Narrow band frequency modulated jammer

Claim 1

A narrow band frequency modulated jamming device comprising: a. a noise source generating means for generating a noise frequency, b. a low-pass filter connected in circuit to the output of said noise source generating means for removal of all frequencies above 500 Hz, c. a variable gain amplifier connected in circuit to the output side of said low-pass filter, the gain of said amplifier being adjusted to produce a predetermined narrow bandwidth of noise and d. a traveling-wave tube, having an input receiving means, an output transmitting means and a helix, said traveling-wave tube being coupled at the helix via a capacitor to the output side of said variable gain amplifier, said capacitor blocking any D.C. component of said variable gain amplifier, the gain of said amplifier having critical gain control adjustment for applying a predetermined modulation voltage to said helix required to shift the phase of the output signal of the traveling-wave tube by approximately 360* from what it would be if modulation were not applied to the helix, said gain control being adjusted until the repeat of the input signal disappears and only signals produced by the modulation are present, e. said traveling-wave tube utilizing a narrow band of the noise frequency generated by said noise generator means to modulate the input signal received on the input receiving means of said traveling-wave tube for retransmission as a jamming signal, the output transmitting means of the traveling-wave tube being characterized by a very narrow RF bandwidth and good carrier suppression, wherein the jamming device appears as clutter to a system being jammed.

Claim 4

A method of jamming active and semi-active missiles of the type vulnerable to narrow band F.M. jamming by retransmitting a signal received on a traveling-wave tube, having input receiving means, output transmitting means and a helix, after modulating it with a narrow band of low frequency noise containing no repeat of the input signal applied to the helix of the traveling-wave tube at that voltage level which shifts the phase of the signal at the output transmitting means of the traveling-wave tube by approximately 360* from what it would have been if modulation were not applied at the helix of the traveling-wave tube and which appears as clutter to the missile being jammed.

Claim 5

A method of jamming active and semi-active missiles of the type vulnerable to narrow band F.M. jamming by retransmitting a signal received on a traveling-wave tube, having input receiving means, output transmitting means and a helix, after modulating it with a narrow band of low frequency noise containing no repeat of the input signal applied to the helix of the traveling-wave tube at that voltage level which shifts the phase of the signal at the output transmitting means of the traveling-wave tube by approximately 360* from what it would have been if modulation were not applied at the helix of the traveling-wave tube and which appears as clutter to the missile being jammed.