Recent Posts

1

Projects, Designs, and Technical Stuff / Re: Brymen BC-86P USB-Adapter - Firmware with USBTMC & SCPI

« Last post by HubertGlaubke on Today at 08:55:01 am »

It sounds like you've been quite industrious in tackling the compatibility issue with your Brymen multimeter and the USB adapter. Converting the firmware from assembler to mikroC, and then to an MPLAB X project with XC8, shows a significant effort in modernizing and maintaining your project.

Using the USBTMC protocol and SCPI commands allows for versatile communication between devices, and it's great that you've been able to implement this functionality in your firmware. Being able to modify VID/PID and string descriptors via SCPI commands adds flexibility and customization options to your setup.

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Repair / Re: Tek FG502 fails at high frequency end of dial - help needed!

« Last post by gcwills on Today at 08:53:48 am »

Success
After a lot of extra time spent on this challenging function generator I stumbled upon a fix for the oscillator dropout. I focused my attention on the area around Q292 and Q290 as it appeared that there were bias issues associated there.
Partly out of desperation I added some resistors from the collector of Q290 to ground and the oscillator was able to maintain oscillation a little further up the dial. I then tried the same approach to the collector of Q292 to no effect so I wondered if increasing the value of R155 (the Q292 load) would have a positive result. As it turned out it did and adding a 100 ohm resistor in series with R155 (820 ohm) allowed the generator to operate fully to the high end of the frequency dial. I then removed R155 and the 100 ohm and substituted a 1K 1/2W resistor. I was able to confirm that the generator worked fine across all of the ranges and waveform settings. The generator was then calibrated according to the manual.

So was this a bodge or a repair? I think it is a repair as the generator didn't have any faulty component and worked albeit in a limited way. It just failed to oscillate on certain settings. My guess is that there was sufficient drift in components around the oscillator causing this issue. Increasing the R155 value a small amount increased the loop gain enough to resolve the issue. Of course I am open to better brains than mine with better explanations?

3

Test Equipment / Re: Choosing between entry-level 12-bit DSOs

« Last post by Fungus on Today at 08:52:55 am »

that lead to proper Sinc reconstruction reveals siglent DHO800X can do it properly unlike Rigol, this can also can help user make decision whether this is important or not.

When was THAT proven?

Siglent has a higher sample rate.

Rigols aren't forced to work at 312.5MS/sec.

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Security / Re: Microsoft repackages apps with a telemetry .NET wrapper

« Last post by bd139 on Today at 08:52:11 am »

There is no good purpose for telemetry, it is needed only for malicious purposes

What a myopic, hysterical, uninformed, and untrue claim.

There are definitely some uses for telemetry that are absolutely beneficial to the user: crash reports and usability research. Developers use crash reports to figure out what the most common application crashes are, so they can fix them.

Stable software benefits the user.

Some developers use telemetry to figure out how people use their software: which features actually get used the most? How do people access them (toolbars? Menus? Keyboard shortcuts? Right-click menus?) Which commands get used in what combinations? For example, knowing which commands are often followed by “undo” tells you it’s an error-prone feature. Microsoft’s use of usability telemetry has directly resulted in lots of usability improvements, for example the handy little menu that appears after pasting to let you format the pasted data. Knowing which features are used and how can help guide what features get prioritized for development.

Usability benefits the user.

Your reasoning is detached from the outcome.

Yes crash reports and usability reports are good data sources.

Do they benefit the user? That depends on the sausage factory in the middle of the process.

I have never seen an outcome that is user beneficial from a usability study. I posit that they are run by people who have no idea what they are doing.

As for the other point, my day job for the last couple of years has been running the reliability engineering team for a very large fintech. If you think that a crash dump results in a viable outcome for end users even 5% of the time then you are naive. Most of the time it is just noise. We get thousands of them an hour. And that is considered normal. Even if we do perform a causal analysis on a statistically common one, finding an engineer who can actually understand or solve the problem in a complex distributed system is an uphill battle as well.


The general theme in the thread above is there aren't a lot of people who know what they are doing. They are all making appropriate looking dances though and people who don't know what they are doing look at those and think they might know what they are doing. It's not turtles, but incompetence from the top to the bottom.

And that's why we shouldn't trust, not because the idea is bad, but the competence is bad.

5

Test Equipment / Re: Choosing between entry-level 12-bit DSOs

« Last post by Mechatrommer on Today at 08:49:19 am »

Screen capture over network still works even on an unsigned app.

not everybody like to connect to network for a mere screen capture, i do it with usb stick. my ethernet cable is super long and its quite a mess trying to run it to my dso, at my lab setup, connecting to usb cable is much easier. and that luckily i have ethernet cable at all so i can do some adb hack albeit a bit inconvenience. ymmv.

6

RF, Microwave, Ham Radio / Re: High bandwidth FM signal generation

« Last post by pdenisowski on Today at 08:49:01 am »

1. Using Software Defined Radios (SDR) - SDRs do not provide large bandwidths as per my requirement
2. Using Analog Front End ICs, such as AFE7900 from Texas. This looks expensive solution and tedious

Any other solutions to think of?

A vector signal generator can provide wide bandwidths, provide complete flexibility in terms of signal characteristics (modulation, noise, etc.), and typically have a relatively simple user interface (but can also be controlled programmatically and/or can use signals created in tools like MATLAB).

That said, they may be slightly outside of your budget

https://www.rohde-schwarz.com/us/products/test-and-measurement/vector-signal-generators/rs-smw200a-vector-signal-generator_63493-38656.html

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Projects, Designs, and Technical Stuff / Re: (Yet Another) DIY Multislope ADC

« Last post by Kleinstein on Today at 08:47:04 am »

The run-up modulation with a 4/60 or 60/4 modulation has a usefull part of 60-4 = 56 cycles that are actually modulated. It is not just the 4 cycles that are effectively lost, but also the 4 the other polarity.
Depending on the integrator hardware 4 cycles (500 ns) for the shortest pulses and settling looks about right.
This gives the residual charge a range of about +-60 cycles range. depending on the delay between reading the comparator and the start of the feedback the range may get a little larger than just 1 feedback step. This way the run-down part could get a little larger than just -31 to + 30 counts. The range is more approximate than accurately calculted through.

A big question is how good the jitter is and if one needs / wants external synchronization to a more stable clock. Chances are the clock from the RP pico is not good enough and would at least need an external oscillator. It is not so much jitter, modulation of the crystal frequency depending on how neighboring pins are set or how much current is drawn. At the very least the pins for the ref. modulation should be away from the clock.

8

Security / Re: Microsoft repackages apps with a telemetry .NET wrapper

« Last post by bd139 on Today at 08:46:28 am »

Of course corporations want to make believe that their spyware (ahem, "telemetry") is the equivalent of a usability study, but it plainly is nothing of the kind. Collecting statistics—on which buttons are clicked most often—doesn't yield any useful information if there is no experimental control. Data without a control is just worthless junk (see most papers in econ and nutrition for examples).

The UI changes that they justify on the basis of this worthless junk are also, you guessed it, worthless. But everybody already knew that if they are remotely familiar with user interfaces in the pre-2005, and compare to what dreck is pushed out these days. There are other reasons for the widespread UI failure ("responsiveness" and touchscreens are a large component) but reliance on uncontrolled UX data collection is surely a major factor.

That's mostly because the user studies are invalid.

What is considered:

1. If we do change X then outcome Y happens.
2. If we do change P then outcome Q happens.

What should have been considered but is never done is a control option:

1. Leave my shit alone and stop pissing around with it.

This is normally isolated from user studies because people don't consider that as a valuable outcome because it does not generate work and people value work more than leaving shit alone and stop pissing around with it.

9

General Technical Chat / Re: The strange case of phase angles

« Last post by strawberry on Today at 08:44:45 am »

simulate in Qspice

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Security / Re: Microsoft repackages apps with a telemetry .NET wrapper

« Last post by bd139 on Today at 08:44:35 am »

Regarding my comment about telemetry being fine, yes it is fine. But if it is constrained properly and the user consents to it.

If someone does a proper analysis then it is a powerful tool for making decisions. That requires some formal framework, proper collection methodology, thinking and statistical analysis around it. And that requires people who are formally qualified to do an analysis in that space (consider RSS / IMA members)

BUT the general approach of the technology industry is to collect everything, hope there is something useful in it and fabricate some official looking outcome from it without publishing your methodology. At the same time, creating a privacy violating dragnet and covering that with marketing. That is NOT ok. And that is Microsoft's approach. In fact their approach seems to be measuring what a completely helpless and powerless set of users will put up with.

It's important to distinguish the two. No absolutes are good for anyone.