Digital Oscilloscope Applications

July 29th, 2011

iOS DIGITAL OSCILLOSCOPE APP

The big term now days, at least for those sporting tablets and smartphones, is “apps”.  So, are there apps for oscilloscope functions?  Yes sir; you bet there are.

For the iPad or the iPhone there is a neat little app from Onyx Apps.  It contains support for waveform viewing and signal generator thus providing a complete generator set and output viewing of the unit under test all in the iPad.  This software app costs about USD$15 and can be found on iTunes.  Here are the basic functions it provides:

Real-time waveform display (60 FPS)
Triggering modes: Normal, Auto, Single
Set trigger level and pre-trigger time
Built-in function generator
Reference signal calibration
Pause function to get a screen capture
Measure signal data using cursors
Use “finger pinch” on screen to set voltage and time base
Double tap screen to enter Black Panel mode
Four color themes to choose from
Retina display support

Input is typically acquired via the built-in microphone. In addition, various options exist for feeding external signals.

Shown below, courtesy of Onyx, is a setup for checking square wave response of an amplifier.

The picture above illustrates some ways of attaching probes to both devices — using USB audio interface for the iPad and a KV Connection cable for the iPhone/iPod touch.

ANDROID DIGITAL OSCILLOSCOPE APP

Likewise, there are apps for Android devices and they are interesting little portable solutions as well.  The DroidTesla is a SPICE (Simulation Program with Integrated Circuit Emphasis) testing simulator that will be of particular interest to those wanting to look in on Integrated Circuits.

DroidTesla claims that it “offers the Trapezoidal(I’ll add a GEAR method later) integration methods to approximate the state of the reactive elements.  Although for most circuits, both methods will provide almost identical results,  it is generally regarded that the Gear method is more stable, but trapezoidal method is faster and more accurate.”

From DroidTesla they now can simulate:
-Resistor
-Capacitor
-Inductor
-Potentiometer (available only in pro version)
-Light Bulb (available only in pro version)
-Ideal operational amplifier
-Bipolar junction transistor (NPN PNP)
-MOSFET N-channel depletion
-MOSFET N-channel enhancement
-MOSFET P-channel depletion
-MOSFET P-channel enhancement
-PN Diode
-PN Led diode
-PN Zener diode
-AC current source
-DC current source
-AC voltage source
-DC voltage(battery) source
-CCVS – current controlled voltage source
-CCCS – current controlled current source
-VCVS – voltage controlled voltage source
-VCCS – voltage controlled current source
-Square wave voltage source (available only in pro version)
-Triangle wave voltage source (available only in pro version)
-AC ampermeter
-DC ampermeter
-AC voltmeter
-DC voltmeter
-Two channe oscilloscope (available only in pro version)
-SPST Switch (available only in pro version)
-SPDT Switch (available only in pro version)
-Voltage controlled switch (available only in pro version)
-Current controlled switch (available only in pro version)
-AND (available only in pro version)
-NAND (available only in pro version)
-OR (available only in pro version)
-NOR (available only in pro version)
-NOT (available only in pro version)
-XOR (available only in pro version)
-XNOR (available only in pro version)
-JK flip-flop (available only in pro version)
-7 Segment Display (available only in pro version)

If you are making an oscillators you have to put a small initial value on some of the reactive elements, they explain.

The DroidTesla is a free download! (You can do an Internet search for it).

There are other apps available.  They will be covered in later columns.  Have a great day.

What is going on with Oscilloscopes?

July 20th, 2011

There are many things brewing.

ONE:  iPad, iPod and smartphone apps that allow interesting functions.

TWO: Oscilloscope Laboratories, maker of “Gunnin for that No. 1 Spot”.

THREE:  Lots of freeware and trialware.  Just google (or bing) around.

FOUR:  Crazy oscilloscope patterns at http://www.youtube.com/watch?v=HM3WWurYmLw

FIVE:  Got any suggestions?   Your turn!

The lissajous pattern on oscilloscope display

June 13th, 2011

The digital oscilloscope is a very ideal device for displaying lissajous patterns. The lissajous pattern it created by feeding a repetitive sine wave into the vertical axis of the digital oscilloscope display and another into the horizontal display axis. The result is a pattern that can show the relative frequency or phase of one compared with the other. For example, if a 1Khz signal were fed into one axis and a 2Khz signal were fed into the other axis the lissajous would display a pattern with one side being twice the figure of the other. Here is what it would look like, below.

If two sine wave signals were at a ratio of 3/2 in frequency it would look lik this:

In the early days of stereophonic recording it was important to know the degree of “separation” between the two channels there was. The oscilloscope was an important tool for the recording and mixing engineers to learn the degree of separation between for the overall “stereo effect”. The same requirements were needed for FM broadcasting and transmission channels.
The degree of “stereoness” can easily be seen on an oscilloscope display pattern. Below is what a typical pattern may look like:

(image: picoscope)

The fullness of the pattern indicates the stereo is more broadly separated. If the two channels were monophonic the pattern would merely becom a single horizontal line.
In my early days as an equipment designer we wanted to keep the separation of the stereophonic signals as far apart as possible throughout the low and middle frequencies because that is where the human ear will hear the greatest stereo effect. But, at higher frequencies it was essential to bring the channels closer together in order to minimze the noise that is generated by most FM demodulators; in other words we used the oscilloscope to help us design circuits that would present to the ear a legitimately sounding stereo playback but with reduction of noise from the high frequency reproduction system.
You can imagine how useful this would be in the recording, mixing and broadcast studios. The digital oscilloscope makes a very viable tool for them to use.

Who Uses a Digital Oscilloscope?

June 6th, 2011

The Digital oscilloscope are not easy to categorize from a classical marketing point of view.  Doing market research in the electronic instruments field is not a well known subject.  Knowing what is needed in the field and what would sell is always difficult for the product development experts.  Developing a sales strategy, identifying the sales channel and knowing how to get in the right distribution space is no easy task.

Trade shows, technical conventions, Internet and newsletters from technical societies is where one begins the journey, perhaps.

Based on the great proliferation of brands and models it would cause one to assume the market is wide and deep.  And, it probably is, at least from the standpoint of the market dynamics and array of potential users.   Here are a few of the users that come to my mind as I just think openly about those with whom I have had personal experience.

Digital Oscilloscope Application Areas and Fields

Electronics (of course, for design of circuits, for example)

Medical

Measuring and Metering, flow and mixing analysis (such as the energy field)

Electric power industry (Smart Grid is coming!)

Manufacturing and production environment – all areas

Automotive – design, manufacturing and testing

College and University laboratories

Broadcasting – monitoring of transmission signals

IT –  Server management, traffic, concentration, density

Media – Movie industry, Hollywood, Disney Imagineering

Hobbyists

Robotics

And, perhaps you could add to the list.

The digital oscilloscope is a very useful instrument….

It can be supposed that more and more uses and applications will be forthcoming as the global industrial space grows more technologically oriented.

A digital oscilloscope can be useful in so many ways.

Think of the digital oscilloscope as a tool for converting the unseen characteristics of the electric world into a graphic presentation that tells one what is going on at the electronic, electromagnetic, photovoltaic, magnetorestrictive or motion movement level.

This is not a scientifically arrived at count, just an educated guess on my part, but I would say there are over 25 brands or manufacturers of digital oscilloscopes representing around 150 models ranging in prices from under $100USD to several thousand dollars USD.

A digital oscilloscope  is a great contribution to the world.

Miniature USB Oscilloscope

June 3rd, 2011

The USB oscilloscope concept provides for a wide range of implementations.   Remember, the three key ingredients of a USB oscilloscope design includes a hardware input device, a display (such as a PC) and the software program.

To highlight this a little more we give, for your consideration,  a physically small hardware input device which is only slightly larger in size than a USB flash storage unit.  We assure you this is not an advert for the manufacturer of this unit selected; rather it is an example of an elegant USB plugin device.

Picture herein is the USBscope50.  It is courtesy of Elan Digital Systems, Elan House, Little Park Farm Road, Segensworth West FAREHAM Hants PO15 5SJ, UK.

Each end of this little scope has  a connector.  One is the standardized USB male connection for easy insertion into the female USB on the display processor unit – such as a PC.  The other end is a BNC connector for the attachment of a cable or probe which will feed the test or measurand signal for processing and eventual display.

Notice the “STACK” marking on the scope case just above an opening whereby a connector may be inserted.  This allows for stacking of additional USBScope50 units to be connected.  This provides for multi-channel applications. Four units may be stacked.

Inspite of the small size this unit, accompanied with its included application software, has a long list of measurement features and specifications.

USBscope50 JAVA Software                        Supports Windows 2K/XP/VISTA/WINDOWS 7 and LINUX

FFT                                                                         2048 point per channel

Math                                                                     2 Math channels, with FFT

Data Export                                                        Via text file to Excel etc.

Full Screen Plot                                                 Yes, for time window and FFT window

The current drain is 200ma from the host.  If more than one unit is used it may be necessary to employ a USB hub to satisfy the additional power consumption requirements.

USB oscilloscope probes and accessories are available, or course.  This USB oscilloscope example is offered as an illustration of a low cost, small size, affordable and flexible solution.

There are, of course, other makers of small, low cost USB oscilloscopes.

 

The above image is complements of EE Times in an article entitled “Scoping out palm-sized USB oscilloscopes.

We hope this is helpful in highlighting this category of the USB oscilloscope story.

The Software used in Oscilloscopes

May 10th, 2011

We now take a look at the software used in oscilloscopes.  The software used in oscilloscopes is an important element to understand.

There are two basic components of a PC based oscilloscope:  The hardware side and the software side.  The hardware is usually, at least in the general case – except  in the case of the USB based oscilloscope where the hardware is external to the PC and plugs in via the USB port – is a board either already in the pc or subsequently added for the purpose of converting it for oscilloscope functionality.

In an obvious and simple case is one where the sound board is used as the input processor for a class of oscilloscopes intended for measuring, viewing and recording repetitive wave forms such as sine waves or sound patterns.  One involved in audio measurements, for example, would be a user of such an instrument.   The soundcard or board has the necessary input to catch the analog signal, amplify it and convert the output to a digital representation that can be then further manipulated as necessary to display, condition, calculate, process or distribute, etc.

There are other boards or cards that can be utilized depending on what purposes the oscilloscope is put to.   Digital storage and digital troubleshooting methods are often the end result and the cards employed may very well be suited for sampling and storing such data for future retrieval, processing and analysis.

There are specialized manufacturers who make cards for amplifying, digitizing, buffering and so on.  That will be the subject of another treatise on another day!

Here are some examples of the software that might be needed for various applications:

Audio Testing:  - Audio Spectrum Analyzer for Real-time, FFT, Oscilloscope, Frequency counter, voltmeter, noise and distortion meter, phase shift meter. Multi-Tone Sound Frequency Sweep Generator. White, pink noise.

FFT:  - Spectrum analyzer designed for time-frequency browsing and scientific data visualization. Oscilloscope waveform, statistical histogram, accumulated spectral trace,Weak Signal reception, continuous data logging, FFT Analyzer and specialized measurement windows.

Software for these uses may be supplied by the manufacture of the card.  It may also be freeware from others who support various applications for their PCs or oscilloscope applications.  In some cases, such as Pico  Technology, they provide SDKs (Software Development Kits) which allows users to write their own software variations to meet special user requirements.  Development kits are often available in various languages allowing the user to integrate the software easily into an embedded or extended system.  Visual Basic , C, C# and C++ are common languages used  for software code writing.   Such software often is written in the form of a driver for a certain set of hardware cards or PCs which allows for easy integration and fine-tuning.

Let us take a look at a simple system.  Such a system being referred to is the “Poor Man’s Oscilloscope” and is based around a conventional PC with a soundcard already installed in it.

Connection to the PC:  The soundard will have an input, usually blue in color, which allows for audio input from outside sources such as a cd player, MP3 or iPOD device.  An audio cable with the miniature stereo plug can be adapted by stripping the opposite ends and baring the three leads, ground, left and right channel such that it can be used as a probe for connecting into the unit under test.

Software:  The software package used in the “Poor Man’s Oscilloscope” is from GoldWave.  This software is compatible with most MS OS versions and Unix but not Mac OS X, sorry.  Goldwave is available as a download at CNET and comes in a trial version or can be purchased for a nominal cost.

From GoldWave:  They say this, “GoldWave is a professional digital audio editor. Use it to play, edit, mix, and analyze audio, or apply special effects, such as fade, equalizer, echo, reverse, time warp, noise reduction, silence reduction, pop/click filter, voice over, etc. Record new files from cassettes, albums, radio, or microphone and restore and enhance them using the wide range of filters and effects. Digitally copy tracks directly from audio CDs to edit or remix them. Convert all your iTunes  M4 songs to MP3, match volume levels between songs, trim leading and trailing silences, adjust equalization to prepare your songs for a perfect MP3 CD or before copying them to your MP3 player.”

Further, “Displays a variety of useful real-time visuals during playback and recording. Supports MP3, iTunes M4A, WAV, WMA, Ogg, and many more formats. Includes built-in tools, such as Batch Processing, CD Reader, File Merger, and Effect Chain Editor. GoldWave does it all, yet it’s fun and easy to use.”

Below is what it’s interface screen looks like.

Note:  Source of “Poor Man’s Oscilloscope” is from Rob Crockett.  His web with further information about his experience with GoldWave is at http://www.ledametrix.com/oscope/index.html.

The software used in oscilloscopes is an important aspect of these instruments.

The DSO Nano

November 18th, 2010

DSO Nano

No.  The DSO Nano is not a pocket music player.  Yes.   It is a digital oscilloscope.  A very tiny one, too, as the name implies.  And, it is a cheap – maybe inexpensive it a better term –  one as well.   It comes from a company called Seeed Technologies.

Looking for cheap, then DSO Nano might be the one

If you want to spend about $89 for a one input oscilloscope this may be the one.   This little featherweight instrument will be suitable for relatively low speed applications such as examining a serial port communications line,  pulse-width modulation process or checking out an analog to digital converter.  But, since it is only one channel it cannot display two pulse trains at the same time nor show them in sync.

Search for DSO Nano on Google brings interesting results

Actually,  there is so much interest in this little fellow that when you google for “DSO Nano” a long list of commentary comes up.  One that I liked was a Youtube video showing how it is packaged, how to load up the battery, turning it on and simple uses.  This video runs for almost 10 minutes.  Find it at  http://www.youtube.com/watch?v=Tn5fFU7nk0U and enjoy a pleasant viewing of the little fellow.

For a hand-held scope that can snuggle right down near the circuit being tested it may fill a need when you cannot afford the big Tektronix or other full-size instrument.  It seems to be very useful, inexpensive and endlessly attractive.   It may be that you would want it just for the coolness of its unique design and novelty.  Here is a picture showing the smiling little display.

The pocket size DSO Nano Oscilloscope

Oscilloscope Tutorial | How to use an Oscilloscope

November 15th, 2010

Oscilloscope Tutorial

Here is my attempt at an Oscilloscope Tutorial without you being physically present in front of me. It is usually far easier to demonstrate these things then to put pen to paper. As a once-upon-a-time college professor it was a very common dilemma teaching students how to use the oscilloscope.  It is a strange and interesting instrument to them because it is very visual and has lots of “knobs” to tinker with! But, the students would ask how to use it and what to do with the images found on the screen. Once the magic of visual representation was understood the scope became their favorite tool in the laboratory.

Simple oscilloscope tutorial on how to use the oscilloscope scope for general purpose applications.

This is a simplified view of the basic oscilloscope instrument:

Simplified Oscilloscope

Oscilloscope Tutorial – The ‘nitty gritty’ details

The sine wave on the graphic screen is what would be seen when looking at the waveform of a pure sine wave generator.   The squares on the graph would be calibrated to volts/division and, therefore, the graphic presentation can be used as a voltmeter.

The red “vertical” knob is to select the range or sensitivity of the measurement being taken.  If  the test signal were coming from the AC outlet of the house power system, for example, the peak voltage would be about 120v times 1.4 for the peak, or about 168 volts.   Thus, if the vertical knob were turned to choose 20v/division the screen be able to display the positive and negative peaks of the 120v rms sine wave.

The other red knob marked “time base” is the adjustment for setting the rate at which the beam sweeps across the screen.  It is calibrated for seconds/div or milliseconds/div and is used to allow a full set of cycles of the test signal to be seen.   Remember the time period of an alternating signal is the reciprocal of the frequency or T = 1/f.  In our example if the sine wave is a 60Hz voltage then the time for one cycle is 1/60 or about 17 milliseconds.  Therefore, the time base setting would be selected accordingly. The small red knob marked “trigger” is an adjustment which alters the level on the circuits inside the oscilloscope to set the level of the voltage of the sweep circuit will trigger the sweep.   Adjusting it can alter when on the sine wave you want the horizontal sweep to begin. The “X” and “Y”  connection points are where the probes or connection leads will be inserted.

The “X” probe lead usually connects to the ground or earth of the circuit or voltage under test whilst the “Y” probe lead connects to the voltage point in the circuit under test. By counting the time divisions within a full cycle of the sine wave the frequency can be calculated.

Many oscilloscopes have two or more vertical inputs and can show two or more signals simultaneously.  Below is shown a dual trace oscilloscope with two vertical inputs and two signals of different frequency being shown.

Dual Trace Oscilloscope

There are many more applications and variations of oscilloscopes but this is a starting point for those new to this kind of electronic instrument.

Note: Images from http://www.ibiblio.org/kuphaldt/socratic/output/scope1.pdf

Thanks for reading this oscilloscope tutorial!

Purchasing a New Oscilloscope?

November 13th, 2010

It is a good strategy to try out a new product prior to making the purchasing decision.  Right?  So, how do you do this when needing a digital scope?  Often they are ordered through a company purchasing department or website where only specifications and reviews/comments from other users are used in the decision making process.

Well, I have a better idea.  Why not go to a retail store where they have them in stock and sample models on the shelf where you can test them and operate the controls to make sure it will do what you want?

And, you ask, where do we find such a retail store?  Not at Walmart or BestBuy or even Radio Shack!  No, they are a totally different kind of enterprise.

There is one place that I highly recommend; it is a place that any electrical engineer or electronics professional cannot go without staying for at least a full hour  drooling over the diversity of products on display.  These retail stores are as big as a Home Depot and have as many skus (stock keeping units) in their inventory as a Walmart Superstore!  These stores carry products from a single 1,000 ohm resistor to a zener diode to computer parts, boards, antennas, transformers, drives, monitors, PCs, laptops, printers, voltmeters, games, batteries and much, much more.   And, yes, digital oscilloscopes.

So, where are these stores?  They are in California, Texas, Arizona, Georgia, Illinois, Indiana, Nevada, Oregon and Washington state.  The name is FRYS.  See:

http://www.frys.com/ac/storelocator/index.jsp

The store I recently visited is the one in Las Vegas, Nevada.  It had 10 models on the shelf ranging in price from  a few hundred to a few thousand dollars.  Brands being displayed were LeCroy, B&K, Tektronix and Fluke.

Visiting a FRYS store is  and experience that will brighten your day and give you a renewed enthusiasm for the good old days when electronic parts stores were in every city.  But, what a store they are.  Clearly, FRYS is thee megastore for electronic components and gadgets.   It is nearly impossible to go in without bringing something back to the lab or office or home.  Last time I visited the Las Vegas store to see what they had in scopes (to write this article) I pickup up a Kingston USB flash with 8GB memory for under $15!

I will be looking for you next time I go to FRYS.  We will meet at the digital oscilloscope section and I will see you playing with the Fluke pocket scope.  Goodbye for now!

The Most Expensive Oscilloscopes on the Market?

October 29th, 2010

I don’t know the most “expensive” oscilloscope – either digital or analog.  But, this I do know:  There are many that go over $10,000 each.   Special series with add-ons and custom features can push prices way up there.

Tektronix is known for its broad line of scopes.  They are truly professional instruments and are often thought of as the king of the business.   Here is an example of one of their high priced models – not the highest, mind you, but one that might typify a high end user where features and performance are important.

The Tektronix MSO3054 Mixed Signal Digital Phosphor Oscilloscope, 500 MHz, 2.5 GS/s, 1M record length, 4+16-ch, Color Display is such a unit.  Its full list of specifications can be seen at:

http://www.testequipmentdepot.com/tektronix/oscilloscope/mso3054.htm

The Test Equipment Depot has this model listed at a starting price of $15,200.00.  This model is modest in size and high on performance and is a contrast to the older large scale models that ride around on a cart.   This one is so small it will easily carry in a brief case or set on a work bench without taking up too much footprint space.

Here is a picture of the cute little fellow:

Tektronix MS03054 It is approximately  8″ by 16″ by 5″ (HWD) and weighs in at around 9 lbs.