# US 2013/0278455 A1 · Efficient pulse doppler radar with no blind ranges, range ambiguities, blind speeds, or doppler ambiguities > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0278455 A1 - Document ID: US20130278455A1 - Status: Published application - Kind: A1 - Application number: 13/453,195 - Filed: 2012-04-23 - Published: 2013-10-24 - Earliest claimed: 2012-04-23 - Assignees: Massachusetts Institute of Technology - Inventors: William S. Song - Web page: https://patentgrep.com/patent/US20130278455A1 ## CPC - G01S 13/22: using irregular pulse repetition frequency {(G01S13/12 takes precedence)} - G01S 13/288: {phase modulated} - G01S 13/582: {adapted for simultaneous range and velocity measurements} - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES ## Abstract A Doppler radar system that avoids blind ranges, range ambiguities, blind speed and/or Doppler ambiguities. Pulse width, repetition interval and pulse type are varied from pulse to pulse within a coherent processing interval. ## Claims ### Claim 1 A method of determining range information for a target comprising: generating a pulse signal comprising a train of transmit pulses, the transmit pulses having a pulse width, pulse waveform, and pulse repetition interval (PRI), at least two of which are each different for at least two consecutive pulses within the train of transmit pulses for a given Coherent Processing Interval (CPI), with the CPI defined by a set of transmit pulses in the train having a deterministic phase relationship of a reference frequency used to generate consecutive pulses; transmitting the pulse signal; receiving a return signal in response to transmitting; and range processing the return signal to determine range information for the target. ### Claim 2 (depends on 1) The method of claim 1 wherein range processing further comprises: Doppler processing the return signal at two or more Doppler offsets. ### Claim 3 (depends on 1) The method of claim 1 wherein the pulse width, pulse waveform, and pulse repetition interval are selected to provide equal energy in the return signal for different target ranges. ### Claim 4 (depends on 3) The method of claim 3 wherein the CPI is divided into a plurality of time bins of a selected bin duration, and the transmit and receive pulse periods are integer multiples of the selected bin duration. ### Claim 5 (depends on 1) The method of claim 1 wherein the CPI is further divided into transmit pulse periods and receive pulse periods, with the transmit and receive pulse periods of arbitrary length within a CPI, but also such that a total transmit duty cycle, D, is uniform from CPI to CPI. ### Claim 6 (depends on 5) The method of claim 5 wherein the arbitrary length is deterministic. ### Claim 7 (depends on 5) The method of claim 5 wherein the arbitrary length is pseudorandom. ### Claim 8 (depends on 5) The method of claim 5 wherein the arbitrary length is determined by an arithmetic algorithm. ### Claim 9 (depends on 1) The method of claim 1 wherein the pulse width and PRI are of arbitrary length, but with a constant duty cycle D achieved over a substantial set of consecutive transmit pulses within a CPI. ### Claim 10 (depends on 1) The method of claim 1 further comprising: radio frequency modulating the pulse signal prior to transmitting such that at least two successive pulses within the pulse train have different modulation; and radio frequency demoduling the return signal prior to range processing. ### Claim 11 (depends on 1) The method of claim 1 wherein transmit pulse width, pulse waveform, and pulse repetition interval (PRI) are each different for at least two consecutive pulses within a given Coherent Processing Interval (CPI). ### Claim 12 (depends on 1) The method of claim 1 wherein the different waveform comprises a random waveform, different coding, or different modulation for the at least two consecutive pulses. ### Claim 13 An apparatus comprising: a pulse train signal generator, for generating a pulse signal comprising a train of transmit pulses, the transmit pulses having at least two of a pulse width, pulse waveform, and pulse repetition interval (PRI) that are each different for at least two consecutive pulses within the train of transmit pulses for a given Coherent Processing Interval (CPI), with the CPI defined by a set of transmit pulses in the train having a deterministic phase relationship of a reference frequency used to generate consecutive pulses; a transmitter for transmitting the pulse signal; a receiver for receiving a return signal; and a range processor, for processing the return signal to determine range information for the target. ### Claim 14 (depends on 13) The apparatus of claim 13 wherein the range processor further comprises: a Doppler processor comprising two or more Doppler offset sections. ### Claim 15 (depends on 13) The apparatus of claim 13 wherein the pulse width, pulse waveform, and pulse repetition interval are selected provide equal energy in the return signal for different target ranges. ### Claim 16 (depends on 15) The apparatus of claim 15 wherein the CPI is divided into a plurality of time bins of a selected bin duration, and the transmit and receive pulse periods are integer multiples of the selected bin duration. ### Claim 17 (depends on 13) The apparatus of claim 13 wherein the CPI is further divided into transmit pulse periods and receive pulse periods, with the transmit and receive pulse periods of arbitrary length within a CPI, but also such that a total transmit duty cycle, D, is uniform from CPI to CPI. ### Claim 18 (depends on 17) The apparatus of claim 17 wherein the arbitrary length is deterministic. ### Claim 19 (depends on 17) The apparatus of claim 17 wherein the arbitrary length is pseudorandom. ### Claim 20 (depends on 17) The apparatus of claim 17 wherein the arbitrary length is determined by an arithmetic algorithm. ### Claim 21 (depends on 15) The apparatus of claim 15 wherein the pulse width and PRI are of arbitrary length, but with a constant duty cycle D achieved over a substantial set of consecutive transmit pulses within a CPI. ### Claim 22 (depends on 15) The apparatus of claim 15 further comprising: a radio frequency modulator, for modulating the pulse signal such that at least two successive pulses within the transmitted pulse train have different modulation; and a radio frequency demodulator, for demodulating the return signal. ### Claim 23 (depends on 13) The apparatus of claim 13 wherein transmit pulse width, pulse waveform, and PRI are each different for at least two consecutive pulses within a given CPI. ### Claim 24 (depends on 13) The apparatus of claim 13 wherein the different pulse waveform comprises a signal with random properties, different coding, and/or different modulation for the at least two consecutive pulses within a CPI.