About a Diy pc oscilloscope found on the Net - Page 2 - diyAudio
Go Back   Home > Forums > Design & Build > Equipment & Tools

Equipment & Tools From test equipment to hand tools

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 17th June 2007, 12:43 PM   #11
EC8010 is offline EC8010  United Kingdom
diyAudio Moderator Emeritus
 
EC8010's Avatar
 
Join Date: Jan 2003
Location: Near London. UK
Default Useful oscilloscopes have knobs on.

But as was pointed out by I_Forgot, an oscilloscope that can only see audio is virtually useless for audio. There is no such thing as too much bandwidth - 20MHz is the absolute minimum and 100MHz is much better. Seriously, virtual oscilloscopes (PCs or Macs pretending to be oscilloscopes) are a waste of time and money. A decent 'scope is one that doesn't miss things and that is easy to use. Virtual oscilloscopes fail on both counts (and so do many digital "real" oscilloscopes). Buy a second-hand 100MHz Tek and be done with it.
__________________
The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...
  Reply With Quote
Old 17th June 2007, 06:31 PM   #12
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
Quote:
Originally posted by FastEddy
Holy Cow! an Apple Scope, free for the downloading!
It will stop at random times if not purchased but does give a good chance to try it. I mostly use mine for signal generator and speaker measurement (where its limited bandwidth is not a huge issue -- bandwidth is limited only by the I/O device and as those get wider bandwidth so does the scope)

dave
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
  Reply With Quote
Old 17th June 2007, 09:39 PM   #13
diyAudio Member
 
FastEddy's Avatar
 
Join Date: Jun 2006
Location: North Californie
" ... bandwidth is limited only by the I/O device ..."

... same same with any 'scope software. A USB 16 bit / 48k, DAC / ADC would be limited to that 48k bandwidth and 16 bit resolution. Most 'puter 'scopes have 8 bit A to D convertrs but much broader resolution (bandwidth) ... so it would be a bad trade off for anything above audio range. I also noticed that several of the music recording software tools can display "oscilloscope like" graphics (like ProTools, etc.), also quite useful to audio types. But your link was the first I knew of this "shareware" 'scope software ... I like it.
  Reply With Quote
Old 17th June 2007, 10:14 PM   #14
cuibono is offline cuibono  United States
diyAudio Member
 
cuibono's Avatar
 
Join Date: May 2006
Location: City of Angles
Here is the circuit I've been using for several months now. I like it.
http://xoscope.sourceforge.net/hardware/hardware.html
Its basically a buffer to protect your pc. I use it with my modified soundcards for audio BW. It has much better sensitivity than any scope I've used, and is easier to read too...

I've found a couple of programs I like:
http://www.zeitnitz.de/Christian/Scope/Scope_en.html
This one is good for basic scope functions.

http://www.sillanumsoft.com/
This one does averaging and frequency analysis, which is nice.

Sometime I'm going to dive into rmaa:
http://audio.rightmark.org/index_new.shtml

-Patrick
  Reply With Quote
Old 18th June 2007, 05:46 AM   #15
diyAudio Member
 
I_Forgot's Avatar
 
Join Date: Jan 2005
Location: Phoenix, Az.
Quote:
Originally posted by FastEddy
" ... bandwidth is limited only by the I/O device ..."

... same same with any 'scope software. A USB 16 bit / 48k, DAC / ADC would be limited to that 48k bandwidth and 16 bit resolution.
Any digital sampling scope, including one that uses a computer sound card, requires some anti aliasing filter at the input to limit bandwidth of the signal hitting the DAC. A 48 ksps DAC would have a theoretical BW of 24 kHz, but a practical BW of 10-15 kHz due to the difficulties in making good sharp cut-off filters.

Not very useful...

I_F
  Reply With Quote
Old 18th June 2007, 04:43 PM   #16
EC8010 is offline EC8010  United Kingdom
diyAudio Moderator Emeritus
 
EC8010's Avatar
 
Join Date: Jan 2003
Location: Near London. UK
Quote:
Originally posted by I_Forgot
Any digital sampling scope, including one that uses a computer sound card, requires some anti-aliasing filter at the input to limit bandwidth of the signal hitting the DAC.
As you say, it's needed. But it's not there. It's assumed that anyone having the money to buy an oscilloscope has a nodding acquaintance with Nyquist and will recognize aliasing when they see it. The reason oscilloscopes don't have an anti-aliasing filter is that it would have to change filter frequency to suit sample rate (which changes dependent on timebase setting and record length).

This lack of anti-aliasing filter and reliance on user-expertise is one of the reasons why I try to steer people away from digital oscilloscopes. You need a whole lot more knowledge to use a digital oscilloscope than an analogue...
__________________
The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
New Oscilloscope? joetama Equipment & Tools 12 6th October 2009 01:32 PM
oscilloscope mike49504 Car Audio 5 19th November 2008 11:24 PM
USB Oscilloscope jleaman Equipment & Tools 0 7th June 2007 02:43 AM
I want to buy an Oscilloscope still4given Parts 68 30th April 2005 12:22 AM
oscilloscope Kilowatt Digital Source 12 22nd January 2002 12:30 AM


New To Site? Need Help?

All times are GMT. The time now is 09:55 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2