heart to the internal diameter of the chest at its widest point just above the dome of the diaphragm.
grid ratio a ratio comparing the height of lead lines in an x-ray grid to the distance between the lead strips.
inspiratory-expiratory ratio the ratio of the inspiratory time to the expiratory time during the breathing cycle. Normally, expiratory time will be longer than inspiratory time; if the inspiratory time is longer than the expiratory time, gas trapping may result.
lecithin/sphingomyelin ratio see lecithin-sphingomyelin ratio.
risk ratio relative risk.
sex ratio the proportion of one sex to the other; by tradition the number of males in a population to the number of females, usually stated as the number of males per 100 females.
signal-to-noise ratio the ratio between the amplitude of a signal being measured and that of the noise.
urea excretion ratio the ratio of the amount of urea in the urine excreted in one hour to the amount in 100 ml of blood. The normal ratio is 50.
zeta sedimentation ratio (ZSR) a measurement comparable to the erythrocyte sedimentation rate, except that it is unaffected by anemia. The packed-cell volume (zetacrit) of a blood specimens is calculated by centrifuging the specimen in a Zetafuge, a specially designed instrument that produces controlled cycles of compaction and dispersion and allows rouleaux to form and sediment rapidly. The zetacrit divided into the true hematocrit gives the zeta sedimentation ratio.

signal-to-noise ratio

An MRI term for the ratio between the amplitude of the received signal and background noise, which may obscure that signal. SNR, and by extension, image quality, can be improved by increasing the number of excitations, field of view, slice thickness, etc., while factoring the electrical properties of the patient being studied and type of receiving coil used.

signal-to-noise ratio

MRI The ratio obtained from the relative contributions of detected true signal to that of random superimposed signals–'noise'. See Magnetic resonance imaging.
References in periodicals archive ?
Caption: Figure 8: Comparison for spectral distortion for 25 words contaminated by white noise with signal-to-noise ratio input (SNRI) of 3 dB, using spectral subtraction with prefiltering of the contaminated signal.
The LO noise defined as a signal-to-noise ratio (dBc/Hz) varies with the LO drive as the drive signal is limited by the LO buffers.
In the first attempt to use voltage-sensitive dyes in ganglia (Salzberg et al., 1973), we were fortunate to be able to monitor activity in a single neuron because the photodynamic damage was severe and the signal-to-noise ratio small.
Our pilot research included perceptual-auditory analysis at various levels of linguistic structure of speech utterances in Russian and German (in comparison) in the same noisy environment: various (pink and white) types of noise with various levels of signal-to-noise ratio as well as effects of linguistic and extralinguistic factors on speech perception in noisy environment.
The lower the signal-to-noise ratio (noise being random), the higher the ratio of errors.
The CS2010SDARS features up to 70 dB of independent signal-to-noise ratio for each channel, 30 MHz of multi-carrier bandwidth for full-band realism and a deep 11.5 seconds of non-repetitive signal playback.
Innovations to the actuator, air-bearing design and optical encoders, coupled with the integration of multiple, state-of-the-art directly embedded DSP controllers, are said to deliver unparalleled control speed over the functional components of the measurement system, while increasing accuracy, reducing test time and providing superior signal-to-noise ratio, according to the company.
The measurement technique is based on the temperature dependence of the fluorescence intensity of a dilute fluorophore added to the fluid, and thereby takes advantage of the inherently high signal-to-noise ratio of fluorescence-based measurements.
In the presence of noise, the sentence recognition threshold (score of 50%) was from -2 to 1 dB signal-to-noise ratio. Functional gain reached 55 dB at 3 kHz.
To ensure the smaller source would provide an adequate signal-to-noise ratio, NDC developed a proprietary detector chamber.
Wavelength Electronics Inc.'s QCL Laboratory Series QCL Driver drives current to QCLs with extremely low electronic noise, enabling chemical sensor developers to narrow center wavelength linewidth, maintain a stable center wavelength and improve signal-to-noise ratio by an order-of-magnitude.
The ultra-high signal-to-noise ratio sensor allows users to set exposure time from 1 msec up to 10 sec and adjust 20 scales of Gain value.