Somebody needs to get this kid into lasers

[carmangary]

"My point (which you continue to miss) is that there is more to the speed setting of 30Kpps that just sending 30,000 individual points each second. It's also a TUNING standard that relates to the performance of the galvos."

Well my point was only that if you program a soundcard to send out 30k samples per second then you are sending out 30k points per second. I don't care if the galvo are able to track those points or not. That has nothing to do with the output of the DAC. That has to do with the person or program that is computing those points.

It seems like you keep telling me that I am wrong yet you are not even talking about the same thing I am.

[buffo]

It seems like you keep telling me that I am wrong yet you are not even talking about the same thing I am.

Ok - let's have a look back at the begining of this thread. I said:

Remember that a good sound card can accurately reproduce a 20Khz audio signal. That's nearly 10 times faster than the maximum small signal bandwith for a set of 30Kpps galvos

And to that you replied:

Huh? Most sound cards will do 48K samples per seconds which means the max output is 48K pps.

Now, you were replying to me, yet you didn't mention anything that I was talking about. I didn't say the audio card could only display 20Kpps, I said it could accurately reproduce a 20Khz signal. I then pointed out that this was an order of magnitude faster than the small signal bandwidth for a set of galvos. The issue was (and continues to be) the relationship between the bandwidth response of a set of galvos to an oscilloscope.

Your reply didn't relate to any of this. You simply said "HUH? 48K samples per second = 48Kpps!" But that isn't relevent to what I was saying, or to what was being discussed. I wasn't talking about Kpps, I was talking about SIGNAL BANDWIDTH. You missed that with your original reply, and have been confusing the terms ever since.

Now, who's not talking about the same thing? Your reply doesn't even begin to address the issue that we were discussing in this thread. When I tried to explain this to you, you kept returning to your original statement. I'm sorry, but if you can't be bothered to follow the thread and at least READ what other people are saying, then there's no point in having a discussion. Particularly since *you* were the one that interjected the off-topic question.

Adam

[carmangary]

Yea, I said HUH as in why are you replying with that mumbo jumbo that has nothing to do with my post. I'm done with this discussion because it is ridiculous.

[buffo]

Yea, I said HUH as in why are you replying with that mumbo jumbo that has nothing to do with my post. I'm done with this discussion because it is ridiculous.

Haha! Ok - if you think simple terms like frequency and bandwidth are "mumbo-jumbo", then I don't need to be discussing this with you. My bad.

Furthermore, your last post confirms that you haven't been paying attention at all... My *first* post, which I quoted above, didn't have anything to do with your musings about laserboy. It had to do with the shock that the kid was going to experience if he switched to galvos and had to suddenly deal with a 10 fold reduction in the amount of data he could display.

So your "HUH" post was the begining of this entire exchange. You were too quick to reply; you obviously didn't even read the whole post! Just quoted the first couple lines and shot from the hip, thus missing the entire point of my post. I wasn't replying with "mumbo-jumbo", I was raising an issue about the difference between an oscilloscope and a set of galvos. If you had paid more attention, or if you had read any of the following three replies from me, you would have figured that out. Instead, you stubbornly stuck to your irrelevent statement and ignored the rest of the conversation. (A pattern which continued *throughout* the discussion.) Disagreement is fine, discussion is fine too. But rudely ignoring someone's post and replying without even trying to understand the point being discussed is downright stupid.

Now, I'll admit that some of my posts take a while to get moving. Sometimes I need to set the stage properly before I make my point. So, yeah, some of my posts are longer than others. But if you're too busy to read an extra paragraph or two before you fire off your reply, then you probably shouldn't be criticizing the post.

Saddly, you were too obstinate to realize your mistake. Sigh... I thought you were more mature than that. I see now that I was wrong.

Adam

[carmangary]

Nice. Now you are insulting my intelligence and calling me immature. I see how it is.

[wes]

shoot,this isn't good.
give it a little time.
maybe you can get to the bottom of this later.
the correct info isn't that important at this point.
peace,
wes

[buffo]

Yea, I said HUH as in why are you replying with that mumbo jumbo that has nothing to do with my post. I'm done with this discussion because it is ridiculous.

Nice. Now you are insulting my intelligence and calling me immature. I see how it is.

POT.KETTLE.BLACK

Adam

[allthatwhichis]

POT.KETTLE.BLACK

It is almost a line of code... POT.KETTLE.BLACK();

[The_Doctor]

Some points that seem to have got lost in the discussion:

No-one's making a specific error of equating sample rate with KHz, the KHz would be half the sample rate. Not important, the 'kpps' still isn't the same.

Not sure that kpps is even useful as a technical term. What IS a point? It's an arbitrary placement in a frame, so you can't always send those at 30K per second either, unless you limit the step size between them. Maybe it's time that whole concept was renamed as ksps for kilosteps per second, to firmly establish that it's the degree of change that is important here, not some arbitrary number of allegedly fixed points. What we need is to establish a step size as an ANGLE for the terminology to make sense, and it's all good. IDEA! How about basing it on the SMALL SIGNAL STEP RESPONSE, and at the same time defining exactly what size 'small' means in particular?! I think so. While we're at it, let's express frame size as an ANGLE instead of an abitrary number of points. It's obvious to me that there is something wrong with the current terminology, when it gets two people each with strong technical backgrounds arguing in this way. ILDA, are you reading me LOUD AND CLEAR?!

Lastly, I haven't seen anyone mention here that proportional galvos operate UNDER the resonant frequency, and loudspeakers operate (mostly) above it. That's why the physics is different.

[buffo]

Not sure that kpps is even useful as a technical term. What IS a point? It's an arbitrary placement in a frame, so you can't always send those at 30K per second either, unless you limit the step size between them.

Thank you Doc... You managed to condense my multi-paragraph post to a few succinct sentences! You and I are clearly on the same page. (And I wholly agree that the whole Kpps concept is flawed; your idea of degrees per second or degrees per step makes a hell of a lot more sense. If only we could convince ILDA of that! ) Now if I can just find a cure for my verbal diarrhea, maybe I can stop writing a book every time I want to make a point.

Lastly, I haven't seen anyone mention here that proportional galvos operate UNDER the resonant frequency, and loudspeakers operate (mostly) above it. That's why the physics is different.

You're absolutely correct. I almost mentioned that resonance is an upper limit for galvos, but I decided that my post was long enough already. But I never even considered the corollary; that speakers operate above resonance. (Well, except for some subwoofers of course.) Nevertheless, it's an important point.