Digitizing Scopes

[CC]

I have all three - 547, 7104, several TDS2012s - in the lab, plus a
TDS3052 and a bunch of 11801-series samplers. The workhorse is the
TDS2012, and lately we just plop a rackmount 2012 in every test rack
we make.

The slower analog scopes are great for low-level stuff... a 1A7A or
7A22 plugin has switchable bandwidth and 10 uV/cm resolution, hard to
beat for analyzing hum and DAC noise.

One nice thing about the digital scopes is infinite persistance, great
for snooping digital data streams and noting worst-case timings in
realtime firmware. You can pull up/down test points at the start/end
of routines, like IRQs maybe, and run the sucker for a couple of hours
and see the extremes. I recently had a rare flakey temperature reading
from an LM71 and found the cause (occasional insufficient chip-select
setup time... it's a long story) with the TDS.

If I had to pick a single scope on a budget, it would be the TDS2012,
although the new Chinese "Agilent" might be good, too. Anybody use one
of those yet?

Yeah, I've got a MSO6054 at work. I now prefer it over the Tek TDS3054,
due mainly to the much deeper memory, and of course 16 digital channels.

I only wish Agilent would have made a 100MHz MSO model, so someday I
could afford to replace my TDS3014 at home.

Good day!

 

[David L. Jones]

I have all three - 547, 7104, several TDS2012s - in the lab, plus a
TDS3052 and a bunch of 11801-series samplers. The workhorse is the
TDS2012, and lately we just plop a rackmount 2012 in every test rack
we make.

The slower analog scopes are great for low-level stuff... a 1A7A or
7A22 plugin has switchable bandwidth and 10 uV/cm resolution, hard to
beat for analyzing hum and DAC noise.

One nice thing about the digital scopes is infinite persistance, great
for snooping digital data streams and noting worst-case timings in
realtime firmware. You can pull up/down test points at the start/end
of routines, like IRQs maybe, and run the sucker for a couple of hours
and see the extremes. I recently had a rare flakey temperature reading
from an LM71 and found the cause (occasional insufficient chip-select
setup time... it's a long story) with the TDS.

If I had to pick a single scope on a budget, it would be the TDS2012,
although the new Chinese "Agilent" might be good, too. Anybody use one
of those yet?

Yes, and I must say it's pretty darn good for the money. Not surprising
considerng that Agilent put their name to it.
It is designed and made by Rigol in China (http://www.rigol.com/), they
even roll their own ADC.
It is not a high end scope, but the value for money is supurb. The
digital filtering, sequence mode stuff and masking functions are
excellent. Response is very good. Beats the low end Tek's IMHO. If it
was own $$$$ I would go Agilent.

The Agilent 6000 mixed signal series is my current favourite, and
before that the Agilent 54621D. I can highly recommend plugging in a
19" LCD into the 6000 series! ;->

Dave

 

[Mike Harrison]

Only if the memory is deep enough.

We have a nice/fancy Agilent scope. The common gripes are:
memory-too-small (and what there is not used right)
the time it takes to boot
noise

The newer Agilents (546xx onwards) are superb in this respect, better than any Tek I've used.

 

[John Miles]

Who measures noise with a scope anyway?

Someone who is not expecting to find noise.

-- jm

 

[qrk]

There is no situation today where an analog scope even comes close to a
digital scope, and the same goes for spectrum and network analyzers.

Ack! For the analog low-noise environment I'd say that analog scopes
are easier to use than digital scopes. I find analog scopes much
better for looking at noise and noise problems. For unknown
situations, I always have an analog scope handy to augment the digital
scope (Tek TDS3054). Once a Tek rep dropped by to show off a digital
scope. He couldn't figure out the signal due to aliasing problems. The
analog scope allowed him to set up the digital scope.

For pulse events with slow rep rates, pre-trigger data, performing
math, and documentation, you can't beat a digital scope. Too bad
Tektronix has such a slow clumsy Ethernet interface.

Are there any high end analog scope products?-or just kick around cheapies
for field work?

Gosh, the old Tek 7000 series scopes have wonderful sampling plugins
that go into the GHz region. Tek also has a fine 25ps rise time TDR
7000 plugin which allows you to see problems in connectors.

 

[Don Lancaster]

Yeah, I've got a MSO6054 at work. I now prefer it over the Tek TDS3054,
due mainly to the much deeper memory, and of course 16 digital channels.

I only wish Agilent would have made a 100MHz MSO model, so someday I
could afford to replace my TDS3014 at home.

Good day!

The last decent HP Agilent oscilloscope was the 130C.

It has been steadily downhill ever since.

--
Many thanks,

Don Lancaster voice phone: (928)428-4073
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
rss: http://www.tinaja.com/whtnu.xml email: [email protected]

Please visit my GURU's LAIR web site at http://www.tinaja.com

 

[[email protected]]

aware of situations when you just can't beat an analogue scope, but
some people claim that in certain (more limited) circumstances, you
just can't beat a digitizing scope. What might those more limited
circumstances be?

Jeff.

There is probably more limitation of an analog scope, but if you have a
scope
that does both, you just push a button and select whatever you want.

greg

 

[David L. Jones]

The last decent HP Agilent oscilloscope was the 130C.

It has been steadily downhill ever since.

The 54600 series onwards are excellent scopes, with real common sense
usability and great performance. The new 6000 series is *much* better
again.
You should try them.

Dave