Good news everyone! Keysight Technologies has sent me an oscilloscope to review! I'm
going to be reviewing the high end 3104T 1GHz mixed signal oscilloscope. And just so you
know, they are letting me keep a lower end version of this scope in exchange for the
time I spent making this review. There is a lot to cover so let's get started.
The 3104T is part of Keysight's 3000T series of oscilloscopes. These are a replacement
for Keysight's 3000A scopes , so don't bother with those. Get a 3000T series instead because
they have touch screens and other cool new features.
Now the first question you might have is "who are Keysight Technologies"? Well, basically
Keysight is Agilent. You already know Agilent, I've been buying their stuff for years and
you've seen them in my videos before. I got the inside story on the name change and here
it is. Basically Agilent used to make equipment for both electronics and life sciences, and
now they've decided to split the company so Keysight focuses on electronic test equipment
only, allowing them to invest more of their profits into developing better products.
Okay, on with the review. Let's start with the biggest feature of this
scope - the touch screen!
Once of the nicest things the touch screen gives you is an on screen keyboard. With every
scope I've ever owned I had to either awkwardly input text with a single knob, or keep notes
with a pen and paper. This is really annoying when you are trying to capture multiple images
and explain things to other engineers. Now you can just type things out.
You can also add annotations to each waveform which is great for documentation and teaching
purposes... and you can have up to 4 annotations on screen at once.
You can drag waveforms around... and you can use the screen to add and remove
up to 8 automatic measurements. You can basically control everything with the touch screen.
So I really like it. And it doesn't seem to collect fingerprints. We are living in a world
where everyone has come to expect a touch screen interface as a standard thing and I'm
hoping that more companies start doing this. If for some reason you don't like it you can
just disable it. The scope also comes with a screen protector in case you are carrying
it around.
Other than the touch screen, it's worth mentioning that the screen resolution is 800x480 and
it's really nice to look at. It's a bit brighter than my 2000 series and the colors seem more
vivid and contrasty. It kind of looks like something you would see on a tablet rather
than an oscilloscope and my camera can't really do it justice.
The build quality of the scope is, in a word, flawless. All the buttons and dials feel nice,
and you can do the classic push to center trick on each channel. There is a fan, but
it's not really loud, it's about the same as any other piece of test equipment in my
lab. Now I want to talk about triggers. The other
thing you can do with the touch screen is a thing called zone triggering. And let me
give you an example. I have a demo set up here with a digital signal that has a rare
glitch. The fading on the intensity graded display tells us this glitch doesn't happen
very often, but it is there. Standard triggering methods and single shot mode are just not
going to reliably capture it. But what we can do now is set up a trigger for whenever
there is a signal in this area on the screen. Now we are only viewing the glitchy signal.
Similarly I can create a zone where the signal must NOT intersect, and now I can view the
waveform only when the glitch never happens. There are a lot of other special triggers
you can use too, such as a pattern trigger that allows you to trigger on specific data.
You can trigger on different rise times, which is useful for digital designers. If your edges
are too slow, you might violate a timing requirement. If your edges are too fast, you might violate
an EMC requirement. Other options include triggering on runt pulses and serial decoding
and triggering for a lot of different protocols. Note that the serial decoding and triggering
is not a standard option, you have to pay extra for it. Here's an example I have set
up where I am triggering on the # character in an RS232 stream of data. It's crazy watching
this happen in real time and it really changes the way you think about debugging. I'll talk
more about the serial decoding later in the review.
It's worth mentioning that the scope comes with 500MHz passive probes. You get these
for everything in the 3000T series. So if you buy a 100MHz model, you are getting 500Mhz
probes. But, if you buy the 1GHz model and want to take advantage of all that bandwidth
you are going to have to buy higher bandwidth probes separately.
The 3000T series has extra connectors next to the BNC jacks. These are for Keysight's
AutoProbe interface which allows you to use active single ended and active differential
probes. Active probes have little amplifiers close to the probe's tip, which results in
less capacitive loading when you are performing measurements. Active probes are ideally what
you want to use when working with high frequency electronics, because even a few picofarads
of loading or long test leads can throw off your measurements, affect rise and fall times,
and even add instability to oscillators and PLLs.
The other thing you get with the 3000T series is the ability to do 50 ohm termination. This
is an oscilloscope feature that you don't see talked about very often and I think it's
very underrated. Pretty much all low end oscilloscopes only let you terminate into 1 megaohm. 50
ohm termination is useful when you want to make high frequency measurements or do RF
work. If you set things up correctly, you can match the impedances, minimize reflections
and get more accurate readings. The next feature I want to talk about is the
waveform update rate. Keysight are very proud of the fact that you can get over 1 million
waveforms per second regardless of how many features you have enabled. The result is a
display that looks very much like an old school analog oscilloscope, with all of the benefits
of digital storage and measurement. Check out this amplitude modulated waveform. Even
my 2000 series with its 50,000 waveforms per second sometimes struggles with this test.
Now from a marketing perspective 1 million waveforms per second sounds amazing, but from
an engineering perspective I think it's better to think of it like this. You only have to
wait a microsecond before you can retrigger. Entry level scopes might only capture a few
hundred or even a few dozen waveforms per second, meaning you'd have to wait many milliseconds
before you can recapture anything. And a lot can happen in a few milliseconds. It is a
huge pain waiting around for rare events that may or may not be randomly captured, so the
more waveforms you can capture per second the better. Here's an example using one of
the built in demo signals. We've got a clock signal that occasionally glitches. It's so
rare that you're not going to be able to see it with your eyes. If we enable persistence
mode we can very quickly see the glitches. The faster the scope's update rate, the quicker
you can capture the problem and in theory you could end up waiting for hours. Now if
I set up a zone trigger we can observe the glitch, and only the glitch.
Next let's talk about capture memory. You can record up to 4 megapoints, which isn't
much. You can get 12 megapoints on low end scopes nowadays. But by default, the 3000T
series comes with a feature called segmented memory. This is a Keysight exclusive and let
me explain how this works. I have a demo set up here where I am sending a short burst of
serial data every 100 milliseconds. This is a pretty common situation if you've ever worked
with sensors. Normally if you want to view the data you'd have to capture it, zoom in,
then spend a lot of time navigating the dead space between each reading. You end up wasting
capture memory. Segmented memory allows you to capture analog and/or digital data in useful
segments. Here I am going to capture 10 consecutive trigger events at a time scale that's actually
useful to me, and I can quickly browse through them with the touch screen. Check this out
- even though you only have 4 megapoints of memory you can capture up to 1000 segments.
Just be aware that you might lose some detail if you capture that many.
Now let's talk about the FFT function. This allows you to view the frequency content of
a signal. Here I've got a 433MHz signal coming out of my tracking generator. The update rate
is extremely fast - in some situations it's faster than a spectrum analyzer. But this
is absolutely not a substitute for a real spectrum analyzer if you want to do serious
RF work. On a real spectrum analyzer you'd clearly see more detail on the distortion.
The dynamic range of an 8 bit oscilloscope ADC just isn't wide enough. So the FFT is
useful for measuring the fundamental frequency of a waveform and maybe a couple of the larger
components and that's about it. So here's a practical example where I am characterizing
the frequency content of some noise on a power supply. You could then design suitable filters
to deal with it. And here's an example of the gated FFT. I
have a signal switching between 1MHz and 25MHz. Let's do a waveform capture, and if I use
the zoom button I can choose the time window for the FFT.
Now I'd like to show you one of the built in demos from the scope to show you what is
theoretically possible with the time correlated gated FFT. The idea is that if you buy the
extra serial decode options, you can use one of the fancy I2C triggers to observe the exact
moment the frequency changes in an FSK signal. Overall I think the time correlated frequency
analysis is a nice feature to have, and I don't know of any other scope in this price
range that can do it. Just keep your expectations realistic. Serious RF engineers are not going
to find this to be a substitute for a more expensive spectrum analyzer or MDO.
Finally I want to open up the math menu. There's more options here than you will ever know
what to do with. Here's an example of a low pass filtered square wave where I am changing
the cutoff frequency to whatever I want. Being able to do this on the fly was pretty mindblowing.
Most of the things I've talked about so far are what you get with just the oscilloscope
and now is a good time to talk about pricing. The lowest end version of the scope costs
$3,350, but I think the type of person who would use this scope would be better off getting
at least getting the 4 channel 200MHz mixed signal version for just under $6000. The scope
I reviewed in this video is the top of the line 1GHz bandwidth model and that goes for
$15,400, and that's without the extra options. Clearly this is not an oscilloscope for hobbyists.
This is a scope for engineering and military professionals, and maybe graduate students.
It's worth noting if you buy a 3000T you can buy software or hardware bandwidth upgrades
later. For example if you buy the 100MHz model you can get a license to upgrade it to 200MHz,
but if you want to upgrade beyond that you are going to have to send it to Keysight for
the upgrade. Now let's talk about all the extra addons
you can get for this scope, and there are a lot of options! I'm going to talk about
some of the most popular individual options you can get, and then I'm going to talk about
the all-in-one bundle. The biggest upgrade you can get is the 16
channel logic analyzer, which turns your oscilloscope into a mixed signal oscilloscope. The price
difference here is $1500. You can use it to analyze 2 different serial buses simultaneously
in hardware, in real time. And you can decode just about every protocol out there - I2C,
SPI, RS232, Flexray and more. The only thing you can't decode with this scope is USB. You
have to get a Keysight 4000 series for that. The serial triggering and segmented memory
work together amazingly well, allowing you to replay what happened in your circuit at
different times. And you can use the scope's search options to search the recorded data
for specific events like alert conditions, specific characters, or even just low level
transmission errors. The only thing you can't search for is entire strings of decoded data.
I just showed you RS232, but you can trigger and search on all kinds of different events
depending on the serial protocol you are using. You can do all of this stuff with zero performance
penalty to the scope's 1 million waveforms per second. It's a really powerful tool for
anyone designing or debugging mixed signal designs.
But... there's a catch. If you buy the mixed signal functionality, you can only trigger
and view data in hex or binary. You don't get to actually decode protocols like I just
showed you. If you want to do that, you'll have to spend about $1,100 for each individual
protocol you want to decode. I personally think this is really expensive, and if you
ever plan on decoding more than one protocol you should just get the all-in-one bundle
that I will talk about later. The next thing you can get is the LAN and
VGA module. You can use it to email your annotated screenshots to the rest of your engineering
team. I have that set up with the quick action button here. This is a really big time saver
and it helps keep you more organized. You can also send images to a networked printer
and control the oscilloscope remotely via your web browser. It uses VNC so you don't
need any extra software. It even works on tablets! At 400 bucks I think this is a great
upgrade to get for anyone working in an office environment. The scope connected to my network
via DHCP and it was one of the easiest things I have ever set up.
For $750 you can get the waveform generator option. This uses the extra BNC output on
the front of the scope. I am going to connect it to channel 1 and show you what it can do.
It can generate a variety of test waveforms. The maximum frequency depends on the waveform.
You can go up to 20MHz for sine waves, 1MHz for things like sinc waves, and 200kHz for
cardiac pulses. (Hopefully you are not running into that problem in real life!). You can
modulate the waveforms with AM, FM and FSK. I found it generates very smooth waveforms
but there is a big limitation. The output is limited to 5 volts p-p for high impedance
loads, and 2.5 volts p-p for 50 ohm loads. This may or may not be enough for your needs.
You can also design your own arbitrary waveforms but I felt that even with the touch screen
the process was kind of awkward. If you do this a lot you'd be better off using their
waveform builder software. I used to use this with my benchtop generator, and it's the best
waveform editing software I've ever used. It is way more powerful and stable than any
software I have used from cheaper manufacturers, but unfortunately it costs as much as a cheap
AWG! Check out the free 30 day trial before buying. Given the price of the waveform generator
option you need to decide how much bench space you have and whether it's worth just buying
a separate AWG, or just go for the all-in-one bundle.
Another feature you can buy is the volt meter and frequency counter combo. The idea here
is that it uses separate circuitry from the scope's ADC to make measurements so it's going
to be more accurate. You'd use this for things like checking power rails and reference voltages.
The problem here is it's only 3 digits, so for a lot of people it's not going to replace
your bench meter. I think the 8 digit frequency counter and
totalizer is more interesting. Frequency counters are one of those instruments that I love to
hate because every engineer needs one, but you tend to use them for short periods of
time. So they tend to just sit around taking up space. Regardless of the bandwidth of the
scope, this frequency counter can count up to 1GHz. So you could use it for checking
the accuracy of clock signals, and maybe checking the carrier frequency of a key fob or RFID
application. At $150, if you don't already have a frequency counter, this option is a
no brainer. Another upgrade you can get is the educator's
kit for $521. This gives you a bunch of test signals that can be internally generated by
the scope, and then you can learn how to analyze them. Professional designers are obviously
not going to go for this, but I can see it being useful for universities and for training
technicians. There are a lot of students out there who graduate still addicted to the auto
scale button. I ended up using some of these signals while testing the scope because the
alternative was to spend hundreds of dollars on evaluation boards, or spend weeks designing
my own. Now I want to show you the power measurement
and analysis option. I used to design power electronics for a living so this really excites
me. If you buy suitable probes, you can measure real and reactive power, calculate the power
factor, and measure the phase angle all on the fly. If you are doing EMC testing, it
can measure the current harmonics for you. You can measure switching losses and see the
energy loss per switching cycle, which will help you make decisions about choosing your
switching frequency. There's also a mode where you can measure the on resistance and saturation
voltage of transistors in circuit, so you're not just relying on theoretical values from
a datasheet. Imagine being able to do this at different temperatures. Now check this
out. If you buffer the scope's internal waveform generator output, you can inject a signal
into your power supply, and create a bode plot of the power supply rejection ratio at
different frequencies. To be able to do this with one instrument is insane. There are other
power measurement options as well but those were my favorite time savers. This option
costs $1400 and if you design power electronics it's worth way more than that.
For $1,100 you can test eye diagrams in hardware. You can do this on cheaper oscilloscopes,
but the 3000T series lets you do it at over 200,000 wfm/s. Depending on your test requirements
this could be overkill or save you a lot of time.
Just so you know, there are even more options you can get for the scope but I don't want
this review to get too long. Check out the links in the video description section to
see all the possibilities. Now let's talk about the bundle. As you noticed,
I wasn't too happy about the pricing on some of these options. So I talked to Keysight
about this. It turns out that you can actually buy all the options in one upgrade! For $2,750
you get everything. The waveform generator, multimeter, frequency counter, all of the
serial decoding and triggering options, training signals, power measurement, everything. Unless
you specifically want only one option, I think this is what you should get.
So, how do I wrap this review up? It's a hell of an oscilloscope. The touch screen is addictive.
After 2 weeks of using it I found myself tapping my other equipment and forgetting that I can't
do that. Between the 1 million waveforms per second, zone triggering, 4 megapoints of segmented
memory, and advanced measurement functions there is clear product differentiation between
the 3000T series and the 2000X series. This wasn't really the case with the older 3000As.
I think a 3000T MSO with the all in one bundle would be a really great choice for any professional
digital or mixed signal designer, or anyone working with power electronics. If you want
to decode USB, check out the 4000 series which is going to be very similar, but even more
powerful. Keysight are also on Youtube. If you want to check out their products, and
watch a few tutorials subscribe to their channels. Thanks for watching!