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By Adam Baddeley, Deputy Editor, BATTLESPACE

The Joint Tactical Radio System (JTRS) Joint Program Office (JPO) is gearing up to extend JTRS. ‘It will go beyond its current 2Mhz-2 GHz frequency band to include waveforms up to 55Ghz and possibly higher, potentially in the hundreds of Ghz,’ according to Colonel Steven Maclaird, JTRS JPO Project Director. Work has recently begun on exploring how best to proceed in what is called the Above 2Ghz effort, and recommendations are due to be presented to the Office of the Secretary of Defense in June. An important avenue being explored by both the JPO and industry is how the Cluster 1 set could meet these additional requirements. Colonel Maclaird is emphatic in emphasising that the additional role would not impair the original Cluster 1 work, “This Above 2 Ghz question is not to impact – key point – not to impact- the current Cluster 1 schedule.”

Until recently the JPO referred to the work on capabilities as Clusters: High Data Rate and High Band. They have now been merged into a single effort. Colonel Maclaird explained, “I am trying to get away from the term cluster. For these two capabilities or quasi-products, we are looking at combining them into what we call the Above 2GHz Effort. What we are doing is to understand the characteristics required for operation at above 2Ghz. Processing, latencies, speed, power consumption and high-speed cryptos all fall into this arena.”

The last week in April was a significant time in the realisation of this vision. Two meetings were held to help identify the way forward. The government’s ‘Above 2Ghz Working Group’ met on 27th April, followed by an Industry event on 29th -30th April. The latter provided an opportunity for companies to present their approaches to this requirement. “We established three teams to develop the information and make decision regarding the future of above 2 Ghz issues,” Colonel MacLaird explained. “Those teams will address three waveform families: wideband satcom, protected satcom and data links. They are tasked with identifying which waveform should be developed within a specific area and recommending a selected acquisition effort.”

For the original 2Mz-2Ghz work, 104 waveforms used by the Department of Defense (DoD) were reduced to 32 and one new waveform, the Wideband Networking Waveform (WNW), was added. A similar effort to reduce the overall number of waveforms used is currently underway for the higher frequencies. Mark Bishop, Lead Engineer Above 2GHz at the JTRS JPO, explained that there are four EHF waveforms and at least that many wide band satcom waveforms. Regarding data links, Colonel MacLaird added, “In my short look at the Common Data Link (CDL), I identified at least 14 waveforms. Therefore the question is “what is common about them?”

Addressing industry’s input into the Above 2Ghz process, Charles S. (Steve) Prewitt, Chief Engineer at the JTRS JPO explained, “The industry/government workshop focused on extending the SCA concept to address waveform portability and standard interface issues to help portability in the above 2GHz arena. This requires implementation of more operations in the Digital Signal Processing (DSP) and FPGA (Field Programmable Gate Array) arenas.”

The Software Communications Architecture (SCA) was not originally designed to operate at above 2Ghz. Extending its frequency range will pose some challenges. Mark Bishop explained, “The challenges come from trying to support higher data rates like hundreds of Mbps waveforms. It drives you to do things faster and implement more of the waveform processing in special purpose processors like DSPs and FPGA type devices. The current SCA does not specifically address portability of that type of code other than in the context defining some APIs. We want to extend the SCA middleware concept into the signal-processing arena to improve waveform portability. We want to address waveform portability and the concept of

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