Decision-making aids for choosing the right oscilloscope

Without a doubt, the most important specification when choosing an oscilloscope is the bandwidth, which determines the maximum frequency of all components of an analogue signal that can be detected by the device.

However, a device with the highest bandwidth is not always the best choice. The decision should be based on the particular application. A bandwidth that is too high can increase interference and noise, because many more disturbing and distorting signal components are detected from external sources. As a guideline, the bandwidth of an oscilloscope should be at least twice the maximum frequency of the desired signal. For high frequency signals, a high bandwidth is required to ensure reliable measurements and prevent distorted signals.

Users requiring a bandwidth of 200MHz for their tasks can choose the DSO-6202FM digital storage oscilloscope from VOLTCRAFT to perform particularly demanding measurement tasks. The oscilloscope contains 14-bit converters with outstanding performance and offers technicians and engineers particularly high quality results both in the laboratory and during service assignments.

If a bandwidth of 80MHz is sufficient for the intended measuring tasks, you can consider VOLTCRAFT’s cost-effective DSO-6084E digital storage oscilloscope.

The amount and accuracy of channels is another important consideration when selecting an oscilloscope. Users can choose between devices with analog or digital inputs. Depending on the number of signals to be measured, a device with one to four channels should be considered. The high end DSO-6202FM offers two analogue inputs that are sufficient for most measuring tasks. If two analogue inputs are not sufficient, you can choose the DSO-6084E with four analogue inputs and conventional 8-bit converters.

Another important aspect for choosing the right DSO is the sample rate, which is critical for the resolution and accuracy of the measurement. The sample rate determines how many details of the lines and waveform can be captured and stored by an oscilloscope. The more points of a wave that can be acquired, the more accurate and finer it can be displayed. For example, the DSO-6202FM works in 8-bit mode with a sample rate of 1 GSample/s and achieves 100 MSample/s in 14-bit mode. The DSO-6084E also offers a sample rate of 1 GSample/s per channel.

With a DSO, acquired signals are stored until its memory is completely full. The storage space required for this is defined by the memory depth. The higher the memory depth, the greater the scope and duration of signal recording. The DSO-6202FM and DSO-6084E offer a memory depth of 40,000 kpts per channel.

An oscilloscope should also have accurate and convenient curve navigation that allows users to move along stored graphs, scale the image section horizontally and vertically and select the appropriate section for further analysing. For large memory depths and complex waveforms, a zoom or precision magnifier like with the DSO-6202FM is essential for an accurate analysis.

When a user touches the display at the desired location, the appropriate magnifying window appears immediately. The built-in 14-bit precision A/D converters provide up to 64 times higher resolution than conventional oscilloscopes. The converter hardware delivers data with a resolution of up to 31.25 µV/div to the magnifying window.

Buyers should also consider the operating concept of the DSO when making their choice. As with all DSO-6000 series oscilloscopes, the intuitive operating concept combined with the multitouch display helps users to find their way around immediately. All settings can be adjusted via the control buttons or directly on the screen.

The two-channel 50MHz function generator in the DSO-6202FM can be operated via the touch panel or conventionally via buttons. Sine, rectangular, ramp and pulse waveforms can be generated. A further 46 arbitrary waveforms including exponential, sine, step and noise are pre-defined. Custom arbitrary waveforms can also be stored. As a special feature, waveforms can be cloned to the function generator at the oscilloscope input, with the selection of the section to be cloned being conveniently accomplished via the touch-sensitive screen.

Automatic measurement and convenience functions are popular with users to analyse displayed graphs; for example, amplitude measurements, time measurements, rise times and period duration. Special features such as the DSO-6084E’s colour temperature view can also help users select the right oscilloscope. As frequencies change, the colour temperature view allows recurring waveforms to be displayed in rainbow colours according to their frequency, making analysis much easier.

Oscilloscope buyers should also be aware of possible additional functions such as the DSO-6202FM’s built-in digital multimeter (DMM) with 4,000 counts. The DMM can be used via safety test sockets on the real panel of the device and has the following data: 1,000 VDC, 400 VAC, 10 ADC, 10 AAC as well as 50nF to 100µF diode test and continuity tester function. Long term measurements can be carried out in the laboratory. Users can store results from the data logger integrated in the DMM internally or on a USB stick.

As a special feature, the DSO-6202FM digital storage oscilloscope from VOLTCRAFT with two analogue inputs and a bandwidth of 200MHz contains a Digital MultiMeter (DMM) with an internal data logger.

Connectivity options should also play a role when choosing the oscilloscope, with the requirements depending on the application. It can be important, for example, whether a device has a slot for a memory card or, like the DSO-6084E, a USB port. With this device, all measurement results and screen contents can be transferred to a PC via USB or network and stored for documentation purposes. When storing to a USB drive, the file name can be conveniently entered on the touch display.

The DSO-6084E is the ideal device if you focus on a cost effective oscilloscope. This versatile model is ideal for use in the laboratory, R&D or for service tasks. Waveforms captured by this DSO are displayed on a touch-sensitive 8" LCD (800x600 pixels). Settings can be adjusted via the control buttons or directly on the screen, with waveform zooming as intuitive as on a smartphone or tablet.

Special functions, such as the ability of the DSO-6084E to decode SPI, I²C, RS-232 and CAN bus signals, can make routine measurements easier and should also be included in the list of selection criteria. With the DSO-6084E, decoded values can be displayed in binary, decimal, hex or in ASCII and updated in event tables. The values of decoded CAN bus signals are shown in colour. This makes it easier to distinguish between data, data length code and frame information. In the event of an error, CAN bus checksums also change colour, facilitating diagnosis and analysis.

Last but not least, buyers should pay attention to the DSO’s scope of delivery. This usually includes at least one probe that is matched to the device. This saves users the trouble of searching for suitable probes. It is vital that probes influence measurement signals as little as possible. We recommend active probes that change voltages less than passive versions. If you are looking for a device with two probes included, you may consider the DSO-6202FM.

In order to be able to use a DSO on the go, operation via an additionally available lithium-ion battery is a great advantage, as with the DSO-6202FM and DSO-6084E. Both models can operate up to three hours without an additional power supply. Battery operation is also helpful in the laboratory for a temporary disconnection from the mains.