Recent Posts

1

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

« Last post by madires on Today at 02:06:56 pm »

From an EU point of view (GDPR) the rules for telemetry are quite clear. Telemetry can't be forced upon the user, i.e. the application has to run also when users deny the collection of telemetry data. Users have to be informed about all the details (what, why, how long stored, and so on).

2

Beginners / Re: Convert US standard 115V to International 230V

« Last post by radiolistener on Today at 02:04:09 pm »

Because you don’t, and that entire reply is proof of this. You just bark back, but never accept responsibility for mistakes, nor accept that others are correct. Look at the part of my sentence above that is in italics. (And which was in italics in the original.)

Your personal subjective opinion about persons is off-topic.

Your first reply in this thread, long after OP had listed the part numbers of the power supplies used, you suggested 1. using a motor-generator set, and 2. to consider switching to an SMPS inside.

Both of those suggestions are completely irrelevant and useless at that point in the discussion because it had already been established that it uses two universal-input SMPSs.

This shows you did NOT read the discussion before replying.

When I posted my first reply in this topic I didn't seen complete list of power supplies which are used on OP device. And correct me if I'm wrong, there is still no such list. Also I noted in the first OP post that his device power consumption is about 2300 Watt. And two PSU which he later provided for example is about 750-900 Watt in total, which is just about 40% of total device power consumption. So there is no way to decide if all of his PSU are compatible with all mains standards. I already explained it, but for some reason you're didn't read it.

I don't see why my post is completely irrelevant, the second part covers SMPS with universal input.

But even if all of their PSU are compatible with all mains standards, that is not enough to claim that medical device which uses these PSU will be compatible with all mains standards.


Regarding to the mains filter mentioned by IanB, it doesn't related with 50/60 Hz at all, their goal is to remove common mode currents in order to reduce EMI. I was talked about different filter which is used on device sensors ADC and in DSP stack to reject 50 or 60 Hz carrier from measured signal which appears due to interference from mains wires and due to leakage through PSU. It is software configured depends on used user environment. In medical device some signals working range may be very close to 50/60 Hz and even may cover that frequency and needs to be carefully processed with take into account the frequency of used mains line. Because interference level from mains frequency is pretty strong and it's presence can affect measurement results. This is why using PSU with universal input is not enough to decide that device is compatible with all mains standards.

3

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

« Last post by pdenisowski on Today at 02:01:51 pm »

if I understand correctly, for 5G it will be more easy than for 2G/3G/4G, because they using phased antenna array to rotate beam, so it will works like radar and allows to get more precise position of transmitter with triangulation, isn't it?

Steering the beam might allow for a rough determination of where in the sector the interference is coming from, but I'm not sure if any network providers who are using it for interference detection.  A more likely application is using it for interference avoidance (in the same way that "tilt" is used in pre-5G).

Incidentally, "triangulation" as a DF or interference-hunting methodology is, in my experience, both very overrated and very misunderstood.  Unless you are in a more or less reflection (multipath) free environment, it's very difficult to get good bearings: calculating the interception of those bearings is trivial, but junk bearings yield junk results. 

Since interference / jamming happens around (or at least is important around) people, this means most practical DF'ing is being done in urban and suburban environments where multipath can be an issue. 

For cellular network operators, they know from the base station stats (RSSI, e.g.) which sector or sectors are being affected, and in most cases you can simply drive (or walk) the sector until you get close and have to hunt on foot (where triangulation is completely useless).

Just wonder is it possible to use some kind of synchronized array of transmitters distributed all around the base stations and transmitted signals in that way so their interference signal at base station location gives false position of the transmitter or just spamming it with a bunch of virtual transmitter positions to make it hard to find which one is real? Are such kind of jammers are used in practice?

There are a lot of "creative" approaches to jamming, but high-end direction finding systems (like the ones we make) can usually still DF people trying to use "creative" techniques.  Generally speaking, for a jammer to be effective it has to be (a) loud, (b) wide, and (c) on, and all three of those things make jammers relatively easy to DF, regardless of how they are implemented.  A weak signal with a low duty cycle that's only a few kHz wide is harder to DF, but it's also not an effective jammer.

4

Microcontrollers / Has anyone used ASAN & MSAN, and relevance to embedded arm32

« Last post by peter-h on Today at 01:57:22 pm »

This came up on the MbedTLS mailing list, where somebody had some weird bug.

A suggestion was running the code with Asan
(https://github.com/google/sanitizers/wiki/AddressSanitizer) and Msan
(https://github.com/google/sanitizers/wiki/MemorySanitizer), both
natively available on Ubuntu.

But doesn't this require building the code for a "PC"?

In the case of MbedTLS one can indeed build a win32 version (and I do have that, done by the guy who did my MbedTLS implementation) although this was quite a lot of work, especially to use the same memory allocation strategy as the embedded target uses, which is quite important since you are processing external data (certificates of various sizes and with different hashes etc).

In my case I do not use the heap other than a one-off malloc for an optional feature which is never freed so fragmentation is impossible.

5

Repair / Re: Rigol DP712 Output Shorted; Fuse? / I Screwed Up

« Last post by shapirus on Today at 01:56:03 pm »

It's interesting. What's the rationale behind using a thyristor for something as simple as discharging the output cap? Why don't they use a resistor instead of it?

6

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

« Last post by Marco on Today at 01:52:37 pm »

Microsoft forcing telemetry on you is 'getting your panties in a twist'? That only seems innocuous compared to them not limiting it to the Store.

Could be worse, they could insert an online certificate check into your application (even though a certificate revocation list is easily possible and inherently superior for both privacy and security).

7

Beginners / Re: Automatic golf ball dispenser

« Last post by soldar on Today at 01:51:39 pm »

LOL...

1. don't HATE, Never hate, it's a bad habit.
One thing i've learned in 50 years is we have so many people in this world and they all have many different personalities and each
have their own psychologies that are associated with them. As humans we can only get along with people who have the same or similar
psychologies as our own, which ultimately means you cannot get along with everyone.. EVER !!!

that being the case, If you hate because someone did something that you didn't agree with (According to your psychology) then you are fighting a losing battle my friend and will do nothing but frustrate yourself and cause yourself health issues later in life.

2. But did it ever occur to you that there were other reasons why people suggest he use a micro ?
YOU ARE CORRECT... It's not necessary. But this person came to us with a very simple problem, but a problem that wasn't simple for him.
as tech people we want to help him AND GIVE HIM IDEAS and even though not necessary now, the introduction
of a dev board now is going to lead him down different paths of possibility that will either help him solve his problem or cause him to think in different directions and help him down the track, or perhaps he has this underlying idea that he didn't bother to mention that does actually require a dev board but now that it was mentioned, becomes a possibility

Mate, it's called  BRAIN STORMING,  it doesn't have to make sense or be necessary at first.
and if he's never used an arduino, and given his curiosity  HE SHOULD LEARN HOW TO USE ONE

Just like a person who has never used a hammer should go out and find nails to pound into timber if for nothing else but the experience.
This project may start as an arduino project, then he'll encounter issues on V 1.0 , then he'll refine it and perhaps on v 6.0 it turns out being
what you said and has nothing to do with arduino.. BUT HE GAINED EXPERIENCE FROM IT that would help him in later projects.

Never hate, it's not productive to anyone

Are you on some spectrum or something? 

You sound like the kind of person who,  at a social gathering, when someone says "I hate it when the toast falls to the floor with the jam side down" would go on to a speech about how hate is so negative and you should make the toast on the floor a positive experience.

And when, in an attempt to get away, they ask you what the time is, you would try to teach them how to make a clock ... which is always a useful skill.

The OP is interested in playing golf, not in learning Arduino.

Look, I am beginning to learn Arduino myself; I think it is useful and entertaining... for me. I do not try to shove my own things down other people's throats because I do not want golfers telling me how great golf is.  And any golfer who tries to talk me into golf, their religion or any other cult, like Linux or Apple, I am going to walk away from. Microcontroller guys can be as bad as other types of fanatics.

8

Repair / Re: Rigol DP712 Output Shorted; Fuse? / I Screwed Up

« Last post by IanJ on Today at 01:51:21 pm »

I can't understand only the function of p-channel MOSFET.

Hmmm, possibly when the thyristor turns on the mosfet will turn on also so that when the output cap is discharged it will also pull/reference the neg output down to earth via the mosfet, i.e. stop any spikes when the thyristor turns on.......if the other end of the 390ohm is tied to earth.

Just a thought.

Ian.

9

FPGA / Re: Help on translate schematics to Verilog.

« Last post by caius on Today at 01:42:48 pm »

> I have these other two KiCad symbols that I'm try to identify,

If you have KiCAD schematic file you can fetch type of symbol from it. Just open it in KiCAD, select symbol and press 'E'.

Thanks for reply.I just need the Verilog modules of the two gates to be implemented as symbols in my Quartus schematics.No ned to be FPGA compliant (well, I'm going to use MAX7000S CPLDs)

10

General Technical Chat / Re: Why don't we make [more] use of water wheels?

« Last post by coppice on Today at 01:41:19 pm »

I have spent the last few weeks roaming about in France and in Provence I saw many waterwheels but none in use. Originally they elevated water or provided motive power for mills or factories. None are in practical use any more. They are kept only as tourist attractions.  Since the wheels and water canals are already there you could think they could be easily adapted to generating electrical power but it looks like it just isn't worth it.

I think you'll find plenty of water wheels preserved as museum pieces all over Europe. There are certainly many in the UK. They can't really be both museum pieces and effective modern power generation platforms. As they stand, their high cost of maintenance is justified as a running cost of the museum. If they have to stand on their own merit, maintenance costs could only be justified if the place is far from the madding crowd, and does not have economic access to grid power.