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Test Equipment / Re: Magnova oscilloscope
« Last post by KungFuJosh on Today at 10:24:47 pm »
Including 19% Tax...

https://www.batronix.com/versand/oszilloskope/Siglent-SDS2354X-hd.html


Oh yeahhhh. Forgot about that ridiculous VAT thing. Yikes.
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The rundown part is only a relatively small part of the result. The question is only if the reference for the rundown are more accurate than a high resolution ADC and stable capacitor, that would be the alternative.
If the postive and negative reference are the same size, not extra constant is needed to calculate the result. Ideally the difference between the reference (including a possible offset of the integrator input voltage) is an additional correction parameter, that has a limited effect. Measuring that parameter is relatively simple by comparing the case of no reference and both references at the same time. It is a little extra effort for a kind of "factory calibration", but the later math is not so bad.  No need to go above some 16 bits, as the rundown part is still only a relatively small part of the result.

How would a fully symmetric rundown look like ?  Only one direction and thus a comparator reading from both directions is not really a good option. It adds the comparator hysteresis / delay problem and also the problem with a very short pulse close to zero initial charge.
A fixed sequence with 2 variable times is kind of the natural choice. The system is fully determistic. There is no big difference from starting positive of negative. At zero res. charge one gets 2 short pulses and when away from zero one of the pulses gets longer and the short one stays the same.  There is just some freedom in the design on how short the pulses can get. Adding a few more cycles there is usually not such an issue.
A possibly tricky point may be the effect of short pulses in the runup. This way the runup steps may be tiny bit different from just the ref. strength and time. In the shown simple runup scheme the number of short pulse directly follows the runup result and a slightly modified cal. constant could compensate. With not too fast a modulation and thus enough time for the short pulses this should still not be a problem.
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Microcontrollers / Re: Signal filtering - Could this work ?
« Last post by gf on Today at 10:16:54 pm »
But it has smooth cut-off slope on frequency response and pretty mediocre rejection ratio at stop bandand, which is not suitable for many DSP applications.

Yes, the selectivity and stopband attenuation are not good.
However, you won't find a FIR filter of the same length that has a better (lower) equivalent noise bandwidth (ENBW).
If noise reduction is the only goal (and selectivity is not important), then boxcar averaging over the entire desired settling time is still the best choice.

Another advantage of a FIR filter is a bounded 0-100% step response settling time, while the settling of an IIR filter is asymptotic. Example: An exponential moving average filter which settles to (say) 99.9% within 30 seconds has an even worse selectivity and stop band attenuation than boxcar averaging over 30 seconds (whose step response settles to 100% in 30 seconds), and the ENBW of this exponential moving average filter is ~3.45 times higher, too. Frequency response is attached for comparison.
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Beginners / Re: buying a oscilloscoop
« Last post by Zenith on Today at 10:12:43 pm »
It comes with probes, probably 100MHz and switchable between 1X and 10X. Mostly the 10X setting is used. I'd guess your friend recommended 100X probes as well, because you work on tube amplifiers and radios.

A way to become comfortable with it is to play with it with a signal generator or function generator. It doesn't have to be a very good one. If you don't have one, a £10 XR2206 based function generator from ebay would do, or you could put something together with a 555 timer chip, or make a multivibrator.
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Metrology / question about short term drift test of Agilent 3458A
« Last post by analogRF on Today at 10:07:03 pm »
I want to do the short term drift test (as per service note 18A) using the CAL? 72 but I cannot keep the unit running 24/7 for 7-10 days.
I can run it for like 5-6 hours per day.
Is it ok to run it say 6 hours a day and get the temp and cal?72 after an ACAL at the end of each day and then turn it off and repeat the next day to
gather enough data? or is it mandatory to run the unit 24/7?
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How did you find out that this will happen?
Probably there is much more config data stored in the EEPROM (time out behavior etc.)...

Most bridges are designed in this way. It's rare for a bridge to need an external "ROM" for basic functionality.

See https://habr.com/ru/companies/ntc-vulkan/articles/485966/

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Findings:

During the boot process, the ASM1051 tries to load the code from the ROM [ie the external SPI flash].

The first thing ASM1051 does is compare the checksum-8 byte from address 0x04 to 0x7E with the value at address 0x7F.

If the calculation of the preamble check is successful, then it can be considered for the "code" (addresses from 0x0082 to 0x807F). The ASM1051 compares this sum with the value at address 0x8083 and checks that there is a byte 0x5A at address 0x8082.

If all checks are correct, then the ASM1051 is loaded from the ROM, otherwise it uses the mask firmware.

ASM1053 datasheet:

https://datasheetspdf.com/pdf-file/917641/ASMedia/ASM1053/1
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Test Equipment / Re: SDS800X HD Wanted Features
« Last post by tautech on Today at 10:05:58 pm »
Have been playing with my 804X all morning, and so far I'm really impressed. Other than the slightly sluggish UI (in particular, the waveform stops updating for an annoying long period of time when I adjust the trigger position), it's hard to believe this is a £355 scope.
Yep, a massive step up from the X-E range.

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So, feature request #3: Can anything be done about the delay between adjusting the horizontal trigger time, and the waveform update resuming?
As you use it more you will discover this is by design and the HW resources available.

ANY operator changes must flush all previous measurement and History records and wait for the user to fully determine their correct settings before everything that's happening in the background recommences......these are proper analytical devices not just something that displays wiggly lines.

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And feature request #4: Use full memory depth for single shot capture. On the Agilent, a single-shot capture grabs more data than just what fits on the screen, so I can press 'single' then pan and zoom the result, including a lot more pre- and post-trigger data. On the Siglent, pressing 'single' fills the screen, but the acquisition begins and ends with what can be displayed, even if that leaves memory unused. Why not fill the memory, so I can trigger on an interesting event and then scroll back and forward to see what happened before and after?
Capture methodology by design has mimicked LeCroy and requires a different workflow to achieve the same functionality as scopes that can zoom out.

OR by using a slow timebase and the Zoom feature and the zoom window active before capture. Try it.  ;)

From SDS2000X HD and up Fixed Mem depth is offered which can offer an order of magnitude more zoom out than the scope you are used to....when the advantage of deep memory displays itself.
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Test Equipment / Re: Magnova oscilloscope
« Last post by KungFuJosh on Today at 10:00:06 pm »
You can also get a 350Mhz 12 bit scope for 3400€ (SDS2354X HD)

Are the Euro prices higher now? In the US, the SDS3034X HD for $3,690.00 and the SDS2354X HD is $2,999.00.
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