# frequency and time

Discussion in 'Electronic Basics' started by Las, Dec 18, 2003.

1. ### LasGuest

I am trying to understand the relationship between frequency (hz) and time
( ms,us) as used on an oscilloscope. Any websites or other help in this area
would be appreciated. Thanks. Eric

2. ### patGuest

time = 1/Frequency
sample :
1 ms = 1 / 1000 hz
1 µs = 1 / 1Mhz
1ms = .001 s or (10-3)
1µs = .000001 s or (10-6)

pat

3. ### John FieldsGuest

If you have a signal displayed on an oscilloscope and you measure the
time (period) between two successive identical features on the waveform
(peaks of a sinusoid, say) and find that the time between the peaks is
1/1000 of a second, then that means that there are 1000 of those
occurrences (cycles) happening every second, so the frequency of the
signal would be 1000 cycles per second.

They are each other's reciprocals, so knowing one all you have to do to
determine the other is to divide the one you know into 1 to get the
other:

T = 1/f

Where T = period in seconds
f = frequency in Hertz (cycles per second) and

f = 1/T

Where the units are identical.

plugging in our 1ms measurement we get f = 1/T = 1/0.001s = 1000Hz

and plugging in our frequency we get T = 1/1000Hz = 0.001s

4. ### SteveGuest

Wow, you've actually jumped on the net, navigated to this group, spent
a minute typing up your question, posted it and sat back and waited

minute?!

I'm noticing that there's not much interesting info being passed on
here, because 80% of the questions can be answered by spending five
minutes with your favorite search engine. Why is it that some people
can find these URLs but others don't even bother to look?

5. ### Ross MacGuest

Until you get used to mentally doing the math, you might want to pick up a
10 dollar calculater with the inverse function...that would be 1/x to do the
time/hz calculations and trig functions when you get to that level...I am
guessing you are a student...so good luck getting your electronics
degree....Ross

6. ### Ross MacGuest

I guess he took the dot basics part of this newsgroup seriously!......I
think some of these posts are just young folks new to all of this, where
many of us have been in this business for a very long time.....have a great
holiday...Ross

7. ### LasGuest

"> Wow, you've actually jumped on the net, navigated to this group, spent
I've found that a discussion is more beneficial than trying to find the
exact information out in the great internet ether. While this may be a
simple subject, the few replies given so far are a better direction than I
would have gotten after spending considerable time googling....I always find
it interesting how people will spend the time to flame someone for no
reason....if I had the attitude of always telling people that I have
mentored to "don't waste my time with such a trivial question" I wouldn't be
much of a mentor.

8. ### Bob FayGuest

The oscilloscope is just giving you a peek at an event that is occurring too
frequently for you to see it. Slow down a bit and picture an event that
occurs only once a week. This is very easy to see. Increase this event many
times like dancing in a room with a strobe light. When the dancers move at a
synchronous speed with the strobe, they appear to be still. The oscilloscope
is the strobe and the input is the dancer. You can observe the details of
the dancer at any time and any speed.

The scope is calibrated so you can determine the length or frequency of an
event. If the scope is set on 1ms, a 1ms event will occur in one grid line
across the face of the scope. This should show 10 complete events across the
face of the scope.

Does this help?

9. ### SteveGuest

I would have expected young people to be very familiar with internet resources!

10. ### John FieldsGuest

Age and familiarity with various resources has nothing to do with it.
You seem to forget that this NG is also a resource, and that there's
nothing wrong with asking simple questions here. This is, after all,
sci.electronics.basics, where simple questions are expected and welcome.
IMO the OP asked a perfectly reasonable question and was entitled to a