Software-defined (tactical) radios

Portable army radios are transitioning to a new generation these years, digital software-defined radios. This opens up all-new opportunities.

Maybe long-time (or archive-)readers remember what I wrote about the rise of electronics at small unit and unit levels. For everyone else:

Well, there is a different approach, and it is rooted in technology rather than organisation and training. A technical solution to problems created by technology. Yes, this often work, too.

Software-defined radios can - in theory - provide a versatile node with no less tasks than our modern touchscreen mobile phones. Once you combine radio emitter and receiver for a certain bandwidth (say, 30 MHz to 2 GHz) with a satellite navigation (GPS and Galileo) chip, sockets for fibre-optic cable/microphone/earphones, a programmable microprocessor of respectable power, a decent flash memory, a useful size of RAM and some kind of USB socket equivalent (for input by digital cameras etc.) you can do maaany things (in theory):

the classic ones

(a) simple encryption

(b) 2-way voice communication

(c) morse communication

(d) simple direction finding regarding other emitters (not frequency-hopping) within the bandwidth (possible with a handheld directional antenna)

and new ones (I don't expect most of these in the early SDR generation)

(1) datalinks up  (such as reconnaissance photos, position reporting) and down ( receiving image, situation updates and even videos)

(2) receiving area-related warnings about minefields or areas full of cluster bomb duds ahead, NBC warnings, air threat warnings, warnings about presence of stragglers and infiltrated opposing forces - and giving a beep and artificial voice warning to the user

(3) direction finding regarding other emitters (incl. frequency-hopping) within the bandwidth (possible with a handheld directional antenna)

(4) triangulation of  other emitters within the bandwidth in cooperation with other radios

(5) early warning of helicopters (if the microphone can pick up the rotor's infrasound noise)

(6) triangulation of helicopters with (if the microphone can pick up the rotor's infrasound noise) in cooperation with other radios

(7) employment as non-emitting digital field telephone with fibre-optic cables (no recovery of cables for reuse necessary)

(8) automatic responder function in IFF (identification friend/foe) at the grunt level (with interrogation signal being a laser or a directional radio emission)

(9) active noise cancellation for the user's ears (with earphones)

(10) jamming nearby communication radios (with low power)

(11) jamming datalinks of spotted hostile drones (with handheld directional antenna)

(12) automatic conversion of voice to text for super-short and jamming-resistant burst transmissions and receiving radio converts text back to an artificial voice

(13) use of one-time pads for encryption

(14) prioritised communication (a superior's voice message could override a subordinate's, for example)

(15) programmed nonsense transmissions that simulate radio comm links that do not exist*

(16) automatic employment of radios as relays for range extension, with automatic routing negotiation

(17) other communications devices such as laser communication emitter/receiver for line-of-sight communication might be linked through the fibre-optic cable

(18) within the limits of the chosen radio bandwidth at least some radio proximity fuzes employed by high explosive ammunitions of mortars bombs, bombs, rockets and shells might be deceived and provoked to explode too early due to jamming

(19) recharging items with small batteries (digital camera, for example)

(20) cooperative sniper detection (by using microphone input)

(21) GPS, GLONASS and Galileo jamming (with limited range)

(22) I kid you not; radio and music player for entertainment

The electronic warfare aspects in this list were inspired by the relatively famous "Shortstop" RF fuze jammer and the (partially) man-portable Chemring RESOLVE product. A software-defined manpack radio that can do most of the above list would likely be noticeably heavier, bulkier and pricier than a communications-only radio, but this might be worth it. After all, separate solutions would have redundant components and weigh much more in sum.

Of course, at the end of the day, you need to be able to make do without radios without collapsing as an organisation. Radio communications may be jammed, interrupted (even HF has its issues with blind spots) or in worst case even compromised. That's a different topic, though.

The best approach to design a complex vehicle is in my opinion to first define the interfaces; especially the communication between electronic components. Once that is done you may move on with final design of the various components. Maybe tactical unit 'design' should be similar ground-up, and "ground" meaning "interfaces". First, get communication compatibility right, then a loooong list of opportunities for what you can do in terms of procedures, tactics and capabilities opens up.

- - - - -

Finally, a little bit more down-to-earth, I'd like to present a family of software-defined radios that might -more or less- be used for such things. Typically, platforms (aircraft, armored vehicles, ships) gather most attention, with the crucial yet obscure radio tech neglected.
The Harris Falcon III family is under consideration (afaik one of the two two contenders) by the Bundeswehr:

Harris Falcon III(R) RF-7800M-MP (backpack radio, at platoon level or in vehicles)
20 Watt power, 30 MHz to 2 GHz, 3.58 kg + pouch and batteries
Harris Falcon III(R) RF-7800M-HH (handheld radio, for NCOs and officers)
5 Watt, 30-870 MHz, 1.20 kg + pouch and batteries

Harris Falcon III(R) RF-7800S SPR(TM) (intra-squad radio for infantry)
2 Watt, 350-470 MHz, 0.3 kg +  pouch and batteries

These three would suffice at company level.Only signaller units / HQs and heavy equipment (radar posts, forward observer vehicles, air defence command vehicles etc.) would need heavier and more capable radios.

The Bundeswehr needs new radios as a replacement for its collection of analogue radios used in the Heer, and preferably they should be good enough to make the improvised use of mobile phones and satellite phones (that became normal outside of the fortified camps on occupation warfare missions) redundant.

The procurement is tricky because the technology is tricky, it is still new, there are no German suppliers, foreign suppliers create licensing and source code access issues. Being late on replacing the old radios means that we skip past some of the teething problems and also dodged the problems that long procurement projects such as the British Bowman had. It does on the other hand leave open a weak spot; the tactical communications of the Heer are obsolete, and spare parts supply will soon become perilous.


*: This makes it much harder to establish a situational picture by triangulating radio emitters and comparing their activity. Such signal intelligence could otherwise figure out which is the superior's and which are the subordinate 's radios, thus uncovering the disposition of forces).

P.S.: I've had my lifetime share of tech lectures already, but in case you are seriously interested in SDR, this might be relevant to your interests:



  1. Check out the Lime SDR, I believe it will sidestep a majority of the issues.
    Of course it is not to mil spec etc, but it is also <300 €, even as niche product.

  2. Fascinating stuff, thanks!