Technology Trend in Spectrum Analyzer

Transcription

1 Technology Trend in Spectrum Analyzer Roberto Sacchi Application Engineer Page 1

2 Agenda The Wireless communication market Swept vs. FFT spectrum analyzer (resolution, selectivity) Digital modulation basics Measurements with Vector Spectrum Analyzer Page 2

3 Wireless Communications Market Extraordinary Growth for Wireless Data as Cellular and Wireless Connectivity Merge TDMB A-GPS cdma 2000 LTE EGPRS S-DMB Over the next few years we will see an increasing number of devices that include a combination of wireless access technologies W-CDMA HSDPA GSM 1xEV-DO HSUPA FM Radio RFID WiFi Continual Evolution of Technologies ir DAB MediaFLO WiMAX DVB-H Bluetooth UWB WiBro R&D Validation Manufacturing Deployment Page 3

4 The trend in the wireless industry Coded Vector Modulations CDMA/OFDM Vector Modulations PSK/QAM/FSK Time-variant Vector Modulations TDMA GSM Blue tooth 3GPP WCDMA WLAN WiMAX DVB-T/H LTE Analog Modulations MWRadio Links AM/FM/PM Page 4

5 Overview What is Signal, Vector and Spectrum Analysis? Spectrum Analysis Display and measure amplitude versus frequency for RF & MW signals Separate or demodulate complex signals into their base components (sine waves) Page 5

6 Overview Types of Tests Made Mo dulation No ise Disto rtio n Page 6

7 Theory of Operation Swept Spectrum Analyzer Block Diagram RF input atte nuato r m ixe r IF gain IF filte r (RBW) e nve lo pe de te cto r Input signal Pre -Se le cto r Or Lo w Pass Input Filte r lo cal o scillato r Log Am p vide o filte r swe e p ge ne rato r Crystal Re fe re nce Oscillato r ADC, Display & Vide o Pro ce ssing Page 7

8 Modern Spectrum Analyzer Block Diagram Pre-amp Analog IF Filter Digital IF Filter Digital Detectors FFT Attenuation Sweep vs. FFT Digital Log Amp YIG ADC Page 8

9 Overview Different Types of Analyzers FFT Analyzer Swept Analyzer A Paralle l filte rs m e asure d sim ultane ously A Filte r 'swe e ps' o ve r range of inte re st f 1 f2 f f1 f2 f Page 9

10 Modern Spectrum analyzer Resolution: Resolution BW 10 khz RBW 3 db 1 0 khz Determines resolvability of equal amplitude signals Page 10

11 Modern spectrum analyzer Resolution BW Selectivity or Shape Factor 3 db 3 dbbw 60 db 60 db BW Se le ctivity = 60 dbbw 3 dbbw Determines resolvability of unequal amplitude signals Page 11

12 Specifications Resolution: RBW Type and Selectivity Typical Se le ctivity Analo g 1 5:1 Digital 5:1 ANALOG FILTER DIGITAL FILTER RES BW1 00 Hz SPAN3 khz Page 12

13 Transmitting Information (Analog or Digital) Modify a Signal "Modulate" Detect the Modifications "Demodulate" Any reliably detectable change in signal characteristics can carry information Page 13

14 Signal Characteristics to Modify (As a Function of Time) Amplitude Frequency Phase Both Amplitude and Phase Page 14

15 The rectangular coder Mapping bits onto analog wave form s Q I Q I Page 15

16 Creating Digital Modulation (1,0) Q +1volt (0,0) We have used the concept of Signal Space to view our modulations. We can use the same idea to engineer these modulations. 1volt +1volt I (1,1) 1volt (0,1) +1v I (0,1) f C 90º Σ 1v Q Page 16

17 FFT Analyzer Block Diagram Digital Data Flow (time) Digital Filter as sembly ADC Ass embly ADC φ 90 o phase shift Real Part (I) Imaginary Part Re-Sampling DSP D e m o d W i n d o w F F T (freq) D I S P L A Y F s (demod time) (Q) Quadrature Anti-alaising and Sampling Decimation Page 17

18 Measurements on digital radios Swept Spectrum Analyzer (with span zero and enough ResBW) Time Domain (CCDF, pulse shaping, tim ing) Frequency Domain (Channe l Powe r, spe ctrum m ask, ) Modulation Domain Ove rall Modulation Quality, Modulation Quality on individual carrie rs Channe l Re sponse, Group De lay In Channe l Spurious Se arch Page 18 Vector Signal Analyzer

19 Measurements in the frequency domain: - Channel power and occupied bandwidth - Adjacent channel power ratio (ACPR) Page 19

20 Modulation Quality Analysis EVM[%] MER[dB] Modulation Error Basic Concept: Q Ideal point Ideal Signal at decision time Error Vector Magnitude Error Vector Measured point Measured Signal at decision time Measured signal is never equal to ideal signal, due to noise, transmitter impairments, propagation phenomena, I Page 20

21 I/Q Impairments: I/Q gain imbalance, Quadrature errors, I/Q offsets I/Qim pairm e nts are typically cause by m atching proble m s due to com pone nt diffe re nce s be twe e n the Iside and Qside o f the blo ck diagram Significant m e asure m e nts: conste llation and EVMm e trics Page 21

22 Agilent Spectrum Analysis Portfolio Price Co de Co m patible ESA World s Most Popular 100 Hz to 26 GHz EXA Se p 07 X-Series Economy class 9KHz to 26 GHz MXA Se p 06 X-Series Mid Performance 20 Hz to 26 GHz 8560EC Series Super midperformance PSA Market Leading Performance 3 Hz to 50 GHz Ne w backwards CC with 856x o ptio n o n X-Se rie s Jul 08 N9340B Hand Held Apr 08 N9320B Basic performance, Benchtop CSA Low cost portable 100 khz to 6 GHz Performance VSA Software World s best analysis & troubleshooting

23 PSA-MXA-EXA-ESA Key Specs Comparison Spec EXA Signal Analyzer MXA Signal Analyzer PSA Analyzer Frequency Range TOI (at 2 GHz, 18 GHz) DANL (at 2 GHz, 18 GHz) Φ Noise (10 khz offset)/ (1 MHz offset) W-CDMA ACPR With noise correction Amplitude Accuracy (to 3 GHz, 95% confidence) 9kHz to 3.6/7/13.6/26.5 GHz +13 dbm +9 dbm -146 dbm/hz -137 dbm/hz -99 dbc/hz -130 dbc/hz -68 dbc -73 dbc ±0.95 db 0.27 db 20 Hz to 3.6/8.4/13.6/26.5 GHz +15 dbm +10 dbm -151 dbm/hz -142 dbm/hz -103 dbc/hz -133 dbc/hz -73 dbc -78 dbc ±0.78 db 0.23 db 3 Hz to 6.7/13.2/26.5 or 42.98/44/50 GHz +17 dbm +12 dbm -153 dbm/hz -147 dbm/hz -116 dbc/hz -145 dbc/hz dbc -81 dbc ±0.62 db 0.19 db Analysis BW 10 MHz 10, 25 MHz 10, 40, 80MHz Relative Speed Fastest Fastest Faster Base Price (3.6 GHz/26.5 GHz) $16.9k - $35.9k USD $27.9k - $45.9k USD $50k - $58k USD

24 Summary Digital platform key points Greater selectivity and resolution with digital filter Speed and dynamic range trade off (FFT vs Swept) Post processing analysis (e.g. demodulation with VSA) Page 24

25 Page 25 The Evolution of Spectrum Analyzers Seminario T&M September 2008