[ktownsend]

Exactly. Measuring things at 10-200 MHz is easy and relatively accessible, and there are only so many things that can go wrong.

Dealing with anything in the GHz range is not only extremely expensive (order or magnitude more), but you also start to deal with far more complex problems that boil down to the need for a very good understanding of the underlying physics of signal transmission: concepts like impedance matching, crosstalk between signals on the PCBs, etc.

The design AND debug requirements are far more complex, and you need to account for a lot more explations of why something isn't working as expected ... and the software/firmware AND physical level.

[exikyut]

Hmm. A followup question: are there any cheats/hacks that would make it possible (if painful) to for example explore the world of USB3, PCIe, or Linux on low-end-ish ARM (eg https://www.thirtythreeforty.net/posts/2019/12/my-business-c..., based on the tiny 533MHz https://linux-sunxi.org/F1C100s), without needing to buy equipment in the mid-4-figure/low-5-figure range, if I were able to substitute a statistically larger-than-average amount of free time (and discipline)?

For example, I learned about https://github.com/GlasgowEmbedded/glasgow recently, a bit of a niche kitchen sink that uses https://github.com/nmigen/nmigen/ to lower a domain-specific subset of Python 3 (https://nmigen.info/nmigen/latest/lang.html) into Verilog which then runs on the Glasgow board's iCE40HX8K. The project basically creates a workflow and hardware to use cheap FPGAs for rapid iteration. (The README makes the point that the synthesis is sufficiently fast that caching isn't needed.)

In certain extremely specific situations where circumstances align perfectly (caveat emptor), devices like this can sometimes present a temporary escape to the inevitable process of acquiring one's first second-hand high-end oscilloscope (fingers-crossed the expensive bits still have a few years left in them). To some extent they may also commoditize the exploration of very high-speed interfaces, which are rapidly becoming a commonplace principal of computers (eg, having 10Gbps everywhere when USB3.1 hits market saturation will be interesting) faster than test and analysis kit can keep up (eg to do proper hardware security analysis work). The Glasgow is perhaps not quite an answer to that entire statement, but maybe represents beginning steps in that sort of direction.

So, to reiterate - it's probably an unhelpfully broad question, and I'm still learning about the field so haven't quite got the preciseness I want yet, but I'm curious what gadgetry, techniques, etc would perhaps allow someone to "hack it" and dive into this stuff on a shoestring budget, on the assumption the ride would be a tad bumpier? :)

[dbetteridge]

USB3.0 bluetooth interference issues anyone?