Radar system

Claim 2

A multiple stage pulse modifying filter having a time delay characteristic which is a function of frequency over a prescribed band of frequencies, each of said stages after the first having a time delay element connected in series with a bandpass filter, said first stage having a band pass filter, the respective input and output terminals of Each subsequent stage being coupled to the respective input and output terminals of the bandpass filter of the preceding stage, the widths of said pass bands each of said bandpass filters and the reciprocals of the time delays of each of said time delay elements being equal to the same quantity for insuring an in phase addition of components lying at the edges of said pass bands, the pass bands of the bandpass filters in adjoining stages intersecting at the one half gain point so as to provide continuous passage to waves lying between the frequency limits of said prescribed pass band.

Claim 3

A multiple stage pulse modifying filter having a time delay characteristic which is a function of frequency over a prescribed band of frequencies, each of said stages after the first having a time delay element connected in series with a bandpass filter, said first stage having a band pass filter, the respective input and output terminals of Each subsequent stage being coupled to the respective input and output terminals of the bandpass filter of the preceding stage, the widths of said pass bands each of said bandpass filters and the reciprocals of the time delays of each of said time delay elements being equal to the same quantity for insuring an in phase addition of components lying at the edges of said pass bands, the pass bands of the bandpass filters in adjoining stages intersecting at the one half gain point so as to provide continuous passage to waves lying between the frequency limits of said prescribed pass band.

Claim 4

A multiple stage pulse modifying filter having a time delay characteristic which is a function of frequency over a prescribed band of frequencies, each of said stages after the first having a time delay element connected in series with a bandpass filter, said first stage having a band pass filter, the respective input and output terminals of Each subsequent stage being coupled to the respective input and output terminals of the bandpass filter of the preceding stage, the widths of said pass bands each of said bandpass filters and the reciprocals of the time delays of each of said time delay elements being equal to the same quantity for insuring an in phase addition of components lying at the edges of said pass bands, the pass bands of the bandpass filters in adjoining stages intersecting at the one half gain point so as to provide continuous passage to waves lying between the frequency limits of said prescribed pass band.

Claim 5

A radar system comprising a source of short duration pulses of radio frequency waves, a multiple stage pulse modifying filter having a time delay characteristic which is a function of frequency of odd order symmetry about the center frequency of a prescribed band of frequencies, each of said stages after the first having a time delay element connected in series with a bandpass filter, said first stage having a bandpass filter, the respective input and output terminals of each subsequent stage being coupled to the respective input and output terminals of the bandpass filter of the preceding stage, the widths of said pass bands of each of said bandpass filters and the reciprocals of the time delays of each of said time delay elements being equal to the same quantity for insuring an in phase addition of components lying at the edges of said pass bands, the pass bands of the bandpass filters in adjoining stages intersecting at the one half gain point so as to provide substantially continuous passage to waves lying between the frequency limits of said prescribed pass band, the input terminal of said pulse modifying filter being coupled to said sources whereby pulses originating in said source are extended in duration in passing through said pulse modifying filter, means for amplifying said extended pulses and transmitting the same, means for receiving echoes of said transmitted pulses, means for inverting the frequency spectrum of said extended pulses about their center frequency, means for applying said received pulses to the input terminal of said filter for shortening the durations of said received pulses, and means coupled to said source and to the output of said filter for comparing the initial short duration pulses and the shortened received pulses.

Claim 6

A radar system comprising a source of short duration pulses of radio frequency waves, a multiple stage pulse modifying filter having a time delay characteristic which is a function of frequency of odd order symmetry about the center frequency of a prescribed band of frequencies, each of said stages after the first having a time delay element connected in series with a bandpass filter, said first stage having a bandpass filter, the respective input and output terminals of each subsequent stage being coupled to the respective input and output terminals of the bandpass filter of the preceding stage, the widths of said pass bands of each of said bandpass filters and the reciprocals of the time delays of each of said time delay elements being equal to the same quantity for insuring an in phase addition of components lying at the edges of said pass bands, the pass bands of the bandpass filters in adjoining stages intersecting at the one half gain point so as to provide substantially continuous passage to waves lying between the frequency limits of said prescribed pass band, the input terminal of said pulse modifying filter being coupled to said sources whereby pulses originating in said source are extended in duration in passing through said pulse modifying filter, means for amplifying said extended pulses and transmitting the same, means for receiving echoes of said transmitted pulses, means for inverting the frequency spectrum of said extended pulses about their center frequency, means for applying said received pulses to the input terminal of said filter for shortening the durations of said received pulses, and means coupled to said source and to the output of said filter for comparing the initial short duration pulses and the shortened received pulses.

Claim 7

A radar system comprising a first source of short duration pulses of radio frequency waves, a multiple stage pulse modifying filter having a time delay characteristic which is a function of frequency of odd order symmetry about the center frequency of a prescribed band of frequencies, each of said stages after the first having a time delay element, a balanced modulator, and a bandpass filter connected in series in the order recited, said first stage having a balanced modulator and a bandpass filter connected in series in the order recited, the respective input and output terminals of each subsequent stage being coupled to the respective input terminal of the balanced modulator and the output terminal of the bandpass filter of the preceding stage, the composite pass band of all said bandpass filters being selected to provide substantially continous passage to waves lying between the frequency limits of said prescribed pass band, a second source of radio frequency waves coupled to each of said balanced modulators, the input terminal of said pulse modifying filter being coupled to said first source whereby pulses originating in said source are extended in duration in passing through said pulse modifying filter, means for amplifying said extended pulses and transmitting the same, means for receiving echoes of said transmitted pulses, means for inverting the frequency spectrum of said extended pulses about their center frequency, means for applying said received pulses to the input terminal of said pulse modifying filter for shortening the duration of said received pulses, and means coupled to said first source and to the output of said filter for Comparing the initial short duration pulses and the shortened received pulses.

Claim 8

A radar system comprising a first source of short duration pulses of radio frequency waves, a multiple stage pulse modifying filter having a time delay characteristic which is a function of frequency of odd order symmetry about the center frequency of a prescribed band of frequencies, each of said stages after the first having a time delay element, a balanced modulator, and a bandpass filter connected in series in the order recited, said first stage having a balanced modulator and a bandpass filter connected in series in the order recited, the respective input and output terminals of each subsequent stage being coupled to the respective input terminal of the balanced modulator and the output terminal of the bandpass filter of the preceding stage, the composite pass band of all said bandpass filters being selected to provide substantially continous passage to waves lying between the frequency limits of said prescribed pass band, a second source of radio frequency waves coupled to each of said balanced modulators, the input terminal of said pulse modifying filter being coupled to said first source whereby pulses originating in said source are extended in duration in passing through said pulse modifying filter, means for amplifying said extended pulses and transmitting the same, means for receiving echoes of said transmitted pulses, means for inverting the frequency spectrum of said extended pulses about their center frequency, means for applying said received pulses to the input terminal of said pulse modifying filter for shortening the duration of said received pulses, and means coupled to said first source and to the output of said filter for Comparing the initial short duration pulses and the shortened received pulses.

Claim 9

A radar system comprising a first source of short duration pulses of radio frequency waves, a multiple stage pulse modifying filter having a time delay characteristic which is a function of frequency of odd order symmetry about the center frequency of a prescribed band of frequencies, each of said stages after the first having a time delay element, a balanced modulator, and a bandpass filter connected in series in the order recited, said first stage having a balanced modulator and a bandpass filter connected in series in the order recited, the respective input and output terminals of each subsequent stage being coupled to the respective input terminal of the balanced modulator and the output terminal of the bandpass filter of the preceding stage, the composite pass band of all said bandpass filters being selected to provide substantially continuous passage to waves lying between the frequency limits of said prescribed pass band, a second source of radio frequency waves coupled to each of said balanced modulators, the input terminal of said pulse modifying filter being coupled to said first source whereby pulses originating in said source are extended in duration in passing through said pulse modifying filter, an intermittently operated transmitter for amplifying said pulses and transmitting the same, means for receiving an echo of said transmitted pulses, means for inverting the frequency of said extended pulses about their center frequency, means for applying said received pulses to the input terminal of said pulse modifying filter for shortening the duration of said received pulses, means for interrupting the path between said receiving means and said filter input terminal for a time interval commencing before and extending throughout the duration of transmitter operation, the initial interruption preceding the initiation of transmission by a time approximately equal to the maximum delay of waves transmitted through said filter, and means coupled to said first source and to the output of said filter for comparing the initial short duration pulses and the shortened received pulses.

Claim 10

A radar system comprising a first source of short duration pulses of radio frequency waves, a multiple stage pulse modifying filter having a time delay characteristic which is a function of frequency of odd order symmetry about the center frequency of a prescribed band of frequencies, each of said stages after the first having a time delay element, a balanced modulator, and a bandpass filter connected in series in the order recited, said first stage having a balanced modulator and a bandpass filter connected in series in the order recited, the respective input and output terminals of each subsequent stage being coupled to the respective input terminal of the balanced modulator and the output terminal of the bandpass filter of the preceding stage, the composite pass band of all said bandpass filters being selected to provide substantially continuous passage to waves lying between the frequency limits of said prescribed pass band, a second source of radio frequency waves coupled to each of said balanced modulators, the input terminal of said pulse modifying filter being coupled to said first source whereby pulses originating in said source are extended in duration in passing through said pulse modifying filter, an intermittently operated transmitter for amplifying said pulses and transmitting the same, means for receiving an echo of said transmitted pulses, means for inverting the frequency of said extended pulses about their center frequency, means for applying said received pulses to the input terminal of said pulse modifying filter for shortening the duration of said received pulses, means for interrupting the path between said receiving means and said filter input terminal for a time interval commencing before and extending throughout the duration of transmitter operation, the initial interruption preceding the initiation of transmission by a time approximately equal to the maximum delay of waves transmitted through said filter, and means coupled to said first source and to the output of said filter for comparing the initial short duration pulses and the shortened received pulses.