which oscilloscope?

[Talal Itani]

Hello,

My boss asked me to evaluate oscilloscopes and to recommend one. I know
Tektronix and LeCroy. Which is better? Are they any others? Ideally, we
would get a 4-channel scope at 300 MHz, with a 5 million sample record
length. Thanks for your advise.

T.I.

 

[Frank Buss]

My boss asked me to evaluate oscilloscopes and to recommend one. I know
Tektronix and LeCroy. Which is better? Are they any others? Ideally, we
would get a 4-channel scope at 300 MHz, with a 5 million sample record
length. Thanks for your advise.

Agilent scopes are nice, too. Some scope companies have local resellers,
which can demonstrate their products at your workplace and even lend you a
scope for some days, so you can evaluate it yourself, if it fits your
needs.

 

[David L. Jones]

Hello,

My boss asked me to evaluate oscilloscopes and to recommend one. I know
Tektronix and LeCroy. Which is better? Are they any others? Ideally, we
would get a 4-channel scope at 300 MHz, with a 5 million sample record
length. Thanks for your advise.

Agilent is the other "big one". In fact Tektronix and Algilent are the "big
two" brands, Lecroy has always come third.

Lecroy have a bad rep for being hard to drive, the newer ones are better
though.

IMO the Agilent's are the easiest and nicest to drive.

The Agilent DSO6034A suits your requirement:
http://www.home.agilent.com/agilent/product.jspx?nid=-536902766.536905498.00&cc=US&lc=eng
300MHz, 8Mpoint memory, 4 channel
A very very nice scope.

You'll need more specific requirements than that to compare scopes in this
category. Any specific uses in mind? e.g. do you need mixed signal
analysis?, high speed serial protocol analysis?, what sample rate?

Dave.

 

[David L. Jones]

Agilent is the other "big one". In fact Tektronix and Algilent are the
"big two" brands, Lecroy has always come third.

Lecroy have a bad rep for being hard to drive, the newer ones are better
though.

IMO the Agilent's are the easiest and nicest to drive.

The Agilent DSO6034A suits your requirement:
http://www.home.agilent.com/agilent/product.jspx?nid=-536902766.536905498.00&cc=US&lc=eng
300MHz, 8Mpoint memory, 4 channel
A very very nice scope.

Or the new 7000 series Agilent:
http://www.home.agilent.com/agilent/product.jspx?nid=-34750.753488.00&cc=US&lc=eng
12.1" XGA display!

Dave.

 

[Talal Itani]

It is nice if we can do mixed signal, but I am sure we have to pay much
more. We will use this scope in the product development lab, for embedded
work. The signal we are working with is 25MHz digital. Rarely we will look
at a clock of 100 MHz. So, I thought 350 MHz analog is what we should get.
Some Tektronix and LeCroy have a very short buffer. The ones with large
buffer start at $5,000. Is one brand better priced than the others?

Thanks.

 

[Talal Itani]

Thanks. This is nice stuff, yet the buffer length (2.4k points) is too
small, I think, for our needs.

 

[Talal Itani]

Evil as in Sinner?

 

[Nico Coesel]

Why do you need a lot of buffer? I test and debug realtime uP-based
things, delay generators and arbs and such, with a Tek TDS2012, which
only has enough buffer for the screen you see.

At some point, a lot of memory is too much memory. It's easier to
think about why something's broken than to analyze a few million
stored events. Even easier to design it right in the first place, ie,
review the design more, debug it less.

Not having to think or jump through hoops to trigger at the right
point can save a lot of time. That is where a big buffer comes in
handy. Also being able to zoom in at a 'problem spot' without having
to re-capture data saves a lot of time and hassle. I do a lot of
checking on FPGA designs using a 2M point logic analyzer. One
acquisition usually gives me all the data I need to verify the design.

 

[Talal Itani]

I have a Tektronix at home, with the 2.k point, and at times it is painful
to use. I see myself trying to scroll and scroll, to see more, and then I
realize that the scope cannot show me more. We are debugging some serial
protocols, so a buffer larger than 2.4 is really needed.

 

[Nico Coesel]

LeCroy scopes seem to appeal to, err, a certain subset of the
population.

Well, the good Lecroys say Iwatsu on the inside

 

[David L. Jones]

It is nice if we can do mixed signal, but I am sure we have to pay much
more. We will use this scope in the product development lab, for embedded
work. The signal we are working with is 25MHz digital. Rarely we will
look at a clock of 100 MHz.

Then perhaps paying for 300MHz bandwidth may be overkill in this case. A
cheaper lower bandwidth mixed signal scope sounds like it would be much
better value for you. In fact, I'd say you'd be crazy if you didn't get a
mixed signal scope for embedded work.
You'll probably find a 100MHz scope will do 95% of the work you want.

You can get a seperate logic analyser (PC based ones are cheap), but it's a
messy solution and you don't get the nice and easy digital/analog signal
integration.

So, I thought 350 MHz analog is what we should get.

If you really do need to look at signal integrity at 100MHz then you will
need 300MHz+ bandwidth, and the probes to match. But bandwidth costs $$$$

Some Tektronix and LeCroy have a very short buffer. The ones with large
buffer start at $5,000. Is one brand better priced than the others?

With price it's a tossing match, features vs price. Hard to say which is
"better priced".
A decent lab scope with that sort of memory is going to start at $5000.
Do you have a rough budget?, that dictates everything.

For example, an Agilent MSO6014A with 4 channels, 100MHz, and 8Mpoint is
$7,802
Lose the mixed signal option and it's $5,748
The Tektronix mixed signal offerings start at higher than that, but they are
higher bandwidth only.

Dave.

 

[steve]

Hello,

My boss asked me to evaluate oscilloscopes and to recommend one.  I know
Tektronix and LeCroy.  Which is better?  Are they any others?  Ideally, we
would get a 4-channel scope at 300 MHz, with a 5 million sample record
length.  Thanks for your advise.

T.I.

We have a few very high end LeCroys for deep memories and a bunch of
low end Tek's for everyday work, but they really skip on memory, for
some reason they charge $1000's more for a decent size memory, no one
here likes the Agilent's

 

[Talal Itani]

Good idea. Thanks. If my highest-frequency digital signal is 25 MHz, do
you think a 100 MHz digital scope is sufficient? What is a digital-learning
scope?

 

[Talal Itani]

For serial protocols a logic analyser will be much for useful, and have a
*MUCH* deeper memory. You can get good value multichannel PC based
analysers for cheaper than a decent scope.

The analyser will either sample the (digital) waveform with an internal or
external clock, much like a scope, or, more usefully only timestamp the
waveform transitions. This allows best use to be made of the devices
memory.

Ca you recommend a manufacturer of PC based logic analyzers ? (surely I can
do a search, but it is better to hear from a person who knows.)

 

[Talal Itani]

I was trying to find one test equipment unit that will do everything I need.
Now I am leaning more towards an analog oscilloscope, to watch my analog
signals, and a PC based logic analyzer. I looked at the links you gave me.
That is very good. Thanks.

 

[Blarp]

To throw a different tack on the subject: what probes do you use?

When trying to find glitches, faulty wave shapes and such in fast cpu
busses, I find the probes being the bottle neck rather than the scope
BW.

I found myself creating probes based on e.g.
http://www.sigcon.com/Pubs/straight/probes.htm

....allowing me to see things on a lowly 100 MHz scope that would not
be revealed on any high grade scope with (good quality) 1/10 or 1/1
probes.

SW sequence related issues are usually solved by clever (written by SW
engineers, not by me SW routines and debug ports. (never needed a
logic analyser).

If everything is OK, but the system stops for no reason, the scope +
appropriate probe comes out. YMMV - so far I get away with it

 

[Tim Williams]

Me neither. The best logic analyzer is in your head; re-read the
source code.

I disagree. The human mind is a terrible bottleneck! ;-)

I've spent many unproductive hours debugging, I should know. (But it's
those five highly productive minutes at the end that really matter...)

Tim

 

[JosephKK]

It is nice if we can do mixed signal, but I am sure we have to pay much
more. We will use this scope in the product development lab, for embedded
work. The signal we are working with is 25MHz digital. Rarely we will look
at a clock of 100 MHz. So, I thought 350 MHz analog is what we should get.
Some Tektronix and LeCroy have a very short buffer. The ones with large
buffer start at $5,000. Is one brand better priced than the others?

Thanks.

You could check out Rigol or Insteck. I think that they are the
underlying manufacturers for Agilent and Tektronix.

 

[René]

For regular digital/embedded stuff, on a 100 MHz scope, any probe will
work. When the fuzzies start to matter, a good fet probe is magical.

Depends on the hardware on hand, I have found (not the easy way, I
might add , that the act of putting a std probe on a wayward adress
/ data line, changes the conditions enough to make the measurement
invalid.
Sometimes the fault does not occur with the probe in place (which in
it self tells you something), sometimes the device stops working
completely.

Or all seems OK. But when the probe is removed, the system crashes
after 5 minutes..

I had good results with the 1K resistive low cap probe, showing
artefacts <100 MHz the std probe would not reveal.
(spikes, shoot troughs, oscillations etc.)

A good fet probe is nice to have, but IMHO the 1K probe was almost as
good. (with *very* short ground lead off course)

And as everybody surely knows here - to resolve a 100 MHz artefact,
one needs as scope with BW magnitudes higher.

 

[Scott Seidman]

Hello,

My boss asked me to evaluate oscilloscopes and to recommend one. I
know Tektronix and LeCroy. Which is better? Are they any others?
Ideally, we would get a 4-channel scope at 300 MHz, with a 5 million
sample record length. Thanks for your advise.

T.I.

Bring in a sales rep to demo different lines. Tek might not be the best
choice, but it is safe, in that when it breaks, nobody can say "Why didn't
you buy a Tek?" The warranty is pretty good, too.