Scopes

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9/17/12
Overview of Oscilloscope Triggering

In this post we will take a look at Oscilloscope triggering. We will cover the basics and look at some of the advanced triggering capabilities found in modern digital scopes. Triggering is often the least understood but one the most important capabilities of a scope. You can think of oscilloscope triggering as “synchronized picture taking”. And one waveform picture actually consists of many individual and consecutive digitized samples. When monitoring a repetitive input signal the oscilloscope performs repetitive acquisitions (or repetitive picture taking) to show a “live” picture of your input signal. This repetitive picture taking of the oscilloscope must be synchronized to a unique point on the input signal in order to show a stable waveform on the scope’s display.

Although some scopes have various advanced triggering modes to choose from, the most common type of triggering is to trigger the scope when the input signal crosses a particular voltage threshold level in either a positive or negative direction. We call this “edge triggering”. In other words, the scope triggers (takes pictures) when the input signal changes from a lower voltage level to a higher voltage level (rising edge trigger) or when the input signal changes from a higher voltage level to a lower voltage level (falling edge trigger). A photo finish of a horse race is analogous to oscilloscope triggering. To accurately record the finish of the race, the camera’s shutter must be synchronized to when the lead horse’s nose crosses the finish line in the forward direction.

Edge Triggering Examples
Let's look at two examples of oscilloscope edge triggering. In the screen-shot below, the scope’s trigger level is set above the waveform. In this case the input signal never crosses the trigger threshold level in any direction. The scope is taking asynchronous pictures of the input signal and we observe what appears to be an unstable waveform. This is actually an example of not triggering – or unsynchronized picture taking.

Untriggered (unsync'd picture taking)
In the below screen-shot, the scope is setup to trigger on rising edges of the input signal with the trigger level set at +2.01 V. In this case, we can see a rising edge of the input signal at exactly center-screen. 

Triggering on Rising Edge @ +2.01 V
Although the default trigger localization on all digital oscilloscopes is at center-screen (horizontally), you can re-position the trigger location to the left or right by adjusting the horizontal delay knob – sometimes called the horizontal position knob. Older technology analog scopes are only able to trigger at the left side of the screen. This means that analog oscilloscopes are only capable of showing portions of waveforms that occur after the trigger event – sometimes called “positive time data”. But DSOs are able to show portions of waveforms both before (negative time or pre-trigger data) and after (positive time data) the trigger event. Observing pre-trigger data can be useful for analyzing waveform data that may have led up to a specific error trigger condition.

Edge triggering is by far the most common method used for scope triggering. Modern digital scopes also include many advanced triggering methods such as Pulse Width, Pattern, and Runt. Let's take a quick look at a few advanced triggering methods in modern scopes.

Advanced Oscilloscope Triggering – Rise/Fall Time
The below screen shot is an example of signal parametric violation triggering. In this case we are showing an example of triggering on a rising edge that fails to meet a specified rise time of 100 ns. This scope can also trigger on falling edge violations, as well as edge speeds that are faster than a user-specified time.

Triggering on rising edges if slower than 100 ns
Advanced Oscilloscope Triggering – Setup & Hold Time
In the below screen-shot we showing an example of a setup & hold time violation. The scope has been setup to trigger on a rising edge of a clock signal (channel-1, yellow trace). The green trace shows the channel-2 waveform, which is a data signal represented as an eye-diagram. When writing data into a storage device, shift register, or latch, the data signal must be stable for a minimum amount of time before the arrival of the clock signal. This is called “setup time”. In addition, the data signal must remain stable (high or low) for a minimum specified time. This is known as “hold time”. 

Edge Triggering Reveals Data Edge Shift
In this particular example we can see that the data signal occasionally shifts in the positive time direction closer to the clock edge. We know that it is an occasional or infrequent timing shift as evidenced by the dimmer intensity of the trace (assuming that the scope has waveform intensity gradation capability). This is a violation of the device’s setup time.

In this post we looked at oscilloscope triggering, from basic to advanced. If you have anything to add to this post use the "Comments" section below and if you have any questions send me an email.




7/17/12
Overview of the Infiniium 90000 Q-Series Oscilloscope

In this post we will look at a video that provides an overview of the most advanced Oscilloscope on the market, the Infiniium 90000 Q-Series. The Q-Series provides up to 63 GHz of true analog bandwidth and the lowest noise floor on the market, both of which are demonstrated in the following video.


Click here for more info on the 90000 Q-series scope




6/25/12
Agilent's New 1000B Series of Economy Oscilloscopes

Recently Agilent released a new family of economy or low cost oscilloscopes called the 1000B series of portable oscilloscopes. The new 1000B series has a lot of features that you typically do not see in scopes at this price range including mask testing and sequenced acquisition capability. The below video (silent)  provides an overview of the 1000 series.


Here is a list of some features and specs for the 1000 series:
  • Bandwidths up to 200 MHz
  • Sampling rates up to 2 GS/s
  • 23 automatic measurements 
  • waveform math capabilities including FFT
  • Simultaneous viewing of main and zoomed waveforms





5/21/12
Overview of the M9703A AXIe Multi-Channel High-Speed Digitizer


The below video provides an overview of Agilent's M9703A mult-channel 12-bit high-speed digitizer based on the AXIe standard. The M9703A is a wideband digitizer, providing 4 or 8 synchronous channels with 12-bit resolution, each running at up to 3.2 GS/s, and offering up to 1 GHz analog bandwidth. The Agilent M9703A also provides very long acquisition capability by implementing up to 4 GBytes internal memory. In addition, to ensure high data throughput, the module also provides a PCIe backplane connection. Overall this is a pretty awesome instrument!


5/7/12
Understanding an Oscilloscope's Update Rate

In this blog post we will look at the waveform update rate specification of an oscilloscope. Although an often overlooked specification, waveform update rates can be extremely important — sometimes just as important as the traditional banner specifications including bandwidth, sample rate, and memory depth. Even though a scope’s waveform update rate may appear fast when viewing repetitively captured waveforms on your scope’s display, “fast” is relative. For example, a few hundred waveforms per second will certainly appear fast to the human eye, but statistically speaking this can be very slow if you are attempting to capture a random and infrequent event that may happen just once in a million occurrences of a signal.

When you debug new designs, waveform update and serial bus decode rates can be critical — especially when you are attempting to find and debug infrequent or intermittent problems. These are the toughest kinds of problems to solve. Faster waveform and decode update rates improve the scope’s probability of capturing illusive events and serial bus communication errors.

All oscilloscopes have an inherent characteristic called “dead-time” or “blind time”. This is the time between each repetitive acquisition of the scope when it is processing the previously acquired waveform. Unfortunately, oscilloscope dead-times can sometimes be orders of magnitude longer than acquisition times. During the oscilloscope’s dead-time, any signal activity that may be occurring will be missed as shown in the figure below.


Because of oscilloscope dead-time, capturing random and infrequent events with a scope becomes a gamble — much like rolling dice. The more times you roll the dice, the higher the probability of obtaining a specific combination of numbers. Likewise, the more often a scope updates waveforms for a given amount of observation time, the higher the probability of capturing and viewing an elusive event — one that you may not even know exists.

The following equation can be used to calculate a scope's dead time percentage:

% DT = Scope’s dead-time percentage = 100 x [(1/U) – W]/(1/U) = 100 x (1 – UW)
where
U = Scope’s spec'd update rate
and
W = Display acquisition window =
Timebase setting x 10

What most users do not realize is a scope's dead time is much much larger than its acquisition time. For instance Agilent's 3000 X-Series family of scopes has an update rate of 1,000,000 time per second at 10 ns/div timebase setting, which is best in its class. Even with such a high update the 3000 X-Series has a dead time percentage:

%DT = 100 x (1 - (1e6 * 1e-7)) = 90%

Lets look at an example where we are analyzing a signal that has a glitch in it that occurs 5 times per second. Using a scope that has an update rate 1e6 per second and a timebase setting of 10ns/div what is the probability that it will capture the glitch in 5 seconds. 

Pt = 100 x (1-[1-RW]^(U x t))
where
Pt = Probability of capturing
anomaly in “t” seconds
t = Observation time
U = Scope’s measured waveform
update rate
R = Anomalous event occurrence
rate
W = Display acquisition window =
Timebase setting x 10

P(5s) = 100 x (1 – [1 – (5/s x 100 ns)]^(1,000,000/s x 5s)) = 91.8%


From the above calculation we can see that there is a 92% chance that the scope would capture the glitch in 5 seconds. The below figure is from the 3000 X-Series measuring a signal with a glitch that occurs 5 times a second. The glitch was captured in 2 seconds. 


If we were using a scope that had an update rate of 3,000 updates per second or less (which is common in low to mid range priced scopes) the probability of seeing the 5 times per second glitch in 5 seconds would be less than 1%. 

In this post we looked at a scope's update rate and its importance to debugging and finding that rare glitch. If you have anything to add to this blog post use the comments section below. 




4/2/12
Mask Testing Feature in Oscilloscopes

In this post we will look at the Mask testing feature found in today's oscilloscopes. Mask testing is a valuable feature that adds pass/fail testing to a scope’s traditional functions. Mask testing lets you capture a ”golden” waveform and define tolerance limits to create a test envelope. Incoming signals are compared to the allowable tolerance range and flagged as pass or fail. You can then select the action the oscilloscope performs if it detects a violation of the mask. Examples of some of these actions include stopping the test after one failure, saving screen images of waveform failures, and making measurements on failure waveforms.

As an example, on an Agilent 3000-X series scope I captured my golden waveform, navigated to the Mask test menu, and selected Automask. The Mask shown below in the figure was setup around my golden waveform. 


In the above figure the failure area for the Mask test is the gray around the waveform. The black area represent the pass area. By adjusting the Y and X parameters (bottom of figure) you can easily tune the size of the pass and fail area of the mask. You can also directly edit the Mask test file for more detailed editing of the Mask pass and failure areas. The below figure shows the example Mask test after being run a number of times.


Notice in the above figure the Mask test statistics. You can see the Mask test was run over 1.7 million times and in that time span 14 failures occurred. You can see in red where the failures occurred. 

The easiest way to perform a Mask test is to capture your golden waveform and use the Automask feature and then adjust the mask as needed. You can also create a custom mask file if you would like. This is done using X and Y parameters and regions. Regions are the separated failure areas in the Mask test. For instance, the above example there are two regions, the top one above the waveform and the bottom one below the waveform. There is typically a limit to the number of Mask regions you can create. For example on Agilent's 3000-X series up to 8 regions can be created for a Mask test. The below figure shows an 8 region Mask test setup.


In this post we looked at the Mask testing feature found on modern scopes. We looked at some Mask test examples using an Agilent 3000-X Series scope. As always if you have any questions feel free to email me and if you have any comments please leave them in the comments section below. 




2/6/12
Power Supply Analysis App for Scopes

The following video demonstrates a power supply analysis application that enables automatic, consistent and fast characterization of Switch Mode Power Supply (SMPS) using InfiniiVision 3000 X-Series, 6000 or 7000 Series oscilloscopes.




1/3/12
Passive or Active Scope Probe?

In this post we will look at what type of scope probe to use, passive or active, and discuss the trade offs of each. For general-purpose mid-to-low-frequency (less than 600-MHz) measurements, passive high-impedance resistor divider probes are good choices. These rugged and inexpensive tools offer wide dynamic range (greater than 300 V) and high input resistance to match a scope’s input impedance. These are the probes that often come with the scope when you purchase it. However, they begin to impose heavier capacitive loading as the frequency of the signal being measured goes up. The input capacitance of the probe and scope combine to create an impedance to between the signal being measured and ground. As the frequency of the signal goes up the impedance created by the capacitance drops. If the impedance drops to low it can effect your signal being measured, this is known as capacitive loading. For instance a capacitance of 10 pF presents only 100 Ohms of impedance to a 150 MHz signal so it is important to know the input capacitance of the passive probe and the scope you are using. Low-impedance (z0) passive probes (talk more about in last section) and active probes (talk more about next) offer higher bandwidths than high-impedance passive probes. All in all, high-impedance passive probes are a great choice for general purpose debugging and troubleshooting on most analog or digital circuits.

For high-frequency applications (greater than 600 MHz) that demand precision across a broad frequency range, active probes are the way to go. They cost more than passive probe and their input voltage is limited, but because of their significantly lower capacitive loading, they give you more accurate insight into fast signals.

In the two figures below we see screen shots from a 1-GHz scope measuring a signal that has a 1-ns rise time. In the first figure an Agilent 1165A 600-MHz passive probe was used to measure this signal. In the second figure an Agilent 1156A 1.5-GHz single ended active probe was used to measure the same signal. The blue trace shows the signal before it was probed and is the same in both cases. The yellow trace shows the signal after it was probed, which is the same as the input to the probe (showing the loading effects of the probe). The green trace shows the measured signal, or the output of the probe.
Passive probe: blue -- signal before probed, yellow -- signal after probed, green -- output of probe
Active probe: blue -- signal before probed, yellow -- signal after probed, green -- output of probe 
A passive probe loads the signal down with its input inductance and capacitance (yellow trace). You probably expect that your oscilloscope probe will not affect your signals in your device under test (DUT). However, in this case the passive probe does have an effect on the DUT. The probed signal’s rise time becomes 1.9 ns instead of the expected 1 ns, partly due to the probe’s input impedance, but also due to its limited 600-MHz bandwidth in measuring a 350-MHz signal (0.35/1 ns = 350 MHz). The inductive and capacitive effects of the passive probe also cause overshoot and ripping effects in the probe output (green trace). The 1.85-ns rise time of the measured signal with the passive probe is actually faster than the probe’s input, due to these capacitive and inductive effects. Some designers are not concerned about this amount of measurement error. For others, this amount of measurement error is unacceptable.

We can see that the signal is virtually unaffected when we attach an active probe such as Agilent’s 1156A 1.5-GHz active probe to the DUT. The signal’s characteristics after being probed (yellow trace) are nearly identical to its un-probed characteristics (blue trace). In addition, the rise time of the signal is unaffected by the probe being maintained at 1 ns. Also, the active probe’s output (green trace) matches the probed signal (yellow trace) and measures the expected 1-ns rise time. Using the 1156A active probe's 1.5 GHz bandwidth (or 1-GHz system bandwidth when the probe is used with 1-GHz oscilloscope) makes this possible. Below is a table comparing high Z passive probes to active probes.


The above table I got from an older publication so the one mistake on the active probe side of the table is bandwidth "up to 13GHz." Agilent currently offers active probes up to 30 GHz. Also one other thing to note is there are low impedance passive probes known as "Resistive divider passive probe" that can have bandwidths up to 6 GHz. They are typically much lower cost than active probes. They must be used with a 50 Ohm input scope, have a lower amplitude capabilities than other passive probes, and do not work well with high impedance signals.

If you have any insights or useful comments to add please use the "Comments" section below.




10/10/11
Determining How Much Oscilloscope Bandwidth is Needed to Accurately Capture a Signal

If you input a 100 MHz sine wave with a 1 Vpp amplitude into an oscilloscope with a max frequency of 100 MHz what will you see on the display? You will still see a 100 MHz sine wave, but it will no longer by 1 Vpp. Instead the measured amplitude will be about 700 mVpp. That is because the max frequency rating of a scope is its 3 dB roll off point, just like how a low pass filter is rated. That means any frequency components at the scope's max frequency will be attenuated 3 dB or 30%. For non-sine wave signals used at the a scope's upper frequency limits the result is even worse because entire frequency components can be eliminated. The figures below show a 100 MHz scope and a 500 MHz scope both measuring the same 100 MHz digital clock signal.
100 MHz Scope Measuring 100 MHz Digital Clock
500 MHz Scope Measuring 100 MHz Digital Clock
In the 100 MHz scope screen shot you can see that all frequency components that make up the digital square wave have been attenuated except for the center frequency. In the bottom 500 MHz scope screen shot we get a much better picture of what the clock signal really looks like. The following are good rules of thumb when determining how much scope bandwidth you need to accurately capture a signal:

  • For analog signals choose a scope bandwidth that is at least 3 times larger then the center frequency of the signal.
  • For square or pulse type waveforms choose a scope bandwidth that is at least 5 times larger then the center frequency of the signal. This will ensure you capture up to the 5th harmonic of the signal.
The two most common types of responses that scope's have at their max frequency are Gaussian response and Maximally-Flat response, which are both shown below.
Scopes with frequency ranges 1 GHz or below typically have the Gaussian response and high bandwidth scopes typically have the Maximally-Flat response. With knowledge of the response of your scope there is a much more accurate calculation you can perform to determine the scope bandwidth needed to measure a digital signal. The first step is to determine the maximum practical frequency component within the signal under test. We refer to this frequency component as fknee. Dr. Howard W. Johnson has written a book on this topic titled, “High-speed Digital Design – A Handbook of Black Magic ”. All fast rising edges have an infinite spectrum of frequency components. However, there is an inflection (or “knee”) in the frequency spectrum of fast edges where frequency components higher than fknee are insignificant in determining the shape of the signal. For digital signals with rise time characteristics based on 10% to 90% thresholds, fknee is equal to 0.5 divided by the rise time of the signal: 
fKnee = 0.5/RT (10% - 90%)

The next step is to determine the required bandwidth of the oscilloscope to measure this signal. The table below shows multiplying factors for various degrees of accuracy for scopes with a Gaussian or a Maximally-Flat frequency response.

This calculation has nothing to do with the frequency or clock rate of your signal, just the rise time. Let's walk through an example with a Gaussian Response scope measuring a signal with a 1 ns rise time and we want 3% accuracy or better. Using the "fknee" calculation above, the highest frequency component (fknee) would be 500 MHz. From the table above, to achieve 3% accuracy or better we need a scope with a max range of at least 950 MHz. For the example we just did the clock rate of the digital signal could have been 100 MHz or 500 MHz, it doesn't matter the rise time is what determined the bandwidth needed.

One last note, don't forget to check/consider the bandwidth of the cabling or probe you are using along with the connection method to the signal!




5/25/11

Modernization Makes Waveform Capture and Playback Easy

A good way to test your design under worst-case conditions is to capture a known good waveform on a scope, download it into an arbitrary waveform generator (arb) and then modify various signal parameters to emulate worst-case input conditions. In the past this required a scope and an arb remotely connected to a PC that was running custom software or some instrument specific software package. That has all changed with the features found in modern arbs and scopes. Now all you need is an arb, a scope, and a usb memory device. In this blog post we will run through an example of capturing and storing 10 bytes of a known good RS232/UART transmit serial bus signal using an Agilent 3000 X-Series scope. We will then transfer the stored waveform data into an Agilent 33522A function/arbitrary waveform generator for replay without touching a PC. We will then look at some example features found on modern arb’s to modify our serial bus signal to test a design under worst-case input conditions.

I am using a serial bus signal for example purposes only. You can apply the techniques here to easily and quickly test for worst-case conditions using virtually any kind of analog or digital signals.

Capturing a “Golden” Waveform on the Oscilloscope
The scope’s timebase is set to 1.000 ms/div to capture 10 bytes of 19.2 kbps RS232/UART serial bus traffic, as shown in the figure below.

After “windowing” on the portion of the waveform we want to capture, we save it as an “ASCII XY data (.csv)” to our USB memory device. The captured waveform was decimated down to 10K points. The saved waveform data can now be imported into various software packages including Microsoft® Excel spreadsheets, MATLAB, and numerous other waveform processing/editing applications. But most importantly, we can import this waveform data directly to our modern arb, which in this example is a 33522A. 

Downloading the “Golden” Waveform into the Arb
To import the saved waveform into the arb, we just need to move our USB memory device from the scope’s front panel USB port to the arb’s front panel USB port. From there a simple push button sequence on the arb’s front panel imports the CSV data and recreates the waveform in memory. The stored waveform consisted of 10,000 points that covered a time-span of 10 ms; this provided an effective/decimated oscilloscope sample rate of 1 MSa/s. The arb will take the time data from the CSV file and automatically set the sample rate of the arb to match it (in this example 1 MSa/s).

Modifying the Baud Rate and Amplitude and Adding Noise
Now that we’ve reproduced the original “golden” waveform, we can easily modify it in order to test for worst-case input conditions. Let’s assume that you know that your receiver responds correctly to the signal conditions of the “golden” waveform running at 19.2 kbps and with normal signal amplitudes and minimum noise. But what if you wanted to test your system running at a much faster baud rate (1.3824 Mbps) and perhaps with additional noise?

Let’s first change the baud rate of this RS232/UART signal to 1.3824 Mbps. Remember that the original baud rate was 19.2 kbps.  Since 1.3824 Mbps is 72 times faster than 19.2 kbps, we should change the arb’s sample rate to 72.0 MSa/s (1 MSa/s x 72). We can add random noise to the signal using the arb’s modulation features. Additive noise can be created using the Sum modulation feature, while noise in the form of jitter can be created using the PM modulation feature. To perform more advanced waveform editing of the signal some modern arb’s like the 33522A have built-in Waveform Editor. These waveform editors typically can be used to modify individual points on the arb or modify the arb using built-in and custom math functions.

The figure below shows an example of the modified test signal now running at 1.3824 Mbps with additive random noise. As you can see, the scope is showing multiple decoding errors under these modified worst-case input signal conditions.


Summary
In the past capturing a design’s waveform with a scope, modifying it for testing purposes, and finally playing it on an arb was a tedius time consuming activity. The combination of a modern scope and arb like Agilent’s 3000 X-Series oscilloscopes and Agilent’s 33500 Series function/arbitrary waveform generators provides a quick and easy way to capture, recreate, and modify digital and analog signals for thoroughly testing a design with worst case signal conditions. To obtain additional information about these instruments go to:


2/15/11

Scope's Segmented Memory Feature Makes Skipping Points a Good Thing

On 2/15/2011 Agilent released its new scope family, the InfiniiVision 3000 and 2000 X-Series. After reading the title of this post the first question that probably popped in your head is: "what about this new scope family is so redefining?" The three main headlines for this new family of scopes that really makes it redefining are it gives you a lot of scope at a great price, it has the capability of 4 instruments in 1, and its upgradability. A lot of scope at a low price means the InfiniiVision X-Series delivers:
  • Largest display in class with a 8.5-inch WVGA display
  • Fastest waveform update rate in class at 1 million waveforms per second
  • Deepest memory in class 4 Mpts with MegaZoom IV technology
  • Offers 33 automated measurements, nine parametric triggers, six serial protocol triggers, as well as seven waveform math functions including FFT
The 4 instruments in 1 includes:
  1. Best in class scope
  2. Logic timing analyzer
  3. Protocol analyzer (optional)
  4. WaveGen built-in function generator (optional)
You heard me right this family of scopes offers an optional function generator. This is an industry exclusive feature! It is a 20 MHz function generator that can do sine, square, ramp, pulse, DC, and noise waveforms. The optional function generator capability is ideal for educational or design labs where bench space and budget are at a premium.
Finally easy upgradability to protect your investment. Project needs change, but traditional oscilloscopes are fixed - you get what you pay for at the time of purchase. With the InfiniiVision X-Series if you need more bandwidth (up to 500 MHz), digital channels, WaveGen, or measurement applications in the future, you can easily add them all after the fact. 
To get more info on Agilent's new InfiniiVision 3000 and 2000 X-Series Oscilloscopes check out the links below:




2/8/11

Scope's Segmented Memory Feature Makes Skipping Points a Good Thing

If you work with signals that have relatively long idle times between low-duty-cycle pulses or bursts of signal activity, then you'll love the segmented memory feature available in today's scopes. Segmented memory allows you to capture more selective signal details with less memory. With segmented memory, the scope’s acquisition memory is divided into multiple smaller memory segments. This enables your scope to capture a whole bunch of successive single-shot waveforms with a very fast re-arm time — without missing any important signal information.  In simpler terms it is a way for you to optimize your scope memory usage by only capturing the signal segments you are interested in. The second advantage segmented memory provides is a user interface that allows you to easily view the signal segments to check overall signal quality or to quickly find that needle in a hay stack bug that you know is out there. After a segmented memory acquisition is performed, you can easily view all captured waveforms overlaid in an infinite-persistence display and quickly scroll through each individual waveform segment. Common applications for this type of oscilloscope acquisition include high-energy physics measurements, laser pulse measurements, radar burst measurements, and packetized serial bus measurements. Below is an example of using segmented memory in a high-energy physics application.

High-energy physics and laser pulse applications 
Segmented memory acquisition in an oscilloscope is commonly used for capturing electrical pulses generated by high-energy physics (HEP) experiments, such as capturing and analyzing laser pulses. With segmented memory acquisition, the scope is able to capture every consecutive laser pulse, even if the pulses are widely separated. the figure below shows the capture of 300 successive laser pulses with a pulse separation time of approximately 12 ┬Ás and an approximate pulse width of 3.3 ns. All 300 captured pulses are displayed in the infinite-persistence gray color, while the current selected segment is shown in the channel’s assigned color (yellow for channel 1).

Note that the 300th captured pulse occurred exactly 3.62352380 ms after the first captured pulse, as indicated by the segment time-tag shown in the lower left-hand region of the scope’s display. With the scope sampling at 4 GSa/s, capturing this amount of time would require more than 14 Megapoints of conventional acquisition memory. If these laser pulses were separated by 12 ms, the amount of conventional acquisition memory to capture nearly 4 seconds of continuous acquisition time would be more than 14 Gigapoints. Unfortunately, there are no oscilloscopes on the market today that have this much acquisition memory. But since segmented memory only captures a small and selective segment of time around each pulse while shutting down the scope’s digitizers during signal idle time, scopes can easily capture this much information using just 8 Megapoints of memory

Agilent’s InfiniiVision Series oscilloscopes are the only scopes in the industry that not only provide segmented memory acquisitions simultaneously on all analog channels (up to four analog channels) and logic channels (up to 16 digital channels) of acquisition, but they also are the only scopes that provide hardware based serial decoding on packetized serial data for each captured waveform segment. The InfiniiVision Series includes the scope I have on my bench, the MSO7054A (although now they are on the B model so looks like I need to upgrade).






9/30/10
Two Big Product Announcements in GPETE


Two big GPETE related product releases this week that I need to cover. First, the #3 volume scope provider LeCroy takes the scope bandwidth lead with the Wavemaster 8Zi-A which offers 45 GHz of bandwidth on one channel, 30 GHz on two channels, and 20 GHz on four channels. Back on June 14th in my post entitled "The World's Fastest Real-Time Scope!" I talked about how Agilent's Infiniium 90000 X-Series oscilloscope family took the bandwidth lead on scopes at 32 GHz of true analog bandwidth over Tek. It looks like Agilent only held that lead for 4 months with LeCroy's announcement today. LeCroy achieves the 45 GHz bandwidth by interleaving three sampling channels together into a single 120 GSample/s channel. Follow the link for more info: Wavemaster 8Zi-A Oscilloscopes

The second product release announcement is Tektronix has just released a family of counters (they refer to them as Timer/Counter/Analyzers). These counters have impressive specs including 12 digits of resolution, 50 ps (FCA3100 Series) or 100 ps (FCA3000 Series) Single-shot Time Resolution, and up to 250 KReadings/s of time stamped measurement data to memory. They can do gapless sampling up to 250 KReadkings/s giving them some modulation domain analysis (MDA) capability. The large display on these counters provide the capability to do histograms and trend charts. I am 99% sure that these new Tektronix counters are OEM'd from Pendulum's CNT-91 and CNT-91R counter family simply because the specs, front panel features, and form factor are pretty much the same. Follow the link for more information on the new Tek counters: FCA3100 and FCA3000 Series



8/24/10
The Battle of the Ultra High Bandwidth Oscilloscopes Continues


Back on 4/27/10 Agilent came out with the Infiniium 90000-X series oscilloscopes, which featured the highest real-time bandwidth at a ridiculous 32 GHz (see my post on it click here). That beat the previous leader, Tektronix by over 10 GHz. Scopes is a highly competitive market with Tektronix currently leading the market, Agilent in second, and Lecroy a distant third. With Tektronix as the market leader it was only a matter of time before they responded to their performance leadership being taken and they did (well kind of). Tektronix announced that by using silicon germanium (SiGe) technology found in IBM's 8HP chips in the high speed input circuits of their scopes they can achieve real time bandwidths of over 30 GHz. Tektronix stated "The 130nm SiGe BiCMOS technology offers x2 performance over the previous generation and targets delivery of oscilloscopes with real-time bandwidth beyond 30GHz.” For their 32 GHz scopes, Agilent uses the non-silicon technology of indium phosphide (InP) in their high speed input ICs. 
In Tektronix's press release they just said they have the technology but gave no mention of when this new technology would be seen in a new scope. It seems to me that they are just trying to tell their current high bandwidth scope customers that its coming so don't run out and switch to Agilent quite yet give us a chance to catch up. If they did have a design that was right around the corner my guess is they would have never made this announcement so I wouldn't expect to see a Tektronix scope break 30 GHz for at least another year probably more. The question is how high will Tektronix go in real-time bandwidth with this new chip technology? My guess is 40 GHz because you have to make a large leap frog over the competition to hold the top performance spot long enough to make the investment worth it (and trust me at bandwidths this high the investment is huge). What is your guess?

For more information on Tektronix's press release click here

For more information on Agilent's Infiniium 90000-X series click here  



7/7/10
Rohde & Schwartz Jump into the Scope Market

At the end of June Rohde & Schwartz announced they are entering the oscilloscope market by introducing two new families of scopes: RTO family and RTM family. The RTO family is for high speed applications and provides bandwidths of 1 and 2 GHz. The RTM is more for the general electronics market providing bandwidths up to 500 MHz.
In case you don't know R&S is a German based company who makes mainly RF/Microwave test and measurement equipment. They are a big player in the wireless and aerospace defense test market.
The scope business is a highly competitive market with Tek out in front, Agilent in second, and LeCroy a distant third. Good luck!

For the official press release click here


6/14/10
The World's Fastest Real-Time Scope!

Although this maybe a bit out of the gpete realm I felt I had to mention that about a month ago Agilent released the Infiniium 90000 X-Series oscilloscope family, which is the fastest most accurate scope family ever. The X-series offers up to 32 GHz of true analog bandwidth in a scope!! This is truly a milestone in test and measurement engineering. I can remember back in '99 digital scopes were just starting to take over and 500 MHz of bandwidth was considered high! Technology is sure moving fast. I have not yet had a chance to play with one of these amazing instruments yet, but I did get a chance to speak to some of the people from the R&D team that worked on them. The engineering that went into the timing, digitizing, and signal conditioning is pretty amazing. Not only that the engineering that went into the probes (up to 30 GHz probing)is amazing. Seeing scopes with this much bandwidth and accuracy makes me think that eventually we may see the spectrum analyzer, signal analyzer, and scope merge into a single instrument (FFTs are a common feature on most scopes today). It is still years off but I can see it coming.

You can check out the world's fastest scope family by clicking on the link below.

Infiniium 90000 X-Series oscilloscope family