The relation between dead time of oscilloscope, capture period and waveform capture rate
The capture cycle consists of effective capture time and dead zone time cycle.In the effective capture time, the oscilloscope captures the waveform sample number set by the user and writes it into the acquisition memory.The captured dead time includes fixed time and variable time. The fixed time depends on the architecture of each instrument.Variable time, which depends on the processing time required, is directly related to the set number of captured samples (record length), horizontal scale, sampling rate, and selected post-processing functions (for example, interpolation, mathematical functions, measurement, and analysis). The ratio of dead zone time to capture period is also an important characteristic of oscilloscope.
The measured signal enters the oscilloscope through the input channel and is adjusted by the attenuator and amplifier in the vertical system.An analog-to-digital converter (ADC) samples the signals at fixed intervals and converts the amplitudes of each signal into discrete digital values called "sample points".The collection module then performs processing functions, such as sample extraction, which generally defaults to the sampling mode.The output data is stored in the acquisition storage as samples.The number of samples stored can be set by the user by record length.
These sample points can also be further post-processed based on user requirements.Post-processing tasks include arithmetic functions (such as averaging), mathematical operations (such as FIR filtering), automatic measurements (such as rising or falling times), and analytical functions (such as histogram or template testing).Other post-processing such as protocol decoding, jitter analysis and vector signal analysis and so on.
For digital oscilloscope, basically there is no restriction on the processing steps of waveform samples.Depending on the structure of the oscilloscope, these post-processing functions are performed either by software through the main processor of the instrument, or by dedicated ASIC or FPGA hardware.The final result is then presented to the user through the display screen of the oscilloscope.
Zhengzhou Defy Metrontec RTO series oscilloscope and traditional differences between digital oscilloscope in signal processing, it USES the specialized independent development of ASIC RTC chip and the FPGA to realize the waveform samples post-processing, such as channel calibration, sample selection, digital filtering, math, histogram, template testing and FFT, automatic measurement, protocol decoding, etc., greatly reduce the workload of the main processor in RTO chip at the same time using digital trigger replaces the analog trigger circuit, trigger circuit of trigger jitter, eliminates the simulation in the traditional high-end oscilloscope in order to reduce this part of the jitter,A lot of DSP postprocessing is required. The innovation in hardware structure greatly reduces the time spent in the post-processing of waveform samples of RTO oscilloscope.
Oscilloscope from signal sampling capture to waveform sample processing display this cycle, known as the capture cycle, after the end of the previous capture cycle, oscilloscope can capture the next new waveform.Therefore, the digital oscilloscope will capture most of the time on the waveform sample post-processing, in this process, the oscilloscope is in no signal state, can not continue to monitor the measured signal.Basically, dead zone time is the time required by digital oscilloscope to process waveform samples.