Curtains for "Jitters"?


The idea was simple: take the military's tangled mess of radios, any replace 'em all with a single, software-based model.But executing the idea has been anything but easy. And now, generals are talking about dropping the notion of a universal radio altogether, Defense News' Greg Grant reports -- right when Pentagon chiefs are trying to decide what to do with about the troubled, $6.8 billion Joint Tactical Radio System.factsheets_JTRFACT.jpgEssentially, the JTRS program [known as "Jitters"] is aiming for something thats almost physically impossible, or at least extremely expensive, experts say... The desire to use a single antenna for many different wavelengths bumps up against laws of physics, which make it difficult to pull in strong signals across the spectrum. An amplifier that works across the whole spectrum will use much more electrical power than one tuned for a specific frequency band. Waveforms and transmissions that are speedily handled by analog systems, such as the widely used Link-16, are much tougher to achieve with digital computation...A better solution... is using such software-defined radios only when absolutely needed. More and more communication of data and even voice can be routed via the Pentagons burgeoning digital network. Such relays could allow the new radios to coexist with older ones...Initially, every JTRS box has to host all the waveforms and all the software for the network. To do so requires high-performance computer processors, which translates into more heat and power.But for the JTRS radio to be carried on missiles to provide guidance and on other platforms such as unattended ground sensors, there is no requirement for all that processing power.So maybe one size does not fit all, [Maj. Gen. Michael Mazzucchi, who commands the Armys Communications-Electronics Lifecycle Management Command] said. Maybe we can have it run just one wave form, then you wouldnt have the same battery, heat and processing speed challenges.Mazzucchi said JTRS also ran into the reality of an ongoing war when the Army realized it needed a lot more tactical network radios and so ordered another 100,000 radios. Those radios are going to last a long time, were not going to now go out and replace those radios in three years with JTRS.The Army is no longer looking at JTRS as a radio replacement program. Instead, its being viewed as a gateway into the network.The article is "absolutely right," one Air Force radio specialist tells Defense Tech.

Yes, we'd all love a one-size-fits-all radio -- especially one which can tie into larger networks without a lot of mucking around with settings for an hour beforehand. But there are huge technical obstacles to be overcome in the meantime, and the Pentagon is being unrealistic about the timeline for deploying the system. (2 MHz to 2GHz? They're not kidding about laws of physics needing to be overcome.)In the meantime, they could save a lot of trouble by procuring more of the newer do-it-all radios like the PSC-5D, PRC-117F, or the PRC-148. These radios already have impressive do-it-all capabilities and save a lot of hassle when it comes to interoperability.

Simply, the miltary has finally started using radios that can talk to different services, in different transmission modes, with different encryption, in addition to their normal mission. Our ETACS [Enlisted Terminal Attack Controllers, the guys who help bring in air support] used to need one radio to talk to the Army, a completely different one to talk to the planes, and yet another (different) radio to talk to the next echelon via SATCOM or HF. Each of these needs an encryption device (external, and bulky of course) plus associated power supply, audio cabling, and antennasAnyway, since the late 90's companies like Racal and Harris have been making radios which have multi-algorithm encryption built right into the radio, can handle lots of transmission modes (aside from the one or two a given service needs), and cover very broad frequency ranges. As an example, an old PRC-77 (the Army radio operators hauled around on their backs) covered 30-78MHz in FM voice mode only, with no internal encryption. (Mind you, that's just the Army; there's the USMC, USAF, USN, etc. to worry about, plus third parties.) A newer "do-it-all" radio like the PRC-148 MBITR covers 30 to 512 MHZ in AM, FM, SINCGARS (Army frequency hopping), HAVEQUICK II (Air Force frequency hopping) for both voice and data, with internal software that can simulate all sorts of external encryption devices.AND the damn thing can talk through satellites.This is typical of what similar radios like the PSC-5D and PRC-117 can do. The only real difference is form factor; the PRC-148 is the size of a largish walkie-talkie (slightly larger if you include the amplifier which makes SATCOM possible), the -5D and -117F are backpack-sized.So now your ETAC doesn't need a Humvee full of radios and encryption devices; he can carry one radio to talk to anyone he wants. Or maybe two if he needs to talk to two people simultaneously....and don't forget that the software-based nature of these new radios means they can learn all sorts of unheard of tricks. For instance, the PSC-5 series of radios can pair up to make a repeater, or retransmit a SATCOM channel over an Army SINCGARS net (for instance) AND vice versa.Well, to a radio guy, that's pure dynamite.JTRS wants to take it further, but in my opinion they're trying to turn over two pages at once. There's simply no precedent for tactical radios which self-program to switch nets (the way that cellphones do when changing service areas) and it could take a decade - easily - to get this off the ground.
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