The lowest measurable levels of non-linear distortion and noise by a measurement system are always constrained by the system's own residual non-linear distortion and noise floor. While
improving the performance of the system hardware might seem like the only option, there are software methods available to compensate for non-linear distortion and reduce noise in the
measurement system...
Humans are exposed to sound and vibration from many different sources, including household appliances, transportation systems, machinery, hand-held power tools, and industrial activities
such as piling and blasting. Excessive exposure to noisy sound and vibration may lead to discomfort or health related problems, such as hearing loss or spinal disorders. It is therefore
important to assess these risks through proper sound and vibration measurements in accordance with the relevant international or national standards...
Mechanical shock testing is a process used to evaluate how well a product (or structure) can withstand sudden mechanical impacts or shocks. This type of testing is particularly important
for products that may experience rough handling, transportation, field operation or other conditions where they might be subjected to abrupt acceleration or deceleration...
Zoom UAC-232 is one of the first audio interfaces that support 32-bit float format. This format provides much higher dynamic range than the 16-bit, 24-bit and 32-bit integer formats both
theoretically and practically. Ideally, the noise level would only cause the least significant bit to toggle while the maximum level would fully utilize all bits...
As with anything related to computers and measurement, the world has moved quickly. The availability of higher-powered computing, much more capable sound cards and external audio
interfaces, and far more sophisticated software has vastly expanded the capabilities of small labs and hobbyists to measure and characterize acoustic and electronic devices...
This article describes the measurements of non-harmonic distortions, in particular how to measure intermodulation distortions. Unlike the harmonic distortion measurement which uses a
single-frequency sine wave as the stimulus, the non-harmonic distortion measurement uses the sum of two or more sine waves of different frequencies as the test signal...
This article describes the measurements of harmonic distortion related parameters, including THD, THD+N, SINAD, SNR, ENOB, NL, SFDR. The measurements of other types of distortion will be
introduced elsewhere. THD (Total Harmonic Distortion) measurement is required in many fields such as audio, acoustics, power supply and vibration...
The sound recording and reproducing techniques had evolved from analog approaches, such as those used by phonograph cylinders, disc phonographs and taper recorders, into digital
approaches using CDs or solid state memories as the recording mediums since 1980s. However, till today, the analog technique based devices have not vanished, as evidenced by the
considerable new sales of turntables and vinyl records...
This report is valid only for the particular Focusrite Scarlett Solo unit we tested. The purpose of these tests was not only to evaluate the performance of Focusrite Scarlett Solo, but
also to find the conditions under which the best performance of Focusrite Scarlett Solo can be obtained...
A step by step guide on how to use RTX6001 together with Multi-Instrument.
Virtins (a portmanteau of "Virtual Instrument") is a Singapore-based company that sells a range of test and measurement software and hardware. Its principal products include USB-based
digital storage oscilloscopes (DSOs), acoustic test and measurement systems, and vibration analysis systems...
This report is valid only for the particular ESI U24XL unit we tested. The purpose of these tests was not only to evaluate the performance of ESI U24XL, but also to find the conditions
under which the best performance of ESI U24XL can be obtained. The information obtained from these tests can be used as a reference for those who want to use ESI U24XL as a test and
measurement instrument to measure other devices or signals...
Using your laptop PC as the heart of a digital oscilloscope has a lot of appeal, as most laptops have a much larger screen than that in most free-standing digital oscilloscopes. But are
USB scopes any good? Typically, the vendors all claim outstanding performance, yet they are all overseas and there's no chance of being able to try their units out...
A typical sound system consists of microphones, audio amplifiers and speakers. All these components have a polarity. The polarity of a microphone refers to in-phase and out-of-phase
condition of voltage developed at its terminals with respect to the sound pressure of a sound wave causing the voltage...
This report is valid only for the particular E-MU Tracker Pre unit we tested. The purpose of these tests was not only to evaluate the performance of E-MU Tracker Pre, but also to find
the conditions under which the best performance of E-MU Tracker can be obtained. The information obtained from these tests can be used as a reference for those who want to use E-MU
Tracker Pre as a test and measurement instrument to measure other devices or signals...
This report is valid only for the particular E-MU 0204 unit we tested. The purpose of these tests was not only to evaluate the performance of E-MU 0204, but also to find the conditions
under which the best performance of E-MU 0204 can be obtained. The information obtained from these tests can be used as a reference for those who want to use E-MU 0204 as a test and
measurement instrument to measure other devices or signals...
This report is valid only for the particular M-Audio MobilePre unit we tested. The purpose of these tests was not only to evaluate the performance of M-Audio MobilePre, but also to find
the conditions under which the best performance of M-Audio MobilePre can be obtained. The information obtained from these tests can be used as a reference for those who want to use
M-Audio MobilePre as a test and measurement instrument to measure other devices or signals...
This report is valid only for the particular VT XLR-to-USB Pre unit we tested. The purpose of these tests was to evaluate the performance of VT XLR-to-USB Pre...
A signal in the time domain can be converted to its counterpart in the frequency domain by means of Fourier Transform (FT). The signal must be sampled at discrete time by an A/D
converter before it can be analyzed by a computer. Discrete Fourier Transform (DFT) can be used to convert the discrete signal (discrete in time) in the time domain to its counterpart
(discrete in frequency) in the frequency domain...
Spectral leakage is the result of the assumption in the FFT algorithm that the time record in a FFT segment is exactly repeated throughout all time and that signals contained in a FFT
segment are thus periodic at intervals that correspond to the length of the FFT segment. If the time record in a FFT segment has a non-integer number of cycles, this assumption is
violated and spectral leakage occurs...
Almost every PC or Pocket PC has a built-in sound card (or sound chip for the case of a Pocket PC). A sound card is usually treated as an audio input and output device for recording,
synthesizing, and replaying speech, music and songs. However, a sound card can do more than that...
Intrigued by the idea of using your PC as the engine for a suite of virtual audio test instruments? Here's a run-down on a powerful software package that will let you use it as a
2-channel audio scope combined with a powerful spectrum analyser, a 2-channel audio signal/function generator and an audio DMM which even includes a frequency counter...
The purpose of this document is to describe and setup a functional test for the USB microphones. The ideal reason for the test is to make sure that the functional test catches inadequate
microphone shielding...
Amateur radio repeaters are in a new age. The internet has made it possible to link repeaters across the world. Even smaller HTs appear with more features than you can learn to use...
几乎每台电脑或掌上电脑都有一个内置声卡。声卡通常被用来作为音频输入输出设备，用于记录、 合成和回放语言、音乐和歌曲。然而，声卡其实可以做得更多。从测控的角度来看，声卡是一个具
有双通道模数转换(ADC)和双通道数模转换(DAC)的信号采集和输出设备……
