General
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Digital storage oscilloscope from the beginning of the millennium
A digital storage oscilloscope (English DSO, Digital Storage Oscilloscope) digitizes the input signal with an analog-to-digital converter and stores the values in a memory. Thus, the bandwidth is given only by the limitation of the analog input amplifier. The advantage of storage is that in this way you can take snapshots of a signal and thus recognize and display unique (transient) events (spikes, data transfers), which is particularly important in digital circuits, e.g., B. with microcontrollers, is very useful. Furthermore, the signal can be "measured" (e.g., to determine the baud rate of data transmission), the frequency and the RMS value can be displayed, the frequency spectrum, and much more depending on the model. The signal is shown in B / W or color on an LCD,
The most important parameter for digital oscilloscopes is the sampling rate, which indicates the rate at which the input signal is digitized. To be able to represent a signal with a given frequency sufficiently accurately in phase and amplitude course, it should be sampled at least at ten times the frequency. Only then can the interesting details in a signal usually be recognized. For a precise analysis of analog signals, for example, to be able to assess the quality of a flank or overshoot, even a factor of 25 to 40 is advisable. Important in this context is also the analog bandwidth of the oscilloscope. A good ratio would be an at least 4-6-fold oversampling in terms of bandwidth per channel, eg 1Gsps for a dual-channel with 100MHz bandwidth - better 2Gsps. Thus signals up to about 10 MHz would be sufficiently accurate.
Also, the memory depth and the converter resolution are interesting. An oscilloscope that samples at the 8-bit resolution and has 2000 * 8-bit memory can store 2000 samples, representing a representation of 2000 * 256 pixels. Eight-bit resolution is a universal value these days, even if it looks low. A normal oscilloscope is not a precision meter, and eight bits are sufficient for display on normal oscilloscope displays.
There are some different ways of converting and storing: Former low-cost oscilloscopes such as the Tektronix TDS1000 series use CCD memory (bucket chain memory, an analog shift register); the measured values are first saved, and then digitized. Disadvantages of this approach are a greater noise, the limited memory depth and dead times during which no input values are recorded. These arise because the conversion of all values from the analog cache takes longer than the time to fill that memory. Therefore, the device must wait until the conversion completes before refilling the memory.
Previously, only more expensive models could be converted in real time with fast Flash AD converters and stored directly in fast RAM. The memory depth is practically unlimited. However, converters are costly, which provide several GS / s. By a trick (several nested slow AD converters), AD converters prevail in cheap models. Oscilloscopes using this trick can be recognized by the sampling frequency decreasing with the number of channels enabled. For example, there is four-channel oscilloscope with four transducers of 250 MS / s, which achieve 1 GS / s for this channel when using only one channel, 500 MS / s per channel using two channels and using three or four channels 250 when using two channels MS / s per channel.
In the really fast devices (several GHz sample rate) a similar trick is common. There, a larger number of sample-and-hold stages and AD converters are integrated into the converter circuits used. The input voltage is then stored time-shifted in the sample-and-hold stages and converted by the slower AD converters compared to the sample rate. The output logic then ensures that the data is output in the correct order. A problem with this procedure is different electrical properties of the parallel converter stages.
Of course, the purpose of use plays a crucial role in the selection. On the laboratory table, where usually only small voltages with a standard ground reference occur, other demands are placed on an oscilloscope than z. As in the service area for industrial control systems, automation technology, etc. There are less high sampling rates important, but rather a larger number of input channels, which are galvanically isolated from each other, dielectric strength to min. 500 Volts, and especially for fault analysis, the ability to set complex trigger patterns, and a built-in large hard disk to automate individual events over long periods of time. An example of such a high-quality device is a Yokogawa Scope order (DL708).
Digital oscilloscopes
General
DSO table oscilloscopes are the classic, self-contained devices that resemble analog oscilloscopes in design. There are also PC DSOs, for example. Many tabletop devices are already so small (shallow depth) and lightweight that they are rightly referred to as portable devices. When you buy an oscilloscope, these devices are the most interesting.
It is now common to find USB or RS-232 interfaces already installed in entry-level models and an (often very simple) Windows software for operation from the PC or at least for reading data to the PC. Also standard are USB or similar interfaces for USB memory sticks or memory cards for storing readings, screenshots, and configurations. Ironically, interfaces and Windows software are often sold separately for branded devices, while they are supplied free of charge to more unknown brands, though the quality of the free software often leaves much to be desired.
Examples of cheap entry-level models under $600 are some, but not all, devices from Rigol, Hantek, Owon, Siglent or Atten. For relatively little money you get a useful oscilloscope for simple applications with a few highlights but also conspicuous limitations and errors in the hardware and software. You can not expect much or any service from these companies for their money.
Appliances, for example, from Instek are a bit more expensive. Devices from the GDS-1000A or GDS-1000U series may be interesting to start or in the meantime the more modern series DS2000 from Rigol, or SDS2000 series from Silent.
Another example of an entry-level model was the TDS1002 from Tektronix (about 1200 euros). However, one has to say that Tektronix has overslept the current development somewhat. The only two kbyte large memory is outdated. Agilent InfiniiVision 2000X series devices begin in a similar price range but with significantly more features.
![[IMG]](http://forum.allaboutcircuits.com/proxy.php?image=https%3A%2F%2Fwww.mikrocontroller.net%2Fwikifiles%2Fthumb%2F8%2F86%2FTektronix.jpg%2F300px-Tektronix.jpg&hash=f02b3da095d3d1474ec902d3c206453f)
Digital storage oscilloscope from the beginning of the millennium
A digital storage oscilloscope (English DSO, Digital Storage Oscilloscope) digitizes the input signal with an analog-to-digital converter and stores the values in a memory. Thus, the bandwidth is given only by the limitation of the analog input amplifier. The advantage of storage is that in this way you can take snapshots of a signal and thus recognize and display unique (transient) events (spikes, data transfers), which is particularly important in digital circuits, e.g., B. with microcontrollers, is very useful. Furthermore, the signal can be "measured" (e.g., to determine the baud rate of data transmission), the frequency and the RMS value can be displayed, the frequency spectrum, and much more depending on the model. The signal is shown in B / W or color on an LCD,
The most important parameter for digital oscilloscopes is the sampling rate, which indicates the rate at which the input signal is digitized. To be able to represent a signal with a given frequency sufficiently accurately in phase and amplitude course, it should be sampled at least at ten times the frequency. Only then can the interesting details in a signal usually be recognized. For a precise analysis of analog signals, for example, to be able to assess the quality of a flank or overshoot, even a factor of 25 to 40 is advisable. Important in this context is also the analog bandwidth of the oscilloscope. A good ratio would be an at least 4-6-fold oversampling in terms of bandwidth per channel, eg 1Gsps for a dual-channel with 100MHz bandwidth - better 2Gsps. Thus signals up to about 10 MHz would be sufficiently accurate.
Also, the memory depth and the converter resolution are interesting. An oscilloscope that samples at the 8-bit resolution and has 2000 * 8-bit memory can store 2000 samples, representing a representation of 2000 * 256 pixels. Eight-bit resolution is a universal value these days, even if it looks low. A normal oscilloscope is not a precision meter, and eight bits are sufficient for display on normal oscilloscope displays.
There are some different ways of converting and storing: Former low-cost oscilloscopes such as the Tektronix TDS1000 series use CCD memory (bucket chain memory, an analog shift register); the measured values are first saved, and then digitized. Disadvantages of this approach are a greater noise, the limited memory depth and dead times during which no input values are recorded. These arise because the conversion of all values from the analog cache takes longer than the time to fill that memory. Therefore, the device must wait until the conversion completes before refilling the memory.
Previously, only more expensive models could be converted in real time with fast Flash AD converters and stored directly in fast RAM. The memory depth is practically unlimited. However, converters are costly, which provide several GS / s. By a trick (several nested slow AD converters), AD converters prevail in cheap models. Oscilloscopes using this trick can be recognized by the sampling frequency decreasing with the number of channels enabled. For example, there is four-channel oscilloscope with four transducers of 250 MS / s, which achieve 1 GS / s for this channel when using only one channel, 500 MS / s per channel using two channels and using three or four channels 250 when using two channels MS / s per channel.
In the really fast devices (several GHz sample rate) a similar trick is common. There, a larger number of sample-and-hold stages and AD converters are integrated into the converter circuits used. The input voltage is then stored time-shifted in the sample-and-hold stages and converted by the slower AD converters compared to the sample rate. The output logic then ensures that the data is output in the correct order. A problem with this procedure is different electrical properties of the parallel converter stages.
Of course, the purpose of use plays a crucial role in the selection. On the laboratory table, where usually only small voltages with a standard ground reference occur, other demands are placed on an oscilloscope than z. As in the service area for industrial control systems, automation technology, etc. There are less high sampling rates important, but rather a larger number of input channels, which are galvanically isolated from each other, dielectric strength to min. 500 Volts, and especially for fault analysis, the ability to set complex trigger patterns, and a built-in large hard disk to automate individual events over long periods of time. An example of such a high-quality device is a Yokogawa Scope order (DL708).
Digital oscilloscopes
General
DSO table oscilloscopes are the classic, self-contained devices that resemble analog oscilloscopes in design. There are also PC DSOs, for example. Many tabletop devices are already so small (shallow depth) and lightweight that they are rightly referred to as portable devices. When you buy an oscilloscope, these devices are the most interesting.
It is now common to find USB or RS-232 interfaces already installed in entry-level models and an (often very simple) Windows software for operation from the PC or at least for reading data to the PC. Also standard are USB or similar interfaces for USB memory sticks or memory cards for storing readings, screenshots, and configurations. Ironically, interfaces and Windows software are often sold separately for branded devices, while they are supplied free of charge to more unknown brands, though the quality of the free software often leaves much to be desired.
Examples of cheap entry-level models under $600 are some, but not all, devices from Rigol, Hantek, Owon, Siglent or Atten. For relatively little money you get a useful oscilloscope for simple applications with a few highlights but also conspicuous limitations and errors in the hardware and software. You can not expect much or any service from these companies for their money.
Appliances, for example, from Instek are a bit more expensive. Devices from the GDS-1000A or GDS-1000U series may be interesting to start or in the meantime the more modern series DS2000 from Rigol, or SDS2000 series from Silent.
Another example of an entry-level model was the TDS1002 from Tektronix (about 1200 euros). However, one has to say that Tektronix has overslept the current development somewhat. The only two kbyte large memory is outdated. Agilent InfiniiVision 2000X series devices begin in a similar price range but with significantly more features.