TECHNIQUE FOR FREQUENCY-HOPPED SPREAD SPECTRUM COMMUNICATIONS

Abstract

A countermeasure to a partial-band follower jammer for frequency hopping spread spectrum communication systems employs an M-ary orthogonal frequency shift keyed (FSK) signaling system having q frequency channels available for hopping. During each signaling interval, the transmitter and receiver operate in either a conventional or unconventional mode. The conventional mode is selected by the transmitter and the receiver with a pseudorandom probability pc. In this mode, the transmitter transmits one of r tones within the corresponding hop (i.e., within one of q channels), and log2 r information bits are conveyed, while the receiver comprises a dehopper followed by noncoherent matched filters. The unconventional mode is selected with probability 1-pc. In this mode, the transmitter randomly chooses one of the r tones and transmits it in one of r channels within each hop, where the r channels are selected pseudorandomly. In the unconventional mode, log2 r information bits are transmitted and the receiver comprises a bank of r radiometers.

Source: Google Patents

35 USC §181 Secrecy Order

Inventor

• 1JOHN E. HERSHEY