USRE49132E1 - Radar altimeter - Google Patents
Radar altimeter Download PDFInfo
- Publication number
- USRE49132E1 USRE49132E1 US17/006,350 US202017006350A USRE49132E US RE49132 E1 USRE49132 E1 US RE49132E1 US 202017006350 A US202017006350 A US 202017006350A US RE49132 E USRE49132 E US RE49132E
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- US
- United States
- Prior art keywords
- signal
- radar system
- noise ratio
- frequency
- preselected
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- 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
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/88—Radar or analogous systems specially adapted for specific applications
- G01S13/882—Radar or analogous systems specially adapted for specific applications for altimeters
-
- G—PHYSICS
- G01—MEASURING; TESTING
- 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
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
-
- G—PHYSICS
- G01—MEASURING; TESTING
- 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
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
- G01S7/40—Means for monitoring or calibrating
- G01S7/4004—Means for monitoring or calibrating of parts of a radar system
- G01S7/4008—Means for monitoring or calibrating of parts of a radar system of transmitters
-
- G—PHYSICS
- G01—MEASURING; TESTING
- 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
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
- G01S2013/0236—Special technical features
- G01S2013/0281—LPI, Low Probability of Intercept radar
Definitions
- the radar altimeter of the present invention is one which maintains a signal to noise level below a value which affords detection by an intercept receiver.
- Radar altimeters are well known. In order to provide covert operation, i.e. not detectable by an intercept receiver, the radar signal should be a minimum to reduce the chances of radar detection by the intercept receiver.
- the novel radar system of the present invention provides a radar altimeter which operates near the oxygen absorption line.
- the frequency of the transmitter is adjusted in accordance with a measurement of the signal to noise ratio of a preselected range bin (return signal) thereby minimizing detection by an intercept receiver.
- FIG. 1 is a graphical representation of signal absorption versus frequency.
- FIG. 2 is a diagrammatic representation of intercept receiver signal to noise ratio versus range measured from the transmitter.
- FIG. 3 is a block diagram of one embodiment of the invention of the present application.
- FIG. 1 As shown in FIG. 1 , atmospheric attenuation of a radar signal is near a maximum when the transmitter frequency is at 60 GHz. It should be noted that FIG. 1 is presented as a representation and is not intended to be a detailed and exact graph of frequency versus absorption. Nevertheless, it can be seen that a change of 8 DB/KM (one way) attenuation occurs by changing the radar frequency from 53 GHz to 57 GHz. Thus, large changes in attenuation are obtainable from small variations in the transmitter frequency, i.e. 4 GHz.
- FIG. 2 shows a diagrammatic representation of intercept receiver signal noise ratio versus range from the transmitter.
- FIG. 2 illustrates the differences between signal noise ratio for microwave signals 20 and GHz signals 25 .
- a constant signal to noise ratio of 15 DB line is shown on the graph.
- a microwave transmitter can be detected at 15 dB signal to noise ratio at 800 K feet. However, at a frequency in the order of 55 GHz, this detection range is reduced to about 60 K feet (10 nautical miles).
- the intercept receiver range reduces to less than 20 K feet. In other words, the intercept detection range is reduced by over 40 times as compared with a microwave system.
- Oscillator 300 provides a carrier signal to be transmitted by transmitter 305 for subsequent transmission through antenna 310 via duplexer 315 .
- Oscillator 300 includes a control input 301 to vary the carrier signal frequency to some extent.
- the radar system shown in FIG. 3 is an altimeter.
- Altimeter return signals are received by antenna 310 and processed through duplexer 315 which feeds receiver 320 .
- the output from receiver 320 is fed into signal-to-noise detector 340 .
- the output of detector 340 is presented to a hold circuit 342 for holding the value of the signal-to-noise ratio upon a predetermined bin selection provided by the output of bin selector 345 .
- the output of hold circuit 342 is then presented as one input to comparator 350 .
- Comparator 350 compares the output of hold circuit 342 to a preselected reference level input.
- the comparator provides an output signal to integrator 360 which integrates the output signal of comparator 350 .
- the output of integrator 360 is then presented to the control input 301 of oscillator 300 for adjusting the oscillation frequency, i.e. the carrier frequency in proportion to the output of integrator 360 .
- the reference signal is a signal representative of a predetermined acceptable signal-to-noise ratio which affords only limited detection by an intercept receiver at a predetermined range.
- Oscillator 300 provides a signal in the order of, for example, 55 GHz which is subsequently transmitted over antenna 310 through transmitter 305 and duplexer 315 .
- Return signals, in time, are operated on by receiver 320 for usual altimeter range determination.
- Receiver 320 provides the usual amplification and detection circuits necessary for standard altimeters.
- An output of receiver 320 is provided to detector 340 which provides signal-to-noise detection in the usual manner well known in the art of radio signals.
- the output of detector 340 a signal indicative of the signal-to-noise ratio, is presented to hold circuit 342 which will hold the value of the signal-to-noise detector 340 when the holding circuit 342 is gated by bin selector 345 . Gating occurs upon a predetermined range which usually would be the maximum range desired in the operating system.
- the output of the holding circuit 342 is then presented to comparator 350 which is compared with the reference signal indicative of the preselected acceptable signal to noise ratio.
- the output of the comparator is then integrated via integrator 360 and presented to the adjustable oscillator 300 for adjusting the oscillation so as to increase or decrease as the case may be to maintain the preselected signal to noise ratio.
- the combination of comparator 350 and integrator 360 provides a negative feedback control means so as to maintain the signal-to-noise ratio as aforesaid.
- FIG. 2 is applicable to a wide range of radar systems including FM/CW, pulsed radar systems, and the like. Such systems are envisioned to be within the scope of the present application and are diagrammatically represented by a transmitter block 305 . Similarly, dependent upon the system employed, receiver 320 is constructed in the manner to be compatible with the method of transmission by transmitter 305 .
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- Engineering & Computer Science (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Physics & Mathematics (AREA)
- Computer Networks & Wireless Communication (AREA)
- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Radar Systems Or Details Thereof (AREA)
Abstract
Description
Claims (20)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US17/006,350 USRE49132E1 (en) | 1984-01-20 | 2020-08-28 | Radar altimeter |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US06/572,286 US10488511B1 (en) | 1984-01-20 | 1984-01-20 | Radar altimeter |
US17/006,350 USRE49132E1 (en) | 1984-01-20 | 2020-08-28 | Radar altimeter |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US06/572,286 Reissue US10488511B1 (en) | 1984-01-20 | 1984-01-20 | Radar altimeter |
Publications (1)
Publication Number | Publication Date |
---|---|
USRE49132E1 true USRE49132E1 (en) | 2022-07-12 |
Family
ID=68617682
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US06/572,286 Ceased US10488511B1 (en) | 1984-01-20 | 1984-01-20 | Radar altimeter |
US17/006,350 Active USRE49132E1 (en) | 1984-01-20 | 2020-08-28 | Radar altimeter |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US06/572,286 Ceased US10488511B1 (en) | 1984-01-20 | 1984-01-20 | Radar altimeter |
Country Status (1)
Country | Link |
---|---|
US (2) | US10488511B1 (en) |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3098225A (en) * | 1961-06-20 | 1963-07-16 | Litton Systems Inc | Measuring process |
US3381292A (en) * | 1965-11-01 | 1968-04-30 | Army Usa | Radar detection system |
US3522605A (en) * | 1962-09-20 | 1970-08-04 | Us Navy | Mti radar low-power hardening |
-
1984
- 1984-01-20 US US06/572,286 patent/US10488511B1/en not_active Ceased
-
2020
- 2020-08-28 US US17/006,350 patent/USRE49132E1/en active Active
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3098225A (en) * | 1961-06-20 | 1963-07-16 | Litton Systems Inc | Measuring process |
US3522605A (en) * | 1962-09-20 | 1970-08-04 | Us Navy | Mti radar low-power hardening |
US3381292A (en) * | 1965-11-01 | 1968-04-30 | Army Usa | Radar detection system |
Non-Patent Citations (4)
Title |
---|
Schlesinger et al, Principles of Electronic Wafare, 1961 by Prentice-Hall, p. 144. * |
Schlesinger et al., "Principles of Electronic Warfare", Prentice-Hall, Inc., 1961, 4 Pages, Englewood Cliffs, New Jersey. |
U.S. Patent and Trademark Office, "Notice of Allowance", U.S. Appl. No. 06/572,286, dated May 28, 2019, pp. 1-6, Published: US. |
U.S. Patent and Trademark Office, "Office Action", U.S. Appl. No. 06/572,286, dated Aug. 5, 1986, pp. 1-4, Published: US. |
Also Published As
Publication number | Publication date |
---|---|
US10488511B1 (en) | 2019-11-26 |
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Free format text: ENTITY STATUS SET TO UNDISCOUNTED (ORIGINAL EVENT CODE: BIG.); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
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Owner name: HONEYWELL INC., MINNESOTA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:RINGDAHL, ROBERT M.;REEL/FRAME:053641/0681 Effective date: 19840117 Owner name: HONEYWELL INTERNATIONAL INC., NORTH CAROLINA Free format text: MERGER AND CHANGE OF NAME;ASSIGNORS:HONEYWELL INC.;HONEYWELL INTERNATIONAL INC.;REEL/FRAME:053641/0830 Effective date: 20020630 |
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