The fastest oscilloscopes and digitizers usually use parallel flash converters and 8-bit resolution. 8-bit or 256-level digitization is enough to express a smooth and easy to understand waveform display. Therefore, why not use DSO as a digitizer? Especially for high-speed signals, it is difficult for both instruments to obtain resolution above 8 bits.
In fact, the results are satisfactory, but there are exceptions. An oscilloscope is a discontinuous acquisition instrument and a digitizer is not. An oscilloscope must have a place to put the data before it captures the signal and then captures more, unless the data is stored in the pixel image using a continuous waveform acquisition similar to the TV frame rate. Such acquisition and equivalent display rates are high, but the data format makes further external analysis of the data volume very large.
In addition to the above special processing, oscilloscope can only continuously collect and display signals at a very low speed.The digitizer can achieve continuous throughput of 100MS/s or higher, limited only by the memory bus speed.For example, a PCI bus digital card, data transmission rate up to 100MB/s, PCI bus can work up to 66MS/s (132MB/s).
Oscilloscope throughput is limited by slow, low I/O capacity data processing speed.Slower digitizers and data recorders can write data directly to a hard drive, archiving several gigabytes of data, while oscilloscopes typically have a maximum of 16MB. If you look at the data transfer rate on the other hand, many applications only need to capture occasional data, but these bursts may be close.This is where the rapid transmission of data records becomes important. Examples of such signals include high-repetition pulse frequency (PRF) scanning radars, time-resolved ultrasonic sonar, time-of-flight mass spectrometers, and nuclear counting applications.