Notes on Next Generation Jammer, GMTI
By Stephen Trimble on 20 June, 2011 in Uncategorised
Notes from a Raytheon interview on Day 1 at the Paris Air Show:
Next Generation Jammer
This is the US Navy’s programme to replace the aging ALQ-99 jammer pod for the EA-6B and EA-18G. Building a new jammer is a tricky job. Just ask the US Air Force. After dropping the mission by retiring the EF-111 Ravens in 1997, the USAF attempted to catch up with the B-52 stand-off jammer system (SOJS) after 2002. That programme was cancelled in 2006 after estimated development costs spiralled from $1 billion to $7 billion. An attempt to revive a scaled-down, $1 billion version called the Core Component Jammer (CCJ) also was dropped two years ago. Now, the navy is working with several contractors to develop the Next Generation Jammer (NGJ). Naval Air Systems Command (NAVAIR) has to get its acquisition strategy right.
The key question at the moment is how many pods would be required to perform an expanded jamming mission spanning from radars to communications emitters, said Travis Slocumb, vice president of strategy and business development for Raytheon. It takes as many as nine different pods for the ALQ-99 to cover the entire spectrum of threats. Ideally, the NGJ could cover the same ground with a single pod.
That’s attractive because a single pod covers only 120 degrees of the compass, so three pods would still be required for each jamming platform to provide 360 degree coverage. The alternative is to split the high-band jamming signals into a separate pod, but that means that the EA-18G would need to carry five pods on every mission, Slocumb said. The navy seems to prefer the single-pod solution, he added, but that means accepting more risk during the development phase. Risk is not a popular word in the Pentagon right now, which isn’t making the navy’s decision any easier.
Ground Moving Target Indicator (GMTI)
The US Air Force, meanwhile, is trying to figure out what to do with the GMTI mission currently performed by the E-8C Joint STARS and RQ-4 Global Hawk Block 40. Alternatives include upgrading the Joint STARS radar, buying a GMTI spin-off of the Boeing P-8A, or perhaps use a smaller aircraft like a business jet. Raytheon products are available for all three options, allowing the company a unique perspective into the ongoing debate.
According to Tim Carey, Raytheon’s vice president for intelligence, surveillance and reconnaissance (ISR) missions, the key, non-budgetary issue in the air force’s debate is a single metric called “minimum detectable velocity”. How fast does the target have to be traveling to be detected by the radar? The physics are already known. One approach is to use a long array with a low-frequency signal, such as the E-8C or the P-8A. The other approach is to use a short array with a high-frequency signal, he said. The latter is the basis for the Raytheon airborne stand-off radar (ASTOR), which the UK operates as the Sentinel R1. The answer will determine whether the USAF decides to buy a larger or smaller aircraft, or simply upgrade the aircraft they have already.
But the other question is not answerable by Carey, presumably because the answer intrudes on classified details. That is, can existing GMTI radar technology detect something moving as slowly as a human on foot? If it can, can the radar also identify whether the moving object is a bipod or a quadruped. The issue is the difference between finding a team of insurgents advancing toward a special operations team — or a herd of sheep.
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