JEM IN THE ROUGH
By Adam Baddeley
The Thales Cluster 2 JEM radio is on target to meet the requirements of the most demanding JTRS users – USSOCOM
“It has been pretty pleasing to see that the development of the JEM (JTRS (Joint Tactical Radio System) Enhanced MBITR (Multi Band Intra Team Radio)) has been able to hit its milestones so successfully,” said Ken Leighton, Director of Product Management, Thales Communications Inc. He added, “With the JEM being the first true production JTRS platform that is going to be available, we would expect there to be a great deal of interest in using it to try out the separate waveforms.” The Cluster 2 JEM -the first of the JTRS radios to be fielded- is due to enter service following a Full Rate Production decision scheduled for February 2005. Progress on the project has been good. So good in fact that Thales have recently submitted a nomenclature request for the JEM. They have requested for it to be referred to as the AN/PRC-148 Version 3 and Version 4 for the maritime and urban variants.
JEM
Speaking at IQPC’s Software Defined Radio conference in London in December Roger Lough, Deputy Program Manager, SOF Tactical radios, United States Special Operations Command USSOCOM, outlined the differences between the JEM and the MBITR.
The JEM contract was awarded to Thales -under an Engineering Change Proposal- to modify the existing AN/PRC-148 MBITR to make it JTRS SCA (Software Communications Architecture) compliant under JTRS Cluster 2 Programme. USSOCOM wanted to keep the mechanical envelope of the of the MBITR at 33 square inches – it measures 8.4 inches by 2.6 inches by 1.5 inches and weighs 28oz. In some areas, the JEM and the MBITR are the same. They both operate in the 30-512 Mhz frequency range and both radios have waveforms that continue to be based in software. The channel bandwidths of 25, 12.5 and 5 Khz remain the same.
The JEM does diverge from the MBITR in some key areas. The introduction of the SCA in the JEM takes the MBITR from a dual DSP (Digital Signal Processing) architecture to one that combines both General Purpose Processing and DSP. The legacy COMSEC is replaced by the software defined Advanced INFOSEC Module (AIM) chip.
Software options are also modified. The JEM will, like its predecessor, operate using UHF AM/FM, VHF AM/FM, ANDVT and Retransmit waveforms. However, the JEM will drop the SINCGARS SIP waveform in favour of the SINCGARS ESIP with MIL-STD 188-220B and will add the new Project 25 waveform.
In physical terms this means that inside the JEM the MBITR RF Amplifier board and the Receiver synthesizer board are retained. However, a new Control Crypto board– on which the AIM chip is installed – and Front Panel boards have been introduced.
Ken Leighton, when discussing the changes said, “The JEM will take the AN/PRC-148 radio and substitute two new boards to make the radio a JTRS compliant platform. The second major advance is the addition of a software programmable infosec chip – the AIM -developed by GD Decision Systems who are a subcontractor on the programme.” He added that Innovative Concepts Inc is providing the required MIL-STD 188-220B in the radio via JTRS compliant software.
“[The JEM] will be the first user of the first generation of software programmable encryption engines. That will enable us to field a radio that can either utilise ‘controlled’ crypto engines or those that are not crypto controlled. [Using the new encryption engines] you cannot only zeroise the key that is loaded into the radio but you can also zeroise the algorithm themselves. The type of controls put in place for a controlled crypto item limits who can either physically own or operate them. [The new chips] mean these controls can be eliminated”
Milestones reached
Recent developments in the JEM include the completion of the Critical Design Review (CDR) on 17th-18th November 2003. Commenting on the CDR, Leighton said, “The major accomplishment (of th