QED

[Aziz]

*LOL*
My bad. Correction: the low-pass filter (integrator) is passing low frequency of course. So it remains only 20 dB/decade with the subtraction method at the end (not 40 dB/decade). I must have tought of the harmonics of the 50/60 Hz, which they will be suppressed.
--------

Yep, the excessive discussion about the 50/60 Hz EMI noise cancellation is really ridiculous. If one can synchronize the detector to it, the better the cancellation. But this isn't a reason to dispute.

Aziz

[moodz]

mains rejection is an old problem = solved.

....ho hum ... mains rejection has been solved for many years in ADC land ... why there are arguments about it I dont know ...
...many patents and basic DSP on this already published and in public domain. Nor do you have to be spot on frequency to achieve rejection so off frequency ( ~ few Hertz ) gensets etc will be rejected also.

example ( 1 of 100's )

http://www.analog.com/static/imported-files/application_notes/AN-611.pdf

...if you are seeing any signal energy that does not come from targets / ground / coil below the PI Tx frequency there is something wrong with your design .

moodz.

[Carl-NC]

I wonder, why the 50/60 Hz mains hum should be a great problem.

Many detectors, especially wideband designs, struggle under power lines. Two approaches to solving this are to either synchronize exactly to the powerline f so that the demod output is DC, or to place the demodulated powerline f out-of-band of the sweep filter.

Exact synchronization seems easy, and is commonly done in walk-through security detectors. I did so in one I designed, and it turned out that even though I had easy access to the powerline f (via the power cord) I still had noise problems at high sensitivity levels due to powerline jitter. I suspect trying to null out a generator would be even more problematic, though I never tried.

- Carl

[Aziz]

Hi all,

I wonder, why the 50/60 Hz mains hum should be a great problem. My coils are facing EMI noise, which is by far more difficult to cancel.

BTW, the static magnetic field/earth field induction is already eliminated by the differential integrator by subtracting the late sample from the early sample. The suppression is 20 dB/decade (first order low-pass filter = one pole low-pass filter). Guess what, it also inherently cancels the 50/60 Hz noise hum.

Now more detailed:
The integrator has a roll-off slope of 20 dB/decade (low-pass filter). By applying the subtraction of the samples via differential integrator, again 20 dB/decade is achieved. Total roll-off slope is 40 dB/decade (or second order low-pass filter).


Get over it guys. The 50/60 Hz EMI noise isn't a real problem. At least to me.

Cheers,
Aziz

[UrbanFox]

Doug, would you read the genset specs at this link....

http://www.macallisterpowersystems.com/414/generator-set-engine-governors.htm

I note the specs are for Caterpillar diesel engines with mechanical governor. Cummins diesel powered gensets using mechanical governors have similar frequency and voltage stability specs.

The method of mains EMI rejection previously described for the QED is described as being operator adjusted to a specific frequency.

Elsewhere, Doug, you have stated........

"PS Ufox AC main line frequency variations of typically + or _ 0.2% will have little effect on the SMR of the QED!
Who the F***K detects near a 500/2,000Kva Gen set! What a D***h**D *of statement by the *Onlyfoxin!"

Well Doug, it is not unusual for a detector to be used in the oversize from a genset powered processing plant. Therefore, it is not my statement that is a D**k H**D statement.

This (idiot smiley) should tell us what happens when you run a ML with a mono coil near a running gen set particularly a petrol motor powered gen set!!!!! Provided that non linear loads are restricted to less than 20% of max generator capacity then on good quality gen sets the frequency variation is + or- .25% and on some as good as + or - .1% you (idiot smily)

Doug, it is evident that the specs presented for the mechanical governor Caterpillar powered Gensets I link to above do not present the 0.2% let alone 0.1% frequency stability you quote.

So Doug, considering "+ or - 0.2% will have little effect on the SMR of the QED", would you tell me what can be expected around a genset with comparable specs to those presented in my link above, when operated under the variable loads expected in a small/medium scale mineral processing plant, using say a 100Kva through to 500Kva relocatable genset.

If you have the technical knowledge to refute my imputation then let's hear it, but please moderate the derogation.

You ask on your forum "Why does Carl-NC of Geotech treat us like children". When are you going to grow up and recognize that name calling, especially from inside your forum, where I and many others cannot reply (and don't want to go to to reply), is for children. Maybe if you grew up you wouldn't be treated like a child.

[Carl-NC]

Carl you sent me a private PM ticking me off for high jacking Aziz's thread.
Did you do the same for Patches junior who was the first to high jack the thread?
For members and guests the deleted posts can be found here:
XXX

Doug,

I have sent you no such private PM, about anything. I have reluctantly allowed this thread to continue despite knowing that little good can possibly come from it, especially when you're involved.

Bugwhiskers has been a technical contributor to this forum. Woody has made valued contributions. Aziz has been a regular. They are all welcomed here to share technical knowledge, even if they have personal frictions; I just ask they check their frictions at the door. Even PJ and others are welcomed, as long as they keep it civil.

To my knowledge, you have never made any useful contributions, anywhere; you just like to start fights, and bash a certain company and anyone who likes their products. All under the pretense of a "public's right to know." Right to know what? Informed decision about what? What, exactly, do you offer anyone? Why BW would believe you have anything useful to offer him is beyond me, so far he's only gotten grief. But that's BW's problem, not mine. My problem is maintaining a decent forum for technical discussions, and keeping trash talk out of it.

- Carl

P.S. -- Doug, did you really place screen captures of my forum on your forum? Have you not bitterly complained (even with legal threats) when people have done that to you? Please delete them. And don't post any more links back to your forum; trying to drag the discussion over to your forum is just plain rude.

[Qiaozhi]

OK children - I've seen the comments posted over on the Australian Electronic Goldprospecting Forum; and you can be assured that I would have deleted the exact same posts that were removed by Carl. Unfortunately I had to spend some precious time reading the deleted posts, and they all violate the rules of the Geotech forum. Some of Aziz's posts were also included in the deletion, but they would not have made sense out of context with the other posts. I will leave Carl to take any further action with the latest torrent of abuse in this instance.

When the QED was first introduced here on Geotech (in the distant past) the discussions were concentrated on technical issues, which is that way we like things here. I don't know what has happened since then, and personally I don't really care. All we ask is that you keep things civil and keep it technical. Forget about the personal issues and attacks, as these will simply be deleted, and try to be friends.

Thank you.

[dougAEGPF]

Doug, Doug, have you forgot what several people have told you before? Multi layer boards work fine when they are laid out for population right. You have been told many times that you have a couple components in the wrong area as they will interfere with each other. As far as which components they are your attitude makes people reluctant to tell you. Simple as that. No more clues till you change your ways of being a PR guy! Understand my friend???

So stop asking the same question every time someone gets your goat. And stop trying to get mine or Robbies or Woodys professional opinions to help you. That is until you are willing to offer us some big money! Our superior knowledge is not free!

The fact is that you don't have a clue about what components you allege are too close together or even if they will interfere with each other!!
Very careful bench and field testing of the latest fully populated QED rev boards do not show ANY of the effects you allude too! In fact quite the opposite! The low circuit noise level contributes to the high S/N of the QED.

[PATCHES JUNIOR]

I would like to know as many other folk here would as to why multilayer SM boards are bad for "harmonics" compared to single layer SM boards.You seem to be a reasonable and knowledgeable person to ask this question and well informed as to the boards that are used in the QED. So come on for the benefit of others here please give us thoughts on this topic.

Doug, Doug, have you forgot what several people have told you before? Multi layer boards work fine when they are laid out for population right. You have been told many times that you have a couple components in the wrong area as they will interfere with each other. As far as which components they are your attitude makes people reluctant to tell you. Simple as that. No more clues till you change your ways of being a PR guy! Understand my friend???

So stop asking the same question every time someone gets your goat. And stop trying to get mine or Robbies or Woodys professional opinions to help you. That is until you are willing to offer us some big money! Our superior knowledge is not free!

[dougAEGPF]

[QUOTE=PATCHES JUNIOR;152523]There you go again Doug. Not everyone can see the link you posted above. Why is that? Are you a "double standard" type of guy asking why post were removed here, but some people can not see them on your site. Open your eyes!

The common interest forum is open for most members and most guests!

[dougAEGPF]

Doug, stop with your silly questions that have been answered. Why is it every time someone gets your goat your only reply is to ask the same type of diversionary questions. I see Huego has already questioned your tactics. Get over it! Everyone is tired of your tactics my friend.

I hope Bugwhiskers take the advice of many, many folks and gets away from your tactics. Stay healthy my friend.

I would like to know as many other folk here would as to why multilayer SM boards are bad for "harmonics" compared to single layer SM boards.You seem to be a reasonable and knowledgeable person to ask this question and well informed as to the boards that are used in the QED. So come on for the benefit of others here please give us thoughts on this topic.

[PATCHES JUNIOR]

Carl you sent me a private PM ticking me off for high jacking Aziz's thread.
Did you do the same for Patches junior who was the first to high jack the thread?
For members and guests the deleted posts can be found here:

http://australianelectronicgoldprospectingforum.com/general-chat-and-discussion-forum/why-does-carl-nc-treat-us-as-children/msg23383/?topicseen#msg23383

There you go again Doug. Not everyone can see the link you posted above. Why is that? Are you a "double standard" type of guy asking why post were removed here, but some people can not see them on your site. Open your eyes!

And Patches Juniors post was moved, did you not see that?

[PATCHES JUNIOR]

Patches junior have you ever claimed that the use of multi layer SM boards in the QED is bad because it will cause problems with harmonics? If so would you care to elaborate? Why are multilayer SM boards worse in this regard than single layer SM boards?

Doug, stop with your silly questions that have been answered. Why is it every time someone gets your goat your only reply is to ask the same type of diversionary questions. I see Huego has already questioned your tactics. Get over it! Everyone is tired of your tactics my friend.

I hope Bugwhiskers take the advice of many, many folks and gets away from your tactics. Stay healthy my friend.

[dougAEGPF]

Patches junior have you ever claimed that the use of multi layer SM boards in the QED is bad because it will cause problems with harmonics? If so would you care to elaborate? Why are multilayer SM boards worse in this regard than single layer SM boards?

[dougAEGPF]

I've removed several posts for civility violations. Woody, Doug, I'll not have you drag your silly fight here. Go somewhere else and hash it out.

Carl you sent me a private PM ticking me off for high jacking Aziz's thread.
Did you do the same for Patches junior who was the first to high jack the thread?
For members and guests the deleted posts can be found here:

http://australianelectronicgoldprospectingforum.com/general-chat-and-discussion-forum/why-does-carl-nc-treat-us-as-children/msg23383/?topicseen#msg23383