Reduction of radar antenna area

Claim 1

A method for obtaining data about a body using pulsed signals reflected from the body in a range direction and in an azimuth direction, comprising: transmitting, toward the body, a predetermined sequence of sub-pulses, said sub-pulses transmitted at a rate that is at least a first predetermined repetition frequency; detecting, for each said sub-pulse, a corresponding sub-pulse reflection from the body; storing a plurality of data items, wherein said plurality of data items includes, for each said sub-pulse reflection, a related data item derived from said sub-pulse reflection; first sampling of said plurality of data items for obtaining a first series of data items; wherein, there is a first sub-pulse sequence, included in said predetermined sequence of sub-pulses, such that each sub-pulse of said first sub-pulse sequence has a corresponding sub-pulse reflection for which there is a related data item of said first series, and wherein said first sub-pulse sequence has a repetition frequency at least that of the first predetermined repetition frequency; second sampling of said plurality of data items for obtaining a second series of data items; wherein, there is a second sub-pulse sequence included in said predetermined sequence of sub-pulses, such that each sub-pulse of said second sub-pulse sequence has a corresponding sub-pulse reflection for which there is a related data item of said second series, and wherein said second sub-pulse sequence has a repetition frequency less than said first predetermined repetition frequency; providing one or more values related to said plurality of data items, wherein said one or more values have a reduction in sub-pulse reflection ambiguity; wherein said step of providing includes the following substeps (A1) and (A2): (A1) reducing, in the azimuth direction, an ambiguity in said one or more of values using said first sampling of said sub-pulse data items; (A2) reducing, in the range direction, an ambiguity in said one or more of values using said second sampling of said data items; using said one or more values having a reduced ambiguity for determining a characteristic of the body.

Claim 2

A method for obtaining data about a body using pulsed signals reflected from the body in a range direction and in an azimuth direction, comprising: transmitting, toward the body, a predetermined sequence of sub-pulses, said sub-pulses transmitted at a rate that is at least a first predetermined repetition frequency; detecting, for each said sub-pulse, a corresponding sub-pulse reflection from the body; storing a plurality of data items, wherein said plurality of data items includes, for each said sub-pulse reflection, a related data item derived from said sub-pulse reflection; first sampling of said plurality of data items for obtaining a first series of data items; wherein, there is a first sub-pulse sequence, included in said predetermined sequence of sub-pulses, such that each sub-pulse of said first sub-pulse sequence has a corresponding sub-pulse reflection for which there is a related data item of said first series, and wherein said first sub-pulse sequence has a repetition frequency at least that of the first predetermined repetition frequency; second sampling of said plurality of data items for obtaining a second series of data items; wherein, there is a second sub-pulse sequence included in said predetermined sequence of sub-pulses, such that each sub-pulse of said second sub-pulse sequence has a corresponding sub-pulse reflection for which there is a related data item of said second series, and wherein said second sub-pulse sequence has a repetition frequency less than said first predetermined repetition frequency; providing one or more values related to said plurality of data items, wherein said one or more values have a reduction in sub-pulse reflection ambiguity; wherein said step of providing includes the following substeps (A1) and (A2): (A1) reducing, in the azimuth direction, an ambiguity in said one or more of values using said first sampling of said sub-pulse data items; (A2) reducing, in the range direction, an ambiguity in said one or more of values using said second sampling of said data items; using said one or more values having a reduced ambiguity for determining a characteristic of the body.

Claim 13

A method for obtaining data about a body from a moving platform using pulsed signals reflected from the body in a range direction and in an azimuth direction, comprising: transmitting, toward the body, a sequence of sub-pulses from the platform wherein a consecutive plurality of said sub-pulses is transmitted within each pulse interval of a series of pulse intervals, so that the following conditions (A1), (A2) and (A3) are satisfied: (A1) said sub-pulses are transmitted at a rate that is at least a first predetermined repetition frequency; (A2) said pulse intervals repeat at a rate that is less than or equal to a second predetermined repetition frequency, said second predetermined repetition frequency being less than said first predetermined repetition frequency; and (A3) for each of said pulse intervals, a reflection from the body of at least one sub-pulse transmitted in the interval, wherein the reflection is distinguishable from every other body reflection of a sub-pulse from the pulse interval; detecting, for each transmitted said sub-pulse, an associated reflection of the sub-pulse from the body; storing a plurality of data items, wherein said plurality of data items includes, for each said associated reflection, a related data item derived from said associated reflection; determining one or more values for a given characteristic of the body by: (B1) using the related data item for each associated reflection of each sub-pulse of said sequence of sub-pulses to reduce azimuth ambiguity in said one or more values, and (B2) using said distinguishable reflections for reducing range ambiguity in said one or more values.

Claim 14

A method for obtaining data about a body from a moving platform using pulsed signals reflected from the body in a range direction and in an azimuth direction, comprising: transmitting, toward the body, a sequence of sub-pulses from the platform wherein a consecutive plurality of said sub-pulses is transmitted within each pulse interval of a series of pulse intervals, so that the following conditions (A1), (A2) and (A3) are satisfied: (A1) said sub-pulses are transmitted at a rate that is at least a first predetermined repetition frequency; (A2) said pulse intervals repeat at a rate that is less than or equal to a second predetermined repetition frequency, said second predetermined repetition frequency being less than said first predetermined repetition frequency; and (A3) for each of said pulse intervals, a reflection from the body of at least one sub-pulse transmitted in the interval, wherein the reflection is distinguishable from every other body reflection of a sub-pulse from the pulse interval; detecting, for each transmitted said sub-pulse, an associated reflection of the sub-pulse from the body; storing a plurality of data items, wherein said plurality of data items includes, for each said associated reflection, a related data item derived from said associated reflection; determining one or more values for a given characteristic of the body by: (B1) using the related data item for each associated reflection of each sub-pulse of said sequence of sub-pulses to reduce azimuth ambiguity in said one or more values, and (B2) using said distinguishable reflections for reducing range ambiguity in said one or more values.

Claim 21

A method for dimensioning an antenna for a moving platform, comprising: establishing a length at least as long as each pulse interval of a sequence of pulse intervals, said sequence having an interval repetition frequency effective for reducing, along a direction substantially transverse to a movement of the platform, a likelihood of correlating a reflection from a body of a signal pulsed in one of said pulse intervals with a reflection from the body of a signal pulsed in a different one of said pulse intervals; first determining a sequence of sub-pulse signals such that: (a) said sequence of said sub-pulse signals can be transmitted within said length, (b) for each said sub-pulse signal of said sequence of sub-pulse signals having a corresponding reflection from the body, the corresponding reflection is distinguishable from every other reflection from the body of said sub-pulse signals in said sequence of sub-pulse signals; and (c) the sub-pulse signals of said sequence of sub-pulse signals have a sub-pulse repetition frequency effective for reducing an ambiguity in detecting said corresponding reflections, along a direction substantially parallel to a movement of the platform, wherein the ambiguity relates to a bandwidth aliasing of said corresponding reflections; second determining an area for said antenna, said area being greater than or equal to a predetermined value, said predetermined value being inversely related to a predetermined number of sub-pulse signals within the sequence of sub-pulse signals.

Claim 22

A method for dimensioning an antenna for a moving platform, comprising: establishing a length at least as long as each pulse interval of a sequence of pulse intervals, said sequence having an interval repetition frequency effective for reducing, along a direction substantially transverse to a movement of the platform, a likelihood of correlating a reflection from a body of a signal pulsed in one of said pulse intervals with a reflection from the body of a signal pulsed in a different one of said pulse intervals; first determining a sequence of sub-pulse signals such that: (a) said sequence of said sub-pulse signals can be transmitted within said length, (b) for each said sub-pulse signal of said sequence of sub-pulse signals having a corresponding reflection from the body, the corresponding reflection is distinguishable from every other reflection from the body of said sub-pulse signals in said sequence of sub-pulse signals; and (c) the sub-pulse signals of said sequence of sub-pulse signals have a sub-pulse repetition frequency effective for reducing an ambiguity in detecting said corresponding reflections, along a direction substantially parallel to a movement of the platform, wherein the ambiguity relates to a bandwidth aliasing of said corresponding reflections; second determining an area for said antenna, said area being greater than or equal to a predetermined value, said predetermined value being inversely related to a predetermined number of sub-pulse signals within the sequence of sub-pulse signals.

Claim 28

A method for reducing ambiguity in reflections of signals transmitted from a moving platform, comprising: receiving a reflected signal in each interval of a predetermined series of intervals; obtaining a data item related to each of said reflected signals; providing interval and sub-pulse sampling frequencies, wherein each of said interval and sub-pulse sampling frequencies sample said data items at different frequencies; first using said data items sampled at said interval sampling frequency for reducing reflected signal ambiguity in a direction traverse to a direction of movement of the platform; second using said data items sampled at said sub-pulse sampling frequency for reducing ambiguity in said reflected signals along a direction coincident with the direction of movement of the platform.

Claim 29

A method for reducing ambiguity in reflections of signals transmitted from a moving platform, comprising: receiving a reflected signal in each interval of a predetermined series of intervals; obtaining a data item related to each of said reflected signals; providing interval and sub-pulse sampling frequencies, wherein each of said interval and sub-pulse sampling frequencies sample said data items at different frequencies; first using said data items sampled at said interval sampling frequency for reducing reflected signal ambiguity in a direction traverse to a direction of movement of the platform; second using said data items sampled at said sub-pulse sampling frequency for reducing ambiguity in said reflected signals along a direction coincident with the direction of movement of the platform.

Claim 32

An apparatus for imaging an area from a moving platform, comprising: transmitter means, on the platform, for transmitting a plurality of pulsed signals toward the area; first signal pulse controller means for determining a first sampling frequency for reducing range ambiguity of reflections of said pulsed signals wherein said range ambiguity is a function of an angle corresponding to signal propagation between the platform and the area in a direction traverse to a direction of movement of the platform; second signal pulse controller means for determining a second sampling frequency for reducing a reflected signal azimuth ambiguity in a direction coincident with the direction of movement of the platform; receiver means for receiving a reflection of one of said plurality of pulsed signals from the area in each interval of a predetermined series of intervals, said predetermined series having a repetition frequency of at least said second sampling frequency; storage means for storing a data item corresponding to each of a majority of said reflections; imaging means for determining a value for a location in the area, said value being a function of said data items; wherein said imaging means samples said data items at a rate no greater than said first sampling frequency for reducing a distortion in said value resulting from data items with corresponding reflected signals having signal range ambiguity; and wherein said imaging means samples said data items at a rate of at least said second sampling frequency for reducing a distortion in said resulting from data items with corresponding reflective signals having azimuth ambiguity.

Claim 33

An apparatus for imaging an area from a moving platform, comprising: transmitter means, on the platform, for transmitting a plurality of pulsed signals toward the area; first signal pulse controller means for determining a first sampling frequency for reducing range ambiguity of reflections of said pulsed signals wherein said range ambiguity is a function of an angle corresponding to signal propagation between the platform and the area in a direction traverse to a direction of movement of the platform; second signal pulse controller means for determining a second sampling frequency for reducing a reflected signal azimuth ambiguity in a direction coincident with the direction of movement of the platform; receiver means for receiving a reflection of one of said plurality of pulsed signals from the area in each interval of a predetermined series of intervals, said predetermined series having a repetition frequency of at least said second sampling frequency; storage means for storing a data item corresponding to each of a majority of said reflections; imaging means for determining a value for a location in the area, said value being a function of said data items; wherein said imaging means samples said data items at a rate no greater than said first sampling frequency for reducing a distortion in said value resulting from data items with corresponding reflected signals having signal range ambiguity; and wherein said imaging means samples said data items at a rate of at least said second sampling frequency for reducing a distortion in said resulting from data items with corresponding reflective signals having azimuth ambiguity.