The best radio for worst events. Over HF links. Hana Rafi - CEO Eder Yehuda - VP R&D

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1 MOBAT MICOM The best radio for worst events Increasing Data Throughput Over HF links Hana Rafi - CEO Eder Yehuda - VP R&D 1

2 Traditional HF Radio -Analog voice & 50,75 bps New Trends on HF - Digital voice, Noise reduction - High Data Rate bps QAM High linearity, SNR,Efficiency 2

3 Requirements from the New HF Radio For HDR performance -Linearity - ISI -High dyn. range -Low ACI & IBN -High Power TX. -High efficiency -Small size. -High MTBF. -feasible. 3

4 HPA and High Data Rate (HDR) Traditional TX Inter-Mod HDR RX SNR Requirements : 31dB : >33 db PSD 31dB SNR ~30dB Frequency 4

5 micom Radio &HPA Solution Linearized Power Amplifier : New MICOM C Spec. Current Spec. Achivments TX PWR 125/175W 125W Availability Inter-Mod >42 db 30-32dB Data Rate Efficiency i >45% 30% Energy PWR con. 280 /390W 416W Size 5

6 Efficiency V.S. PAR (Peak to Average Ratio) Power density probability npsk efficiency CPFSK nqam -5dbm 0dbm Power level 6

7 New HF Generation & micom HDR Road-Map n*isb Radio, 125/175W and HPA HDR Modems 9600, K bps Enhanced STD gateway (IP) Enhanced digital voice 7

8 Technical session on Linearized techniques & Achievements on micom radio Mr. Yehuda Eder Thank you, have a productive day 8

9 Problem description Pout Linear Non Linearity caused by: PSD ACI BBN Pin PA/transmitter linearization RGC Receiver Gain Control TGC/ALC Transmitter Gain Control D/A-A/D Resolutions Local Oscillators phase noise Receiver/Transmitter BW Group Delay Variation ISI IBN Freq. 9

10 Available Solutions Linear Power Transceiver : Linear Power Amplifier, Class-A or A/B with large backoff : Low efficiency, high cost AGC, TGC,ALC : HELD (Input regulation based on average signal level should be held) HF channel receive signal variations may cause problems to the receiver performance and the linearity. Linearized Power Amplifier High Efficiency and IMD 10

11 RGC Receiver Gain Control TGC/ALC Transmitter Transmitter Gain Control Special techniques for attack-release of GAIN CONTROL must be used. T > delta between 2 peaks Data AGC GAIN Typical AGC TIME 11

12 A/D D/A Quantizing Noise Distortion & Noise in CODECs Integral non-linearity Differential non-linearity. Total Harmonic Distortion (THD). Total Harmonic Distortion Plus Noise (THD+N) Signal to Noise and Distortion Ratio (SINAD, or S/N+D). Effective Number Of Bits (ENOB). Signal to Noise Ratio (SNR). Analog Bandwidth (Full Power, Small Signal) Spurious Free Dynamic Range (SFDR). Two Tone Inter-modulation Distortion. Noise Power Ratio (NPR). 12

13 Local/Synthesizer Oscillators phase noise The synthesizer is the source of: IBN BBN High noise near the carrier = SNR degradation 13

14 Receiver/Transmitter BW In band ripple Group delay variances 14

15 PA characteristics - linear scale 15

16 Typical class AB PA characteristics (measurements) Power Gain Phase Transfer Function 16

17 PA linearity vs. SNR MIL-STD B Requirement: Intermodulation distortion (IMD). The IMD products of HF transmitters produced by any two equal-level signals within the 3 db bandwidth shall be at least 30 db below either tone for fixed station application, and 24 db below either tone for tactical application. The 24/30dB limits the SNR performance. Summary Performance tests results: IMD (below tone) SNR the IMD should be improved for better SNR 17

18 PA Linearization Techniques Power Amplifier Linearization Techniques: Feed Forward Pre-Distortion EER Envelope Elimination Restoration Cartesian Feedback Our approach: High Efficiency Class-AB amplifier with Cartesian Feedback & EER to achieve high linearity and high efficiency. 18

19 Linearization Techniques Feed-forward V i P. A. 2 G V o 1 G 2 2 Error Amplifier - High complexity -Wide BW - Low freq. Range 19

20 Linearization Techniques pre-distortion V o F(*) linear V i Predistorter V i V i V m P. A. V o V i F(V m ) - High complexity V i V m -Wide BW -Low freq. Range 20

21 Linearization Technique Digital adaptive pre-distortion L. O. I \ Q Mod. P. A. F(V m ) V o Adaptive Predistortion Predistorted Phi(kT s ) D / A D / A I(kT s ) Q(kT s ) Polar to C artesian Pre-distortion calculation Var. At tt. D a t a I/Q (kt s ) Cartesian to Polar Amp(kT s ) A d r e s s Look-up table (A i,phi i ) old (A i,phi i ) new A / D I \ Q Demod. D em odutated I/Q (kt s ) Adaptation algorithm Tables RF / analog elements Digital elements Down Converter 21

22 Linearization Technique Digital Pre-distortion - Preliminary Results 22

23 EER (Envelope Elimination and Restoration) Envelope modulator S t V ( ) 1 t V DD V i t V ( t) cos t ( t) c Signal separation t cos t ( ) S c 2 t P. A. V o -High Efficiency - limited performance 23

24 PA without AM- AM loopto PM I pol =[ ] ; Q pol =0 Gain PA Characteristics ti Two Tone Intermodulation. ti - AM loop 40 green - Source blue - PA red - PA with linearizer Vin [Volt] Amp [db] Phase [ o ] Vin [Volt] IM3 = 25 dbc AM loop improvement > 20 db

25 PA with AM-to-PM ( 0 25 ) AM loop I pol =[ ] ; Q pol =[ ] Gain PA Characteristics green - Source blue - PA red - PA with linearizer Two Tone Intermodulation. - AM loop Vin [Volt] 180 mp [db] A -20 Phase [ o ] Vin [Volt] IM3 = 25 dbc AM loop improvement = db For QAM modulation Cartesian loop is required

26 Analog Cartesian Loop -Block Diagram Closed loop, Narrowband (< 200 khz) S nom = 43 dbm S max = 50 dbm ; S min = 30 dbm N max = dbm / Hz RF Out S LO = 10 +/- 2 dbm L.O (Syn) AMP coup. (10dB) I/Q Modulator (17 dbm mixer) AMP digital atten. 15 db AMP digital atten. 15 db AMP P A - 2 db LPF Directional Coupler -20 db I_Tx Q_Tx loop filter -6 db splitter I_T s Q_T s f s FPGA 12 D / A LPF I REF loop filter err_i + err_q 12 Q D / A LPF REF + - RF components - Analog components Offset and I / Q balance compensation circuits Digital components I_dem Q_dem atten. 4 B AMP I/Q DeMod. (17 dbm mixer) digital atten. 15 db atten. 5 db atten. 10 db 26

27 Analog Cartesian Loop Performance 27

28 Micom Linearization solution EER & Cartesian loop 110 V AC (option) P IN =1 Watt Signal Processing Unit RF modulated-to-polar 28 / 48 V DC LPF Envelope DC P.S. LPF DC feedback Harmonic filter P TX =500 Watt Cartesian Linearization (complex closed loop) Phase modulated RF P A Att. 28

29 Micom Radio implementation DSP/ FPGA Digital BB Reconst. LPF IF 1 =1.05 MHz Digital IF D/A BPF IF 2 = 1.05 MHz BW= 12.1 KHz Envelope follower Bi-directional IF amp. BPF IF 2 = 45.1 MHz BW= 12.1 KHz MHz Tx. ALC (fine + course) Var. Att. DC P.S. Exc. P A Harmonic filter f s = 20 MHz F inj = khz F inj =46.15 MHz step=1.25 KHz Synt. F inj = MHz step=8.75 KHz Synt. BPF IF 2 = 20 khz LPF BPF Rec. AGC BW= 3 KHz Var. Var. anti-alias Att. Att. anti-alias IF 2 = 45.1 MHz IF 1 =5 MHz BW= 400 KHz Digital IF A/D Tx. ALC Tx. ALC (fine + course) (course) 14 LNA Att. Pre- Sel. Att. f s =20 MHz 29

30 Micom Digital part implementation Audio sources Audio Amp. Audio Amp. Data sources LPF anti-alias codec codec BPF BPF DSP/FPGA ALE TGC TGC vocoder Data modem SSB mod. I ref (kt) Q ref (kt) Cartesian feedback Error detector Freq. compensation I fbck (kt) Loop filter Q fbck (kt) Phase gen. Envelope generator I Tx(kT) Q Tx (kt) NCO (/PLL) I/Q mod. Envelope follower 14 Digital BB f s = 4-5 MHz Digital IF 14 IF=4.5-5 MHz f s = MHz REF clk Data targets LPF Audio targets Audio circ. Audio circ. Audio power Amp. reconstruction LPF reconstruction codec codec vocoder ALE Data modem CPU BPF Noise blanker SSB demod. AGC I/Q demod. AGC Digital IF 14 IF 1 = MHz f s1 = MHz IF 2 = 20 khz f s2 = khz Multiport RS232 USB port H/W control Ethernet port MMI 30

31 Micom simulation results Two Tone Intermodulation. - Complex loop green - Source blue - PA red - PA with linearizer 0 Amp [db] IM3 = 20 dbc Complex loop improvement ~ 25 db 31

32 Two complex tones - baseband spectrum f 1 = -30 Hz, f 2 = 25 Hz 32

33 Two complex tones - I/Q Qplot I ( t) a sin(2 f t) a sin(2 f 2t 1 ) Q( t) a sin(2 f t / 2) a sin(2 f 2t 1 / 2) 33

34 Single tone (modulating signal) I/Q plot 34

35 Non-Linear PA 35

36 Micom Simulation 36

37 Linearized PA 37

38 Single tone time waveforms (RF or modulating signal) 38

39 I/Q Qplot 39

40 Micom Short and Long term solutions 40

41 Thank you 41

42 micom HDR-ISB System Solution micom 2*ISB Radio 125/175W ready for W micom MD-9600/19200 STD gateway Q1-Q

TSEK02: Radio Electronics Lecture 8: RX Nonlinearity Issues, Demodulation. Ted Johansson, EKS, ISY

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