Radio Architecture Matters: A Review of RF Sampling vs. Zero-IF
analog.com
analog.com
I am a ham radio operator and with many radio devices delivered these days I witness the following. Mostly high quality components are used but they are assembled in a way that lacks knowledge of harmonics, interference, cross-talk, parasitic effects in general. PC board design makes it obvious and results in a sub-quality end product.
It seems like a basic engineering craft which got lost in the last 30 years.
An even more cheaper accessible intro to RF is just plain old analog electronics. Building amplifiers ,etc.
I had the good fortune of being exposed to both Pozar, an excellent lecturer and a wizard of an RF lab postdoc when studying RF engineering, and the utility of simply spending lots and lots of time in the lab, trying all sorts of implementations of filters, transmission lines, antennas and whatever caught our fancy, prototyping with wild abandon, verifying (or getting stymied by) the results, refining our measurement skills along the way...
Priceless.
Then all RF design jobs disappeared overnight and I ended up doing PLC coding instead of working with radio - but, hey, University was great fun, and RF design definitely is one of the fields where there's still room for intuition and a bit of artistry in addition to just knowing the hard theory of the subject.
TLDR: To answer your question, to reduce the reliance on a relative few engineers, the market solved it with a few products that are 'just good enough'. This has become a self perpetuating cycle, race to the bottom. There will still be many analog/RF EEs but relegated to a few niche sub-industries serving mainly the DoD and RFIC industries. Even the telecom industry is planning to pipe back raw, downconverted baseband data to a central location to do SDR DSP rather than rely on a modem at the basestation. All for flexibility in lieu of power/efficiency, NRE etc.
I don't even know where to start on your "temporal dynamic range" comment....
This is the right idea, in many cases, the "HW" team might focus on RF but does "antennas to bits" (i hate that term) because of the need to get a prototype up and running to test it. If you have baseband circuit and DSP experience you could be poised for a lateral move especially since the operational frequency will be less critical for your skills. For example, without years of mmWave experience a move into doing mmWave RF wouldn't make sense but that doesn't mean you can't work on other parts of the mmWave system.
RF HW design is very much a systems engineering field and folks that have experience in each block are more desirable than ones that focus on only one piece in most cases.
The problem is you can't tweak these things with a software update. Their relative inflexibility makes them unpopular outside of a defense or research setting but analog solutions are typically higher in performance than digital solutions but that can depend on definition as well.
I spend most of my time in theoretical work of some kind, but get a real urge to build...
That's an interesting way to describe AliExpress shovelware, but OK, yeah it's a "management decision"
Signals crash course: Radio comms have a channel they need to fit into (let's say 1.1GHz - 1.2GHz as an example). This means that what you send over the air is basically a high frequency (~1.15GHz) sine wave. You encode data by slowly varying this sine wave (amplitude and/or frequency). The variations are going to be super slow, as fast changes in either amplitude or frequency will make your signal go outside the frequency limits. It's only the sine wave (aka the "carrier frequency") that's high frequency (1.15GHz in our case).
There are several ways to digitize this signal. You can do "direct RF sampling" - you need a very high sampling rate (2.4GHz+ due to Nyquist in our case) and just sample the high frequency signal. You can multiply (in analog domain) the RF signal from the antenna by another frequency to keep all the slow changes but change the carrier frequency. This means that you don't need such a high lower sampling rate (you can get away with much less than GHz). If your new carrier frequency is just some low but non-zero frequency, that's super-heterodyne (IF). If it's zero, that's Zero-IF.
One issue they didn't mention, but probably shows up in the noise figures is that homodyne receivers suffer from 1/f noise in the relatively wide band "direct conversion" amplifiers. Of course all of the heterodyne receivers suffer from 1/f up-conversion at the mixer.
It seems they are now settling on RF sampling for the newer transciever architecture technology but sometime direct RF is also being used for example this latter terminology is referred by Intel for their new line of FPGA and RF transceivers product integration.
It's rather intriguing that for RF sampling technology, Intel has recently join the bandwagon and called it a game changing technology when the RF sampling is integrated with high speed FPGA [1].
Intel Delivers a Game-Changing, Analog-Enabled Direct RF FPGA Portfolio:
https://community.intel.com/t5/Blogs/Products-and-Solutions/...
They’re some of the best in the business at technical marketing.
Id also push back against the article in the sense that I think the industry shot itself in the foot trying to provide too many options that all overlap. But, I do agree with the sense that minimizing the radio architecture to only what it needs to operate is smart.