Re: PC Based Oscilliscopes

From: Telamon (telamon_spamshield_at_pacbell.net.is.invalid)
Date: 01/22/05 

Date: Sat, 22 Jan 2005 21:44:34 GMT

In article <MPG.1c5c3d153e17de829896ac@localhost>,
 Dr. Anton T. Squeegee <SpammersAreVermin@dev.null> wrote:

> In article <uLadnd295aUM_G_cRVn-qg@comcast.com>,
> james.douglas@genesis- software.com says...
>
> < Top-posting corrected. Please don't top-post! See this link for
> the reason why: http://www.html-faq.com/etiquette/?toppost
>
> > "Jim Douglas" <james.douglas@genesis-software.com> wrote in message
> > news:Re6dnVkvnsMeDGzcRVn-gw@comcast.com...
> > > Anyone use these? Any recommendations good or bad? I am looking
> > > at some
> > that
> > > have Scope, Meter, Spectrum Analysis, etc. Are the "multi-use"
> > > type PC scopes any good? I see some that are down around
> > > $200-300? which is in my price range.
> > >
> > > Thanks!
> > >
> > >
> > > Jim Douglas www.genesis-software.com Carrollton, TX USA 75006
> > > Latitude 32.9616 Longitude 96.8916
>
> > Thanks for all the input, I am going to pass on the PC stuff and
> > shop EBay and ?? for a good used scope. Any recommendations other
> > than EBay?
>
> Sure. Check http://www.arrl.org/hamfests.html for hamfests in your
> area. They happen all over the country (heck, all over the world) at
> various times during the year, and the swap meet portion of any
> hamfest bears (usually) a 95% or higher focus on electronics in terms
> of test gear, radios, computers, etc.
>
> If you've never been to such an event in your life, I would
> (SHAMELESS PLUG ALERT) take a look at an article I wrote on my own
> page at this link:
> http://www.bluefeathertech.com/technoid/Scrounger.html
>
> This is a guide to scrounging at both surplus places and swap meets.
> I hope you find it helpful.
>
> Happy hunting.

It is very rare for a cross posted article to RRS to be useful. Most are
Trolls. I enjoyed your web page on scrounging. I'm taken aback on the
prices that you posted about equipment however quoted below.

> Dr. Anton T. Squeegee wrote:

> > If you want some serious bandwidth, you should have a look at the
> > Tek 7904 or 7104. The base frames have bandwidths of 500MHz and 1GHz,
> > respectively, and you should be able to get a good 7904 with plug-ins
> > for a little over $300.

A TDS7104 sold new in the $30K to $40K range depending on options. I
have priced this scope at used equipment resellers in the $8 to $10K
range. The equipment is sold in calibration and working with a short
warranty like 30 days for verification that the equipment is in proper
working condition from resellers.

At prices under $1K even with no guarantees I expect this equipment is
hot at those prices. All equipment from the major makers have serial
numbers throughout the equipment and in the firmware. If you ever send
this equipment in for repair you might be in for an unpleasant surprise.

In the last few years there is a new class of scope called real time.
The reason I'm responding to this thread is that you just happened to
mention a real time scope the TDS7104. Tek calls real time scopes DPO or
Digital Phosphor scopes. Most digital scope are repetitive sampling
making them a poor choice for low frequency events like an intermittent
pulse and these are useless for high speed single shot events. The DPO's
resemble an analog scope with memory. There are the best suited digital
type for single shot or low frequently occurring events. The DPO's are
designed for a very high re-acquisition rate compared to digital
sampling types, which is why they are better suited for the low
frequency events as they are more likely to be actually sampling the
input during an event rather than being in another part of the
processing cycle. DPO's have a rapid processing cycle and also have most
of that cycle being actual sample time so they are able to catch that
infrequent pulse. The repetitive sample high speed scopes generally have
cycle times of 200KHz or slower and most of that cycle time is signal
processing and display. Repetitive sampling scopes are good at any type
of recurring signal like clocks. They are poor choice at looking at data
streams with long patterns. The only way you can look at long patterns
is at the bit level or eye mode. 

-- 
Telamon
Ventura, California

Relevant Pages

  • Re: PC Based Oscilliscopes
    ... prices that you posted about equipment however quoted below. ... In the last few years there is a new class of scope called real time. ... DPO's have a rapid processing cycle and also have most ... Repetitive sampling scopes are good at any type ...
    (sci.electronics.equipment)
  • Re: Oscilloscope grounding question...
    ... fuses, wall power polarity, battery conditioning and source ... As the equipment dumped on a 'faringee' is usually dusty for some good ... Scope models exhibiting internal open circuits included, from memory, ...
    (sci.electronics.design)
  • Re: "LVD" versus "GPSD" when supply voltage is 24V (SELV from fixed installation)
    ... voltage is below 50V (and therefore outside the scope of the LVD)? ... However as your equipment is electrical the EMC directive will almost certainly apply, even if it's obvious that no testing is required. ... See the various books by Tim Williams for good practical advice on EMC compliance. ...
    (sci.engr.electrical.compliance)
  • Re: VFD induces terrible vibration in 2 different motors. SOS
    ... the best analog scope ever made: ... rusty Degree in Electronics. ... But sure as hell:) I wuz not going to stick probes into equipment I ... I damaged my one HP KB Electronics VFD a couple years ago. ...
    (rec.crafts.metalworking)
  • Re: FFT Spectrum Analyzer using Digitizer
    ... analyzer (not that it matters, any equipment will give essentially the ... If possible, handle a full cycle length of your signal - in other words, ... use only sine waves that have a full number of cycles within the ...
    (comp.dsp)