thiết kế modul trong FPGS
1 copyright 1998,1999,2000 Andraka Consulting Group, Inc. All Rights reserved Modulation and Demodulation Techniques for FPGAs Ray Andraka P.E., president, A ndraka C onsulting G roup, I nc. the 16 Arcadia Drive • North Kingstown, RI 02852-1666 • USA 401/884-7930 FAX 401/884-7950 2 copyright 1998,1999,2000 Andraka Consulting Group, Inc. All Rights reserved You can do Math in them things??? 3 copyright 1998,1999,2000 Andraka Consulting Group, Inc. All Rights reserved Overview • Introduction • Digital demodulation for FPGAs • Filtering in FPGAs • Comparison to other technologies •Summary 4 copyright 1998,1999,2000 Andraka Consulting Group, Inc. All Rights reserved Digital Communications • Historically only base-band processing • High sample rates for down-converters • Down-conversion traditionally analog • Digital down-conversion with specialty chips • FPGAs can compete 5 copyright 1998,1999,2000 Andraka Consulting Group, Inc. All Rights reserved Why Digital? • Frequency agility • Repeatability • Cost 6 copyright 1998,1999,2000 Andraka Consulting Group, Inc. All Rights reserved Digital Challenges • A to D converter • High sample rates • Arithmetic intensive 7 copyright 1998,1999,2000 Andraka Consulting Group, Inc. All Rights reserved e - j ω c t = cos( ω c t)- j sin( ω c t ) Decimate by R Video Bandpass Filter 2 f (t) cos( ω c t) Phase Split ω c -ω c -ω c ω c -2ω c 00 0 √2f(t)e j ω ct Conventional Demodulator 8 copyright 1998,1999,2000 Andraka Consulting Group, Inc. All Rights reserved - j sin( ω c t) cos ( ω c t) Lowpass Filter √ 2 f (t) Lowpass Filter √ 2 f (t) I Q Decimate by R ω c -ω c -2ω c 00 -2ω c 0 e -j ω ct Re-arranged Demodulator * 9 copyright 1998,1999,2000 Andraka Consulting Group, Inc. All Rights reserved Complex Mixer Re[A k ] Im[A k ] Complex Baseband Signal (Passband for Demodulator) Complex Passband Signal (Baseband for Demodulator) Numerically Controlled Oscillator sin(ω c t) cos(ω c t) Re[S k ] Im[S k ] ω c Phase or frequency input 10 copyright 1998,1999,2000 Andraka Consulting Group, Inc. All Rights reserved Frequency Synthesizer Phase Angle to Wave Shape Conversion Waveform Out Phase Angle Modulation Waveform Synthesis (NCOs) • Various Methods – Look up table (LUT) – Partial products – Interpolation – Algorithmic • Most methods use a frequency synthesizer [...]... Modulator n+8 I[0] Q[0] 6-LUT I[1] Q[1] 6-LUT I[2] Q[2] 6-LUT I[3] Q[3] 6-LUT . 1998,1999,2000 Andraka Consulting Group, Inc. All Rights reserved Modulation and Demodulation Techniques for FPGAs Ray Andraka P.E., president, A ndraka C onsulting. Inc. All Rights reserved Overview • Introduction • Digital demodulation for FPGAs • Filtering in FPGAs • Comparison to other technologies •Summary 4 copyright