I remember similar parts in the past costing at least an order of magnitude more for less performance and functionality.
Its not that long ago you couldn't buy such functionality as a chip, even at exotic niche product prices. Times change, and devices like this do have volume applications now. Hittite describes (or is it described now they are part of ADI) itself as a microwave company. That tells you what their core market is.
Tektronix was making their own custom high speed ADCs when they sold their silicon fab to Maxim and then they bought from Maxim and others got access to those high speed ADCs as well.
Yes and what we have seen has nothing to do with the impurities of the applied signal. Yes impurities above Nyquist will fold back and show up, but even with my DSA815's 'crappy' TG this would be far down in the noise (i.e invisible).
And (but maybe I misunderstood David) reconstruction will not restore the original 24 MHz waveform.
Tektronix was making their own custom high speed ADCs when they sold their silicon fab to Maxim and then they bought from Maxim and others got access to those high speed ADCs as well.
That was 20 years ago. Back then Maxim would not have been able to sell a high performance converter to a Chinese company. Even now Chinese companies wanting state of the art converters end up sending delegations to Washington to plead for them.
I had not considered that but I am sure it was the case because of export restrictions. They continued to make custom ICs for Tektronix as well for at least some time. I have one Maxim marked part with Tektronix part number with a date code of the 50th week of 1994 which fits with the other Maxim parts showing up in the late 24xx series oscilloscopes which were made between 1989 and 1996. Wikipedia says the date was 1994.
This fits with the earlier post marmad made about leakage. I know I have run across that before but did not recognize it because the terminology was different. A sharper reconstruction filter would allow one to get closer to the Nyquist frequency.
I had not considered that but I am sure it was the case because of export restrictions. They continued to make custom ICs for Tektronix as well for at least some time. I have one Maxim marked part with Tektronix part number with a date code of the 50th week of 1994 which fits with the other Maxim parts showing up in the late 24xx series oscilloscopes which were made between 1989 and 1996. Wikipedia says the date was 1994.
I thought all the 24xx scopes used CCDs for sampling, and had very mediocre ADCs. I think Tek made those CCDs, and they were pretty neat technology for the time.
No, this wouldn't help. Reconstruction filters are, of course, low pass filters designed to remove spurious high-frequency content (above Nyquist) in the sampled data. As stated in the physics post I made (and visible in the examples), leakage "...introduces spurious low frequency components in the sampled data." A look at the power spectra graph from that post confirms that the "power of the fundamental frequency" leaks into other lower frequencies.
interested.
As I noted before, there has been a continual development of adaptive sampling-frequency algorithms (to minimize the mismatch between input frequency and sampling rate) over the last few years to combat leakage (specifically for use with FFTs). There are a number of various papers on it if you're interested.
Now I am confused. Are you referring to the analog antialiasing filter before the digitizer or the reconstruction filter after the digitizer? If aliasing occurs then the later cannot do anything about it.
Now I am confused. Are you referring to the analog antialiasing filter before the digitizer or the reconstruction filter after the digitizer? If aliasing occurs then the later cannot do anything about it.
Both are low-pass filters. Leakage is a phenomenon that is not associated with aliasing (since it happens below Nyquist) and is not preventable by antialiasing or reconstruction filters.
If the source in my electronic design has a max. frequency of 100 MHz, then where can I expect to get the higher frequencies from? Interference, noise, higher harmonics?
Everybody is discussing here that the low-pass filter in the analog front-end of the Rigol scope is no good, as it is not a higher order filter and does not have a steep slope behind the cut-off frequency.
But who cares if the signals in the electronic design are below or at max. 100 MHz?
I have a hard time to understand where the higher frequencies can come from, and if there are any, that their impact is noticeable.
Would like to have a better understanding on unexpected higher frequencies that can show up, their origin (interference, noise, harmonics) and their impact?
Aren't the higher harmonics far enough away, even if the analog filter isn't perfect?
Or is that where the problem originates, that the higher harmonics are relatively close to the original signal, and are not cut-out by the simple filter in analog front-end of the Rigol DS1054Z?
I like the paper but I am surprised someone wrote one about this and I do not understand how it applies in this case.
Everybody is discussing here that the low-pass filter in the analog front-end of the Rigol scope is no good...
Higher harmonics: Let's say we have a 100 MHz square wave. With a square wave at 100 MHz, the fundamental frequency is at 100 MHz, the 3rd harmonic is at 300 MHz, the 5th harmonic is at 500 Mhz. Doesn't the low-pass filter cut-out frequencies above 300 MHz? I believe it does!
As you approach the Nyquist frequency there's this thing called "aliasing" which you willfully seem to be ignoring.
As you approach the Nyquist frequency there's this thing called "aliasing" which you willfully seem to be ignoring.I think the point he was trying to make is that the first harmonic of a 100MHz square wave (300MHz) would be a fair bit beyond the DS1054Z's front-end roll-off and not cause much aliasing.
But I agree that in the grand scheme of things, such a specific case is of rather limited use.
I want to come back to my question: if none of the signals in the electronic design, either the source, the intermediate signals in the signal path or the output signal has a frequency above the limit...
Interference: Can this really go up to 100 MHz with a noticeable impact? Don't believe so.
Noise: Can this really go up to 100 MHz with a noticeable impact? Don't believe so.
If not, it is a design failure I would say, if a 100 MHz scope does not even handle a 100 MHz square wave (DS1104Z with 100 MHz BW, 250 MS/s per channel).
If not, it is a design failure I would say, if a 100 MHz scope does not even handle a 100 MHz square wave (DS1104Z with 100 MHz BW, 250 MS/s per channel).
And you'd be wrong. Again.
According to all your "uncertainties" about not knowing for sure if there is a higher frequency or not, that suggestion about buying a 200 MHz scope should not hold either to be consistent with your "uncertainty". Because your "uncertainty" can not guaranty either that there is not a higher frequency than 200 MHz in the signal path either, although you are measuring 100 MHz signals.
But the "uncertain" guys here want to have a whopping margin of 10x.
And when Nyquist says that the sampling frequency should be two times, I believe that 2,5 is already an extra margin. But the "uncertain" guys here want to have a whopping margin of 10x.
No wonder that you need to reach out in your pocket for a scope which is way over dimensioned for the kind of electronic toys which you are designing