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Help me choosing new Oscilloscope

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tggzzz:

--- Quote from: 2N3055 on April 09, 2023, 02:03:00 pm ---
--- Quote from: tggzzz on April 09, 2023, 01:17:36 pm ---
--- Quote from: Performa01 on April 09, 2023, 10:39:52 am ---
--- Quote from: smallfreak on April 08, 2023, 10:21:28 am ---The MSO5074 is at the same price level, excelling only in the proposed 8G sampling that might have a marginal advantage at the max 350MHz on a single channel.

--- End quote ---
This is not correct. Signal detail at higher frequencies depends on the input bandwidth, nothing else. So it is a frontend feature only.

--- End quote ---

Yes.


--- Quote ---The sample rate on the other hand has to be twice the max. input frequency in order to satisfy Nyquist.

--- End quote ---

No. Or rather the sample rate has to be at least twice the bandwidth of the signal to satisfy Nyquist[1].

I have a 1972 portable scope (which can be stored underwater!) which takes one sample every 75µs (i.e. 13kS/s), and has a bandwidth of >5GHz; it measures risetimes of <0.14ns.

Back in the 80s I used a top-of-the-range HP 1GHz scope, which sampled at 25MS/s.

Nowadays you can see that principle in action in various scopes with modes called various things like Equivalent Time Sampling, and in the mixer of every SDR dongle (multiGHz inputs sampled at ~10MS/s).

[1] Standard interview question... You have an audio signal transmitted on a 10MHz carrier. What is the minimum sampling rate you can use?

--- End quote ---

Again with that.
Nobody cares for repetitive sampling scopes. We are talking about real time samplings scopes.

--- End quote ---

Many many people care about repetitive sampling scopes. One obvious question: if nobody cares, why do all the main manufacturers of professional scopes have modes based upon repetitive sampling? Current Keysight literature answers that :

--- Quote ---Advantages of Equivalent Time Sampling Scopes
•    Lower sampling rate allows higher resolution ADC conversion
•    Wider bandwidth
•    Lower noise floor
•    Lower intrinsic jitter
•    Can include front end optical modules
•    Can achieve solutions at a reduced cost
--- End quote ---

Note the reduced cost point. Samplers are orders of magnitude cheaper than ADCs with the same resolution.

Another point was given by David Hess: avoiding Gibbs Phenomenon artifacts https://www.eevblog.com/forum/projects/oscilloscopes-what-happened-to-equivalent-time-sampling/msg1781960/#msg1781960

And another: resolving short time intervals e.g. a 100MHz/3.5ns risetime analogue scope easily resolving <1ns intervals. DSOs use ETS for that. timehttps://www.eevblog.com/forum/projects/oscilloscopes-what-happened-to-equivalent-time-sampling/msg1783850/#msg1783850

I suggest you (re)read that thread.


--- Quote ---And you are wrong: repetitive sampling scopes EFFECTIVE sample rate is defined by 1/t of sampling aperture time and fine resolution timing of taking sample in regards to trigger timing.
Fact that it takes samples sparsely is of no influence to Nyquist.

--- End quote ---

You are going to have to get your story straight.

First you claim that "nobody is interested in repetitive sampling rates", and then you try to demonstrate that by using a parameter that is mainly relevant to repetitive sampling!


--- Quote ---There is a reason nobody cares about repetitive sampling scopes anymore (outside special applications).

--- End quote ---

That could only be correct if you were using "special application" to mean "any application I don't personally use". That illustrates more about you than about scopes' capabilities and uses.


--- Quote ---On your interview question, answer is more than 20 something MS/s. Because you didn't specify you want to down convert RF and extract audio you need to satisfy Nyquist to grab full data...

--- End quote ---

You just failed the interview test.

Provided the sampling aperture is sufficiently small, you only need to capture at, say, 44kS/s. Downsampling is not required.


--- Quote ---We are talking about oscilloscopes here, not radio receivers or software radio.... Stop confusing people with ortogonal information...

--- End quote ---

I gave examples of high-end professional scopes, and amplified the key points by reference to other technologies based on the same principles.

2N3055:

--- Quote from: tggzzz on April 09, 2023, 03:31:34 pm ---
--- Quote from: 2N3055 on April 09, 2023, 02:03:00 pm ---
--- Quote from: tggzzz on April 09, 2023, 01:17:36 pm ---
--- Quote from: Performa01 on April 09, 2023, 10:39:52 am ---
--- Quote from: smallfreak on April 08, 2023, 10:21:28 am ---The MSO5074 is at the same price level, excelling only in the proposed 8G sampling that might have a marginal advantage at the max 350MHz on a single channel.

--- End quote ---
This is not correct. Signal detail at higher frequencies depends on the input bandwidth, nothing else. So it is a frontend feature only.

--- End quote ---

Yes.


--- Quote ---The sample rate on the other hand has to be twice the max. input frequency in order to satisfy Nyquist.

--- End quote ---

No. Or rather the sample rate has to be at least twice the bandwidth of the signal to satisfy Nyquist[1].

I have a 1972 portable scope (which can be stored underwater!) which takes one sample every 75µs (i.e. 13kS/s), and has a bandwidth of >5GHz; it measures risetimes of <0.14ns.

Back in the 80s I used a top-of-the-range HP 1GHz scope, which sampled at 25MS/s.

Nowadays you can see that principle in action in various scopes with modes called various things like Equivalent Time Sampling, and in the mixer of every SDR dongle (multiGHz inputs sampled at ~10MS/s).

[1] Standard interview question... You have an audio signal transmitted on a 10MHz carrier. What is the minimum sampling rate you can use?

--- End quote ---

Again with that.
Nobody cares for repetitive sampling scopes. We are talking about real time samplings scopes.

--- End quote ---

Many many people care about repetitive sampling scopes. One obvious question: if nobody cares, why do all the main manufacturers of professional scopes have modes based upon repetitive sampling? Current Keysight literature answers that :

--- Quote ---Advantages of Equivalent Time Sampling Scopes
•    Lower sampling rate allows higher resolution ADC conversion
•    Wider bandwidth
•    Lower noise floor
•    Lower intrinsic jitter
•    Can include front end optical modules
•    Can achieve solutions at a reduced cost
--- End quote ---

Note the reduced cost point. Samplers are orders of magnitude cheaper than ADCs with the same resolution.

Another point was given by David Hess: avoiding Gibbs Phenomenon artifacts https://www.eevblog.com/forum/projects/oscilloscopes-what-happened-to-equivalent-time-sampling/msg1781960/#msg1781960

And another: resolving short time intervals e.g. a 100MHz/3.5ns risetime analogue scope easily resolving <1ns intervals. DSOs use ETS for that. timehttps://www.eevblog.com/forum/projects/oscilloscopes-what-happened-to-equivalent-time-sampling/msg1783850/#msg1783850

I suggest you (re)read that thread.


--- Quote ---And you are wrong: repetitive sampling scopes EFFECTIVE sample rate is defined by 1/t of sampling aperture time and fine resolution timing of taking sample in regards to trigger timing.
Fact that it takes samples sparsely is of no influence to Nyquist.

--- End quote ---

You are going to have to get your story straight.

First you claim that "nobody is interested in repetitive sampling rates", and then you try to demonstrate that by using a parameter that is mainly relevant to repetitive sampling!


--- Quote ---There is a reason nobody cares about repetitive sampling scopes anymore (outside special applications).

--- End quote ---

That could only be correct if you were using "special application" to mean "any application I don't personally use". That illustrates more about you than about scopes' capabilities and uses.


--- Quote ---On your interview question, answer is more than 20 something MS/s. Because you didn't specify you want to down convert RF and extract audio you need to satisfy Nyquist to grab full data...

--- End quote ---

You just failed the interview test.

Provided the sampling aperture is sufficiently small, you only need to capture at, say, 44kS/s. Downsampling is not required.


--- Quote ---We are talking about oscilloscopes here, not radio receivers or software radio.... Stop confusing people with ortogonal information...

--- End quote ---

I gave examples of high-end professional scopes, and amplified the key points by reference to other technologies based on the same principles.

--- End quote ---

Omg...

williamlee:
Is it because 99.9% of oscilloscope user doesn`t need the "eye diagram"? so, the sampling rate is quite ok for 1G or 2G?   
The "real-time" still belongs to the analog scope, right? why does the digital scope need the "sampling rate"? because of the "ADC"?
My point of view that MSO5000 is the best C/P value for 90% of applications especially for logic is better value. It makes sure that SDS2000XP also good for the C/P value.  ;D ;D

If MSO5000 has 50-ohm support and the same frond-end which is like 1054z......
If SDS2000XP has 4G sa/S......
If the R/S, Tek, and LeCroy prices are very very close to Rigol and Siglent ...... too many dreams |O :-DD

tggzzz:

--- Quote from: 2N3055 on April 09, 2023, 03:58:55 pm ---
--- Quote from: tggzzz on April 09, 2023, 03:31:34 pm ---
--- Quote from: 2N3055 on April 09, 2023, 02:03:00 pm ---
--- Quote from: tggzzz on April 09, 2023, 01:17:36 pm ---
--- Quote from: Performa01 on April 09, 2023, 10:39:52 am ---
--- Quote from: smallfreak on April 08, 2023, 10:21:28 am ---The MSO5074 is at the same price level, excelling only in the proposed 8G sampling that might have a marginal advantage at the max 350MHz on a single channel.

--- End quote ---
This is not correct. Signal detail at higher frequencies depends on the input bandwidth, nothing else. So it is a frontend feature only.

--- End quote ---

Yes.


--- Quote ---The sample rate on the other hand has to be twice the max. input frequency in order to satisfy Nyquist.

--- End quote ---

No. Or rather the sample rate has to be at least twice the bandwidth of the signal to satisfy Nyquist[1].

I have a 1972 portable scope (which can be stored underwater!) which takes one sample every 75µs (i.e. 13kS/s), and has a bandwidth of >5GHz; it measures risetimes of <0.14ns.

Back in the 80s I used a top-of-the-range HP 1GHz scope, which sampled at 25MS/s.

Nowadays you can see that principle in action in various scopes with modes called various things like Equivalent Time Sampling, and in the mixer of every SDR dongle (multiGHz inputs sampled at ~10MS/s).

[1] Standard interview question... You have an audio signal transmitted on a 10MHz carrier. What is the minimum sampling rate you can use?

--- End quote ---

Again with that.
Nobody cares for repetitive sampling scopes. We are talking about real time samplings scopes.

--- End quote ---

Many many people care about repetitive sampling scopes. One obvious question: if nobody cares, why do all the main manufacturers of professional scopes have modes based upon repetitive sampling? Current Keysight literature answers that :

--- Quote ---Advantages of Equivalent Time Sampling Scopes
•    Lower sampling rate allows higher resolution ADC conversion
•    Wider bandwidth
•    Lower noise floor
•    Lower intrinsic jitter
•    Can include front end optical modules
•    Can achieve solutions at a reduced cost
--- End quote ---

Note the reduced cost point. Samplers are orders of magnitude cheaper than ADCs with the same resolution.

Another point was given by David Hess: avoiding Gibbs Phenomenon artifacts https://www.eevblog.com/forum/projects/oscilloscopes-what-happened-to-equivalent-time-sampling/msg1781960/#msg1781960

And another: resolving short time intervals e.g. a 100MHz/3.5ns risetime analogue scope easily resolving <1ns intervals. DSOs use ETS for that. timehttps://www.eevblog.com/forum/projects/oscilloscopes-what-happened-to-equivalent-time-sampling/msg1783850/#msg1783850

I suggest you (re)read that thread.


--- Quote ---And you are wrong: repetitive sampling scopes EFFECTIVE sample rate is defined by 1/t of sampling aperture time and fine resolution timing of taking sample in regards to trigger timing.
Fact that it takes samples sparsely is of no influence to Nyquist.

--- End quote ---

You are going to have to get your story straight.

First you claim that "nobody is interested in repetitive sampling rates", and then you try to demonstrate that by using a parameter that is mainly relevant to repetitive sampling!


--- Quote ---There is a reason nobody cares about repetitive sampling scopes anymore (outside special applications).

--- End quote ---

That could only be correct if you were using "special application" to mean "any application I don't personally use". That illustrates more about you than about scopes' capabilities and uses.


--- Quote ---On your interview question, answer is more than 20 something MS/s. Because you didn't specify you want to down convert RF and extract audio you need to satisfy Nyquist to grab full data...

--- End quote ---

You just failed the interview test.

Provided the sampling aperture is sufficiently small, you only need to capture at, say, 44kS/s. Downsampling is not required.


--- Quote ---We are talking about oscilloscopes here, not radio receivers or software radio.... Stop confusing people with ortogonal information...

--- End quote ---

I gave examples of high-end professional scopes, and amplified the key points by reference to other technologies based on the same principles.

--- End quote ---

Omg...

--- End quote ---

A revealing response to the technical points.

tggzzz:

--- Quote from: williamlee on April 09, 2023, 04:03:19 pm ---Is it because 99.9% of oscilloscope user doesn`t need the "eye diagram"? so, the sampling rate is quite ok for 1G or 2G?   
The "real-time" still belongs to the analog scope, right? why does the digital scope need the "sampling rate"? because of the "ADC"?
My point of view that MSO5000 is the best C/P value for 90% of applications especially for logic is better value. It makes sure that SDS2000XP also good for the C/P value.  ;D ;D

If MSO5000 has 50-ohm support and the same frond-end which is like 1054z......
If SDS2000XP has 4G sa/S......
If the R/S, Tek, and LeCroy prices are very very close to Rigol and Siglent ...... too many dreams |O :-DD

--- End quote ---

There is indeed a lot of overlap in the capability of different classes of instrument. A good engineer knows not only how to use each tool to its best advantage, but also where a tool is insufficient and a different tool should be used.

Where digital systems are concerned, often a scope isn't the best tool. Once a scope has been used to ensure signal integrity[1], often it is better to flip into the digital signal domain by using logic analysers, protocol analysers, and printf() statements.

That's particularly true with low-end scopes, some of which I'm told only process what's on the screen and ignore all the captured information that's off the screen. Even very cheap (<<cost of a scope) logic analysers and protocol analysers can produce better results.

As for cost, new modern scopes cannot be afforded by many individuals. Nonetheless, good Tek/HP scopes (and other tools) are available at remarkably low prices, and - in conjunction with other tools - be used for many complex cases. (Examples: I get 350MHz Tek scopes for £50, 21GHz HP/Tek Spectrum Analysers for £350, and bus pirate protocol analysers and generic logic analysers cost ~£30)

[1] i.e. to ensure the analogue waveform will be correctly interpreted by the receiver as a digital signal. A classic tool to do that is, of course, the eye diagram.

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