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Frequency Divider for older Oscilloscopes??
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Jorge Ginsberg:

--- Quote ---"I want to observe a signal that is between 990MHz and 1000MHz. What is the minimum sampling frequency that I need to use?".

Those answering 2GS/s faced an uphill struggle...."
--- End quote ---

You can use any sampling frequency. What is of interest here is how fast the sample is taken, not how often that sample is repeated.
You can take samples at a rate of 1000 samples per second... 10,000 samples per second... etcetera. 
If a waveform is repetitive, you can take a sample every 1000 waves and still reconstitute the original waveform correctly.
Here the important thing is not the frequency but the duration of the pulse that takes the sample and being a frequency between 900 MHz and 1 GHz, whose period ranges from 1.11 ns to 1 ns, the duration of the sampling pulse should be of the order of 0.1 ns or less.
tggzzz:

--- Quote from: Jorge Ginsberg on July 19, 2021, 10:24:06 pm ---
--- Quote ---"I want to observe a signal that is between 990MHz and 1000MHz. What is the minimum sampling frequency that I need to use?".

Those answering 2GS/s faced an uphill struggle...."
--- End quote ---

You can use any sampling frequency. What is of interest here is how fast the sample is taken, not how often that sample is repeated.
You can take samples at a rate of 1000 samples per second... 10,000 samples per second... etcetera. 
If a waveform is repetitive, you can take a sample every 1000 waves and still reconstitute the original waveform correctly.
Here the important thing is not the frequency but the duration of the pulse that takes the sample and being a frequency between 900 MHz and 1 GHz, whose period ranges from 1.11 ns to 1 ns, the duration of the sampling pulse should be of the order of 0.1 ns or less.

--- End quote ---

The question did not specify that the waveform was repetitive, so that cannot be assumed.
Jorge Ginsberg:

--- Quote from: tggzzz on July 19, 2021, 10:34:18 pm ---
--- Quote from: Jorge Ginsberg on July 19, 2021, 10:24:06 pm ---
--- Quote ---"I want to observe a signal that is between 990MHz and 1000MHz. What is the minimum sampling frequency that I need to use?".

Those answering 2GS/s faced an uphill struggle...."
--- End quote ---

You can use any sampling frequency. What is of interest here is how fast the sample is taken, not how often that sample is repeated.
You can take samples at a rate of 1000 samples per second... 10,000 samples per second... etcetera. 
If a waveform is repetitive, you can take a sample every 1000 waves and still reconstitute the original waveform correctly.
Here the important thing is not the frequency but the duration of the pulse that takes the sample and being a frequency between 900 MHz and 1 GHz, whose period ranges from 1.11 ns to 1 ns, the duration of the sampling pulse should be of the order of 0.1 ns or less.

--- End quote ---

The question did not specify that the waveform was repetitive, so that cannot be assumed.

--- End quote ---

If you are talking about "frequency" and you mention "900 Mhz to 1000 Mhz" then you are talking about a repetitive signal.
And to capture a single pulse, which occurs only once and never repeats again I would never use a sampling scoloscope.  I would rather use an optical memory oscilloscope like the Tektronix 7000 series oscilloscopes had, capable of storing a pulse on the screen.
tggzzz:

--- Quote from: Jorge Ginsberg on July 20, 2021, 10:17:29 am ---
--- Quote from: tggzzz on July 19, 2021, 10:34:18 pm ---
--- Quote from: Jorge Ginsberg on July 19, 2021, 10:24:06 pm ---
--- Quote ---"I want to observe a signal that is between 990MHz and 1000MHz. What is the minimum sampling frequency that I need to use?".

Those answering 2GS/s faced an uphill struggle...."
--- End quote ---

You can use any sampling frequency. What is of interest here is how fast the sample is taken, not how often that sample is repeated.
You can take samples at a rate of 1000 samples per second... 10,000 samples per second... etcetera. 
If a waveform is repetitive, you can take a sample every 1000 waves and still reconstitute the original waveform correctly.
Here the important thing is not the frequency but the duration of the pulse that takes the sample and being a frequency between 900 MHz and 1 GHz, whose period ranges from 1.11 ns to 1 ns, the duration of the sampling pulse should be of the order of 0.1 ns or less.

--- End quote ---

The question did not specify that the waveform was repetitive, so that cannot be assumed.

--- End quote ---

If you are talking about "frequency" and you mention "900 Mhz to 1000 Mhz" then you are talking about a repetitive signal.

--- End quote ---

No! Is an AM radio wave repetitive? Or FM etc?


--- Quote ---And to capture a single pulse, which occurs only once and never repeats again I would never use a sampling scoloscope.  I would rather use an optical memory oscilloscope like the Tektronix 7000 series oscilloscopes had, capable of storing a pulse on the screen.

--- End quote ---

I have a dual beam Telequipment storage scope, for no good reason other than fun. Analogue storage scopes always were a pain, used when nothing else was available.

The early digitising scopes had severe limitations, but the current ones are remarkably good. While a good analogue scope is worth using, one-off events are the killer use case for digitising scopes.
Jorge Ginsberg:

--- Quote ---I have a dual beam Telequipment storage scope, for no good reason other than fun. Analogue storage scopes always were a pain, used when nothing else was available.

The early digitising scopes had severe limitations, but the current ones are remarkably good. While a good analogue scope is worth using, one-off events are the killer use case for digitising scopes.
--- End quote ---

More than 25 years ago, I used the Tektronix 7934 with analog storage and it was never a "pain"....
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