06 December 2020

Radio-based Situational Awareness Tools

Hey kids, let's play a game. It's called Global Thermonuclear War.

If you don't know the reference you need to hand in your Geek credentials

Too much? OK, I'll dial it back just a bit. Pick a scenario, any scenario, that is likely to occur where you live:

    • Hurricane
    • Earthquake
    • Wildfire
    • Tornado
    • Winter storm
And for the win:
    • A Carrington Event-level solar storm. Much like thermonuclear war, but more widespread and without all the mushroom clouds, or dead people (at first).
When the Sun gets pissed and takes aim at us all we'll be able to do
is hang on and watch

In this blog I've spent a lot of time talking about establishing 2-way communications in scenarios like these, but let's assume, for some reason, you can't transmit. It could be because your transmitter is damaged, or atmospheric propagation is so disrupted that you can't get through to anyone. You still need to be able to listen - to monitor the airwaves on as many modes (AM, FM, sideband, digital, etc.) as possible to establish and maintain situational awareness, and to evaluate propagation.

The most fundamental tool in this scenario is a simple battery powered AM/FM radio. Nothing too fancy. One of the inexpensive wind-up emergency radios like the C. Crane Solar Observer will do fine. The point is to be able to monitor broadcast bands for updates. 

A very capable little wind-up radio.
Not very sensitive or selective, but ideal for basic situational awareness needs

A step up from this would be a radio that offers improved sensitivity and selectivity and adds shortwave (but not SSB) reception into the mix. Several all-band radios like the Tecsun PL-310ET get surprisingly good reception performance ratings. This inexpensive little radio (less than $50 on Amazon) has actually spawned a cult following among DXers.

This cheap little radio is so good it's developed a cult following among serious reception DXers

Most of these inexpensive radios only offer shortwave (AM) reception outside of the commercial broadcast bands. This is OK for basic situational awareness monitoring, but if you also want to monitor Amateur Radio, military, marine, SHARES, Red Cross or other activity in the sideband regions you'll need a radio capable of single sideband (USB/LSB) reception. This requires a bit more of an investment, but the options are still reasonable. The Eton Elite (formerly badged as a Grundig) is another 'cult' radio, with many claiming it offers best-in-class performance along with USB/LSB reception.

Eton Elite Executive. Offers both USB & LSB coverage.
About $150 on Amazon

All of these radios will require an external longwire antenna for best performance on the lower bands, and to be honest, none of them are 'screamers' when it comes to low band reception, but they are good enough for the situational awareness mission. You can easily make a simple longwire antenna (nothing more than a piece of random wire with an alligaor clip on the end - just clip it to the external antenna), or you can get one of the inexpensive reel antennas made by Tecsun or Sangean. I prefer the reel models because they are easier to set up and deploy. 

The Tecsun clip-on reel antenna.
They also make a model with a 1/8" audio plug
for use with radios with a built-in antenna jack.
Very, very handy

One word of caution when looking for a radio in this category. Several excellent radios, like the Tecsun PL-880, use non-standard lithium-ion batteries rather than off-the-shelf AA or AAA batteries. In my mind this disqualifies them for use in the situational awareness role. If I can't run a portable receiver using replacable batteries that I can get at any grocery store, then I want nothing to do with it.

Many of you are probably asking, "Why not just set up my ham radio?" Valid question. One of the objectives with a situational awareness receiver is ease-of-use - something a non-technical family member could pick up and intuitively use. Most desk-top ham radios have somewhat complex operating interfaces, power requirements (12 volt battery or power supply) and antenna requirements, making them unsuited to the portable situational awareness radio task. There are a few, mostly small QRP rigs like the Yaseu FT-817/818 and the new Icom IC-705, that would fill the role nicely, but most other rigs require a specialized setup and/or don't cover things like the FM broadcast bands. 

There are a few handheld Amateur radios like the Kenwood TH-D74 that could fill this role, but they are pricey and SSB reception is compromised by the antenna arrangement.

A strong contender in the situational awareness radio category is a simple SDR receiver plugged into your laptop computer. Something like the inexpensive RTL-SDR USB receiver ($25 on Amazon) offers amazing performance. These little receivers are all based on the RTL2832U chipset (hence the name 'RTL-SDR'). The computer software that controls the receiver is free and, although a bit complex, allows monitoring AM & FM broadcast bands, Amateur Radio bands, utility bands, just about everything bouncing around the ether (except for the cell phone frequencies, which are blocked by law). These receivers are optimized for performance in the higher bands (above 30 mHz) and performance is less than optimal on the lower bands, but still usable. I can't recommend these little USB dongles enough, and there's always at least one in my computer bag. Plus, they are just fun to play with!

These amazing little devices are no bigger than a USB thumb drive

The software that drives these RTL2832U chip based receivers is available on the RTL-SDR.com website, and the user has a huge number free and paid packages to choose from - more than 25 at last count! A great way to spend a lazy rainy day is fiddling around with one of these receiver dongles and the various software packages that drive them. And yes, there are Linux, Android and MacOS packages available.

While I admit that the software interfaces are not necessarily 'intuitive', many are easy to quickly figure out, with things like frequency changes or mode changes handled with a simple mouse click. Getting non-technical family members up-to-speed on how to use them should be quick and easy. 

HDSDR software interface for RTL-based SDR receivers.
One of over 25 packages available on the RTL-SDR.com website

If you want to step up in receiver performance, particularly on the low bands, there are more capable (and more expensive) SDR receivers available from companies like AirSpy and SDRPlay. I've been using an SDRPlay RSP2 for a few years now, and recently slaved it to my Icom IC-7300 using the RadioAnalog PTRX-7300 add-on board. I'll be upgrading to the new RSPdx model that offers much improved performance below 30 mHz., and the old RSP2 will go into my field kit bag for portable receiver operations.

RSPdx receiver, offering much improved low-band reception

So there you have it. This post is not a comprehensive treatise on situational awareness radio tools, it's just intended to get the thought processes started. Honestly, this topic deserves wider coverage and can quickly descend down the rabbit hole of emergency service scanners, military-grade receivers, beacon networks, magloop antennas, and tin foil hats. 

So what's my plan if I need to go into the monitoring mode? Simple. I'll plop a very capable AM/FM portable radio (likely my trusty C. Crane EP analog radio) on the kitchen table for the XYL to use to listen to local broadcast stations, and I'll go down to the shack and fire up the SDRPlay receiver and start monitoring Amateur Radio frequencies in the 20, 40 & 75 meter bands.

To wrap this up, let me point you to Thomas Witherspoon's excellent write-up on his list of the best portable shortwave receivers over at the SWLing.com website. It's a fun, and very informative, read, and will help point you in the right direction if you are in the market for a portable situational awareness receiver.

W8BYH out (for now on this topic...)

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