ソフトウェアラジオとC++ そしてFMエアチェックのための信号解析と数値計算にまつわるよもやま話 / Software radio and C++

A presentation for Kichijoji.pm 20, Freakout Holdings, Inc., Minato-ku, Tokyo, Japan, 22-NOV-2019

Transcript

1. ιϑτ΢ΣΞϥδΦͱC++ 1
   ͦͯ͠FMΤΞνΣοΫͷͨΊͷ৴߸ղੳͱ਺஋ܭࢉʹ·ͭΘΔΑ΋΍·࿩
   1 ͜ͷൃදͰͷC++͸C++11Ҏ߱ͷ࢓༷Λલఏͱ͍ͯ͠·͢ɻ
   Kenji Rikitake / Kichijoji.pm 20 1
   

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2. Kenji Rikitake
   Γ͖͚ͨ ͚Μ͡
   ྗ෢ ݈࣍
   22-NOV-2019
   kichijoji.pm 20
   Freakout Holdings, Inc.
   Minato-ku, Tokyo, Japan
   @jj1bdx
   Kenji Rikitake / Kichijoji.pm 20 2
   

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3. ٕज़࢜ʢ৘ใ޻ֶ෦໳ʣ
   ྗ෢݈ٕ࣍ज़࢜ࣄ຿ॴ ॴ௕
   ৘ใॲཧ҆શ֬อࢧԉ࢜
   ϖύϘݚڀॴ ٬һݚڀһ
   ୈҰڃ཮্ແઢٕज़࢜
   ୈҰڃΞϚνϡΞແઢٕ࢜
   ΞϚνϡΞແઢྺ 43೥8ϲ݄
   Cྺ 33೥ɺC++11ྺ ͨͬͨͷ3೥
   ຊݚڀ΁ͷϖύϘݚڀॴͷ͝ࢧԉʹਂ͘ײँ͠·͢
   Kenji Rikitake / Kichijoji.pm 20 3
   

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4. Kenji Rikitake / Kichijoji.pm 20 4
   

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5. 1970೥୅ྲྀߦͬͨFMΤΞνΣοΫ
   FM์ૹ͸Իָͷࢁͩͬͨ
   ࢲ΋͍ͬͺ͍ϥδΧη2Ͱ࿥Իͯ͠·ͨ͠
   ʢ2019೥ͷࠓͰ΋࿥Ի͍ͯ͠Δਓୡ͸͍ͬͺ͍͍·͢ʣ
   2 Puding Jahodový, Public domain, h4ps:/
   /commons.wikimedia.org/wiki/File:Sharp_5P-37G_wiki.jpg, via Wikimedia
   Commons
   Kenji Rikitake / Kichijoji.pm 20 5
   

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6. Kenji Rikitake / Kichijoji.pm 20 6
   

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7. 21ੈلͷϥδΦ͸ιϑτ΢ΣΞ
   USBσόΠε3Ͱप೾਺ม׵ͱଳҬ੍ݶ
   ม׵ͨ͠৴߸͸ ιϑτ΢ΣΞ Ͱॲཧ
   ίʔυ͕ॻ͚Ε͹͋ͳͨ΋ϥδΦ͕࡞ΕΔ!
   ΤΞνΣοΫͨ͠MP3ϑΝΠϧ΋εϚϗͰฉ͖์୊!
   3 Photo of Airspy HF+ Dual Port by Kenji Rikitake
   Kenji Rikitake / Kichijoji.pm 20 7
   

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8. प೾਺ม׵ͱଳҬ੍ݶͷྫ
   82.5MHzΛத৺ͱ͢ΔFM์ૹͷ৔߹
   82.308MHz - 82.692MHz
   ↓
   -0.192MHz - 0.192MHz
   ±192kHzͷ384kHz෯ͷ৴߸ʹม׵
   Kenji Rikitake / Kichijoji.pm 20 8
   

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9. ෛͷप೾਺
   ࣮਺ͷ৴߸:
   ࣮ࡍͷՄೳੑ(1):
   ࣮ࡍͷՄೳੑ(2):
   ཧ༝:
   …ͳͷͰ࣮਺ͷ৴߸͚ͩͰ͸৴߸ͷҐ૬ΛಛఆͰ͖·ͤΜ
   ෛͷप೾਺Λߟ͑ͯ΍Δඞཁ͕͋Γ·͢
   Kenji Rikitake / Kichijoji.pm 20 9
   

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10. IQ৴߸: ࣮਺৴߸Λෳૉ਺ʹม׵
    ࣮਺ͷ৴߸: ͔ΒҎԼͷ৴߸Λੜ੒͠·͢
    ରԠ͢ΔIQ৴߸:
    ͨͩ͠ ʢͳͥ͜Ε͕ Ͱͳ͍͔ͱ͍͏ͱిؾͰ͸ ͸ిྲྀͷҙຯͳͷͰ͢ʣ
    ͜ΕΛॻ͖௚͢ͱ ʢۃ࠲ඪʣ
    I৴߸ʢ࣮਺෦ʣ:
    Q৴߸ʢڏ਺෦ʣ:
    Kenji Rikitake / Kichijoji.pm 20 10
    

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11. IQ৴߸ͩͱԿ͕͏Ε͍͔͠
    IQ৴߸:
    std::complex IQsample ͱͯ͠ఆٛ
    ৴߸ͷৼ෯ ͸ std::abs(IQsample)
    ৴߸ͷҐ૬ ͸ std::arg(IQsample)
    std::arg(z) = std::atan2(z.imag(), z.real())
    AM์ૹͳΒ ͦͷ΋ͷɺFM์ૹͳΒ Λඍ෼͢Ε͹෮ௐͰ͖Δ
    Kenji Rikitake / Kichijoji.pm 20 11
    

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12. 50೥લͷFM์ૹ։͔࢝࣌Βͷ೰·͍͠໰୊:
    FMͷ
    ඼࣭Լ͛Δ
    Ϛϧνύε
    Kenji Rikitake / Kichijoji.pm 20 12
    

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13. Ϛϧνύε
    ෳ਺ܦ࿏Λ௨Δి೾ͷׯব
    ৼ෯΍Ґ૬͕มԽͯ͠࿪Ή
    Ґ૬͕࿪ΉͱFM์ૹͩͱͱͯ΋ෆշͳԻ͕͢Δ
    ैདྷͷରԠ: Ξϯςφͷࢦ޲ੑͷมԽ͙Β͍͔͠Ͱ͖ͳ͔ͬͨ
    Kenji Rikitake / Kichijoji.pm 20 13
    

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14. ϚϧνύεͰຊདྷͳ͍৴߸͕ݟ͑Δྫ4
    4 Lithium57, English transla3on: MichaelBillington, h:ps:/
    /commons.wikimedia.org/wiki/
    File:Mul3path_propaga3on_diagram_en.svg from Wikimedia Commons, public domain
    Kenji Rikitake / Kichijoji.pm 20 14
    

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15. ϚϧνύεʹΑΔৼ෯ͷมԽ5
    5 Audacity simula.on and graphics by Kenji Rikitake
    Kenji Rikitake / Kichijoji.pm 20 15
    

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16. Ϛϧνύε͸஗Ԇ೾ͷ৞ΈࠐΈ6
    6 I, Cantalamessa, h.ps:/
    /commons.wikimedia.org/wiki/File:Mul>path_impulse_response.png from Wikimedia
    Commons, licensed CC BY 2.5
    Kenji Rikitake / Kichijoji.pm 20 16
    

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17. ஗ԆΛϞσϦϯάͯ͠ٯԋࢉ͢Δ
    FM৴߸: ৼ෯͸ҰఆɺҐ૬/प೾਺ͷΈมԽ
    ৼ෯ͷมԽ→৴߸͕࿪ΜͰ͍Δ
    มԽͨ͠ৼ෯Λ໭͢Α͏ͳ৞ΈࠐΈΛड৴ଆ
    Ͱ΍ͬͯ͠·͑͹Α͍
    ʢLeast Mean Square / Constant Modulus Algorithmʣ
    Kenji Rikitake / Kichijoji.pm 20 17
    

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18. ٯԋࢉͷͨΊͷFIRϑΟϧλ (airspy-fmradion)
    using IQSample = std::complex;
    using IQSampleVector = std::vector;
    inline IQSample MultipathFilter::single_process(const IQSample filter_input) {
    m_state.emplace_back(filter_input);
    m_state.erase(m_state.begin());
    IQSample output = IQSample(0, 0);
    // for (unsigned int i = 0; i < m_filter_order; i++) {
    // output += m_state[i] * m_coeff[i];
    // }
    volk_32fc_x2_dot_prod_32fc(&output, m_state.data(), m_coeff.data(),
    m_filter_order);
    return output;
    }
    Kenji Rikitake / Kichijoji.pm 20 18
    

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19. Vector Op*mized Library of Kernels (VOLK)
    x86/ARMͷ৴߸ॲཧͷͨΊͷϥΠϒϥϦ
    SIMD໋ྩ౳ͰΧϦΧϦͷϋϯυνϡʔχϯά
    h"p:/
    /libvolk.org/
    ʢFM෮ௐઐ༻ͷؔ਺͕͋ͬͨΓ͢Δ͘Β͍ΨνͰ͢ʣ
    Kenji Rikitake / Kichijoji.pm 20 19
    

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20. ྗ෢ͷGPLv3࣮૷ = airspy-fmradion
    h"ps:/
    /github.com/jj1bdx/airspy-fmradion
    ΋ͱ΋ͱ͸So#FMͱ͍͏FMड৴ઐ༻ػ
    ࠓ͸த೾୹೾AM/FM/SSB/CWͳΜͰ΋͟͝ΕʹਐԽ
    ͓ͦΒ͘ੈքॳͷOSSͰ࣮૷ͨ͠ϚϧνύεϑΟϧλ
    macOSͱLinuxͱRaspberry PiͰಈ͖·͢
    ʢGUIෆಘҙͳͷͰʣίϚϯυϥΠϯπʔϧ Ͱ͢
    Kenji Rikitake / Kichijoji.pm 20 20
    

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21. ࠷ޙʹҰ۟
    ౙͷ໷ʹ
    ཕΛ఻͑Δ
    ి཭૚
    ʢౙͷ໷ʹ֤஍Ͱൃੜ͢Δཕ͕ి཭૚Λհͯ͠த೾์ૹ΍3.9MHzʢ75mόϯυʣͷ୹೾์ૹͰ೔ຊதʹ͘·ͳ͘఻ΘΔ༷Λࣔͨ͠Ұ۟ɻͳ͓ɺཕʢΒ͍ʣ͸ຊདྷՆͷقޠɻʣ
    Kenji Rikitake / Kichijoji.pm 20 21
    

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22. ܾҙද໌
    2020೥ʹ౦ژʹ໭ͬͨΒ
    ؤுͬͯ΋ͬͱՔ͍Ͱ
    ΑΓΑ͍ݚڀͱٕज़Ͱ
    ࣾձʹߩݙ͠·͢
    Kenji Rikitake / Kichijoji.pm 20 22
    

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23. Thank you
    Ques%ons?
    Kenji Rikitake / Kichijoji.pm 20 23
    

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