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very accurate timer

F

fragget

Jan 1, 1970
0
Hello, this is my first post here so here it goes...

I'm looking for a highly accurate timer, I need one that could measure a time in nanoseconds

if possible. I figured this would not be impossible since the clockspeed of a modern

computer is 3 Ghz, which means measuring a time up to a third of a nanosecond would be

possible. However a nanosecond is also fine by me;P
I really hope someone can help me out here on how to get such a component or how to make one;)

Thanks in Advance;)

Dave


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D

David L. Jones

Jan 1, 1970
0
fragget said:
Hello, this is my first post here so here it goes...

I'm looking for a highly accurate timer, I need one that could measure a time in nanoseconds

if possible. I figured this would not be impossible since the clockspeed of a modern

computer is 3 Ghz, which means measuring a time up to a third of a nanosecond would be

possible. However a nanosecond is also fine by me;P
I really hope someone can help me out here on how to get such a component or how to make one;)

Thanks in Advance;)

Dave

Just buy one:
http://www.thinksrs.com/products/SR620.htm
Will cost you $5000 though, but if this is for work tell'em it'll cost
you more than that to dick around trying to build something suitable.

Dave :)
 
M

martin griffith

Jan 1, 1970
0
Hello, this is my first post here so here it goes...

I'm looking for a highly accurate timer, I need one that could measure a time in nanoseconds

if possible. I figured this would not be impossible since the clockspeed of a modern

computer is 3 Ghz, which means measuring a time up to a third of a nanosecond would be

possible. However a nanosecond is also fine by me;P
I really hope someone can help me out here on how to get such a component or how to make one;)

Thanks in Advance;)

Dave


--------------= Posted using GrabIt =----------------
------= Binary Usenet downloading made easy =---------
-= Get GrabIt for free from http://www.shemes.com/ =-

Just waiting for Bill S to jump in with an ECL problem solver
answer....


martin
 
J

John Larkin

Jan 1, 1970
0
Hello, this is my first post here so here it goes...

I'm looking for a highly accurate timer, I need one that could measure a time in nanoseconds

if possible. I figured this would not be impossible since the clockspeed of a modern

computer is 3 Ghz, which means measuring a time up to a third of a nanosecond would be

possible. However a nanosecond is also fine by me;P
I really hope someone can help me out here on how to get such a component or how to make one;)

Thanks in Advance;)

Dave

What are you trying to measure?

John
 
martin said:
Just waiting for Bill S to jump in with an ECL problem solver
answer....

ECL will get you a 500MHz clock. When I did it for real, we actually
used Gigabit Logic's GaAs and an 800MHz clock, then interpolated
between clock edges with analog ramps to get down to 10psec resolution
- the jitter on our clock was about 60psec so the 10psec was entirely
theoretical.

The version I designed a few years later using ECLinPS and a 500MHz
clock was to have used a 500MHz Vectron crystal oscillator with around
1psec of jitter.

John Larkin now sells stuff to do the job.

http://www.highlandtechnology.com/DSS/V660DS.html
 
J

Joerg

Jan 1, 1970
0
Hello Dave,

Hello, this is my first post here so here it goes...

I'm looking for a highly accurate timer, I need one that could measure a time in nanoseconds

if possible. I figured this would not be impossible since the clockspeed of a modern

computer is 3 Ghz, which means measuring a time up to a third of a nanosecond would be

possible. However a nanosecond is also fine by me;P
I really hope someone can help me out here on how to get such a component or how to make one;)

Bill mentioned the digital + analog method which is what I'd do. If you
feel uncomfortable around blazingly fast analog stuff either get help or:

Run several fast counters in parallel but shift their clocks. For
example, if your ECL counter runs 500MHz but you want a 500psec
granularity you run four in parallel. #1 gets the straight clock. #2
gets the clock delayed by 500psec, #3 delayed by 1nsec and #4 delayed by
1.5nsec.

They all receive the same start and stop signal. Of course, you'll have
to look into the setup and hold stuff so you don't accidentally choke a
counter. Now your PC needs to read the results of all four and then
determine the exact timings by looking at which one started first, how
many clock cycles it did, which one stopped last and how many cycles
that one did. The readout process can be slow because now the counters
are stopped.
 
J

John Larkin

Jan 1, 1970
0
ECL will get you a 500MHz clock. When I did it for real, we actually
used Gigabit Logic's GaAs and an 800MHz clock, then interpolated
between clock edges with analog ramps to get down to 10psec resolution
- the jitter on our clock was about 60psec so the 10psec was entirely
theoretical.

The version I designed a few years later using ECLinPS and a 500MHz
clock was to have used a 500MHz Vectron crystal oscillator with around
1psec of jitter.

You could now do EclipsLite to 2 GHz at least.
John Larkin now sells stuff to do the job.

http://www.highlandtechnology.com/DSS/V660DS.html

That one interpolates a 40 Mhz clock! I just sold 8 of them to a guy
who's going to shine a laser beam through turbine blades, time the
interruptions, and figure out blade vibration modes.

John
 
fragget said:
Hello, this is my first post here so here it goes...

I'm looking for a highly accurate timer, I need one that could measure a time in nanoseconds

if possible. I figured this would not be impossible since the clockspeed of a modern

computer is 3 Ghz, which means measuring a time up to a third of a nanosecond would be

possible. However a nanosecond is also fine by me;P
I really hope someone can help me out here on how to get such a component or how to make one;)

Thanks in Advance;)

Dave

Frequency counters have gating circuits so that you can measure a pulse
time.

The HP5340A cost me $300 a decade ago. No idea what they go for today,
but it should be less.
 
U

Ulrich Bangert

Jan 1, 1970
0
Dave,

before you start up to construct something on your own which is by FAR not
trivial go out and buy one of the following devices:

Racal Dana 1991 or Racal Dana 1992 or Racal Dana 1996 counters.

These have a nominal 1 ns resolution for single shot time interval
measurements. If you use their IEEE488 you get out some digits more and you
can see that the rms jitter of the counter itself is in the order of 300 ps.
These devices are no more build today but can be bought surplus at very
cheap prices. Most of them are equipped with a high quality OCXO timebase.

If you are out for a bit more resolution and want to spend some dollars
more, go out and get yourself a HP/Agilent 53131 counter which has a nominal
500 ps resolution. If you want even more resolution and spend more $s buy
the HP/Agilent 53132 with nominal 150 ps resolution. Both models are from
the current program.

If you need to get better, choices start to get rare: A surplus HP5370A/B
(no more build today) will give you a 20 ps resolution for single shots at a
reasonable price. A Stanford Research SR620 will give you the same
resolution but be prepared for a smaller shock when looking at the price
tag.

If you can avoid DON'T build something on your own. There are hundreds of
ways to perform sub-ns timing measurement but you can spend months to years
in order to learn the tricks that are necessary to make simple sounding
theory work in reality.

Best regards
Ulrich Bangert
 
M

Mike Monett

Jan 1, 1970
0
fragget said:
Hello, this is my first post here so here it goes... I'm looking
for a highly accurate timer, I need one that could measure a time
in nanoseconds if possible. I figured this would not be impossible
since the clockspeed of a modern computer is 3 Ghz, which means
measuring a time up to a third of a nanosecond would be possible.
However a nanosecond is also fine by me. I really hope someone can
help me out here on how to get such a component or how to make
one;)
Thanks in Advance;)

Hi Dave,

If you can use averaging, you can count an accurate clock several
thousand times and average the counts. This is how at least one of
the HP counters worked. The rms error decreases with the square of
the number of counts. This places a practical limit on the minimum
error you can achieve before you run out of time, or the signal
drifts.

If you can use averaging, you can also use the Binary Sampling
technique descibed below. This bypasses the square root averaging
barrier. The example shown is a 1MHz square wave, and using this
technique gave 1 picosecond rms jitter in one second.

Regards,

Mike Monett

Antiviral, Antibacterial Silver Solution:
http://silversol.freewebpage.org/index.htm
SPICE Analysis of Crystal Oscillators:
http://silversol.freewebpage.org/spice/xtal/clapp.htm
Noise-Rejecting Wideband Sampler:
http://www3.sympatico.ca/add.automation/sampler/intro.htm
 
Ulrich said:
Dave,

If you can avoid DON'T build something on your own. There are hundreds of
ways to perform sub-ns timing measurement but you can spend months to years
in order to learn the tricks that are necessary to make simple sounding
theory work in reality.

This is good advice, but while we spent three years getting our
prototype working, the interpolation system only needed a month or so
of work.

Our biggest single problem was caused by the printed circuit
department, who "knew" that the ordering of the inner layers of a
printed circuit board didn't matter, so had a six layer board made with
the ground planes on layers 3 and 4, rather than 2 and 5 as I'd
carefully specified in my release note to the printed circuit
department.

It took us months to work out why the board wouldn't work - every time
I looked in on the engineer who was working on the board (nominally my
boss at that point) I'd point out to him that he had the board layers
stacked up wrong in his pile of documentation, but it took about six
weeks before he drilled down through the board to check. Once the penny
dropped, he sort of got the board working by replacing all the critical
tracks with lengths of sub-minature coax (50VMTX, still stocked by
Farnell) but we had to get another batch of boards made before we had
anything that looked like a prototype.

The two outer layers of the board weren't FR4 epoxy glass, but Teflon
cloth bonded with isocynate resin, and the board were biggish - triple
extended Eurocards, largely to accomodate mixed DIN41612 connectors
with coax inserts - and they cost us about $1500 each. Populating them
cost as much again.

They'd be a lot cheaper today and - as John Larkin has pointed out -
appreciably faster.
 
G

Glen Walpert

Jan 1, 1970
0
Dave,

before you start up to construct something on your own which is by FAR not
trivial go out and buy one of the following devices:

Racal Dana 1991 or Racal Dana 1992 or Racal Dana 1996 counters.

These have a nominal 1 ns resolution for single shot time interval
measurements. If you use their IEEE488 you get out some digits more and you
can see that the rms jitter of the counter itself is in the order of 300 ps.
These devices are no more build today but can be bought surplus at very
cheap prices. Most of them are equipped with a high quality OCXO timebase.

If you are out for a bit more resolution and want to spend some dollars
more, go out and get yourself a HP/Agilent 53131 counter which has a nominal
500 ps resolution. If you want even more resolution and spend more $s buy
the HP/Agilent 53132 with nominal 150 ps resolution. Both models are from
the current program.

If you need to get better, choices start to get rare: A surplus HP5370A/B
(no more build today) will give you a 20 ps resolution for single shots at a
reasonable price. A Stanford Research SR620 will give you the same
resolution but be prepared for a smaller shock when looking at the price
tag.

Another interesting option for better, from the "47uF capacitor"
thread:

http://www.acam.de/index.php?id=23&L=0

Just buy an evaluation system rather than try to build a system on a 2
layer board like the 47uF cap OP foolishly thinks he wants to do.
 
R

Robert Latest

Jan 1, 1970
0
On 13 Oct 2006 02:25:45 -0700,
in Msg. said:
weeks before he drilled down through the board to check. Once the penny
dropped, he sort of got the board working by replacing all the critical
tracks with lengths of sub-minature coax (50VMTX, still stocked by
Farnell)

Really? 50vmtx didn't turn up anything useful at Farnell.

robert
 
Robert said:
On 13 Oct 2006 02:25:45 -0700,


Really? 50vmtx didn't turn up anything useful at Farnell.

Try order code 157-284 or manufacturer's list number 5633JZZD - it's on
page 59 of volume 2 of my Farnell catalogue.
 
Joerg said:
Hello Dave,



Bill mentioned the digital + analog method which is what I'd do. If you
feel uncomfortable around blazingly fast analog stuff either get help or:

Run several fast counters in parallel but shift their clocks. For
example, if your ECL counter runs 500MHz but you want a 500psec
granularity you run four in parallel. #1 gets the straight clock. #2
gets the clock delayed by 500psec, #3 delayed by 1nsec and #4 delayed by
1.5nsec.

They all receive the same start and stop signal. Of course, you'll have
to look into the setup and hold stuff so you don't accidentally choke a
counter. Now your PC needs to read the results of all four and then
determine the exact timings by looking at which one started first, how
many clock cycles it did, which one stopped last and how many cycles
that one did. The readout process can be slow because now the counters
are stopped.

There is a cuter variation on this called the vernier chronotron. See

http://scitation.aip.org/getabs/ser...00030000003000159000001&idtype=cvips&gifs=yes

which points to an article of that name in Review of Scientific
Instruments -- March 1959 -- Volume 30, Issue 3, pp. 159-166 by Harlan
W. Lefevre and James T. Russell of the Hanford Laboratories Operation,
General Electric Company, Richland, Washington.

I got to hear about it in 1970, when one of my colleagues at Plessey
Pacific got talking about his Ph.D. project which involved building a
similar instrument with bistables built with pairs of tunnel diodes.

I'd known him - vaguely - when we were both Ph.D, students at
Melbourne, both using the university mainframe for our - very different
- projects. He was simulating his tunnel diode bistables and thought
that he had proved that he'd made them designable. They were certainly
very fast.
 
J

John Larkin

Jan 1, 1970
0
Frequency counters have gating circuits so that you can measure a pulse
time.

The HP5340A cost me $300 a decade ago. No idea what they go for today,
but it should be less.


A 5370A or B can be had on ebay or from a broker for under $1000. They
have 20 ps single-shot resolution and around 30 ps RMS jitter,
typically.

My friend Bernard did this one...

http://www.greenfieldtechnology.com/datasheet/GFT2002.pdf

John
 
J

Joerg

Jan 1, 1970
0
Hello Bill,
There is a cuter variation on this called the vernier chronotron. See

http://scitation.aip.org/getabs/ser...00030000003000159000001&idtype=cvips&gifs=yes

which points to an article of that name in Review of Scientific
Instruments -- March 1959 -- Volume 30, Issue 3, pp. 159-166 by Harlan
W. Lefevre and James T. Russell of the Hanford Laboratories Operation,
General Electric Company, Richland, Washington.

I like that term "millimicrosecond region". That must have driven the
physicists among the readers crazy. Can't read the full paper, I wish
they would make these public domain after such a long time.

I got to hear about it in 1970, when one of my colleagues at Plessey
Pacific got talking about his Ph.D. project which involved building a
similar instrument with bistables built with pairs of tunnel diodes.

Ah, Plessey. Good old company. Before things folded I stocked up on
their famous mixer SL6440. It has a dynamic range from here to the
Klondike yet doesn't need a lot of L.O. power. It's a pity no other
company bought the rights and kept producing it.
 
J

Joerg

Jan 1, 1970
0
Hello John,
A 5370A or B can be had on ebay or from a broker for under $1000. They
have 20 ps single-shot resolution and around 30 ps RMS jitter,
typically.

Even rather mundane test equipment could possibly be capable after some
mods. When I repaired the HP4191 here in the lab I found that it had two
very nice 300psec timed samplers in there, plus triggered ramp
generators with remarkable precision. Milled module enclosures, rigid
coax and all the good stuff.


Very pretty design! Did he have a pro do that enclosure? The only thing
I wouldn't like is the buttons. Those tend to wear out quickly.
 
M

Mike Monett

Jan 1, 1970
0
Very pretty design! Did he have a pro do that enclosure? The only thing
I wouldn't like is the buttons. Those tend to wear out quickly.

Resolution : 1ps
Jitter : 30ps rms

Why claim 1ps when the system jitter is so large? You are paying for
useless digits. Averaging to improve the SNR would take forever, and the
system would probably drift before the rms error got close to 1ps. So the
resolution spec is meaningless. IMHO, the resolution spec should be >= rms
jitter.

Regards,

Mike Monett

Antiviral, Antibacterial Silver Solution:
http://silversol.freewebpage.org/index.htm
SPICE Analysis of Crystal Oscillators:
http://silversol.freewebpage.org/spice/xtal/clapp.htm
Noise-Rejecting Wideband Sampler:
http://www3.sympatico.ca/add.automation/sampler/intro.htm
 
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