So you have decided to go ahead and purchase your first piece of testing equipment and you have been met with a vast market of oscilloscopes. We informed you guys as best we could on the specifications to look out for in our guide on digital storage oscilloscopes. Like we said there are so many applications for a decent 4 channel scope, it can be invaluable when debugging electronic circuits.
The Mixed Signal Oscilloscope
An MSO provides all the functionality of the DSO but adds in a connector port to the front panel that allows you to connect a logic probe to your scope. The logic probe provides 16 separate digital channels as well as the full functionality of a digital storage oscilloscope and sounds too good to be true, but I promise you it isn't. It's just quite a bit more cash to fork out to be able to view your digital channels alongside your analog channels. What do we mean by alongside? Well on one screen you are able to view 16 digital channels and 4 analog channels on the same time domain. It's invaluable if that’s what you need to do. It can also get a little hectic, cramming all those signals onto the one 7 inch display.The DSOs functions were made relatively clear in that article, however, you don't get the ability to attach digital channels to your scope and look at them with time correlation to your Analog channels. If that was your requirement; The Mixed Signal Oscilloscope is the unit you'd find yourself looking at.
The Logic Analyser
Logic Analyzers are a great product that comes to mind for a similar purpose, they can also be picked up for as little as $189 (See the Saleae Logic 4). These enable you to view a number of digital channels via a USB connection to your PC. 4, 8 and 16 channel devices are available from Saleae that all do the same thing at different rates; simultaneously record digital channels as well as interface with analog channels. You can observe and zoom into your different signals, annotate and record all through a really clean-cut intuitive PC interface (see image below).
The sample rate of the Saleae products starts at 12 million samples per second which are great for enthusiasts and beginners but falls quite short of the > 1GSa/s of the Oscilloscopes. The lower sample rate isn't really a big deal for most uses of the logic analyzer, as you are more likely to be viewing the macro-level interactions of different digital signals than zooming into 1ns time domains on each channel. The Saleae products also let you record (almost) indefinitely, the only limit being your computers RAM, oscilloscopes usually having 10MB+ RAM whereas most PCs these days have 4-8GB.
Our Recommendation
We find that this initial decision of DSO to MSO has broadened to 3 different choices. You could get a Digital Storage Scope with 4 channels (we recommend the Rigol DS1054z, a great performance per dollar scope from RIGOL) that has the capability to simultaneously measure 4 separate analog channels, however, it doesn't come with wide-range digital channel options of the MSO.
Alternatively, if the price is no issue ,you can just go ahead and splurge on the MSO. It gives you the functionality of a DSO and a souped-up 16 channel logic analyzer for a bit of a price increase. For the DS1074z MSO counterpart, the increase is rough $400. Be aware that the limitation with the MSO is the memory depth, as it cannot compete with the ridiculous amounts of RAM available when using a PC/Logic Analyzer.
If you are looking to cover reading digital channels you could grab a Saleae device that will allow you to interface with most serial communications chips on your circuit as well as analyze and annotate those signals. Salae has done a really good job of making a logic analyzer and with the ability to select if a channel is analog or digital, you essentially get a basic 20MHz scope for that price point. The software you get to interface with your Logic analyzer is also really intuitive, we could go really in depth with how much we love this but we won't for now. Just know that it is extremely straightforward and easy to use. This is a big plus on the side of the Saleae product range.
All in all, we find that there isn't one answer to this question that suits everyone. Your intended use for the scope will be the biggest factor in deciding which option is best for you. Don't overlook the capacity of the Saleae products when it comes to this purpose, though, they can be a great alternative when cash is an issue. That being said, you really can't beat how accurately an MSO can measure a signal.
If you think we have missed out on any aspect of this particular conversation, don't hesitate to kick off the discussion with us below. I am always keen to hear where our community leans when it comes to testing and measuring equipment!