PC based Oscilloscopes

I am about to buy a PC based oscilloscope to save money. I tried nscope but it is not available to buy in Amazon, i am trying Pico 2000 series. But as the frequency increases the cost increases. I am trying for 10MHz, i have one clarification before i make a decision, suppose if i want to see the crystal frequency operating at say 70Mhz, i cannot measure it using the scope is understood. But is it possible for me to down convert it using some circuit and measure or some other technique can i use? Please advise.

For frequency measurement you need a frequency counter not an oscilloscope.
An Oscilloscope draws graphs of voltage against time so you can inspect the shape of a waveform, if you add some kind of shifting or dividing circuit between the source and the 'scope you are looking at the wave shape from that circuit, not the original.

Brian.

betwixt said:

For frequency measurement you need a frequency counter not an oscilloscope.
An Oscilloscope draws graphs of voltage against time so you can inspect the shape of a waveform, if you add some kind of shifting or dividing circuit between the source and the 'scope you are looking at the wave shape from that circuit, not the original.
Brian.

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I am sorry i mean to say i want to see the waveform which may be at 100MHz which is more than the PC based oscilloscope capability. How to overcome this?

High frequencies are a problem for PC based scopes because there is no mechanism that can send very fast samples for storage and display. Bear in mind that to display the shape of a waveform at 100MHz you need to sample much faster so the shape can be reconstructed later. For example, if you wanted to take 10 samples per cycle your sampling speed would be 1 gigasamples per second. With current technology it isn't feasible to digitize and display in real time so storage within the scope is needed followed by a slower transfer to the PC using USB. It gets very expensive!

The only feasible way to lower the sampling speed is to synchronize the sampling to the frequency then take samples from consecutive cycles. For example, if you sample 10 times from a 100MHz signal you take sample 1 from the first cycle, sample 2 slightly later in the second sample, sample 3 slightly later in the third cycle and so on. The problem is that although you can observe higher frequencies, you lose the ability to see changes in the wave shape on a cycle by cycle basis.

I'm afraid there is no low cost alternative to a dedicated instrument.

Brian.

electronicsman said:

I am about to buy a PC based oscilloscope to save money. I tried nscope but it is not available to buy in Amazon, i am trying Pico 2000 series. But as the frequency increases the cost increases. I am trying for 10MHz, i have one clarification before i make a decision, suppose if i want to see the crystal frequency operating at say 70Mhz, i cannot measure it using the scope is understood. But is it possible for me to down convert it using some circuit and measure or some other technique can i use? Please advise.

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Hi electronicsman!

I got myself an 20 year old professional FLUKE 4-channel 200MHz digital storage scope off ebay for just around €300 including shipping, it beats any pc-based scope in that price range any given day. That would be my suggestion, look for second hand, especially those with CRT screen.

electronicsman said:

I am sorry i mean to say i want to see the waveform which may be at 100MHz which is more than the PC based oscilloscope capability. How to overcome this?

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You may overcome this by getting a GW Instek GDS2000A at 100MHz bandwidth.
This is entry-level scope for professional use.

There is no Entry-level scope for hobby use, the technology in use that all of our electronics products are made, this is advanced and we must follow the same speed, or change profession and become farmers.
But neither farmers can use entry-level tractor for hobby.
Neither our doctors can use Entry-level hobby tools in a hospital.

Thanks for the suggestion. Yes finally I bought owon MetroQ SDS1022 20MHz oscilloscope.

So, you are from India.
The scope price this is at 199E or dollars, this is better than PC based Oscilloscope, but not sufficient than any other application than sound analysis.

In the positive side of things, you will earn your own experiences and if you do advance in electronics, your next one will be better selected.

The software for some of these PC based oscilloscopes is often not very good, as the writer of these programs have probably never actually used them in practice. I would save my money and get a good second-hand stand alone scope instead.

Kiriakos-GR said:

But not sufficient than any other application than sound analysis.

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I really don't know what is sound analysis. I am working on motor applications and i can observe the waveforms at present, seems to be ok. I really don't know the disadvantages, probably if i want higher frequencies i should plan for high end.

pjmelect said:

The software for some of these PC based oscilloscopes is often not very good, as the writer of these programs have probably never actually used them in practice. I would save my money and get a good second-hand stand alone scope instead.

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Yes some of them have bad software? Do all bench scopes have good software?


Picoscope is well established and has good software from my limited experience and from what I've heard. There are many ways that running on a PC is an advantage (big screen, mouse, lots of processing, easy to get screenshots etc).

That said its 2019 and I'm still waiting for computers (and IT departments) to work reliably. Standalone scopes not subject to automatic updates, the whims of IT, and il-timed virus deep scans are refreshingly reliable.

electronicsman said:

I really don't know what is sound analysis. I am working on motor applications and i can observe the waveforms at present, seems to be ok. I really don't know the disadvantages, probably if i want higher frequencies i should plan for high end.

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This model is capable to demonstrate on screen only 2.000 points Wfm/s , this is like viewing entire information of 2 kHz waveform, at 4 kHz signal you will have 50% loss or reviewed information.
I do SMPS repairs, my scope can do 80.000 Wfm/s , I can not use anything with less than 60.000 Wfm/s in this application, it would hide valuable information and it would be tremendously slow too.

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asdf44 said:

Do all bench scopes have good software?

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Two brands delivering mature software in their scopes within 2019, Keysight & GW Instek and no one else.