Tektronix made a number of oscilloscopes like you describe including
some interesting hybrids. Phillips made some oscilloscopes
contemporary to the Tektronix 2232 series but supporting 4 channels,
200 MHz bandwidths, and with more features. I have avoided them
because of the lack of service information.
Here are the Tektronix analog oscilloscopes that include at least some
form of digital storage roughly in order:
The Tektronix P7001 attaches to a 7704A (200 MHz) between the display
and mainframe:
The Tektronix 7854 (400 MHz) works like a P7001 but is all one unit.
It uses the analog timebase for digital storage which has the side
effect of allowing equivalent time sampling without a clock delay
timer. With a 7B87 timebase, it also supports low speed real time
single shot captures with pretrigger. The user interface and
programming make a great companion to your HP RPN calculator.
The Tektronix 468 is a 465 (100 MHz) with a digitizer module (8 bits
and 25 MS/sec) mounted on top. It apparently supports some type of
equivalent time sampling called "jitter correction" in the manual but
is still limited to a 10 MHz bandwidth in storage mode.
The 2232 (100 MHz 100 MS/sec), 2224 (60 MHz and 100 MS/sec), and 2230
(100 MHz 20 MS/sec) support real time sampling, equivalent time
sampling, and peak detection. The other 22xx series oscilloscopes
operate with real time sampling only and no peak detection. The 2221A
(100 MHz 100 MS/sec) and 2221 (100 MHz 20 MS/sec) are single timebase
versions of the 2232 and 2230.
My 2230 is my go to oscilloscope although if I need to backup
waveforms for later, I use my 2232 instead because my 2230 does not
have the memory backup option.
The Tektronix 2252 is a 2247A (100 MHz 4 channels) with limited
digital storage using sequential sampling.
Some of the above oscilloscopes have much higher storage resolution
than you would expect. The 2252 is 12 bits vertical. The 7854 is 10
bits horizontal and vertical.
Of the above, the 2230 and 2232 are the most common and easiest to
maintain. The 2221 and 2221A are just as easy to maintain because
they are essentially the same as the 2230 and 2232. The 7854 is the
most versatile but lacks real time operation and peak detection.
On Sun, 30 Dec 2012 17:09:00 -0500, Bryce Schroeder
<bryce.schroeder@...> wrote:
Did HP (or Tek, or anyone for that matter) make any oscilloscopes that were
basically analog scopes, but with the ability to digitize what is seen on
the display (at some lesser resolution than what you might be able to see
on the actual display, presumably)? As I understand it - which may
admittedly be incorrect - some of the older spectrum analyzers are sort of
like this.
So, this hypothetical oscilloscope type would basically have the analog
display "in parallel" with an ADC, such that you could look at the screen
and see the waveform displayed like an analog scope, or use the ADC to see
a digital approximation. (Presumably the digital stuff could also be used
to capture and store one-shot things like a regular digital oscilloscope.)
This would be opposed to a purely digital oscilloscope where the ADC and
memory is always between the signal and the display.
The reason for doing this, of course, would be that the analog display
would be "higher resolution" than the ability of the ADC, but the digital
stuff would enable automation and storage ability. This would stop being
important once digital was high-enough resolution to look more or less
indistinguishable to humans.
Did such "hybrid" oscilloscopes ever exist? If so, what are some model
numbers?
Thanks for your time - sorry if that was a bit lengthy.
David Hess