13-03-2012, 04:29 PM
DIGITAL STORAGE OSCILLOSCOPE
What is an OSCILLOSCOPE ?
An oscilloscope (also known as a scope) is a type of electronic test instrument that allows observation of constantly varying signal voltages, usually as a two-dimensional graph of one or more electrical potential differences.
A Digital Storage Oscilloscope (DSO)
A DSO is also like a conventional oscilloscope except that it uses digital memory to store the waveform. Thus it first digitizes the input analog signal by an analog to digital convertor and displays the waveform.
OPERATION
The analogue signal being monitored is fed into a pre amp, which changes it’s
amplitude so that it falls within the input range of the Analogue to Digital Converter
(ADC) and the trigger detector. When the resulting voltage crosses a threshold set by
the user the trigger unit signals the device to start recording. The ADC samples the
output of the pre amp at regular intervals and the digital output from the ADC is then
stored in consecutive locations in the memory. When the memory is full the recording
is stopped.
The Digital to Analogue Converter (DAC) continuously scans through the
recording producing a repeating analogue signal representing the contents of the
memory, which is sent to the Cathode Ray Tube (CRT) for display. This is required
because the CRT image will fade away if not continuously refreshed.
Concept of SAMPLING in DSO
In a DSO the conversion analogue to digital does not happen continuously, but at discrete periodic times, the so called sampling points. It can be better understood by the following diagram.
ADVANTAGES AND DISADVANTAGES
The most reliable advantage of a DSO is that it stores the signal in digital form so prevents degradation.
The only disadvantage of a DSO is that due to the use of ADC and some other extra components it is costly as compared to analog oscilloscopes.
APPLICATION
The application of a DSO is similar to a conventional oscilloscope except for its long term observation as captured data could be saved to disk and several readings could be taken over time and compared.
What is an OSCILLOSCOPE ?
An oscilloscope (also known as a scope) is a type of electronic test instrument that allows observation of constantly varying signal voltages, usually as a two-dimensional graph of one or more electrical potential differences.
A Digital Storage Oscilloscope (DSO)
A DSO is also like a conventional oscilloscope except that it uses digital memory to store the waveform. Thus it first digitizes the input analog signal by an analog to digital convertor and displays the waveform.
OPERATION
The analogue signal being monitored is fed into a pre amp, which changes it’s
amplitude so that it falls within the input range of the Analogue to Digital Converter
(ADC) and the trigger detector. When the resulting voltage crosses a threshold set by
the user the trigger unit signals the device to start recording. The ADC samples the
output of the pre amp at regular intervals and the digital output from the ADC is then
stored in consecutive locations in the memory. When the memory is full the recording
is stopped.
The Digital to Analogue Converter (DAC) continuously scans through the
recording producing a repeating analogue signal representing the contents of the
memory, which is sent to the Cathode Ray Tube (CRT) for display. This is required
because the CRT image will fade away if not continuously refreshed.
Concept of SAMPLING in DSO
In a DSO the conversion analogue to digital does not happen continuously, but at discrete periodic times, the so called sampling points. It can be better understood by the following diagram.
ADVANTAGES AND DISADVANTAGES
The most reliable advantage of a DSO is that it stores the signal in digital form so prevents degradation.
The only disadvantage of a DSO is that due to the use of ADC and some other extra components it is costly as compared to analog oscilloscopes.
APPLICATION
The application of a DSO is similar to a conventional oscilloscope except for its long term observation as captured data could be saved to disk and several readings could be taken over time and compared.