I'm confused about some things. I hope I don't sound like a jerk, but I want to dissect some things. So critical analysis to follow.

Apparently this rangefinder is meant to work using time of flight, and I don't understand how that's possible. It takes light about 1ns (10^-9) to travel a single foot. That means in order to have 1-foot accuracy you need to have a counter that is at least 1GHz. Am I wrong?

I looked up the data sheet for the DS00VQ100 chip and it's only 12.8MHz. Also, according to the data sheet, minimum span is 156.25ns or 23.44 meters. The data sheet is not very well put together though, so it's confusing what this means. I can't tell whether they mean to say this is the minimum span, meaning it can measure anything over 23m, or whether that's the accuracy period at any distance.

Question: How are you getting centimeter accuracy at less than 1m range? According to the IC from the manufacturer, unless I'm reading this wrong, their chip isn't even physically capable of this. Moreover, this isn't just a range problem, but an accuracy problem.

Let's do some easy math. As I said previously, based on speed of light, you need a 1GHz counter in order to get single-foot accuracy using time of flight. Am I wrong? I know there are mathematical methods for figuring out the distance using slower counters, by doing phase shift, etc., but we're talking only about time of flight.

If the counter is 12.8MHz that is 12.8 * 10^6 cycles per second. 1 / (12.8*10^6) = 7.81 x 10^-7, which means approximately 78ns maximum accuracy. 78 nanoseconds is the smallest period of time that the chip is capable of measuring, and that's assuming an increment with each clock cycle. Each cycle of the clock will take 78 nanoseconds. Now remember what I pointed out previously, according to the data sheet the minimum span is 156.25ns. Does that number now seem familiar? It should, 7.81 x 10^-7 x 2 = 1.5625 x 10^-7. So, the obvious implication is that even though the IC clocks at 12.8MHz, it needs two clock cycles in order to count. Two cycles equals one counter increment.

So what this means is that if the light takes 2 nanoseconds to travel, the counter will register 156. Anything less than 156 will register 156. If the light takes 170 nanoseconds, the counter will register 312. So in other words, the measurements will always be plus or minus 156 feet. We can divide that by 2 since we know the light travels the distance twice. So 78ft accuracy!!! Doesn't matter if you're measuring something 1 meter away or 1000 meters away, your result will always be + or - 78ft.

And what does 78.1 feet equal? It's about 23.44 meters, which was the figure also given in the data sheet. Suddenly this picture is coming together.

78 foot accuracy seems rather useless to me. What baffles me though is how you're claiming to be getting centimeter accuracy and at distances far lower than 23m. The only way I can see for this to be possible is if the IC is performing a mathematical operation, doing a multi-frequency phase shift or something else along these lines. Does the IC control the laser frequency? If so then it would be possible to do something like this. I am under the impression though that the IC simply counts, nothing more, and you manage all the laser circuitry yourself.

Is there something I'm missing?