The capabilities will reduce radio frequency emissions and enhance target identification, the company said.
"We understood that the warfighter needed an improved identification capability, so Raytheon is both increasing the capability of the interrogator system and reducing RF emissions," said Glen Bassett, director of Advanced Communication and Countermeasures for Raytheon's Space and Airborne Systems business.
IFF interrogators provide troops with the capability to identify civil targets that operate in the airspace. The Mode S IFF interrogators ordered by the Army last year can track and identify targets passively rather than filling the airspace with RF waves.
The new Mode S and passive receive capability will be initially integrated on the Air Traffic, Navigation, Integration and Coordination System's host platform, and has applications for other air defense systems, Raytheon said.
Additional details of the new capabilities and contract modification were not disclosed.