Currently, oscilloscopes are used not only for observing the change of an electric signal over time; they are equipped with many other functions designed for observation purposes.
Contemporary oscilloscopes are digital devices. They are usually equipped with TFT-LCD colour graphic displays of different resolution. In case of basic models and portable devices, display resolution starts with 320 x 240 pixels; in case of popular devices characterized by good measurement capabilities, it is about 480 x 350 pixels; and in case of the most advanced devices, we talk about resolution of 800 x 600 pixels.
The more pixels, the better the graphic representation of waveforms. What is more, apart from waveform envelopes, a lot of helpful information, such as measurement grid, trigger markers, cursors, current settings for X and Y axes, voltage and time values connected with observed electric signal, is displayed on the screen.
Placing a lot of information in a legible form on the small screen requires not only the use of colours, but also above-mentioned good resolution. The size of a display (its diagonal) is equally important. Obviously, the bigger the display, the better the quality of presented information. However, when it comes to portable devices, big display has influence on the dimensions and weight of the device. That is why, stationary devices are equipped with 5-10 inches displays, whereas portable ones are equipped with displays of up to 5 inches.
Another important parameter worth considering when buying an oscilloscope is the Y track frequency range. Track frequency range of basic devices equals 25MHz; such devices let us observe signals of up to about 5MHz. Advanced devices operate in frequency range of 50 or even 100MHz. Thanks to this fact, we are able to visualize the change of an electric signal up to approx. 20MHz. Frequency range above 100MHz is reserved for laboratory equipment, technically advanced devices which are far more expensive than, so-called, popular models.
High bandwidth lets us faithfully reproduce the details of the change of electric signals that are heavily distorted: square waves, spike waves, waveforms full of ringing or having lots of harmonics.
An oscilloscope with low frequency range and long rise time of such signals will not show them correctly – steep slopes of spike waves and oscillations will be softened and the resulted image will be distorted.
Sampling rate is another important feature of oscilloscopes. It defines the frequency with which analog-to-digital converter included in the Y track of the device makes a reading.
In order to visualise digital signals or distorted analog signals, frequent sampling of the signal is necessary.
It ensures that the meter will not omit important details or anomalies that appear irregularly. Having the above-mentioned in mind, manufacturers provide devices with the sampling frequency of the input signal that is ten times faster than frequency range.
Digital data describing the waveform of the signal must be logged in memory. Memory size determines the length of observation made by oscilloscope and shown on the display within one cycle. Large amount of memory lets us register important moments that take place after triggering of the time base, it allows us to observe non-periodic waveforms, and to detect anomalies and disturbances. Memory size is a key parameter when it comes to examining digital serial buses, microprocessor systems and digital systems. There is a correlation between memory size and sampling rate: the higher the sampling rate, the more storage space must be provided in the meter for the purpose of registering a given part of the waveform.
Before we decide to buy a given device, we have to consider how many signals we would like to observe and compare on the screen at the same time (from one to four). It seems that two channels are enough for most applications. Such configuration let us observe the most important time correlations between input and output.
The role of the triggering system is to begin (synchronize) the process of signal acquisition, to plot its waveform, and to register data in memory.
The more sophisticated the triggering system, the more chances we have to detect anomalies and unusual events.
Basic kinds of triggering include edge triggering and level triggering, however, pulse width triggering, waveform rise time triggering, TV signal triggering, logic state triggering, triggering with the use of combination of logical states, and, in case of the most advanced devices, digital bus triggering or triggering on the basis of the area designated on the screen by the operator tend to be useful too. What is more, triggering can be automated, made individually, come from the specified channel or can be generated with the use of external source.
Contemporary oscilloscopes are not stand-alone meters. They are equipped with interface that allows us to connect the meter to the computer (via USB or RS232) and to manage settings, make measurements and download readings. By connecting the oscilloscope to the computer, we can automate and archive measurements.
There are several kinds of oscilloscopes. Apart from classic devices that can be placed on the desk, we can buy portable oscilloscopes (so-called scopemeters). Handheld meters are perfect for repair and maintenance works. They are characterized by high mobility; their parameters are comparable to those of stationary equipment (often they are even better). They do not take much space and they can operate in semi-standing position. They usually combine functions of an oscilloscope and functions of a digital multimeter.
In the offer of AXIOMET, you will find three universal, 2-channel digital oscilloscopes with extended functionality and very good parameters:
Net price from 394.23 GBP
|Type of oscilloscope||digital|
|Number of channels||2|
|Memory record length||1Mpts/ch|
|Sampling||1Gsps (in real time), 50Gsps (in equivalent time)|
|Kind of display used||LCD 7", color, contrast adjustment|
|Vertical resolution||8 bit|
|Trigger modes||automatic, normal, single|
|Max. input voltage||400 V|
|Horizontal accuracy||±0.01 %|
|Input coupling||AC, DC, GND|
|Power supply||100...240V AC, 45...440Hz|
|Overall dimensions (W x D x H)||323.1x135.6x157 mm|
|Measuring instrument features||
|Trigger||video signal, impulse width, rising-edge, falling-edge|
|Kind of output connector||USB A socket|
The above-mentioned oscilloscopes have similar processing parameters for Y track. Their input sensitivity is within the range of 2mV/div...10V/div with impedance of 1MΩ. Signal in Y track is converted to digital form with the use of an 8-bit transducer. Time base for X track is 25, 5 or 2.5ns/div, depending on the model. Thanks to X input socket and external trigger socket, X-Y operation mode without time base is available.
Built-in USB and RS232 ports let us connect the meter to the computer, control the device, and use the device as a measurement system component (software is included in the set). Oscilloscopes are powered directly from the mains (240VAC). Their dimensions are as follows: 323 x 135 x 157 mm (in case of AX-DS1022C7 model) and 399 x 110.5 x 148.5 mm (in case of the other versions).
All three oscilloscopes are equipped with extensive trigger modes that allow triggering from any channel or external source: edge (rising, falling), pulse width, video signal. They automatically measure 32 waveform parameters, they eliminate distortion and noises coming from signals with the use of a digital filter, and they are equipped with value averaging function based on the last 256 runs.
You can store measurement results in device memory. The oscilloscopes can operate in FFT mode. Input waveform and FFT are displayed on divided screen. Thanks to this fact, it is possible to evaluate the signal in terms of time and frequency.
AXIOMET oscilloscopes are characterized by extended functionality, good parameters, and attractive price. These useful and universal tools tend to be perfect for repair and maintenance works, but they also can be successfully used in maintenance departments and design offices. What is more, thanks to the possibility of connecting the meter to the computer and measurement automation, these oscilloscopes can be used for testing in the production process of electronics.