Software Defined versus Traditional Radio

Pro or contra? Neither, I use both platforms, and each has its own advantages and disadvantages.
In a traditional receiver, all the actual work of making sense of a signal is done by physical components. These cost money.
In software defined radio receiver, the signal is first converted to a digital form, and the heavy hauling is done by a computer. This approach results in lower cost for the end user, but not without drawbacks.
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Specialized or multi-tool?

Oldschool gear accomplish a limited set of objectives easily, and a software-defined receiver will do a wider range of tasks better, but getting good results requires more user input.

Comparison? Not possible, really, because a $20 dongle offers so much more than a classic portable, which only needs four batteries. The PL-680 receives airband, can wake me up in the morning and comes in a nice leather case. But the RSP2 can shows 10 Mhz worth of frequencies. And the PL-310 for $50 shows temperature and usable out of the box, which cannot be said of any same-price upconverter. But the RSP2 has three antenna ports and doesn't look like a refugee from the 70's. And the 680 makes me happy with a signal by pressing a large red button, when the RSP2 needs a computer.
But... arguments are utterly pointless, if you want to use either platform, you'll buy what you desire - my point here, and the purpose of this post is exploring the alternative option, because you might get pleasantly surprised. That's unlikely if performance enters the equation, as the RSP2 is head and shoulders above a PL-680, but despite its many strengths, a traditional solution might be better in some circumstances.

"Software defined" needs a computer

All software defined radios require a host computer and a display for tuning. A computer can be an ordinary laptop or desktop PC with an operating system of your choice, a Raspberry Pi microcomputer or even a smartphone.
If you're reading this, you probably already have a suitable device, only software is needed.

Software means a learning curve

Give a 5-year old a traditional receiver, and s/he will tune to a station in a few minutes. That cannot be said of any software defined radio, because operation requires rudimentary computer driving skills. More expensive SDRs come with more complicated software, a necessity to utilize all of the advanced features, but complete familiarity will take time.
If you're used to turning knobs and dials, a software environment will be alien, and won't feel right for the first few times, but you'll quickly grow to appreciate how easy tuning and signal acquisition is, and will wonder how could you live without seeing activity on an entire band with just a few clicks.
On the other hand, if "listening" automatically means "watching" a waterfall, maybe it's time to invest in a portable receiver and give your fingers a workout. Turning a dial and "discovering" a faint transmission, then wondering where the "elephant in a cutlery store" racket originates from is a totally different experience than using an EiBi database or

You want shortwave?

Fifty of your local currency buys either a Tecsun PL-310 or a Ham It Up v1.3 upconverter.
It's on your tongue: which is a better $50 spent? Depends on what you yearn: any upconverter needs an RTL-SDR dongle, connectors and a computer, and a PL-310 needs three batteries. For strong signal reception, like Radio World Superpower, both do the job, but the very second you try to push the envelope and hunt for or elusive signal, an RTL-SDR with upconverter leaves a traditional radio behind.
So an ultra portable is worse? Not necessary, because I can put an ultra-portable in my pocket, go to a lovely spot, and listen to radio in the dark by pressing a button and turning dials. However, on the same antenna at home for $50, software-defined offers much more signals and "I got that" success for the same money.
Should you spend 50 on a traditional receiver? Hell yeah, absolutely, go ahead and order a PL-310, ease of use overshadows reception performance when and if circumstances warrant an ultra- portable, an upconverter is just a board or box, which will not be usable in three seconds.

Value for money

An RTL-SDR dongle covers frequencies between 30Mhz and 1800-ish MHz, with 2.4 Mhz visible spectrum. Add an upconverter, and you're looking at 0.5 MHz to 1800 Mhz for $70 with antennas and cable.

More expensive SDR products, around the $200 mark, for example the SDRPlay RSP2 covers 1 kHz to 2 Ghz with 10 Mhz visible bandwidth. 200 dollars is a large chunk of money for most of us, yet old-timers and amateur radio operators (often the same subset) migrate to SDRs, because $200 is nothing when you look at prices of traditional gear.
13,000 dollars buys a new car, or an Icom IC-R7500 wideband receiver. Without a doubt, it is a highly capable receiver, with such features as NOAA APT reception capability, which is possible with any dongle in the image above.
Make no mistake, I do not question its performance capabilities, but even if 13 grand means the last numbers on a 7-figure bank account, is it really 65 times better than a mid-level SDR?

Traditional gear (usually) just works

Give any oldschool radio equipment power, and it will more than likely work, receive or transmit signals. Possible points of failure are much less than with a software defined radio setup, however, if hardware-based gear fails, it's usually gone without either complicated or expensive repairs.
Recent SDRs from well-established manufacturers are quite reliable, but as this niche market is fairly new, there's no data spanning decades. I'm using a 4-year old dongle I bought for $10 and it's as good as on the day I opened the envelope, and the same can be said for the Icom IC-R5 traditional portable wideband handheld I enjoy for nearly a decade.
Time will tell.

Visible signals are good and bad for you

A traditional receiver shows you the tuned frequency, and nothing else.
A software defined receiver shows adjacent range as well, how much depends on unit used: RTL-SDR dongles show 2.4 MHz worth of signals, a mid-range $200 SDR displays 10 Mhz worth of signals, and the $300 HackRF visualizes 20 Mhz.

Do you want to see signals? Or do you prefer turning a knob? Up to you, really, due to mental  obsession of seeing information, and the compulsive need to know what's happening with a Hollywood star or across a band, most readers will say "Yes" to seeing information.
Traditional gear will force you to use your ears. If not talking digital modes, hearing is a wonderful perfunctory sense, an invaluable tool for listening to audio signals. Read the above sentence again and chastise me for stating the obvious, then ask yourself the question: when was the last time you sat down and actually listened? Not the noise-suppressed, best SNR version, but the raw, unfiltered, unadultered signal received by the antenna?

User's needs catered for

Most traditional equipment, as soon as the product leaves the assembly line, can not be modified. What you bought is what you'll be using for the lifetime of the radio, and if you don't like any aspect of operation, well, life is though.
A software defined radio contains the necessary components for signal reception, but everything else, from gain settings to filters is done is software. Which is written by people with an email address and online presence, so if you dream of <insert feature set here>, you can get in touch with the appropriate person.
I bring up SDRplay again, that company has a forum, where users voice their misgivings, requests and what they love. Regular communication from the company boss is normal. He listens. He publishes Youtube videos. Or visit FlightAware forums, CEO contributes regularly. Or go to Outernet discussions, and talk to Syed, who runs that outfit. Visual estate here is restricted to list more examples, try to talk directly to an Icom or Yaesu engineer to get a solution to your particular problem. Good luck.
Front-end software with SDRs is shaped by customers, and gets better and better in order to accommodate user's needs, for instance, there's seemingly a new version of SDRuno or SDRSharp every two weeks.

Digital modes and large number of projects

Traditional gear can often decode digital transmissions, such as APCO 25 used by emergency services. However, 4-500 dollars, or more, for specialized equipment is the norm.
In comparison, two $10 dongles (or feel rich for once, and buy two bundles for $50) can accomplish the same task with software (here's a guide). And those dongles can be used for many more other purposes, such as Aircraft tracking, receiving weather satellites, AIS signals, etc.

Open source or free

The majority of SDR manufacturers are open minded about who's allowed to use their software, so choices exist, therefore you're not locked into a menu system. Any RTL-SDR dongle can be used with several front-end software.
Independent developers release new software almost on a weekly basis; most of them are free. Occasionally, you'll have to pay for software, but only if you want, and prices are affordable: smartphone app to use with an RTL-SDR dongle with a cheap cable costs $10, and it's a one-time purchase with automatic updates.

Emergency preparedness

The first thing to go in a SHTF scenario is electrical power, and most traditional receivers only require a set of batteries for hours of operation, whereas most software defined radios are limited by the host computer's battery capacity. To overcome this inherent limitation, use a smartphone as a host and invest in mobile battery banks.
Best of both worlds: if you have a hand-cranked shortwave receiver stashed right next to jugs of water and shelves of beans, buy an RTL-SDR dongle to learn more about radio for minimal cost. Knowing how to improve a rubber duckie with pigtails will let you use that transceiver more efficiently, Rick and Co could have avoided Negan if they had lookouts with better comms to coordinate a devastating counter-attack, but I'm getting sidetracked now. 

SDR is the future

Traditional radio manufacturers quickly caught on, only took Icom aeons to announce a new receiver (Icom IC-R8600) with unheard-of features like a 4.3" color touchscreen. It's hard not be sarcastic in relation to a $1000+ product, when $30 buys you a 4.3" color touchscreen a.k.a smartphone and an additional $100 gets an upconverter and two premium RTL-SDR dongle bundles with 5 antennas.
Sight unseen, an R8600 will outperform any 8-bit RTL-SDR dongle, however, I'd place my bets on a $300 laptop and either a $200 Airspy or RSP2 for half the price. There's a reason the R8600 is SDR based...
If you're used to traditional, well, the future is bright and software-driven.
If you're used to software-defined, explore options the old world offers: principles are the same, method of operation will be different, but just like with an old mechanical camera, the joy will be immensurate.
Traditional or software-defined, pro or contra, savor both platforms.

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