FM/chirp detector/analyzer and method

A method for detecting frequency-modulated signals whose frequencies are swept at chirp rates, the method comprising:

• A. generating translated signals by translating input signals by a frequency difference that is repeatedly swept linearly at a first sweep rate;
• B. delaying the translated signals to produce delayed signals that are delayed versions of the translated signals in which the delay depends on the frequency component being delayed, the difference in delay for a given frequency difference being substantially the negative of the frequency difference divided by the first sweep rate;
• and
• C. responsive to the delayed translated signals, generating an output signal proportional to the instantaneous frequency of the translated signal, the time rate of change of an output signal component thereby indicating the chirp rate of the frequency-modulated signal component that gave rise to it.

Apparatus for indicating frequency range and any chirp rate of a signal, comprising:

• first means, adapted to receive a first signal being measured, for generating in response to the first signal, a second signal whose time of occurrence, relative to a repetitive preset time-frame, depends on the frequency of the first signal;
• and
• second means, operatively receiving the second signal, for generating a third signal representative of the instantaneous frequency of the second signal,
• whereby a third signal is produced whose time of occurrence, relative to the repetitive preset time-frame, indicates the frequency range of the first signal, and whose rate of change within the time-frame is indicative of any chirp rate of the first signal.

Method of indicating frequency range and any chirp rate of a signal, the method comprising the steps of:

• responsive to a first signal being measured, generating a second signal whose time of occurrence, relative to a repetitive preset time-frame, depends on the frequency of the first signal;
• and
• responsive to the second signal, generating a third signal representative of the instantaneous frequency of the second signal,
• whereby a third signal is produced whose time of occurrence, relative to the repetitive preset time-frame, indicates the frequency range of the first signal, and whose rate of change within the time-frame is indicative of any chirp rate of the first signal.

Apparatus for detecting frequency-modulated signals whose frequencies are swept at chirp rates, the apparatus comprising:

• a bandpass filter receiving a first signal for producing a second signal;
• first means, receiving the second signal, for translating the frequency of the first signal by a repetitively varying amount to produce a third signal;
• a weighting filter receiving the third signal for producing a fourth signal;
• a dispersive delay line receiving the fourth signal for producing a fifth signal;
• a frequency discriminator receiving the fifth signal for producing a sixth signal representing the instantaneous frequency of the fifth signal,
• wherein the rate of change of the sixth signal indicates any chirp rate of the first signal;
• a differentiator receiving the sixth signal for producing a seventh signal representing the rate of change of the sixth signal;
• and
• processing means receiving the seventh signal for producing an eighth signal representative of -k.sup.2 /(k"+k) wherein k is the repetition rate of said first means and k" is the rate of change of the sixth signal.