Recent Posts

1

General Technical Chat / Re: Is LinkedIn worth keeping?

« Last post by tom66 on Today at 02:22:48 pm »

I maintain a LinkedIn account but rarely contribute.

I have gotten all of my previous jobs through the platform, besides the very first one, so I regard it as being useful from that end, but it is mostly recruiter spam these days.

2

Test Equipment / Re: UNI-T UDB3000S Series: UDP3305S / UDP3305S-E

« Last post by pope on Today at 02:22:13 pm »

Looks like the increased the prices. I was about to pull the trigger but now I'm gonna have to look for a different brand. Oh well...

3

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

« Last post by ebastler on Today at 02:21:06 pm »

I don't see that as much of a problem in practice, especially if you're aware of it. Four simultaneous 200MHz signals aren't easy for hobbyists to find. It's really easy to drop down to two channels if you're in doubt. You'll probably see a difference on the Siglent, too, if it's anything more than a simple sine wave.

If you're always working at 200MHz on four channels then you need a better 'scope than either of these. Probably active probes, too (if you're using probes).

It's enough to have one 200 MHz signal, which you need to observe in context with two other (potentially lower-bandwidth) signals. Not that exotic a requirement for those who decided to get a 200 MHz, 4-channel scope. On the DHO800/900, with only 312 MSa/s per channel, you will be out of luck.

4

Beginners / Re: Switching a 3KW (240V) immersion heater: Solid state or mechanical relays?

« Last post by IanB on Today at 02:19:35 pm »

It's an LED downlight with a 1m power cord attached to it.  So you install it into your ceiling and then... ahhh... WTF?

My garage is fitted out with switched plug sockets distributed across the ceiling. I was therefore able to buy replacement light fixtures fitted with mains plugs, and just plug them into those sockets. Having switched sockets for lighting is a common thing in the USA.

5

Programming / Re: Linux Dependency Black Hole

« Last post by shapirus on Today at 02:17:05 pm »

I also think things are getting worse. The reason are all those pesky new/better/wonderful ways to install software... that are full of shit. They don't want to learn how to create debian packages, or think they will make some money going that way, or fame/glory/whatever, so they have to invent the wheel again and again. But, while apt is almost the perfect wheel, those new wheels, well, not so much.

Apt is almost perfect, yes, but only as long as you install the software available in the distribution's repositories and, ideally, don't mix the distro releases (that can be done too, but requires experience and understanding).

The core issue with, almost universally, linux package management, is dynamic linking. Once you want to install something that was linked with a library that is not (or no longer is) a part of your distribution, you're screwed. That's where hell begins. It's good if there's a source .deb package: you can usually build a binary package from it using dpkg-buildpackage, and it will be linked against your available libs, and will install just fine. It's worse when you have plain sources. It's terrible when you have just binaries linked against libs in a 5 year old distro.

This is where packaging systems like AppImage can be helpful: they contain statically built binaries with no external dependencies. They will still work in 20 years just like they do today (provided it's the same CPU architecture), unless they depend on some specific kernel calls, which is not typical for general userspace apps. Good luck trying to run anything built for any Linux distro in 2005 today, unless it's a static binary.

I can see why software developers want to bundle their binaries as AppImage: spending time to learn how to build a gazillion different packages for a gazillion of different distros, not to mention another gazillion of their releases, would be insane. Why do that if you can build a universal package (actually several: by the number of target CPU architectures) that will be guaranteed to work on any linux distro?

Linux packaging is perfect as long as you stay strictly within a given distribution's ecosystem. Once you try to take a step outside (and you will, unless you have a purely academical interest in it), it becomes a nightmare.

6

Test Equipment / Re: SDS800X HD Bug Reports + Firmware

« Last post by eTobey on Today at 02:16:28 pm »

Another little issue:
The timout counter for closing the menu is not restart, when a sub menu settings is choosen. At least on cursors menu and search menu, and i guess on every menu.

Not a big one, but still annoying and confusing.

7

Test Equipment / Re: SDS800X HD Bug Reports + Firmware

« Last post by eTobey on Today at 02:14:28 pm »

Zoom function not working properly after loading mask:
Creating a mask and loading breaks the zoom function. See picture.

Also:
Creating a mask does not show the view that was set up for it.

I really would like that this feature "would" work with the zoom.

It does work.
You did not set it up properly.

You missed a little detail: i made a custom mask by hand.

8

General Technical Chat / Re: Is LinkedIn worth keeping?

« Last post by tggzzz on Today at 02:06:20 pm »

I joined linkedin when it first appeared. Seemed like a good idea.

Then acquaintances started to repeatedly request that I "recommend them". Er no. "Recommendation" implies more than "have talked to them on the phone".

I left pretty soon afterwards.

I've recently rejoined to see what's happened to colleagues who have now retired. I get a lot of spam from "people" (and I use that term loosely) advertising things/themselves.

Only tolerable since it is easy to train spamfilters

9

RF, Microwave, Ham Radio / Re: Quansheng UV-K5(8) firmware modding

« Last post by radiolistener on Today at 02:05:34 pm »

I was used Chirp on windows. But now I'm on linux and looking for linux software which is open source. Chirp is more general software, I want some specific for the radio to avoid a bunch of unwanted code and data.

At a glance it looks that k5prog is good enough for all modding stuff. I saved backup of EEPROM calibration data.

But I still didn't tried to flash custom firmware, because I don't know how to backup existing firmware.

It looks that there is no way to read existing firmware through baofeng cable. Is it correct?

10

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

« Last post by 2N3055 on Today at 02:03:56 pm »

I would not stress potential hacked, extreme-bandwidth applications here. Very few users will try to go there. But even without considering hardware hacks, it is worth mentioning that 2 GSa/s (as in the SDS800X HD) are sufficient to support 200 MHz bandwidth in 4-channel mode, while 1.2 GSa/s (DHO800/900) are not.

I don't see that as much of a problem in practice, especially if you're aware of it. Four simultaneous 200MHz signals aren't easy for hobbyists to find. It's really easy to drop down to two channels if you're in doubt. You'll probably see a difference on the Siglent, too, if it's anything more than a simple sine wave.

If you're always working at 200MHz on four channels then you need a better 'scope than either of these. Probably active probes, too (if you're using probes).

On simple Arduino, I/O pins have sub 1ns transitions. Spectra of that goes over 1GHz...

If you are always working on 4ch and 200 Mhz you need better scope than Rigol that undersamples.
That better scope IS the SDS824xHD that can do that job competently.
Unlike DHO800/900 that cannot because of violating Nyquist.