FREQ COUNTER help

Basically i need to count the photons in the upper atmosphere this is done every other 1msec then transmitted back down to earth at a rate of 833khz via a telemetry system, i need to count from 1 to 65536 so a resolution of 1 is fine.

Thanks

I'm going to be the master at this newsgroup business !¬)

So you already have a circuit that detects 'photons', and a telemetry circuit, but cannot somehow design a simple counter circuit?

Sorry, does not compute.

Luhan

"Paul Taylor"

( Hint - it is a rate expressed in cycles per second )

An electronic counter will count events ( cycles, pulses, rabbits) for just as long as you let it.

Seems your upper frequency is really 65.536 MHz, after all.

....... Phil

cursor

Bingo!

Ok, so use a 16 bit counter which you read-and-reset every ms. You need a VHF capable prescaler (/256 or so) and then feed it into some counter or microcontroller with an external counter input.

Meindert

I have bought in a photometer which in turn is connected to a bought in pulse amplifier discriminator (pad), 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.

Thanks

Sorry Phil I thought this was a serous newsgroup of course got the joke, still it sounded good if you could of got one? i thought for a minute you where referring to something else I had read about on the net where they actually read 1 period and do some maths ect... never mind thanks for your help any way.

How are you getting the stuff "up there"? balloon or scud?

martin

He's at the University of Est Anglia, so he is probably sufficiently well educated to follow the sort of stuff I dish out.

Come on, John, tell us how you really feel about Bill! ;-)

One does have to adjust the level to match the audience. TTL for you, ECLinPS and GaAs for the more sophisticated.

If he doesn't, there is the option of a frequency multiplying PLL to consider.

It doesn't need to be synchronous. Only the first stage needs to be able to start and stop in one cycle. The rest of it can be a ripple counter. If you wait for things to calm down after the first stage is stopped, the rippling will finish before you read the counter.

In article , Meindert Sprang wrote: [...]

... or ...

You can use two counter circuits and toggle between them every ms. This way you've got a little time to latch the value away.

You really need a few more flip-flops up in the front end to make sure you don't have any glitches happening because a count cam just at the open of close of the 1mS gate.

Also, but not likely to be what you need: If the frequency range is limited, you can measure the time from the start of the 1mS to the first edge and from the end of the 1mS to the next edge there after and assume the rest.

Why? His one-liner would've been at the bottom of 32 lines. You can't rationalize that difference John. Oh, and in another thread I noticed you getting pissy about it. Forget the valium, mmm?

Tim