An oscilloscope is a fundamental tool for most electrical engineering tasks.
Many of you reading might already know about oscilloscopes. For those who do not, here is a quick overview of why oscilloscopes are needed (as compared to other test equipment) and when/why to use them.
There many different kinds of measurement test equipment used in a modern electronic R&D setting. Of all the varieties, some of the most common are oscilloscopes, spectrum analyzers, and network analyzers.
- Oscilloscopes measure voltage versus time
Four channel, general purpose digital oscilloscope
- Spectrum Analyzers measure amplitude versus frequency
Spectrum analyzer with tracking generator
- Vector Network Analyzers measure the amplitude and phase of an incoming signal. VNAs also typically perform calculations to measure the quality, power, and spectral flatness of the signal source. They are commonly used to measure the amplitude, phase, reflection and many other characteristics of devices like antennas, filters, amplifiers, and other radio-frequency devices.
The most common type of network analyzer: a vector network analyzer (VNA)
Now that you can begin to appreciate the different types of useful test equipment found in labs, I would like to introduce my very first purchase:
Keysight MSOX2024A; an entry level, 4 channel, 200 MHz mixed domain oscilloscope!
This is one of Keysight’s (formerly Agilent technologies) entry level digital oscilloscopes. It features 200 MHz of analog bandwidth, up to 2 GS/s acquisition rate (1 GS/s when 2-4 channels are enabled), an 8-bit digital input, and a 20 MHz built-in function generator.
What does all of that mean? Well, the analog bandwidth (usually in the MHz to GHz range) denotes highest frequency input signal which the hardware can process. Most bench-top scopes range from 50 MHz up to around 500 MHz. Scopes in the GHz range are less common as they are much more expensive ($$,$$$ to $$$,$$$ and even $,$$$,$$$).
The sample rate denotes the highest speed at which the digital hardware can capture individual points along the analog signal being measured. Again, most bench scopes range from 500 MS/s (mega samples per second) to around 2.5-3 GS/s on higher end models (with analog bandwidths still in the MHz range). Of course, those GHz speed scopes can do tens if not hundreds of GS/s depending on the model.
This oscilloscope is mixed signal capable (hence the name MSOX [Mixed Signal Oscilloscope] ). That means it can measure both analog and digital signals at the same time, and display the measurements side-by-side in the same time domain. This particular scope can measure up to 8-bits, or 8 individual digital channels. Here is an example of a mixed signal measurement from an Agilent product image:
You can see that there are 8 digital channels being captured below a yellow waveform, (which corresponds to analog channel 1 on this particular scope).
The last major feature of this scope is the built in function generator. A stand alone function generator with this kind of capability would cost $400-500. The scope I scored came with lots of software upgrades installed as well (increased memory depth, segmented memory, function generator).
Needless to say, this is an exciting milestone and I can only imagine what new lessons can be learned with such a capable instrument.