You can be very annoying John. I was talking about the clock speed only
since that is what he asked.
---
You're a liar. Here's his post, in toto:
<OPEN QUOTE>
Hey folks!
I am set out to build an ultrasonic distance
measurement module using 89c51.
The range I have in my mind is about 1 inch to say 25 inches. Is the
speed 89c51 offers enough for such kind of ventures? If not what
would
be the solution? Also some help regarding which transducers to use
would be welcomed.
Regards!
<CLOSE QUOTE>
Where does it say anything about clock speed? It doesn't. He asks
if the µC is fast enough, which is what you should have addressed.
In order to come up with an answer for that question you'd have had
to look a little deeper and figure out what it is that needs to be
happening while that acoustic pulse is making its way to the target
and back, and to do that you'd need to know a little bit about the
architecture of the 89C51. Specifically, what's the relationship
between the input clock and the instruction cycle times and is there
enough time in there to allow you to accumulate 0.001" ticks.
Is there?
---
If we were dealing with light then it would be
on the order of 13 THz instead of 13mhz for the same accuracy. (hence even
at 1000 times worse accuracy your still dealing with a 13ghz clock.)
---
If frogs had wings...
We're not dealing with light, we're dealing with sound, so all of
that diversionary crap is just that. crap.
And get the suffixes right if you expect to be taken seriously, LOL!
---
You seem to read what you want just so you can make a point that doesn't
exist. (I never claimed that one could get accuracy of 0.05% in the real
world)
---
Sure you did.
By suggesting that he use a 13MHz clock in order to get 0.001" thick
slices of something that propagates through air at Mach1, you
intimated as much.
What you _didn't_ say was why that +/- 0.05% accuracy wasn't
obtainable. You _guessed_ that it might not be, to your credit, but
you gave no reason for your guess, which is the same sort of garbage
science you railed against in another thread.
---
My claim is simply to give a reasonable upper bound on the clock speed for
accuracy given everything else is ideal.
---
See earlier 89C51 timing issues...
---
When it is computed it is
perfectly reasonable. Do the same with the speed of light and it is not.
---
See earlier "If frogs had wings" paragraph.
---
WHAT DOES THIS MEAN? It means he can use a 20mhz clock and not have any
issues(except maybe one of latency but thats not the clocks fault). 20mhz
clocks are easy to come by but 13Thz clocks are not.
---
Yawnnn.....
---
You seem to think that I am saying that it is reasonable to actually get
that type of accuracy in the real world. I assume you do this for attention
or to feed your ego because you ignore my statements that say its probably
not.
http://scitation.aip.org/getabs/ser...00073000010003671000001&idtype=cvips&gifs=yes
They seem to get 0.05% accuracy.
---
That might seem to be the case to a neophyte lacking in reading and
writing skills and unskilled in mensuration, but 0.05% _resolution_
is not the same as 0.05% _accuracy_.
Shall I explain the difference to you or would you rather keep your
tail between your legs and hit Wiki?
Also, they get that resolution in isothermal air (that means it's
the same temperature everywhere in the flight path of the signal)
and they get it using BPSK _and_ TOP. Judging from the primitivity
of the OP's post, his application was strictly TOF.
---
---
That application uses a phasing technique. I didn't care enough to
read whether they also use TOF since the OP's application was,
ostensibly, for TOF only.
---
---
That's just a bunch of stuff about air acoustics that everybody who
does air acoustics knows anyway.
I guess you didn't know that.
---
Read the first sentence of the introduction and compute the accuracy
requirements they are required to get. Ofcourse I'm sure you'll claim that
these guys are fools and your the genius.
---
Oh, you want to play that way, do you?
OK, moron, _They're_ not each fools, you are.
They're doing cutting edge R&D and all you're doing is looking for
ways to try to keep everyone from discovering what a stupid **** you
really are.
I don't think you've got the resources to hide that fault. Do you?