"Regarding the change to the ship’s design affecting its primary radar,
the DDG-1000 originally was to have been equipped with a dual-band radar (DBR)
consisting of the Raytheon-built X-band SPY-3 multifunction radar (MFR) and
the Lockheed-built S-band SPY-4 Volume Search Radar (VSR).
(Raytheon is the prime contractor for the overall DBR.) Both parts of the DBR
have been in development for the past several years. An attachment to the June 1, 2010,
letter stated that, as a result of the program’s restructuring,
the ship is now to be equipped with “an upgraded multifunction radar [MFR] and no volume search radar [VSR].”
The change eliminates the Lockheed-built S-band SPY-4 VSR from the ship’s design.
The ship might retain a space and weight reservation that would permit
the VSR to be backfitted to the ship at a later point."
Navy DDG-51and DDG-1000 Destroyer Programs:
Background and Issues for Congress
Updated October 22, 2018