Testing of two threshold modes for the U.S. Air Force’s new ground surveillance sensor is complete, but the Multi-Platform Radar Technology Insertion Program (MP-RTIP) remains behind its original schedule and still has yet to tackle testing on more advanced variants.

The first two modes, to collect synthetic aperture radar (SAR) and ground moving target indications (GMTI), are now complete, according to Col. Jim Shaw, commander of the 851st Electronic Systems Group, which oversees development of the Northrop Grumman/Raytheon active electronically scanned array radar.

These modes are already used by existing radars, but in developing them for MP-RTIP, the Air Force had problems with radar calibration, which contributed to delays.

To move ahead with at least a portion of the $1.2 billion MP-RTIP, the service sidelined work on the so-called “concurrent modes,” which are new capabilities, to wrap up work on the SAR and GMTI capabilities.

Testing on the SAR and GMTI modes required 186 flights, totaling 1,063 hours on Northrop’s Proteus manned aircraft. About 376 hours and 64 flights — nearly half the total — were needed to conduct radar system level performance verification (RSLPV) on these basic modes. The RSLPV phase was required to validate earlier findings because of the calibration problems.

The MP-RTIP sensor will now proceed with flights on Proteus to refine the concurrent modes. These include the ground high-range resolution (HRR) and concurrent moving-target indicator (MTI) modes. Ground HRR allows the sensor to collect precise electrical measurement of a target’s length; it will be used to enhance target identification. The concurrent MTI is desired because today’s systems must suspend collection in one mode to switch to another. This mode is needed to enhance tracking abilities.

Air Force officials hope work on the concurrent modes will be finished this summer with verification testing concluding in the fall. Then, the sensor will be integrated onto the Global Hawk Block 40 unmanned air system (UAS) aircraft already built by Northrop. The first Block 40 has been built, and first flight is expected in early July. The Air Force plans to field 14 Block 40 Global Hawks.

However, slips in the initial operational test and evaluation (IOT&E) program for the Block 20/30 Global Hawk, which precedes work on the Block 40, are having a domino effect on the aircraft’s development. Pentagon officials are still discussing how much of a delay is needed to execute IOT&E for the Block 20/30 — it was scheduled to take place between August and November, and at least six months more is expected to be required to finish.

The MP-RTIP and Block 40 aircraft are also to be used by NATO for its ground-surveillance program.

Photo: Northrop Grumman