Using Clock Rate as a timer(?)

Hey!

I'm currently working on a project in which i need to measure the distance of a device using the time it needs for a Electromagnetic to travel to the device and back.So you can imagine the accuracy of time i need to measure the distance! I've seen various modules and timer ICs online but most are sophisticated and a bit over my current capabilities (i'm willing to learn though), so i was wondering if could use my laptop's clock rate (2.5 GHz!) as a timer which increments a counter(any suggestions on counters?) and then i could use that data to calculate the distance.

Thx in advance!

So let's be clear.

This has nothing to do with Arduinox.

That's OK, we will happily discuss it.

Note for one, that laptop clocks are often "spread spectrum" to reduce interference, and thus useless as timebases.

The 2.5GHz clock in only on-chip, generated by a PLL, and if it were brought out would have to
be an LVDS pair. Typically the motherboard doesn’t see anything like these speeds due to the
much higher stray capacitances on a PCB compared to a processor die. There is no PCB-mounting
logic chips than can handle logic that speed to my knowledge, its all done on silicon.

What you are asking about is time-domain reflectometry. Have you googled that?

So you can imagine the accuracy of time i need to measure the distance!

No I can’t, that’s something you have to tell us, we have no idea what you want until you tell
us (with numbers, not adjectives). Perhaps you meant ‘precision’ or ‘resolution’, not ‘accuracy’?

Hey!

Thx guys for clarifying the idea for me!

MarkT: time-domain reflectometry is very similar to what i was looking for (Thx!) but instead i want my EM waves to propagate in free space (not in a wire). What i meant in my original post is that i want to transmit waves to a receiver and then send another signal from the Rx(ofcourse it'll have Tx) to the transmitter(will also have aRx) and then measuring the time it needs for the signal to travel we can deduce the distance between the Tx and Rx. I am looking for a precise timer to measure the time because i want the margin error to be ~2cm (1cm needs ~0.3x10^-9 s = 0.3ns).

I've found some timers (specifically STG3157) that could achieve this but most are industrial and hard to use, any suggestions? Can I use a different crystal (higher frequency) with a common RTC like the rtc ds1307 ?

Any suggestions would be greatly appreciated! Thanks for your replies!

Paul__B: i know this isn't directly linked with the arduino that's why i posted this in General Electronics :p

I am looking for a precise timer to measure the time because i want the margin error to be ~2cm (1cm needs ~0.3x10^-9 s = 0.3ns).

This is simply not possible for a hobbyist.

mero55: Hey!

Thx guys for clarifying the idea for me!

MarkT: time-domain reflectometry is very similar to what i was looking for (Thx!) but instead i want my EM waves to propagate in free space (not in a wire). What i meant in my original post is that i want to transmit waves to a receiver and then send another signal from the Rx(ofcourse it'll have Tx) to the transmitter(will also have aRx) and then measuring the time it needs for the signal to travel we can deduce the distance between the Tx and Rx. I am looking for a precise timer to measure the time because i want the margin error to be ~2cm (1cm needs ~0.3x10^-9 s = 0.3ns).

That's called radar. Perhaps you need something like: http://www.infineon.com/cms/en/product/rf-and-wireless-control/mm-wave-mmic/24-ghz-radar-industrial/channel.html?channel=5546d46145f1f3a40146140e9c1c1956

I've found some timers (specifically STG3157) that could achieve this but most are industrial and hard to use, any suggestions?

That's an analog switch, not a timer

Can I use a different crystal (higher frequency) with a common RTC like the rtc ds1307 ?

Any suggestions would be greatly appreciated! Thanks for your replies!

Paul__B: i know this isn't directly linked with the arduino that's why i posted this in General Electronics :p

Implementing your own radar is ambitious, to say the least - what experience do you have in RF and microwave circuitry?

Hey!

That's called radar.

I know radars work the same way( actually the same) but i wanted to implement it in a 'different form'. Your link was very helpful btw.

Implementing your own radar is ambitious, to say the least - what experience do you have in RF and microwave circuitry?

Well...i'm no expert and i haven't built anything similar before, so i think i hv little to no experience xD.

Thank you guys for your support! I really appreciate it :p

Has anyone told you that you have a snowball's chance in hell of doing this ?

mero55: Hey!

I'm currently working on a project in which i need to measure the distance of a device using the time it needs for a Electromagnetic to travel to the device and back. . . .

. . . . I am looking for a precise timer to measure the time because i want the margin error to be ~2cm

What is your project? In particular, what is the range between the two tranceivers and are they moving relative to each other? It's not obvious to me that finding a very high resolution timer is the biggest challenge in the problem stated.

You have heard of https://www.kickstarter.com/projects/pozyx/pozyx-accurate-indoor-positioning-for-arduino ??

You also haven't stated the distance you need to measure to 2cm? Dwight

You also haven’t explained what "a different form " (of radar) is .
What is the source of the electromagnetic wave ?

Since the speed of light is 30 billion centimeters per second, you need a higher clock speed to get 2cm accuracy.

I thought of mentioning that but since the OP knew his clock speed and knew the the speed of electomagnetic waves yet continued to entertain his fantasy I didn't see any point in injecting ang reality into the discussion. If the OP had ANY understanding of science or technology whatsoever I haven't seen any sjgn of it. For starters, where's the math ? Has anyone seen any indication of any grasp of math ?