sampling rate

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sampling rate

[′sam·pliŋ ‚rāt]
(engineering)
The rate at which measurements of physical quantities are made; for example, if it is desired to calculate the velocity of a missile and its position is measured each millisecond, then the sampling rate is 1000 measurements per second.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

high-resolution sampling rates

Following is a list of common digital sample sizes and sampling rates for high-quality audio. See high-resolution audio, DSD and high-resolution audio sources.

Sample                         Stereo  Size     Sampling Rate       Transfer (Bits)  Samples Per Second      Rate

   16     44,056 (44.1 kHz)**  1409 kbps

   16     48,000 (48 kHz)      1536 kbps

   24     88,200 (88.2 kHz)    4234 kbps

   24     96,000 (96 kHz)      4608 kbps

   24    176,400 (176.4 kHz)   8467 kbps

   24    192,000 (192 kHz)     9216 kbps

   24    384,000 (384 kHz)    18432 kbps


   Compressed MP3 files (for comparison)

           Common MP3 file:    128 kbps

           High-res MP3 file:  320 kbps


   ** Standard music CD (see  CD-DA)

sampling

(1) In statistics, the analysis of a group by determining the characteristics of a significant percentage of its members chosen at random.

(2) Converting analog signals into digital form. Audio and other analog signals are continuous waveforms that are analyzed at various points in time and converted into digital samples. The accuracy with which the digital samples reflect their analog origins is based on "sampling rate" and "sample size." See A/D converter.

Sampling Rate - When to Measure
The sampling rate is the number of times per second that the waveform is measured, which typically ranges from 8 to 192 thousand times per second (8 kHz to 192 kHz). The greater the rate, the higher the frequency that can be captured. For a comparison of high-quality samples, see high-resolution sampling rates.

The sampling rate must be at least twice that of the analog frequency being captured. For example, the sampling rate used to create the digital data on a CD is 44.1 kHz, slightly more than double the 20kHz frequency an average person can hear. The sampling rate for digitizing voice for a toll-quality conversation is typically 8,000 times per second (8 kHz), twice the 4 kHz required for the full spectrum of the human voice. See analog and Nyquist theorem.

Sample Size - The Measurement
Also called "resolution" and "precision," the sample size is the measurement of each sample point on a numeric scale. Known as "quantizing," the sample point is turned into the closest whole number. The more granular the scale (the more increments), the more accurate the digital sample represents the original analog signal. See oversampling, quantization and PCM.


Sampling Sound
The faster the sampling rate and the larger the sample size, the more accurately sound can be digitized. An 8-bit sample breaks the sound wave into 255 increments compared with 65,535 for a 16-bit sample.







Sampling Dialog
This recording dialog from an earlier Sound Blaster sound card shows typical sampling options for digitizing sound into Windows WAV files.







DSD - A High-Res Sampling Technique
Direct Stream Digital (DSD) is a dramatic departure from PCM. Instead of turning samples into a number with a range of values, DSD samples are only 1-bit long (0 or 1), depending on whether the wave is moving up or down from the previous sample point (see DSD).
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References in periodicals archive ?
Despite the fact that Qualisys has video frame rates of up to 1000 Hz, the comparison could be done only up to sampling frequencies of 60 Hz.
Simulation was carried out for two sampling frequencies of the radio signal envelope [f.sub.sampl] = 12 kHz and [f.sub.sampl] = 24 kHz.
The difference in prediction error of the VSPRA algorithm for the two sampling frequencies 12 kHz and 24 kHz was 0.35 dB.
3) concludes that algorithms in which a small prediction error is achieved (VSPRA with sampling frequencies 12 and 24 kHz), work with relatively small prediction ranges in time when the mobile station moves at the highest speed.
Different sampling frequencies correspond to different magnitudes of angles of the individual rotation steps.
Caption: FIGURE 7: Simulated turbulent wind velocities for different sampling frequencies.
While this may be tractable when mixing quarterly and monthly observations, other sampling frequencies may be problematic.
The problem of mixed sampling frequencies is exemplified in Figures 1 and 2.
One solution to the problem of mixed sampling frequencies is to convert higher-frequency data to match the sampling rate of the lower-frequency data.
An important consideration when migrating from the previous LIMS was to ensure that all the scheduled samples continued to be logged correctly without any interruption to the flow of samples, and provision had to be made to cater for the different sampling frequencies typically found in process industries such as the refinery business.
This arrangement allows various sampling frequencies to be configured.
The new Regulation has been introduced as a means of harmonising microbiological testing criteria across the EU, defining minimum testing levels, sampling frequencies, target pathogens, specifications and appropriate methodology.