Time/bandwidth interchange system

Claim 2

In a pulsed sensor system wherein the target return signals consist of a series of chirp pulses extending over the time interval corresponding to the target swath to be mapped, the method of time/bandwidth interchange comprising the steps of: providing a constant-frequency pulse in response to each of said chirp pulses, offsetting each of said constant-frequency pulses in frequency linearly with range, delaying each of said offset constant-frequency pulses as a function of frequency, such that pulses from adjacent resolvable targets do not overlap in time, and rechirping said delayed, offset constant-frequency pulses into narrow-band chirp signals.

Claim 3

In the method of time/bandwidth interchange wherein wide-band frequency modulated pulses are converted to constant-frequEncy pulses each linearly offset in frequency in proportion to the time between wide-band pulses, the improvement comprising the steps of delaying each of said offset, constant-frequency pulses as a function of frequency such that succeeding delayed, offset constant-frequency pulses do not overlap in time, and mixing each of said delayed, offset constant-frequency pulses with a signal having a rate of frequency variation equal to the rate of change of said frequency function.

Claim 4

In the method of time/bandwidth interchange wherein wide-band frequency modulated pulses are converted to constant-frequEncy pulses each linearly offset in frequency in proportion to the time between wide-band pulses, the improvement comprising the steps of delaying each of said offset, constant-frequency pulses as a function of frequency such that succeeding delayed, offset constant-frequency pulses do not overlap in time, and mixing each of said delayed, offset constant-frequency pulses with a signal having a rate of frequency variation equal to the rate of change of said frequency function.

Claim 5

The combination with a source of wide-band pulsed signals having a predetermined rate of frequency modulation of a system comprising: means to provide a constant-frequency pulse in response to each of said pulsed signals and to offset each succeeding constant-frequency pulse from the former linearly in frequency by an amount proportional to the time between the pulsed signals, and means operatively connected to said last named means to delay said offset constant-frequency pulses as a function of frequency such that succeeding delayed, offset, constant-frequency pulses do not overlap in time.

Claim 6

The combination with a source of wide-band pulsed signals having a predetermined rate of frequency modulation of a system comprising: means to provide a constant-frequency pulse in response to each of said pulsed signals and to offset each succeeding constant-frequency pulse from the former linearly in frequency by an amount proportional to the time between the pulsed signals, and means operatively connected to said last named means to delay said offset constant-frequency pulses as a function of frequency such that succeeding delayed, offset, constant-frequency pulses do not overlap in time.

Claim 7

The combination set forth in claim 3 further comprising means operatively connected to said delay means to provide narrow-band pulsed signals from said delayed, offset, constant-frequency pulses.

Claim 8

The combination set forth in claim 4 wherein said narrow-band pulses providing means comprises second oscillator means having a rate of frequency variation equal to the rate of change of the frequency function of said delay means, and second mixer means to mix the output of said second oscillator means with said delayed, offset constant-frequency pulses.

Claim 9

The combination set forth in claim 3 wherein said constant-frequency pulse providing means comprises oscillator means having a rate of frequency variation equal to said predetermined rate of frequency modulation, and mixer means to mix the output of said oscillator means with said wide-band pulsed signals, thereby providing said offset constant-frequency pulses.

Claim 10

In a pulsed sensor system including transmitter means for generating a chirp output pulse of a predetermined length and slope and receiver means for receiving a number of target response chirp pulses for each transmitted pulse, the time between said transmitted pulse and said target response pulses being proportional to the range of the targets, a time/bandwidth interchange system which reduces the frequency bandwidth of said target response pulses by time-expansion of the information contained therein, said time/bandwidth interchange system comprising, in combination: input means operatively connected to said receiver means, first mixer means operatively connected to said input means to provide constant-frequency response pulses from said target response pulses, each of said constant-frequency response pulses being offset in frequency linearly with range, dispersive delay means operatively connected to said first mixer means to delay said offset, constant-frequency response pulses as a function of frequency such that delayed, offset, constant-frequency response pulses from adjacent resolvable targets do not overlap in time, and second mixer means operatively connected to said dispersive delay means to provide narrow-band chirp pulses from said delayed, offset, constant-frequency response pulses.

Claim 11

In a pulsed sensor system including transmitter means for generating a chirp output pulse of a predetermined length and slope and receiver means for receiving a number of target response chirp pulses for each transmitted pulse, the time between said transmitted pulse and said target response pulses being proportional to the range of the targets, a time/bandwidth interchange system which reduces the frequency bandwidth of said target response pulses by time-expansion of the information contained therein, said time/bandwidth interchange system comprising, in combination: input means operatively connected to said receiver means, first mixer means operatively connected to said input means to provide constant-frequency response pulses from said target response pulses, each of said constant-frequency response pulses being offset in frequency linearly with range, dispersive delay means operatively connected to said first mixer means to delay said offset, constant-frequency response pulses as a function of frequency such that delayed, offset, constant-frequency response pulses from adjacent resolvable targets do not overlap in time, and second mixer means operatively connected to said dispersive delay means to provide narrow-band chirp pulses from said delayed, offset, constant-frequency response pulses.

Claim 12

The time/bandwidth interchange system set forth in claim 7 wherein said first mixer means comprises a first swept oscillator whose output frequency varies at a rate equal to said predetermined slope during the time associated with the range of the target swath to be mapped and a first mixer circuit to mix the output of said first swept oscillator with said amplified target response chirp pulses, and wherein said second mixer means comprises a second swept oscillator whose output frequency varies at a rate equal to the rate of change of the frequency function of said delay means and a second mixer circuit to mix said delayed, offset, constant-frequency responsE pulses with the output of said second swept oscillator.

Claim 13

The time/bandwidth interchange system set forth in claim 7 wherein said input means includes gate circuit means to gate target response pulses to said first mixer means only during the time associated with the target swath to be mapped.

Claim 14

The time/bandwidth interchange system set forth in claim 7 wherein said input means includes dispersive delay means to stretch said target response chirp pulses in time linearly with frequency.

Claim 15

The time/bandwidth interchange system as set forth in claim 7 wherein said dispersive delay means includes delay line means having a delay that is a function of frequency, the input of said delay line means being connected to receive said offset constant-frequency response pulses, means coupling the output of said delay line means to the input thereof, thereby causing said pulses to be repeatedly passed through said delay line means, and means extracting said pulses after a predetermined number of passes through said delay line means.

Claim 16

The time/bandwidth interchange system as set forth in claim 11 wherein said coupling means includes non-dispersive, fixed delay means.

Claim 17

The time/bandwidth interchange system set forth in claim 7 wherein said dispersive delay means includes: a first number of dispersive delay lines, and a second number of oscillator/mixer circuits each electrically disposed between said first mixer means and one of said delay lines, whereby the output of said first mixer means is divided among said dispersive delay lines by said oscillator/mixer circuits sequentially according to the frequency of said output.

Claim 18

The time/bandwidth interchange system set forth in claim 13 wherein said second number is one less than said first number.

Claim 19

The time/bandwidth interchange system set forth in claim 13 wherein each of said oscillator/mixer circuits includes a constant-frequency oscillator.

Claim 20

The time/bandwidth interchange system set forth in claim 7 wherein said first mixer means comprises a number of oscillator/mixer circuits which are sequentially activated during the course of the mapped swath, each of said circuits being activated at least one time, and wherein said dispersive delay means comprises a number of dispersive delay lines equal to said number of oscillator/mixer circuits each of which delay lines is electrically disposed between a corresponding oscillator/mixer circuit and said second mixer means.

Claim 21

The time/bandwidth interchange system set forth in claim 16 wherein said second mixer means comprises a number of second mixer/oscillator circuits equal in number to said number of dispersive delay lines, each of said second mixer/oscillator circuits being disposed to provide narrow-band chirp pulses from the output of one of said delay lines.

Claim 22

The time/bandwidth interchange system set forth in claim 7 wherein said dispersive delay means includes a plurality of dispersive delay lines connected in series between said first and second mixer means.

Claim 23

The time/bandwidth interchange system set forth in claim 18 wherein said dispersive delay means further includes amplification means electrically inserted between each of said plurality of dispersive delay lines.