Introduction to RADAR by NI

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NI AWR Design Environment Radar Design Solutions

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NI AWR Design Environment - At a Glance

Fully Integrated Design Platform

Microwave Office - MMIC, RF PCB and module circuit design

Visual System Simulator – RF/Communications/Radar systems design

AXIEM - 3D planar electromagnetic (EM) analysis

Analyst - 3D finite element method (FEM) EM analysis

Analog Office - Analog/RFIC circuit design

NEW: AntSyn – Antenna synthesis and optimization

Global Presence (Sales & support office loations)

California, Wisconsin, Colorado, Massachusetts

United Kingdom, Finland, France and Germany

Japan, Korea, Taiwan, China and Australia

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Visual System Simulator for Radar Design VSS provides detailed behavioral modeling of the RF and signal processing

of a radar system, including simulated or measured 3D antenna patterns

Features at a Glance

• Models include : RF components, Signal

processing and antenna models

• Signal processing blocks

• Moving target indicator (MTI)

• Moving target detection (MTD)

• Constant false alarm rate (CFAR)

• Antenna model

• Accept gain pattern

• Phased array element

• Channel model

• Doppler

• Clutter

• Target model

• Radar cross section (RCS)

• Radar signal generators

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Visual System Simulator for Radar Design • Supports signal processing algorithm modeling and debugging languages

such as C++, LabVIEW, MATLAB and VBA

• Frequency domain simulation provides

• Budget, line-up and spurious analyses for RF architectures

• Target detection

• Antenna and phased array models based on 3D and planar EM simulators or

data from range measurements

• LabVIEW compatability

Transmitter

Receiver

Pulse

Generator

Signal

Processing

Antenna LO Target

LabVIEW or VSS VSS (SW) or PXI (HW)

VSS VSS

LabVIEW or VSS VSS (SW) or PXI (HW)

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Design-to-Deployment With NI

FURUNO: First Pass Success

The Challenge:

Designed to predict weather and monitor hurricanes and rain fronts, weather

radar systems can be large in size. FURUNO set out to develop a compact,

low-cost weather radar system with flexibility in the signal-processing unit to

accommodate various potential design changes, incorporating a way to verify

the system-level performance by co-simulating the digital and analog

sections.

The Solution:

Adopting the NI platform to take advantage of the co-simulation capability

between Visual System Simulator (VSS) and LabVIEW software allowed us to

realize the system-level simulation of digital and analog sections together.

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Learn More…

Online

• ni.com/awr

• awr.tv

Email

• [email protected]

Bullock Engineering Research Copyright 2013

8

Introduction to RADAR Presented For Besser Associates, Inc.

By

Scott R. Bullock Instructor, Besser Associates

www.BesserAssociates.com


9


Scott R. Bullock [email protected]

• BSEE BYU, MSEE U of U, PE, 19 US Patents, 23 Trade Secrets

• Books & Publications

– “Transceiver and System Design for Digital Communications”, 4th edition

• http://iet.styluspub.com/Books/BookDetail.aspx?productID=395134

• http://www.theiet.org/resources/books/telecom/tsddcfe.cfm

– “Broadband Communications and Home Networking”

• http://sci.styluspub.com/Books/BookDetail.aspx?productID=369239

• http://digital-library.theiet.org/content/books/te/sbte002e

– Multiple Articles in Microwaves & RF, MSN

• Seminars - Raytheon, L-3, Thales, MKS/ENI, CIA, NASA, Titan, Phonex, NGC, Others

– Courses for Besser Associates

• Introduction to RADAR - http://www.besserassociates.com/outlinesOnly.asp?CTID=253

• Transceiver and Systems Design for Digital Communications, Radar, and Cognitive Processes – new 5-day course

• http://www.besserassociates.com/Courses/Course-Description/CTID/260 - Includes Directional Volume Search, Acquisition, Track

• Introduction to Wireless Communications Systems - http://www.bessercourse.com/outlinesOnly.asp?CTID=235

• Transceiver and Systems Design for Digital Communications - http://www.bessercourse.com/outlinesOnly.asp?CTID=208

• Cognitive Radios, Networks, and Systems for Digital Communications - http://www.bessercourse.com/outlinesOnly.asp?CTID=251

• College Instructor

– Graduate Presentation on Multiple Access to Polytechnic, Farmingdale//Brooklyn, NY

– Advanced Communications, ITT

– Engineering 201E, PIMA

• Key Designs

– Radar Simulator for NWS China Lake – Acquisition, Target Tracking, Missile Tracking, MTI

– Navy’s Integrated Topside INTOP – Integrate Radar with EW, EA, Comms

– Radar Communications using CP-PSK Modulated Pulses for the SPY-3 Radar and PCM/PPM


10


RAdio Detecting And Ranging

RADAR

RADAR is a method of using electromagnetic waves to

determine the position (range and direction), velocity

and identifying characteristics of targets.


11


Radar Applications

• Military – Search and Detection

– Targeting and Target Tracking

– Missile Guidance

– Fire Control – Acquisition, Track

– Airborne Intercept

– Ground and Battle field Surveillance

– Air Mapping Systems

– Submarine and Sub-Chasers

• Commercial – Weather, Navigation, Air Traffic Control

– Space and Range

– Road and Speeding

– Biological Research – Bird and Insect Surveillance and Tracking

– Medical – diagnosis, organ movements, water condensation in the lungs, monitor heart

rate and pulmonary motion, range(distance), remote sensor of heart and respiration

rates without electrodes, patient movement and falls in the home

– Miniature – Seeing aids, early warning collision detection and situational awareness


12


Two Basic Radar Types

• Pulse Radar

– Transmits a pulse stream with a low duty cycle

– Receives reflected pulses during the time off or dead time between pulses

– Single Antenna

– Determines Range and Altitude

– Susceptible To Jamming

– Physical Range Determined By PW and PRF

– Low average power

– Time synchronization

• Continuous Wave CW Radar

– Transmits a CW signal and receives a Doppler frequency for moving targets

– Frequency Modulated CW FM-CW also provides both range and velocity

– Requires 2 Antennas and high SNR

– More Difficult to Jam But Easily Deceived

– Simpler to operate, timing not required


13


Pulsed Radar

• Most radar systems are pulsed

• Transmit a pulse and then listen for receive signals, or echoes

• Avoids problem of a sensitive receiver simultaneously operating

with a high power transmitter.

• Radar transmits a low duty cycle, short duration high-power RF-

pulses

• Time synchronization between the transmitter and receiver of a

radar set is required for range measurement.

• Returns that come from the 1st pulse causes distortion in the

returns after the next pulse


14


Radar Modulation

• 100% Amplitude Modulation AM, ON/OFF keying

– Turns on/off a carrier frequency

• Pulse Width PW amount of time that the radar is on for one

pulse

– Determines the minimum range resolution

• Pulse Repetition Frequency PRF = number of pulses per

second

• Pulse Repetition Interval PRI is the time between the start of the

pulses

• Pulse Repetition Time PRT = Pulse Repetition Interval PRI =

1/PRF

• PRF can determine the radar’s maximum detection range

Bullock Engineering Research

15

Copyright 2014 www.BesserAssociates.com

Radar Turns on/off the

Carrier Frequency

Pulse Width = 1us

Pulse repetition time = PRI = 7us = 1/PRF

PRF = 1/7us = 143 kHz

V

t

• Burst of Carrier Frequency – Radar burst

• Low duty cycle, high power

• Duty cycle = PW/PRI x 100 = 1us/7us x 100 = 14%

carrier wave = 4cycles/1us = 4MHz


16


Basic Radar Uses On/Off

Keying of a CW Waveform

Oscillator

Modulator

On/Off Switch

Continuous Waveform - CW

Pulse Train: PRF

Radar Pulses

V

t PW

PRI = PRT

PRF = 1/PRI

t

V

PW

PRI = PRT

PRF = 1/PRI

Radar

PW/PRF

Control


17


Pulse Distortion

P1

PRI = 1/PRF Long P1 returns cause

distortion to P2 returns

t

V

Long returns from P1 causes distortion to the returns of P2

P2


18


Basic RADAR

Transmit Radar Pulse

Radar Directional Antenna

Target

Reflection

off a Target


19


19

Basic Radar Diagram

Transmitter Reflective

Radar

Surface

Transmit

Channel

Low Noise

Receiver

Receive

Channel

RADAR

TARGET


20


Radar Path Budget

• Tracks Signal & Noise Levels from Radar – to Target – back to Radar

– Power Out (PA), Tx Losses, Tx Ant Gain, Channel Losses, Target Reflectivity, Channel Losses, Rx Ant Gain, Rx Losses, Rx Detect S/N

– Required S/N

• Radar Budget - Allocation of Power and Noise

• Radar Tx PA to Radar Rx Detector (LNA)

• Used in Solving Tradeoffs

– Size, cost, range

• Radar pulses are reflected off targets that are in the transmission path – Targets scatter electromagnetic energy

– Some of the energy is scattered back toward the radar

– Provides gain referenced to an isotropic reflector, similar to antenna gain


21


21

Effective Isotropic Radiated

Power EIRP

EIRP = Effective Isotropic Radiated

Power = RF Power x Antenna Gain

RF

Power

Gain

RF

Power

Target

Target

ERP = Effective Radiated Power

EIRP = ERP + Gdipole (2.14dB)

ERP = EIRP - Gdipole (2.14dB)


22


22

Sun

Focusing

Sun Rays

To Increase

Power

Focusing Radio Waves

To Increase

Power

Magnifying

Glass

Directional Antenna

Receiver

Focusing Increases Power To

Provide Gain


23


Radar Cross Section RCS

• RCS (s) - size and ability of a target to reflect radar energy m²

• RCS(s) = Projected cross section x Reflectivity x Directivity

• The target radar cross sectional area depends on:

– Target’s physical geometry and exterior features

– Direction of the illuminating radar

– Transmitted frequency,

– Material types of the reflecting surface.

• Difficult to estimate

– Equals the target’s cross-sectional area theoretically

– Not all reflected energy is distributed in all directions

– Some energy is absorbed

– Usually measured for accurate results


24


Radar RCS Patterns

Sphere s = pr2

Flat Plate

Corner Reflector

Similar to

Antenna

Gains


25


25

Radar Transmitter

Power to Target

Freespace

Attenuation

Water

Vapor

Rain

Loss

Oxygen

Absorption

Multipath

Loss

EIRP

LAtmos Lmulti

Transmitter

Reflector

Target Pt

Gt

Power at Target Including other losses

Lt = LAtmos x Lmulti

Power at Target (ideal)


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26

Radar Received

Power from Target

LAtmos Lmulti

Freespace

Attenuation Water

Vapor

Rain

Loss

Oxygen

Absorption

Multipath

Loss

Receiver

Reflector

Target

Gr

Pr

Ptarg


Power received at Radar (ideal)

Power at Radar including losses


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27

Radar Antenna Gain and

Channel Losses

Freespace

Attenuation

Water

Vapor

Rain

Loss

Oxygen

Absorption

Multipath

Loss

EIRP

LAtmos Lmulti

Transmitter

Receiver

Reflector

Target

Duplexer

Pt

Pr

Power at Radar (Ideal)

One-way Loss: Lt = LAtmos x Lmulti

Two-way Losses = Lt x Lt = Lt2 = Ls

Including other losses in the path

Assume Antenna Gain Gt = Gr


LAtmos Lmulti

Freespace

Attenuation Water

Vapor

Rain

Loss

Oxygen

Absorption

Multipath

Loss

Lt = LAtmos x Lmulti Gr

Gt


28


28

Radar Example

Given: What is Pr in dBm?

f = 2.4 GHz, , l = .125

Pt = 100W

R = 1000m

Gt = Gr = 1000

Total 2-way loss Ls = 10

s= 140 m2

100(1000)2(.125)2(140)

(4p)3 (1000)4(10) Pr =

=1.10235x10-8W = 1.10235x10-5mW

Prdbm = 10log(1.10235x10-5) = -49.6 dBm

Freespace

Attenuation

Water

Vapor

Rain

Loss

Oxygen

Absorption

Multipath

Loss

EIRP

LAtmos Lmulti

Transmitter

Receiver

Reflector

Target

Duplexer

Gr

Pt

Pr

Gt


LAtmos Lmulti

Freespace

Attenuation Water

Vapor

Rain

Loss

Oxygen

Absorption

Multipath

Loss



29


Free Space Attenuation

• Forms of free-space attenuation depends on how it is used

– Afs = (l/(4pR))2 will be less than 1 and multiplied

– Afs = ((4pR)/l)2 will be greated than 1 and divided

– Afs = 10log (l/(4pR))2 = 20log l/(4pR) = will be a negative number and added

– Afs = 10log ((4pR)/l)2 = 20log (4pR)/l = will be a positive number and subtracted

– Important to determine if it is added or subtracted to avoid mistakes

• Given:

– Pt = 100W = 50dBm, l = .125, R = 1000m

– Afs = (l/(4pR))2 = 98.9 x 10-12 need to multiply: Pr = 100W x 98.9 x 10-12 = 9.89 x 10-9

– Afs = ((4pR)/l)2 = 1.01065 x 1010 need to divide: Pr = 100W/(1.01065 x 1010)= 9.89 x 10-9

– Afs = 20log l/(4pR) = -100 dB need to sum: Pr = 50dBm + (-100dB) = -50dBm

– Afs = 20log (4pR)/l = 100 dB need to subtract: Pr = 50dBm - 100dB) = -50dBm


30


Two-Way Radar Losses in dB

• Two-way free space loss in dB – Once for the radar transmitter to target path

– Once for the target to radar receiver path

– Total Free Space Loss = AfsdB + AfsdB = 2 x AfsdB = 2 x 20log l/(4pR)

• Two-way Losses in Radar in dB – Atmospheric loss 2 x Latmos dB

– Multipath loss 2 x Lmult dB

– T/R switch or Circulator loss 2 x Ltr dB

– Antenna loss, Polarization, Mis-pointing, Radome 2 x Lant dB

– Implementation loss 2 x Li dB

– Losses in dB:

– Ltotal dB = 2 x Latmos dB + 2 x Lmult dB + 2 x Ltr dB + 2 x Lant dB + 2 x Li dB


31


RADAR Equation

to Assess Radar Performance

P r = Radar received power

P t = Radar transmitted power

G t = Transmitter antenna gain

G r = Receiver antenna gain

G2 = Gr Gt assumes the same antenna at the radar

l = wavelength

R = slant range

Ls = total two-way additional losses

s = radar cross section of the target RCS

Log Form

Pr = PtG tG r Afs AfsGtarg1/Ls

10logPr = 10logPt + 10logG + 10logG + 10logAfs + 10logAfs + 10logGtarget - 10log(Ls)

Pr dBm = Pt dBm + 2GdB + 2Afs dB + Gtarget dB – Ls dB

P(mW) = dBm or P(W) = dBw


32


32

Radar Example in dB

AfsdB = 10log(l2/(4pR)2) = 20log(l/(4pR) = 20log[(.125)/(4p1000)] = -100.05dB

Gtarg = 10log(4ps/l2) = 10log(4p x 140/.1252) = 50.5dB

Given: What is Pr?

f = 2.4 GHz, , l = .125

Pt = 100W = 50dBm

R = 1000m

Gt = Gr = 1000 = 30dB

Total 2-way loss Ls = 10 = 10dB

s= 140 m2 Pr dBm = Pt dBm + 2GdB + 2Afs dB + Gtarget dB – Ls dB

Pr dBm = 50dBm + 2 x 30dB + 2 x -100.05 dB + 50.5 dB – 10dB = -

49.6dBm

Freespace

Attenuation

Water

Vapor

Rain

Loss

Oxygen

Absorption

Multipath

Loss

EIRP

LAtmos Lmulti

Transmitter

Receiver

Reflector

Target

Duplexer

Gr

Pt

Pr

Gt


LAtmos Lmulti

Freespace

Attenuation Water

Vapor

Rain

Loss

Oxygen

Absorption

Multipath

Loss



33


Range Determination

• Range calculation uses time delay between objects – Time delay is measured from source to reflector and back

– Time delay divided by two to calculate one way range

• Sound-wave reflection – Shout in direction of a sound-reflecting object and hear the echo

– Calculate two-way distance using speed of sound 1125 ft/sec in air

– Measure two way delay of 5 seconds

– Range = 1125ft/sec x 5/2 = 2812ft

– Measure distance to lighting using the time arrival of the thunder


34


34

Sound Wave Reflection

Hi

Hi

Determine the distance using range formula

Listen to multiple echoes off difference distances

Best echo effects when the yell is short – short pulse width


35


35

Sound Wave Reflection

Hi

Hi

Determine the distance using range formula

Listen to multiple echoes off difference distances

Best echo effects when the yell is short – short pulse width


36


Radar Range Calculation

• Radar uses electromagnetic energy pulses

• Pulse travel at the speed of light co

• Reflects off of a surface and returns an echo back to the radar

• Calculates the two-way distance or slant range

• Slant range = line-of-sight distance from radar to target

• Takes in account the angle from the earth

• Ground range = horizontal distance from radar to target

• Slant range calculated using ground range and elevation

• Radar energy to the target drops proportional to range squared.

• Reflected energy to the radar drops by a factor of range squared

• Received power drops with the fourth power of the range – Need very large dynamic ranges in the receive signal processing

• Need to detect very small signals in the presence of large interfering

signals


37


Slant Range

Slant Range = Rslant

Radar

Directional

Antenna

Target

Ground Range = Rgnd

Elevation = EL

Rslant2 = Rgnd

2 + EL2: Rslant = (Rgnd2 + EL2)1/2

Sinf = El/Rslant: Rslant = El/sinf

Cosf = Rgnd/Rslant: Rgnd = Rslant x cosf

f

Given:

Elevation = 5000 ft

Angle = 300

Calculate Slant Range =

Rslant = El/sinf = 5000/sin(30) = 10,000 ft

What is the Ground Range =

Rgnd = Rslant x cosf = 10,000 x cos(30) = 8660.25 ft

Rslant2 = Rgnd

2 + EL2: Rgnd = (Rslant

2 - EL2) 1/2 = (10,0002 - 50002) 1/2 = 8660.25ft


38


Range Calculation

Electromagnetic energy pulse travels at the speed of light co

Given: tdelay = 1ms

Calculate Slant Range =

R = (1ms x 3 x 108 m/s)/2 = 150km

R = slant range

tdelay = two way time delay – Radar-Target-Radar

co = speed of light = 3 x 108 m/s


39


39

Radar Range Equation

Double the range requires 16 times

more transmit power Pt

Radar detection range = the maximum range at which a

Target has a high probability of being detected by the radar

Basic Radar Equation

Radar Range Equation (solving for Rmax range for minimum signal Smin):


40


Range Ambiguity

• Caused by strong targets at a range in excess of the pulse repetition

interval or time

• Pulse return from the first pulse comes after the second pulse is sent

• This causes the range to be close instead of far away

• Radar does not know which pulse is being returned

• Large pulse amplitude and higher PRF amplifies the problem

• The maximum unambiguous range for given radar system can be

determined by using the formula:

Example: PRI = 1msec, T = 1us

Calculate Max unambiguous Range = (1ms – 1us) x 3 x 108/2 = 149.9km


41


Range Ambiguity

P1 P2

PRI Range Ambiguities

t

V


42


Range Ambiguity Mitigation

• Decreasing the PRF reduces the range ambiguity

– Longer the time delay, higher free-space loss, smaller the return

• Transmit different pulses at each PRF interval

– Higher receiver complexity

– Requires multiple matched filters at each range bin and at each azimuth

and elevation

– Increases rate of the DSP required for each separate transmit pulse and

matched filter pair

• Vary the PRF, depending radar’s operational mode

– Requires changing the system parameters

– Used most often to mitigate range ambiguity

– Used in the presence of other jamming pulses

– Desired returns from the second pulse move with the PRF

– Undesired returns do not move since they are reference to the first pulse

– Changing the PRF allows Radar Communications using PPM


43


Minimum Detectable Range

• Radar minimum detectable range – return cannot come back during pulse width

T = Pulse width, Trecovery = time for pulse to recover

• Very close range targets equivalent to the pulse width not be detected

• Typical value of 1 μs for the pulse width of short range radar corresponds to a

minimum range of about 150 m

• Longer pulse widths have a bigger problem

• Typical pulse width T assuming recovery time of zero:

• Air-defense radar: up to 800 μs (Rmin = 120 km)

• ATC air surveillance radar: 1.5 μs (Rmin = 225 m)

• Surface movement radar: 100 ns (Rmin = 15 m)

P1

t

V R1 R2

R3

Minimum Detectable

Range Pulse

Does not interfere with

the Radar pulse

Tmin for Rmin = Pulsewidth


44


Plan Position Indicator (PPI)

• The return is displayed on a Plan Position Indicator

(PPI)

– Rotating Search Radars illuminates the targets on the PPI

according to the angle received

– Range is displayed according to the distance from the center

of the PPI

– Uses a range gate to lock on the range of the PPI


45


PPI and A-Scope Displays

N

S

00

900

1800

2700

AoA = 770

Range

Gate

PPI A-Scope

Range

Gate

V

t


Besser Associates ©Besser Associates, Inc. 2015 All rights reserved

Thank you for Attending !

For more information on this subject and more, please consider

attending;

Transceiver and Systems Design for Digital

Communications, Radar, and Cognitive Processes

August 22 to 26 in San Jose, CA

Contact us at [email protected]

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Introduction to RADAR by NI