Choosing an Oscilloscope or logic analyzer

Question

Thanks in advance, 
 
 I am familiar with basic multimeters or avo-meters. 
 I wanted to know what kind of features and speeds, digital or digital and analogue, or which Oscilloscope to get for, 
 - reading slow-ish serial communication, UART, I2C, SPI, weigand output, at normal micro controller speeds (9600, 19200, 115200), and 3.3v, 5v, and 12v mostly 
 - no analogue voltage or ADC or sound, but mainly digital communication 
 I would like to "capture" or set "triggers" for messages coming from a device, maybe transfer it to usb drive or pc, optionally, view it as hex or ascii in Oscilloscope. 
 
 Optionally, 
 - reading output from HDMI 2.1 ( 48Gbps in bandwidth ) or latest display port 
 - reading output from USBC with alt display port, like between PS5 and PSVR2 
 
 From what i have seen advertised, 1-2 channel, 100-200mhz,

Real-time sampling rate up to 1 gsa/use 
 IRecord length up to 14 Mpts

How does that equate to bitrate? can something with these specs capture hdmi signal at 48Gbps? would i need more channels for HDMI and USB C with display port? 
 do i need an adapter to clip onto tiny connectors like usb c and hdmi? a breakout accessory of sorts? 
 
 Update: 
 I was looking to get information about "regular" oscilloscopes in the range of $500-2K. 
 I see that logic analyzers(for slower speeds) in combination of something like wireshark for usb related packet capturing/monitoring might work better, as an affordable oscilloscope would only work for up to 100Mbps or 200Mbps.

michaelkellett · Accepted Answer

You don't mention your budget but you won't get a scope capable of direct connection to HDMI (the 4.9Gbit part) under $50k. You'll need 16GHz scope bandwidth and matching differential probes. 
 Unlesss you are doing something very odd you would be better off with an HDMI analyser but it won't be cheap. 
 USBC at ultra speed - same applies. 
 For the low speed stuff I'd suggest a Picoscope - you get lots of decoders in the basic price and the scope parts work well. You'll need 4 channels and/or one with a logic analyser. 
 You might get away with a logic analyser - I can recomend the ones from ZeroPlus which I own and use. There are others. It can be very difficult to debug serial prootocols without a real scope - signal integrity problems are common and the best an analyser can do is tell you that there is a problem - it won't help you work out what it is. 
 All the major scope manufacturers offer mixed signal scopes with protocol decoders at various prices. 
 If you budget is very tight then go for a logic analyser using open source software (Sigrok) and a cheap scope if you end up needing it. 
 MK

Gough Lui · Answer

Scopes capable of HDMI 2.1 or even USB 3.0+ are extremely expensive. You'll be looking well above $50k. Even then, for what you want to do, you probably can't afford the precision cables and test fixtures needed to connect them - or you might have to build your own. Then you'll have to also invest in high-enough bandwidth differential probes - you can't just "connect with a wire". Just having a scope is not enough. 
 A 100-200MHz scope is really only usable for relatively low-speed signals by comparison, in part because most low-cost scopes really don't have all that much memory. 14M points is better than nothing, but at 1GSa/s to get nice 200MHz bandwidth captures, that's a capture memory length of 14ms. If you can't trigger on what you want or there is no decoder, then that's potentially extremely limiting. That being said, regular UART could probably be done at about 1-8MSa/s, so you can get a few seconds out of the memory buffer depending on the baud rate. 
 If you work purely in digital, a logic analyser may be a better option overall. 
 - Gough

Gough Lui · Answer

If you're still interested, there are not many USB 3.2-capable oscilloscopes - these would be something like: 
 
 Keysight Infiniium UXR0164A 
 R&S RTP164B 
 Tektronix MSO / DPO70000 
 
 Plus whatever software options they want for them. There maybe a few more (from Rigol, Teledyne LeCroy) but they're not cheap. Unless you've got a deep knowledge of USB protocols and how to use the equipment, and have the test fixtures, they'll not be of much use to you. 
 HDMI 2.1 uses 4x12Gbit/s channels, so you're probably going to want something even better for that ... 
 Put it this way - if a signal has a certain bandwidth, whatever you're using to measure it needs to have even more bandwidth than that to accurately capture it . Even then, at such high rates, you're likely only capturing fractions of a second of data for analysis - oscilloscopes don't run continuously like a data-logger for example. 
 - Gough

Choosing an Oscilloscope or logic analyzer

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