Understanding Analog Speed Rates

I'm doing some research about analog vs TTL drivers and modulation and such and am a little confused on some points. Clarification would be most excellent

I've always imagined analog as perfectly smooth; why do many analog lasers/drivers list a speed in KHz or pps? Is analog not perfectly smooth? Or is that speed just the fastest that the components on the driver can handle actually changing the power going to the laser?

And if that is indeed what is going on, why is analog so much better than TTL? If I could make a driver that had 1 MHz TTL (which is very doable), would it not be smoother than a 10 or even 30k analog driver?

Thanks!

-Alex

I think it is the speed at which the laser output reliably follows an input square wave. It would be able to follow other waveforms at a faster speed. Here are the graphs for one of the flexmods:

the reason analogue is better is you can adjust the power of a laser to make any colour you want.

ttl is just on or off.

the thing with analogue is, how is the speed measured? from 0 to full power or 0 to lasing.

I thought TTL was the more basic adjustment of duty cycle, altering the brightness of the laser. Shouldn't this allow for a wide range of color blending?

ttl is on and off only. you cannot adjust the power therefore you can only make 7 colours with an rgb projector with ttl modulation

Meatball said:

I thought TTL was the more basic adjustment of duty cycle, altering the brightness of the laser. Shouldn't this allow for a wide range of color blending?

Click to expand...

Maybe if the beam weren't scanned. There have been a couple threads somewhere on it already.

TTL modulation is good for scanning, when you need to turn off the beam between, say, 2 different figures, without left a track from one to the other ..... where analog is better with multicolor units (like RGB), cause the possibility to dim the beams permit you to change colors in a large range.

About the "speed" indicated, is just a technical parameter that say you how the electronic of the driver follows your driving signal, in turning on and off, or dimming, the laser beam.

Just as example ..... if you have a "10 KHz" speed TTL driver (yes, also TTL have "speed" parameter, not only analog), this means that the driver can turn on and off your beam at the maximum speed of 10 KHz, or 10000 times per second, if you prefer ..... if you use it for a projector that work under this speed, all your figures will result correctly drawed ..... if you use it for a projector with higher frequency of working, the driver is unable to correctly turn on and off the beam at the right points, so your figures can appear incomplete (when the delay in in the turn-on phase, so he beam don't turn on quick enough), or with some extra lines (when the delay is in the turn-off phase, so the beam don't turn off quick enough) ..... this "speed" indication also affect the rise time and fall time of the signal, and this usually, with "bad" drivers, is seen in the terminals of a scanned beam (i mean, when you draw, as example, a line with a blank space in the center with your projector ..... if the speed and rise/fall times are good, you can see the end of the blank space in your line with clear and well defined end and start points, where instead when the speed or rise/fall times are not good, you see those end and start points with some extra light, that can look like a "dimming" tract)

Also, another parameter that the producers usually don't indicate, is the response time ..... this is the "delay" between the signal and the action, like, the delay between the moment you give the "on" signal, and the moment your laser effectively turn on ..... this anyway affect only high-end, very quick systems, that need to project images in specific, precise points, and if the projector is used just for lightshows, is not so important.

Also, yes, TTL can be used for "dim" the beam with PWM system, but this is not good for projections, only for fixed beams (otherwise you get a "dotted line" in result, instead than a continuous dimmed line)

Thanks everyone! I think I understand a bit more now