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Generating Signals Basic CW signal Block diagram Applications Analog Modulation Types of analog modulation Block diagram Applications Digital Modulation Overview of IQ modulation Block diagram Applications Signal Generation and Digital Modulation Fundamentals 2

Voltage Voltage Time Frequency Oscilloscope Spectrum Analyzer RF Microwave Millimeter 6 GHz 20-70 GHz 300 GHz 4

Synthesizer Section Output Section Frac-N ALC Modulator Output Attenuator Phase Detector f VCO Reference Oscillator divide by X Reference Section ALC Driver ALC Detector ALC = automatic level control 5

Frequency Input Tune Voltage Voltage-Controlled Oscillator (VCO) Tuning Range: Output Frequency Range Tuning Gain: V / Hz VCO Slope: F for V Voltage Phase-Noise: dbc/hz 6

Reference Signal VCO Phase Detector Error Voltage Loop Amp/Filter Tune Voltage 7

Power Power F R E Q U E N C Y, A M P L I T U D E, A N D S P E C T R A L P U R I T Y Frequency Uncertainty Frequency Amplitude Uncertainty Frequency: range, resolution, accuracy, switching speed Amplitude: range, resolution, accuracy, switching speed, reverse power protection Spectral purity: phase noise, spurious, harmonics, subharmonics Frequency 8

CW output Sub-harmonics from multipliers used to extend the frequency output Phase noise (dbc/hz) from LO s Non-harmonic spur from power supplies and other contributors Harmonic spur ~30dBc from non-linear components Broad Band Noise Floor Thermal noise of source 0.5 f0 f0 2f0 9

R A D A R / E L E C T R O N I C W A R F A R E E X A M P L E Transmitter signal Spurious signal Return signal (-85 dbm) Radar/Electronic Warfare Example False target/threat detection & interference Spurious signal jam yourself Very small received signal (-130 dbm) Satellite Example In channel receiver interference degrades sensitivity and range Spurious signal jam your neighbor Small received signal (-50 dbm) Cellular Example Out of channel interference pollutes neighbors receiver sensitivity & degrades range and data rates 10

Phase Noise Phase noise can prevent resolution of unequal signals. 11

-30 Absolute SSB Phase Noise at 10 GHz in dbc/hz -40-50 -60-70 Reference -80-90 Oscillator -100 Noise -110-120 -130-140 -150-160 -170 Broadband noise floor, thermal noise of source VCO noise 1 10 100 1k 10k 100k 1M 10M 100M f(hz) PLL BW Phase detector noise 12

Antenna Simplified Receiver Block Diagram ADC FPGA Local Oscillator In Clock In Clock In MXG DDS Ref out Ref In 13

U S I N G A P O W E R S E N S O R Calibration Amplifier Attenuator P in P out Power Sensor U2000B USB Gain db = 10 log P out P in Gain db = P out dbm P in (dbm) P in = input power to amplifier Watts P out = output power from amplifier (Watts) 14

... W H E R E T H E I N F O R M AT I O N R E S I D E S A t sin[2πf t + Φ] AM, Pulse FM, PM 16

Baseband Signal Amplitude (AM) Frequency (FM) Phase (PM) 17

Voltage Carrier Modulation depth %, db Important Characteristics for Amplitude Modulation Modulation frequency (rate) Depth of modulation (Mod Index) Distortion (%) Time Modulation frequency Where are AM signals used? AM Radio Antenna scan ASK (early digital 100101) 18

Voltage V(t) = A cos[2πf c t + βsin2πf m t] β is the modulation index, where β = ΔFdev /Fm Time Important Characteristics for Frequency Modulation Frequency Deviation (ΔF dev ) Modulation Frequency (F m ) Accuracy Resolution Distortion (%) Sensitivity (dev/volt) 19

Voltage V(t) = A cos[2πf c t + β2πf m t] Where β =Δθ, the peak phase deviation Important Characteristics for Phase Modulation Time Phase deviation (Δθ) Modulation Rate (F m ) Accuracy Where are PM signals used? PSK (early digital 1010) Radar (pulse coding) 20

Power Voltage Pulse Repetition Interval (PRI) T t Pulse Width Time Rise time Where are Pulse Modulated signals used? Radar High Power Stimulus/Response Communications On/Off ratio Important Characteristics for Pulse Modulation 1/T Pulse width (t) PRF (1/T) Duty cycle (t/t) On/Off ratio (db) Rise time (ns) 2/t 1/t Frequency 21

A D D I N T E R N A L M O D U L AT I O N G E N E R AT O R VCO ALC Modulator Output Attenuator Pulse Mod. Freq. Control ALC Driver FM, PM input AM input Pulse Mod input LF Generator Reference Oscillator FM Source AM Source Pulse Source 22

Level (dbm) Receiver In-channel signal (modulated signal) Required SG Modulation distortion = Receiver Distortion % x 10 -(margin(db)/20) Distortion Frequency 23

S I G N A L C H A R A C T E R I S T I C S A R E M O D I F I E D D I S C R E T E LY Amplitude (ASK) Frequency (FSK) Phase (PSK) Both Amplitude and Phase (QAM) 25

S I M U LTA N E O U S M O D U L AT I O N O F T W O M O D U L AT I O N T Y P E S Independent Amplitude and Phase Modulation Integrated IQ Modulator Q Independent FM and Pulse Modulation I 32 QAM Constellation Diagram FM during the pulse = chirp 26

Phase Magnitude Change 0 deg Phase Phase Change 0 deg 0 deg 0 deg Both Change Frequency Change 27

{ Q { Q-Value Phase 0 deg I I-Value 28

Binary Data bit = 0,1 Transmitting Digital Bits (f1 = 0, f2 = 1 ) Transmission Bandwidth Required f(t) = f1 T 010101010 f2 2/ T Main lobe width is 2 Sample rate Symbol = Groups/blocks of Bits 2 bits/symbol (00 01 10 11) 3 bits/symbol (000 001..) 4 bits/symbol (0000 0001..) Symbol Rate = Bit rate # bits per symbol f(t) = S Symbol 1 (00) Symbol 2 (01) Symbol 3 (10) Symbol 4 (11) 2/ S Main lobe width is 2 Symbol rate 29

Modulation format Number of bits per symbol Constellation Transmission bandwidth Q BPSK 1 1 0 I F 01 Q 00 QPSK 2 I 11 10 F/2 Q 0000 16 QAM 4 I Symbol Rate = #symbols/sec. (Hz) F/4 30

Q IQ Modulation Bandwidth Frequency Response/Flatness IQ Quadrature Skew IQ Gain Balance Phase 0 deg I flatness F b w 31

I: IQ inputs to produce Modulated Carrier 01 Q 00 90 degree phase shifter π/2 Carrier synthesizer section RF I Q: 11 10 Good interface with digital signals and circuits Can be implemented with simple circuits Fast, accurate state change 32

A D D I N G A N I Q M O D U L AT O R A N D B A S E B A N D G E N E R AT O R Synthesizer VCO I-Q Modulator 90 Output Freq. Control ALC Driver Reference I Q DAC DAC Pattern RAM and Symbol Mapping Baseband Generator 33

DAC s convert digital IQ signals to analog IQ signals Pattern RAM Binary Info to be transmitted Symbol Mapping and Baseband Filters Map to digital symbols then to Digital I Q signals DAC DAC I Send to IQ Modulator Q 00 -> 1+j1 11000101101 01001011100 10101010 01 -> -1+j1 10 -> -1-j1 11 -> 1-j1 34

Combination of high performance modules create uncompromising vector signal generator performance in PXIe form factor M9316A Vector Modulator M9312A Source Output M9303A Synthesizer M9300 Reference 35

Amplitude RF DUT Baseband DAC DSP RF LO Payload Data BER Spec Line Frequency BER 36

Level (dbm) RF DUT Baseband In-channel signal DAC DSP RF LO Out-of-channel interferer Payload Data IF Rejection Curve Frequency 37

A C P R DUT Spectral Output from Amplifier ACPR of DUT Input from Source Spectral regrowth ACP Margin Margin (db) 0 1 2 3 4 5 10 15 Error contribution (db) 3.0 2.5 2.1 1.8 1.5 1.2 0.4 0.2 38

EVM DAC Q Q Magnitude Error (IQ error mag) Q I Test Signal Error Vector Magnitude I Θ Ideal (Reference) Signal Phase Error (IQ error phase) I 39

N9310A EXG MXG M9380A M9381A M9383A PSG UXG Signal Studio Software 41

A D D I T I O N A L I N F O R M AT I O N More Webcasts: www.keysight.com/find/webcastseries Signal Sources: www.keysight.com/find/sources Signal Analyzers: www.keysight.com/find/sa 42