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Design and test of RADAR systems
Agenda Radar Overview Tools Overview VSS LabVIEW PXI Design and Simulation Simulating the frond end Modeling signal processing Prototyping with real hardware
Overview of RADAR RADAR = radio detection and ranging Radar is an electromagnetic system for the detection and range of objects Where the reflection of the transmitted waveform is used for detection and range And its range (R) is determined by the equation out Rc Rc back R out back 2Rc Transmit Pulse R 2Rc Receive Pulse
Types of RADAR Signals CW (Continuous Wave) Detects velocity but not range FM CW Detects range through frequency difference of reflection Requires separate Tx and Rx Antennas Pulsed CW Detects range through round trip time of pulse Unambiguous range determined by pulse interval Pulse repetition frequency (PRF) PRF = 1 PRI Unambiguous Range c Ru = 2 PRF
Note on Unambiguous Range If PRF is 1000Hz then PRI = 1ms Maximum unambiguous range = 150km If we distribute the return signal over 200 bins 1 2 3 4 200.. 5us = 150km / 200 = 0.75km resolution A target 225km will have a delay of 1.5ms and will be mapped back to the 100 th range bin (0.5ms or 75km). Hence, this is called range ambiguity.
Designing a RADAR System Baseband (Digital) Pulse Generator Transmitter Analog (RF) Channel & Environmental LO Antenna Target Signal Processing Receiver AWR Visual System Simulator
RADAR Design and Test Ideal flow enables design tools to be leveraged by test group PXI and LabVIEW can be used in design-through-test Focus of Today s Discussion
Tools Overview
AWR s Visual System Simulator EDA Solution for System Design Mode s include: Time Domain Complex Envelope Spur Analysis RADAR library includes Full system simulation CFAR, MTI, and MDT Target and antenna modeling RF Link simulation includes Amplifier, Mixer, Filter Co-simulate with MWO circuits Co-simulate with hardware
National Instruments HW and SW NI LabVIEW Software Graphical programming environment Instrument control Signal processing algorithms Visualization and graphing NI PXI Hardware PC-based instruments RF signal generators and analysers Instrument Control Visualization & Display Signal Processing
Signal Processing in LabVIEW Modulation & Demodulation Signal Operation Signal Creation Filtering (FIR, IIR, etc.) Spectrogram
Connecting LabVIEW and VSS + Characterize simulated RF parts with LabVIEW measurements Prototype systems designs with physical hardware Control instruments from AWR s VSS environment
Importing LabVIEW Code in VSS VSS Environment LabVIEW Environment LabVIEW controls and indicators get mapped to input and output ports of a LabVIEW Node on the VSS diagram
RADAR Pulse Generation Pulse Generator Transmitter LO Antenna Target Signal Processing Receiver
Chirp Pulse Creation in LabVIEW Basic chirp signal can be created by FM modulating a ramp message signal.
RADAR Tx Chain Analysis Pulse Generator Transmitter LO Antenna Target Signal Processing Receiver
Transmit Chain Analysis Analysis methods in VSS include Link budget analysis Spur analysis Custom analysis possible in LabVIEW AMP_B Behavioral PA or NL_S TP M_PROBE PORTDIN BPFB AMP_B BPFB IN MIXER_B OUT BPFE AMP_B BPFE IN MIXER_B OUT BPFB AMP_B BPFB ISOLATOR PORTDOUT 1 2 10MHz LO LO 9015MHz TONE TONE MMIC PA 340MHz 8665MHz
Link budget Analysis Results: Cascaded NF = 4.65dB Available Gain = 59.5dB Power level at 9015MHz = 59.55dBm 5 4 DB(C_NF(TP.Start,TP.Stop,0,1,0,1))[1] RFB Tx System RFB C_NF for TX 4.647 db p1 60 40 Gain RFB Cumulative Gain for TX DB(C_GA(TP.Start,TP.Stop,1,0,1))[1] RFB Tx System 14 59.54 db p1 3 20 2 1 Noise Figure p1: Cascaded Noise Figure, Signal, Cumulative, db Freq=9015 MHz 0 p1: Available Gain, Cumulative, db Freq=9015 MHz 0-20 S4\BPFB (F1) S4\AMP_B (A1) S4\BPFB (F2) S4\MIXER_B (Mixer1) S4\BPFE (F3) S4\AMP_B (A2) S4\BPFE (F4) S4\MIXER_B (Mixer2) S4\BPFB (F5) S4\AMP_B (A5) S4\AMP_B (A4) S4\BPFB (F6) S4\ISOLATOR (S8) TX_ANTENNA (S7) S4\BPFB (F1) S4\AMP_B (A1) S4\BPFB (F2) S4\MIXER_B (Mixer1) S4\BPFE (F3) S4\AMP_B (A2) S4\BPFE (F4) S4\MIXER_B (Mixer2) S4\BPFB (F5) S4\AMP_B (A5) S4\AMP_B (A4) S4\BPFB (F6) S4\ISOLATOR (S8) TX_ANTENNA (S7)
Time Domain Analysis LabVIEW can be used for custom time domain analysis Complex signals using the measured phase (Θ) vs. time Linear pulse phase vs. time has constant change Θ(t) should have a U-shape dθ/dt should have a linear slope d 2 Θ/dt 2 should appear as a DC signal +
Basic Pulse Analysis in LabVIEW Input Waveform First derivative should appear as a ramp on a linear pulse Second derivative should appear DC on a perfectly linear pulse
Demo: Measuring Pulse Linearity Pulse is no longer linear due to group delay through a narrowband filter.
Generating Pulses with Hardware PXIe-5673 Vector Signal Generator Frequency: 100 MHz to 6.6 GHz Phase Noise: -110 dbc/hz (10 khz offset at 1 GHz) Bandwidth: up to 100 MHz QuickSyn Synthesizer Frequency: 200 MHz to 20 GHz Phase Noise: -138 dbc/hz (10 khz offset at 1 GHz) AM, FM, and Pulse modulation
Using a VSA to Analyze Pulses PXIe-5665 Frequency Range: 20 Hz to 14 GHz Phase Noise: -130 dbc/hz (10 khz offset at 1 GHz) Bandwidth: up to 50 MHz Phase Matrix VSA Frequency Range: 100 khz to 26.5 GHz Phase Noise: -118 dbc/hz (10 khz offset at 1 GHz) Bandwidth: up to 350 MHz
RADAR Antenna & Target Modeling Pulse Generator Transmitter LO Antenna Target Signal Processing Receiver
Antenna Characterization with a VNA PXIe Controller PXIe-5630 VNA PXI Motion Control Motor rotates antenna PXIe-5630 VNA Frequency: 10 MHz to 6GHz Measurements: S11 & S21 Dynamic Range: >100 db Typical Accuracy: < ± 0.1 db, 0.1 deg Sweep Speed: 400 us/pt
Antenna Modeling Parameters include Gain Effective Area Efficiency Directivity Polarization VSWR Free Space Impedance Z in and Z out respectively
Modeling the Target in VSS Delay and Doppler due to target velocity and distance Reflected Signal RCS EIRP Sets signal power received at target according to distance For statistical variation on RCS PWR
RADAR Rx Chain Analysis Pulse Generator Transmitter LO Antenna Target Signal Processing Receiver
Receive Chain Analysis Analysis metrics include Noise figure/sensitivity P1dB Group delay M_PROBE AMP_B OUT MIXER_B IN BPFE AMP_B BPFE OUT MIXER_B IN BPFB AMP_B BPFB ORTDOUT BPFB 10MHz LO 350MHz LO LNA PORTDIN 9015MHz TONE TONE 340MHz 8665MHz
Time (us) DB(C_HDRM(TP.Start,TP.End,1,0,1,1,1))[1,T] RFB RX System DB(C_HDRM(TP.Start,TP.End,1,0,1,1,1))[1,7] RFB RX System Receiver RF Analysis Noise RFB C_NF for RX 3.5 Figure 80 RFB Cascaded Headroom of RX link P1dB p2p1 p9p8 p7 p6 p5 p4 p3 3 2.5 2 1.5 3.153 db p1: Cascaded Noise Figure, Signal, Cumulative, db p2: Cascaded Noise Figure, Signal, Cumulative, db Freq=10 MHz Freq=10 MHz PWR=-70 PWR=-66 p3: Cascaded Noise Figure, Signal, Cumulative, db p4: Cascaded Noise Figure, Signal, Cumulative, db Freq=10 MHz Freq=10 MHz PWR=-62 PWR=-58 p5: Cascaded Noise Figure, Signal, Cumulative, db p6: Cascaded Noise Figure, Signal, Cumulative, db Freq=10 MHz Freq=10 MHz PWR=-54 PWR=-50 p7: Cascaded Noise Figure, Signal, Cumulative, db p8: Cascaded Noise Figure, Signal, Cumulative, db Freq=10 MHz Freq=10 MHz PWR=-46 PWR=-42 p9: Cascaded Noise Figure, Signal, Cumulative, db Freq=10 MHz PWR=-38 60 40 20 0 p1: P1dB Headroom, Gain Adjusted, db Freq=10 MHz PWR=-46 p2: P1dB Headroom, Gain Adjusted, db Freq=10 MHz PWR=-70 p2 p1 22.9 db -1.06 db 1-20 S1\BPFB (F6) S1\AMP_B (A4) S1\BPFB (F1) S1\MIXER_B (A1) S1\BPFE (F4) S1\AMP_B (A2) S1\BPFE (F2) S1\MIXER_B (A3) S1\AMP_B (A6) S1\BPFB (F3) S1\BPFB (F6) S1\AMP_B (A4) S1\BPFB (F1) S1\MIXER_B (A1) S1\BPFE (F4) S1\AMP_B (A2) S1\BPFE (F2) S1\MIXER_B (A3) S1\AMP_B (A6) S1\BPFB (F3) 2 1.5 RFB C_GD RX p1: Absolute Group Delay, us PWR=-70 C_GD(TP.Start,TP.End,0,1,0,1,0)[X,T] (us) RFB RX System 1 p1 Group Delay 0.5 7 9 11 13 RX IF Frequency (MHz)
RADAR Receiver Algorithms Pulse Generator Transmitter LO Antenna Target Signal Processing Receiver
Receiver Algorithms Basic Algorithms Range and velocity through correlation Advanced Algorithms Enable detections in difficult environments Examples include: Moving Target Indicator (MTI) Moving Target Detector (MTD) Constant False Alarm (CFAR)
WVFM(S13\TP.Compressed.Chirp,180,4,0,0,0,0,0,0) Chirp System WVFM(S13\TP.Compressed.Chirp,180,4,0,0,0,0,0,0) Chirp System Range Detection Through Correlation Chirp generator PORTDIN SUBCKT DCOUPLER_3 2 1 1 2 PORTDOUT 4 3 Output of Correlator 41.8 us 3.143 3 3 Coupler 2 1 To Tx Link 0 0 20 40 60 80 100 120 140 160 180 Time (us) Range from target 6Km TP From Tx Link 2 0.15 0.1 Output of Correlator 155.9 us 0.1475 3 1 CORRELATOR Correlator PORTDIN 0.05 0 0 20 40 60 80 100 120 140 160 180 Time (us) Range from target 23Km
Input MDT Algorithm in LabVIEW
Example output of MTD Algorithm
Conclusion RADAR design requires combination of HW and Software RF front end design design and test Receiver algorithm prototyping National Instruments provides a complete solution for Visual System simulator for front end simulation LabVIEW for pulse creation and signal processing PXI instruments for physical RADAR test