orumin
October 08, 2016
270

# 第12回カーネル/VM探検隊

October 08, 2016

## Transcript

1. ϥδΦ͸Α͘Θ͔Γ·ͤΜ͕ɺετϨʔτํࣜΑΓεʔύʔϔ
ςϩμΠϯํࣜͷ΄͏͕Α͍ͱࢲ͸ࢥ͍·͢ɻ
XXXX
Oct 8th, 2016
1 / 18

2. CAUTION
ແઢ๣ड಺༰ͷୈࡾऀ΁ͷ࿙Ӯɼ઄༻͸೔ຊࠃ๏཯ɼి೾๏ୈ 59 ৚ɼୈ
109 ৚ʹΑΓܐࣄേ෇Ͱېࢭ͞Ε͍ͯ·͢
ແ໔ڐແઢہʹΑΔ (ಛఆͷແઢҎ֎ͷ) ૹ৴͸ి೾๏ୈ 4 ৚ͷෆ๏ແ
ઢہʹ͋ͨΓɼേͤΒΕ·͢
͜͜Ͱ͍͏ແઢہͱ͸ϒϩʔυόϯυ์ૹͷϥδΦɼςϨϏͷૹ৴ࢪઃͩ
͚Ͱͳ͘ɼి೾๏ୈ 2 ৚ୈ 5 ߸Ͱఆٛ͞ΕΔʮແઢઃඋٴͼແઢઃඋͷ
ૢ࡞Λߦ͏ऀͷ૯ମʯΛࢦ͠·͢
2 / 18

3. ϥδΦͷ࢓૊Έ
߭ੴϥδΦ
ৼ෯มௐͷ৔߹
同調回路
検波器
ローパス
イヤホン
アンテナ
3 / 18

4. ৼ෯มௐ೾ͷݕ೾
4 / 18

5. ಉௐճ࿏
ω0 =
1

LC
, f0 =
1

LC
ΠϯμΫλ͸ిྲྀͷมԽʹΑͬͯىిྗ͕ൃੜ
ίϯσϯα͸ిѹͷมԽʹΑͬͯిՙ͕มԽ
VL(t) = L
diL
dt
, iC(t) = C
dVC
dt
ฒྻճ࿏Ͱ͸ɼ֤ૉࢠʹ͔͔Δిѹ͸౳͍͠
VL = VC
ిؾճ࿏Ͱ͸ɼશͯͷૉࢠʹྲྀΕΔిྲྀͷ࿨͕ྵʹͳ
Δ iC + iL = 0
d2i(t)
dt2
+
1
LC
i(t) = 0
同調回路
5 / 18

6. ݕ೾ճ࿏
৴߸͔ΒแབྷઢΛͱΓͩ͢
߭ੴ΍μΠΦʔυ͕ϑΟϧλͱͳͬ
͍ͯΔ
࣮͸ḊͼͨΧϛιϦͷਕͱΤϯϐπ
ͷਊͰ΋ΠέΔ
δΦʣ
import numpy as np
from scipy.signal import hilbert
t = np.linspace(0,1,2048)
E0 = 1
fc = 20
phi_c = 0
fm = 2
m = 0.9
phi_m = 0
E = E0*np.cos(fc*2*np.pi*t + phi_c)
x = m*np.sin(fm*2*np.pi*t + phi_m)
E_m = E0*np.cos(fc*2*np.pi*t + phi_c) \
*(1 - (m/2)*(1-np.sin(fm*2*np.pi*t+phi_m)
signal = hilbert(E_m)
envelope = np.abs(signal)
6 / 18

7. ΞφϩάϥδΦͷมભ
߭ੴϥδΦ
ਅۭ؅ϥδΦʢฒࡾɼฒ࢛ɼߴҰͳͲʣ
࠷ॳ͸ग़ྗΛೖྗʹ໭͢ਖ਼ؼؐʹΑΔ૿෯͚ͩ
εʔύʔϔςϩμΠϯ
http://www.marutsu.co.jp/wp/datatech/4562/
7 / 18

8. ϥδΦࠓੲ
͖͞΄Ͳ·Ͱ͸ɼੲͷ࿩
ΞφϩάϥδΦͩͱ৭ʑ໘౗
૿෯ͱ͔νϡʔχϯάͱ͔ग़ྗஈͷՃ޻ͱ͔
ΈΜͳେ޷͖ DSP ͱμΠϨΫτίϯόʔδϣϯड৴
εʔύʔϔςϩμΠϯͷ IF Λ 0Hz ʹͨ͠ߏ଄
8 / 18

9. DSP ϥδΦ
TV Ͱ΋ϥδΦͰ΋ಉ͡ɽ࣮͸ܞଳి࿩Ͱ΋ಉ͡
৴߸Λ A/D ม׵͠ɼίϯϐϡʔλʹऔΓࠐΉ͚ͩ
͜ͷਤ͸νϡʔφʔνοϓͷ R820T ͷσʔλγʔτΑΓ
9 / 18

10. I/Q ৴߸
ೖྗͷ RF ʹɼہ෦ൃৼث͔Β 90 ౓ͦΕͧΕҐ૬͕ҟͳΔ΋ͷΛՃ͑Δ
In-phase ৴߸
νϡʔφʔνοϓ͸ I/Q ৴߸ʢϕʔεόϯυ৴߸ʣΛಘΔ
10 / 18

11. RTL2832U
ΈΜͳେ޷͖ֈνοϓʂ
޿Ҭଳͷड৴͕Մೳʂ
Ξοϓίϯόʔτճ࿏Λ௥Ճͨ͠Β GPS ৴߸΋ड৴Մೳ
͍͍ͩͨ 1 GHz ͙Β͍·Ͱड৴Մೳ
11 / 18

12. RTL2832U
12 / 18

13. RTL2832U
13 / 18

14. ͱ͜Ζ͜ͷ USB υϯάϧͬͯ
ͦ͏Ͱ͢ɼϫϯηά TV ड৴༻
ͳΜͱळ༿ݪͰ 500 ԁͰߪೖ
Ξϯςφ͸ΞϚνϡΞແઢͷ 144/430 MHz ༻Ͱɼ3000 ԁ͙Β͍
14 / 18

15. ͔͍͔ͭͨʂ
RTL-SDR υϥΠόΛಋೖ
͋ͱ͸৭ʑௌ͚ͩ͘ʂ
15 / 18