We already know that sample rate is speed at which samples of input signal are collected and stored to memory. Those samples are transferred to computer at some transfer rate dictated by host computer and bus bandwidth. In case of USB oscilloscope as external hardware of personal computer memory depth plays major role.Īs the name suggests USB connectivity enables to transfer samples from oscilloscope’s memory to personal computer via USB. Some oscilloscope’s connectivity enables only post-measurement transfer of data while for other such as USB oscilloscope PoScopeMega1 represents major link between the device and personal computer. Standard interfaces (GPIB, RS-232, USB, Ethernet) and network communication modules enable some oscilloscopes to deliver a vast array of functionality and control. The connectivity of an oscilloscope delivers advanced analysis capabilities and simplifies the documentation and sharing of results. Memory depth refers to exactly how many samples can be stored. Digitized data is then stored in the oscilloscope’s memory. Connectivity and memory depthĭigital oscilloscopes use ADC (analog to digital converter) to digitize input waveform.
Reason for decreasing resolution is explained under next section (Memory depth). PoScopeMega1 has 12-bit vertical resolution which can be switched to 8-bit. In a digital oscilloscope, an array of sampled points is reconstructed on a display with the measured amplitude on the vertical axis and time on the horizontal axis. These snapshots can then be arranged in the appropriate order in time so as to reconstruct the input signal. Each snapshot corresponds to a specific point in time on the waveform. The magnitude of each sampled point is equal to the amplitude of the input signal at the instant in time in which the signal is sampled. Sampling is the process of converting a portion of an input signal into a number of discrete electrical values for the purpose of storage, processing and/or display. The bandwidth of the scope together with the probe should similarly be at least 3 to 5 times the maximum signal bandwidth for better than +/-2% measurement error. For digital signals – square signals, oscilloscopes must capture the fundamental, third and fifth harmonics or the display will lose key features. Complex signals, according to mathematics theory, can contain many spectral (sine wave) components. Bandwidth is defined in the frequency domain, not the time domain. Most typical users choose an oscilloscope to display and measure complex signal, seen as a graph of signal amplitude over a time. Additionaly it provides third analog channel for generating analog signal (output). PoScopeMega1 USB oscilloscope has two analog channels and 16 digital channels. All channels shlould have good range, linearity, gain accuracy, flatness and resistance to static discharge. Others, called mixed signal oscilloscopes (MSOs), have a mixture of analog and digital channels. Some oscilloscopes have purely analog channels (these instruments are called DSOs – digital signal oscilloscopes). The type of signal a channel carries also varies. Most commonly, they have two or four channels. The number of oscilloscope channels varies. Let’s have a look a the most important ones which need to be taken into account when deciding about your new oscilloscope.Ī channel refers to an independent input to the oscilloscope. They can vary from vendor to vendor and from model to model. USB oscilloscope performance properties are very important when buying USB oscilloscope.
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