How did you make that leap into controlling the average rate at 2MHz?
Poisson time of arrival lamda=2E6 mean events per second makes for two to occur at something like 0.5(lamda*25n)^2 or 0.125% ? Or two or more to occur at 0.127%.
Newp- counter clock inputs are asynchronous to the system clock which must be synchronized with the telemetry, so you're not going to get off that easily, assuming you want to avoid bad data points entirely. Then the OP states rate measurements to be made every other millisecond, so two counters are not necessary.
In article , rick H wrote: [....]
k Hmmmm ... maybe this calls for a flash ADC to estimate the number of coincident photons and an adder instead of a counter.
-- -- kensmith@rahul.net forging knowledge
-- I don't, but so far in the discussion it doesn't matter. All I've done is to describe a general-purpose EPUT counter which can accumulate a maximum of 65536 hits before it overflows, which is what the OP asked for. If he has issues with interpulse timing and the like I expect that he'll bring them into the discusion where they can be resolved. Or not.
It matters plenty if you start guessing the accuracy of the enable required to achieve an accuracy (though you called it resolution) of +/-1 event. Which you did.
-- Rick
-- The assumption, asshole, for the porpoise of describing the initial archietexture, was that the 65536 pluses were spaced equidistantly in a window 1.0 pulse or minus something millie seconds wide. Why are you getting your panties in such a bunch about what _might_ be happening in that window before the OP's even gotten back to us with what he _really_ wants?
-- Great idea! I was also thinking if the width of a single photon event was specified, then smearing could be used to gate a fast clock which would actually provide the edges for the counter's clock as well as the 1ms window.
Like I said, Phil's abuse is tediously repetitive - but he lives in Sydney, and wouldn't know any better.
-- Bill Sloman, Nijmegen - but educated in Melbourne
20:1 slower than the peak rate was the rule of thumb amongst the photochemists I've worked worked with.
I'm sure you are right - I'll have to think about why ...
-- Bill Sloman, Nijmegen
Since you were the one who didn't know how rotten a simple TTL one-shot actually is, and had to be dragged through the calculations repeatedly until the penny finally dropped, I think you had better give up that second bottle of chardonnay until your brain gets back into contact with reality.
Judging form your performance, you'd be better off with a few more slips.
-- Bill Sloman, Nijmegen
** But it ain't abuse - it is fact.
And the facts do not change.
YOU get to like it or lumpy it - you criminal f*****ad.
....... Phil
Bill I think it is best if you ignore him and not get pulled into his in-mature childish temper tantrums, that is probley what he wants any way back to the job in hand. I have been having problems with my email so have been unable to reply to any postings so far i have got a counter working with a 1sec gate pulse ect... but when i go to 1msec this is where the problems start?
If they were equidistant (only ever *your* assumption, not *the* assumption), then where did your figure of 10ppm materialize from and why would that figure need to be a "first-cut look"? Can't you take the numbers 1e-3 and 65536 and divide them?
No wedgies here, old chap. I simply pointed out that your assumptions were flawed and hence your post was meaningless. You're the one getting all steamed up.
I'll leave you to post the last insult, I suspect it's your style.
-- Rick
"Paul Taylor = another criminal pile of pommy shit"
----------------------------------------------------- Paul Taylor BSC (Hons) Electronics Technician School of Environmental Science University of East Anglia Norwich NR4 7TJ
** FUCK OFF - you bloody impostor !!........ Phil
Hi John sorry for the delay in replying the thread has sort of like split of in all direction and i have been having problems with my news server, in a nutshell
I have bought in a photometer which in turn is connected to a bought in pulse amplifier discriminator (pad) this is from electron tubes part AD7, this needs to be feed into a counter to count the pulses which I am to build, the telemetry system is already in place which I haven't built, the bottom line is I need to count the output from the pad which counts the sodium particles and get this count back down to earth.
I have a 1khz gate pulse for the count and 833khz (Clock signal) for sending out the data via the telemetry system which is already in the rocket, i need to count upto 2 power 16 or 65536 it is expected to loose the first bit so
32768 is an excepted maximum count.Thanks
John you said about smearing could be used sorry but I don't understand what this is? can you explain.
If the system works with a one second window, it ought to work with a
1millisecond window - logic doesn't usually start fallig over before you get down to micorsecond time intervals.As for rattling Phil Allison's cage - the longer we keep him mad, the better the chance that he will blow a blood vessel and lose his capacity to manipulate a keyboard. This would be a rather pyschopathic motivation if one considered Phil to be fully human.
-- Bill Sloman, Nijmegen
In effect, what you're planning to do is open the gate for 1 ms, close the gate, send the accumulated counts at 833 kHz by some modulation scheme, reset the counter, open the gate, and so on. Sounds feasible. If you want contiguous time slices things get a bit more complicated. Let's see. After 1 ms shift out the data, reset counter, let accumulate while the shifted data is transmitted. Sounds good if your transmission scheme can handle it.
- YD.
-- Remove HAT if replying by mail.
No, warewolves.
For vampires's it's wood.
Bye. Jasen
--- TTL one-shots aren't horrible, they just have potentially large worst-case timing variations which can easily be trimmed out with a variable resistor.
LOL, it wasn't me who couldn't tell whether the circuit was charging or discharging the capacitor, and it wasn't me who wanted to use the impossible-to-reach Vcc and ground for the "worst-case" scenarios either. As far as being dragged through the calculations goes, ISTR it was you who had to be shown, over and over, that the numbers you were coming up with were bogus until you finally realized what you were doing wrong. After all, It wasn't me who wrote: "Shit. I blew it." was it?
-- John Fields Professional Circuit Designer
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