RF HOW WORKS! (Hello RF!)

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RF HOW WORKS!(Hello RF!)

• ??????
• ???

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????(Impedance)

• Impedance ?
• ????? ???? ??? ?? R?, ??? ??? ??? ????? L(??)?
  C(????)? ?? ??? ??? ?? ? AC ??? ????.
• ?? Impedance
• Generally 50 Ohm
• Cable TV 75 Ohm
• Telephone line 600 Ohm
• Speaker 48 Ohm
• Impedance ??

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??? (dB)

• 10log (P1/P2) or 20log(V1/V2)
• Deci bel? ?????, ?? Deci ? '10'? ???? ??? ?????
  ? ?? ??? bel ? ??? ?? ??? ????? Bell lab? ??.
• ??? ??? log scale? ???.
• ?? ??? ?(value)? ??? ? ??.
• 10? 10dB, 100? 20dB, 10,000? 40dB
• 1/100? -20dB, 1/100,000 -50dB

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dBm, dBmV, dBuV

• Power Voltage X Current (PVI)
• Voltage Current X Resistor (VIR)
• 0dBm 1mW (10Xlog1mW)
• 0dBmV 1mV (20Xlog1mV)
• 0dBuV 1uV (20Xlog1uV)
• 0dBm 47dBmV _at_ 50ohm
• 0dBm 49dBmV _at_ 75ohm
• 0dBmV 60dBuV

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Time domain vs. Frequency domain - 2

• Time domain??? sine(?? cos)??? ??? frequency
  domain??? 1?? ???? ??
• Time domain??? impulse(??? ???? ??) ??? frequency
  domain??? ???? ?? ??? ?? ???? ??.

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???? ?????(Spectrum Analyzer)

• X-axis (Frequency domain)
• SPAN
• Center Frequency
• Y-axis (Magnitude)
• dBm, dBuV, dBmV
• RBW (Resolution BandWidth)

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Time domain vs. Frequency domain - 1

• time domain??? ?? frequency domain??? ?.
• (time domain??? ?? ???? MIXER?? ?)

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Example 1 (40Mhz 0dBm)
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Example 2 (Spectrum view)
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Example 3 (Spectrum view)
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Signal Quality

• 1. MER(Modulation Error Ratio) ?? S/R, ?? dB
• I/Q ????? ideal signal states?
• received signals? ??? dB? ??
• 2. EVM(Error Vector Magnitude), ??
• EVM? MER? ??? ???? ?? ??
• 3. BER(Bit Error Rate) ?? ??.
• ?? bit error? ??? ? ??
• ??
• (BER? ??????? ????
• ???? ??? ??)

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M-QAM vs signal

1. M? ???? ?? BER? ???? ?? S/N? ??
2. ?? S/N?? M? ??? ?? BER? ??

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PLL How works!

• - Phase Lock Loop -
• 1. ??? ???? ??? ??.
• 2. Feedback? ? ???? ??? ???? ???? ??
• 3. ?? UP-converter? LO(Local Oscillator)? ??

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UP Converter How works!

• Up Converter? Mixer? BPF(Band Pass Filter)? ??.
• Mixer? ???? ???? ???? ???.
• Filter? ??? ?? ???? ?? ?? ? ??.
• ??? ????? Filter?? SAW Filter? ??.

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Why I/Q use ?

• Scalar Modulation
• ???? (AM), ??? ??(FM)
• ???? (PSK)
• Vector Modulation
• COS(In-phase)? SIN(Quadrature-phase)? ??
  ??(Orthogonal)??? ??? ??
• ??? ????? ??? ??? ?? ? ?? ?????? ??? ?? ? ??.
• - QPSK , QAM
• Multiple Access Modulation
• CDMA, TDMA

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QAM Parameters.

• Modulation Aspect
• -. 4, 16, 32, 64, 128, 256 QAM
• -. Exist different symbol to constellation
  mapping method.
• (Gray encoding, DAVIC Gray Encoding DVB Gray
  encoding)
• -. Spectrum inversion

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QAM Parameters
-. Symbol rate. -. IF (Intermediate Frequency)
??/?? 6MHz??? 44MHz ?? 7/8MHz ??? 36MHz -.
Roll-off
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QAM Parameters

• 2. FEC(Forward Error Correction)
• -. ANNEX B ?? ? ?? ??
• -. ANNEX A/C ?? ? ?? ??
• -. Reed-solomon code
• -. Interleaver