This request for information (RFI) is for market research and planning purposes only and does not constitute a solicitation for proposals. Responses to this notice are not offers and cannot be accepted by the Government to form a binding contract. The purpose of this RFI is to identify sources capable of providing an airborne Direction Finding (DF) system. The information provided in this RFI is subject to change and is not binding on the Government. All submissions become Government property and will not be returned. The Government will not pay for information received in response to this RFI.