⡆᫆ GPS ࣔࢪ࣮ࣗࣝࢆ⏝࠸ࡓ LAN ⏝㧗⢭ᗘ᫬้ྠᮇᢏ⾡࡟㛵ࡍࡿ᳨ウ

኱ྠ኱Ꮫ⣖せ ➨54ᕳ㸦2018㸧

⡆᫆ GPS ࣔࢪ࣮ࣗࣝࢆ⏝࠸ࡓ LAN ⏝㧗⢭ᗘ᫬้ྠᮇᢏ⾡࡟㛵ࡍࡿ᳨ウ

Precision time synchronization technique for LAN employing simple GPS receiver module

᱓㔝 ⱱ*

Shigeru Kuwano*

Summary

Precision time synchronization is essential for the ultra low latency services in the 5G era, and the requirement of time synchronization is sub-millisecond in general and lower than 1 μs for mobile base stations. To achieve this accuracy by network-based synchronization scheme, distributed time server system employing GPS is an candidate for standard LAN that has large jitter in packet latency. We developed a simple and low cost network time protocol (NTP) server with simple GPS receiver module and small PC board. The achieved time synchronization accuracy of GPS module is within +/- 1μs under practical receiver deployment environment, and that of NTP server and a client in LAN are within +/- 10 μs and +/- 200 μs, respectively.

࣮࣮࢟࣡ࢻ㸸᫬้ྠᮇ㸪GPS㸪ࢿࢵࢺ࣮࣡ࢡࢱ࢖࣒ࣉࣟࢺࢥࣝ(NTP) Keywords㸸 Time synchronization, GPS, Network time protocol (NTP)

㸬ࡣࡌࡵ࡟

5G ௨㝆ࡢࢿࢵࢺ࣮࣡ࢡ࡛ࡣ㸪⌧≧ࡢࣃࢣࢵࢺࢿࢵࢺ

࣮࣡ࢡࡢ௙⤌ࡳࢆά⏝ࡋࡘࡘᵝࠎ࡞ရ㉁ࡢࢧ࣮ࣅࢫࢆ

ᥦ౪ࡍࡿࡇ࡜ࡀせồࡉࢀࡿ

㸬≉࡟㸪⮬ື㐠㌿➼ࡢࣜ࢔

ࣝ ࢱ ࢖ ࣒ ⣔ ࡢ ࢧ ࣮ ࣅ ࢫ ࡟ ᑐ ࡋ ࡚ ࡣ 㸪 Time Sensitive

Network(TSN)

࡛♧ࡉࢀࡿࡼ࠺࡞ప㐜ᘏ࠿ࡘ㐜ᘏኚື

ࡢᑠࡉ࠸ࢿࢵࢺ࣮࣡ࢡࡀせồࡉࢀࡿ㸬ࡇࡢࡼ࠺࡞ప㐜 ᘏࡀせồࡉࢀࡿࢧ࣮ࣅࢫ࡟࠾࠸࡚ࡣ㸪ྛ➃ᮎࡢ᫬้ࡢ 㧗⢭ᗘ࡞ྠᮇࡀᚲせ࡛࠶ࡾ㸪౛࠼ࡤᦠᖏ㟁ヰࡢᇶᆅᒁ

࡛ࡣ 1μs ௨ୗࡢ᫬้ྠᮇ⢭ᗘࡀせồࡉࢀ㸪ࡉࡽ࡟࿘Ἴ

ᩘ࡛ࡣ 50ppb ௨ୗࡢྠᮇ⢭ᗘࡀせồࡉࢀࡿ

㸬

ࡇࡢࡼ࠺࡞㧗⢭ᗘྠᮇࢆᐇ⌧ࡍࡿࡓࡵ㸪GPS ⾨ᫍࢆ

ά⏝ࡋࡓྠᮇᢏ⾡࡜ࢿࢵࢺ࣮࣡ࢡ࣮࣋ࢫࡢྠᮇᢏ⾡ࢆ

ే⏝ࡋࡓྠᮇࢩࢫࢸ࣒ࡀ᳨ウࡉࢀ࡚࠸ࡿ

㸬ࡇࡢሙྜ㸪 GPS ⾨ᫍ࡟ᦚ㍕ࡉࢀ࡚࠸ࡿཎᏊ᫬ィ࡟ྠᮇࡍࡿ㉸㧗⢭

ᗘ࡞Ⓨ᣺ჾࡸࢿࢵࢺ࣮࣡ࢡ୰࡛ࡢࣃࢣࢵࢺࡢ㐜ᘏ᫬㛫

ࢆ㧗⢭ᗘ࡟ィ ྍ⬟࡞ࢿࢵࢺ࣮࣡ࢡ⿦⨨ࢆ⏝࠸࡚ࢩࢫ ࢸ࣒ࢆᵓᡂࡋ࡚࠾ࡾ㸪㧗࠸ྍ⏝ᛶࡀせồࡉࢀࡿ࢟ࣕࣜ

࢔ࡢࢿࢵࢺ࣮࣡ࢡࡸ௻ᴗෆࡢᑓ⏝⥙࡟㐺⏝ࡉࢀࡿ㸬

୍᪉㸪㏻ᖖࡢ LAN ࡟࠾࠸࡚ࡣࡑࢀࡒࢀࡢࢿࢵࢺ࣮࣡

ࢡ⿦⨨ࡣ㠀ྠᮇ࡛ືసࡋ࡚࠾ࡾ㸪ࢿࢵࢺ࣮࣡ࢡ࣮࣋ࢫ ࡢྠᮇᢏ⾡ (Network Time Protocol(NTP) ࠾ࡼࡧ Precision Time Protocol(PTP))࡛➃ᮎࡢྠᮇࡀᅗࡽࢀࡿ㸬ࡇࡢ㝿㸪 NTP ࡸ PTP ࡢࢧ࣮ࣂ࡜ࡋ࡚ࡣ GPS ࡸཎᏊ᫬ィ࡟ᚑᒓྠ

ᮇࡋࡓࡶࡢࡀ⏝࠸ࡽࢀࡿࡀ㸪LAN ෆ࡟ከᩘ㓄⨨ࡉࢀࡿ

ࡇ࡜ࡣ࡞ࡃ㸪㏻ᖖࡢࢡࣛ࢖࢔ࣥࢺࡀࢧ࣮ࣂ࡟࢔ࢡࢭࢫ ࡋ࡚ྠᮇືసࢆ⾜࠸㸪ࡑࡢ࿘ᮇࡣ Linux ࢆ⏝࠸ࡓࢩࢫࢸ

࣒࡛㏻ᖖᩘ༑⛊࠿ࡽᩘ༓⛊࡟ 1 ᅇ⛬ᗘ࡛࠶ࡿ㸬ࡲࡓ㸪ࢧ

࣮ࣂ㸫ࢡࣛ࢖࢔ࣥࢺ㛫ࡢ㐜ᘏ᫬㛫ࡶࢿࢵࢺ࣮࣡ࢡࢺࣛ

ࣄࢵࢡኚືࡢᙳ㡪ࢆཷࡅ࡚᫬㛫࡜࡜ࡶ࡟኱ࡁࡃኚືࡍ

ࡿ㸦ࢪࢵࢱ㸧 㸬ࡇࡢࡓࡵ㸪㧗࠸᫬้⢭ᗘࢆᚓࡿࡇ࡜ࡣ㞴 ࡋࡃ㸪ᩘ ms 㹼ᩘ༑ ms ࡢ⢭ᗘ࡜࡞ࡾ㸪ྠᮇ㢖ᗘࡀప࠸

ሙྜ࡟ࡣᩘ⛊⛬ᗘࡢㄗᕪࡀ⏕ࡌࡿࡇ࡜ࡶ࠶ࡿ㸬㏻ᖖࡢ

ேࡀ௓ࡍࡿࢧ࣮ࣅࢫ࡟࠾࠸࡚ࡣࡇࡢ⛬ᗘࡢ⢭ᗘ࡛༑ศ

࡛࠶ࡿࡀ㸪௒ᚋࡢࣔࣀࡢ࢖ࣥࢱ࣮ࢿࢵࢺ (Internet of

Things(IoT)) ࡛⮬ື㐠㌿➼ࡢ࣑ࢵࢩࣙࣥࢡࣜࢸ࢕࢝ࣝ࡞

ࣜ࢔ࣝࢱ࢖࣒ࢧ࣮ࣅࢫࢆᐇ⌧ࡍࡿࡓࡵ࡟ࡣ㸪࣑ࣜ⛊࢜

㸨

኱ྠ኱Ꮫ᝟ሗᏛ㒊᝟ሗࢩࢫࢸ࣒Ꮫ⛉

࣮ࢲࡢ᫬้ㄗᕪࡣチᐜ࡛ࡁ࡞࠸㸬

NTP ࢆ⏝࠸ࡓࢩࢫࢸ࣒࡛ྠᮇ⢭ᗘࢆ㧗ࡃࡍࡿࡓࡵ࡟

ࡣ㸪ࢧ࣮ࣂ࡜ࡢ㛫ࡢࣃࢣࢵࢺ㐜ᘏᦂࡽࡂࢆᢚ࠼ࡿࡇ࡜

࡜ࢧ࣮ࣂ࡬ࡢ࢔ࢡࢭࢫ㢖ᗘࢆቑຍࡉࡏࡿࡇ࡜ࡀ᭷ຠ࡛

࠶ࡿ㸬≉࡟๓⪅࡟㛵ࡋ࡚㸪ࢧ࣮ࣂࢆศᩓ㓄⨨ࡋ࡚ࢧ࣮ࣂ

㸫ࢡࣛ࢖࢔ࣥࢺ㛫ࡢࢺࣛࣄࢵࢡኚືࢆᢚ࠼࡚㐜ᘏኚື

ࢆᑠࡉࡃࡍࡿࡇ࡜ࡀ᭷ຠ࡛࠶ࡿ㸬ࡲࡓ㸪ࡇࡢሙྜ㸪ࢡࣛ

࢖࢔ࣥࢺࡢࢧ࣮ࣂ࡬ࡢ࢔ࢡࢭࢫࡍࡿ㢖ᗘࢆቑຍࡉࡏࡿ

ࡇ࡜ࡀྍ⬟࡛࠶ࡾ㸪⤫ィⓗ࡞ฎ⌮࡟ࡼࡾ㐜ᘏኚືࢆᢚ ᅽࡋࡓ㧗⢭ᗘ࡞ືసࡀྍ⬟࡜࡞ࡿ㸬

ᮏ✏࡛ࡣ㸪 NTP ࢧ࣮ࣂࢆᐇ㦂ᐊࡸࣇࣟ࢔࡜࠸ࡗࡓ⠊

ᅖࡢ LAN ࡈ࡜࡟㓄⨨ࡍࡿศᩓᆺࡢྠᮇࢩࢫࢸ࣒ࢆ᳨ウ ᑐ㇟࡜ࡋ㸪ࡇࢀࢆᐇ⌧ࡍࡿୖ࡛ᚲせ࡜࡞ࡿపࢥࢫࢺ࡛

ᵓ⠏ྍ⬟࡞⡆᫆ GPS ࣔࢪ࣮ࣗࣝ࡜ᑠᆺ࣐࢖ࢥࣥࢆ⏝࠸

ࡓ NTP ࢧ࣮ࣂ࠾ࡼࡧ NTP ࢡࣛ࢖࢔ࣥࢺ࡟ࡘ࠸࡚⾜ࡗ ࡓྠᮇᛶ⬟ホ౯࡟ࡘ࠸࡚㏙࡭ࡿ㸬ࡲࡎ㸪⡆᫆ GPS ࣔࢪ

࣮ࣗࣝࢆ⏝࠸ࡓࢩࢫࢸ࣒࡟ࡘ࠸࡚ᴫㄝࡋࡓࡢࡕ㸪ࡑࡢ ᛶ⬟ホ౯⤖ᯝ࡟ࡘ࠸࡚㏙࡭ࡿ㸬ḟ࡟㸪⡆᫆ GPS ࣔࢪࣗ

࣮ࣝࢆ⏝࠸ࡓ NTP ࢧ࣮ࣂ࡞ࡽࡧ࡟ LAN ෆ࡟㓄⨨ࡋࡓ NTP ࢡࣛ࢖࢔ࣥࢺ࡟ࡘ࠸࡚㸪ࡑࡢྠᮇᛶ⬟ࡢホ౯⤖ᯝ

࡟ࡘ࠸࡚㏙࡭ࡿ㸬

㸬⡆᫆ *36 ࣔࢪ࣮ࣗࣝࢆ⏝࠸ࡓྠᮇࢩࢫࢸ࣒

ࢩࢫࢸ࣒ᵓᡂ

᳨ウࡍࡿྠᮇࢩࢫࢸ࣒ࡢᵓᡂࢆᅗ 1 ࡟♧ࡍ㸬ࢿࢵࢺ

࣮࣡ࢡୖ࡟ᑠᆺ GPS ࣔࢪ࣮ࣗࣝࢆ᥋⥆ࡋࡓᑠᆺࡢ࣐࢖

ࢥࣥࣔࢪ࣮ࣗࣝࢆ」ᩘ㓄⨨ࡋ㸪ࡑࢀࡒࢀࢆ NTP ࢧ࣮ࣂ

࡜ࡋ࡚ືసࡉࡏ㸪NTP ࢡࣛ࢖࢔ࣥࢺࡣ㏆᥋ࡢ NTP ࢧ࣮

ࣂ࡟ྠᮇࡍࡿᵓᡂ࡜ࡍࡿ㸬

ᅗ 1: ྠᮇࢩࢫࢸ࣒ࡢᵓᡂ

*36 ࣔࢪ࣮ࣗࣝ

ᅗ 2 ࡟ GPS ࣔࢪ࣮ࣗࣝࡢᵓᡂࢆ♧ࡍ㸬GPS ࣔࢪ࣮ࣗ

࡛ࣝࡣ 4 ௨ୖࡢ GPS ⾨ᫍ࠿ࡽࡢಙྕࢆྠ᫬࡟ཷಙࡋ㸪

ࡑࢀࡽࡢ⾨ᫍࡢ఩⨨᝟ሗ㸪㏦ಙ࠾ࡼࡧཷಙࢱ࢖࣑ࣥࢢ

࡜࠿ࡽࣔࢪ࣮ࣗࣝࡢ ఩᝟ሗ࡞ࡽࡧ࡟᫬้᝟ሗࢆ₇⟬

ࡋฟຊࡍࡿ㸬ཷಙᑐ㇟࡜࡞ࡿ⾨ᫍࡣࣔࢪ࣮ࣗࣝ࡟ࡼࡾ

␗࡞ࡾ㸪GPS ⾨ᫍࡢࡳ࡛ࡣ࡞ࡃ㸪Galileo, GLONASS㸪

BeiDou ࡟ᑐᛂࡋࡓࡶࡢࡸ㸪᪥ᮏࡀᡴࡕୖࡆ㐠⏝ࢆ㛤ጞ

ࡋ࡚࠸ࡿ‽ኳ㡬⾨ᫍ(QZSS)࡟ᑐᛂࡋࡓࡶࡢࡶ࠶ࡿ㸬୍

⯡࡟ཷಙྍ⬟࡞⾨ᫍᩘࡀከ࠸᪉ࡀࡼࡾ㧗࠸⢭ᗘ㸦ሙᡤ

࠾ࡼࡧ᫬้㸧ࡀᐇ⌧ྍ⬟࡛࠶ࡿ㸬

ᅗ 2: GPS ࣔࢪ࣮ࣗࣝࡢᵓᡂ

ࣔࢪ࣮ࣗࣝฟຊಙྕ

࣭ ఩᝟ሗ

 ఩᝟ሗࡣࢸ࢟ࢫࢺࢹ࣮ࢱ࡜ࡋ࡚ฟຊࡉࢀࡿ㸬ࣇ࢛

࣮࣐ࢵࢺࡣᶆ‽࡛࠶ࡿ NMEA0183 ࡟ࡋࡓࡀࡗ࡚࠾ࡾ㸪

ཷಙ⾨ᫍᩘ㸪ྛ⾨ᫍࡢཷಙ≧ែ㸪఩⨨᝟ሗ㸪᫬้᝟ሗ㸪  ఩⢭ᗘ࡟㛵ࡍࡿ᝟ሗ࡜࠸ࡗࡓᵝࠎ࡞᝟ሗࡀ 1 ⛊ࡈ࡜

࡟ฟຊࡉࢀࡿ㸬GPS ࣔࢪ࣮ࣗࣝ࠿ࡽࡢ NMEA0183 ࣇ࢛

࣮࣐ࢵࢺࡢࢹ࣮ࢱࡢ୍౛ࢆᅗ 3 ࡟♧ࡍ㸬

ᅗ 3: NMEA0183 ࣇ࢛࣮࣐ࢵࢺࡢ౛

࣭ࢱ࢖࣑ࣥࢢ᝟ሗ

ᅗ 3 ࡟♧ࡍࡼ࠺࡟㸪ୡ⏺ᶆ‽᫬ (UTC) ࡟㛵ࡍࡿ᫬้᝟

ሗࡣ ఩᝟ሗ࡜ྠࡌࡃ NMEA0183 ࣇ࢛࣮࣐ࢵࢺ࡛ฟຊ ࡉࢀࡿࡀ㸪ࢱ࢖࣑ࣥࢢ࡟ࡘ࠸࡚ࡣ㸪 1 ⛊࡟ 1 ࣃࣝࢫࢆ⏕

ᡂࡍࡿ Pulse Per Second(PPS)ಙྕ࡜ࡋ࡚ฟຊࡉࢀࡿ㸬 GPS ࣔࢪ࣮ࣗࣝෆ࡛₇⟬ࡉࢀࡿ PPS ࣃࣝࢫࡢࢱ࢖࣑ࣥ

ࢢࡣ㸪 UTC ࡢࢱ࢖࣑ࣥࢢ࡜ᇶᮏⓗ࡟ࡣྠᮇࡋ࡚࠸ࡿࡀ㸪

ࣔࢪ࣮ࣗࣝࡢ⮬㉮ࡢෆ㒊ࢡࣟࢵࢡ࠿ࡽ⏕ᡂࡉࢀࡿࡓࡵ㸪 5)

)URQWHQG

*36 6LJQDO 3URFHVVLQJ

8$57

*3,2 336

$QWHQQD

*3**$1(

00$

Ҥౕɼܨౕɼ߶ౕɼำଌӶ੗਼

*3*6$$

)

ำଌӶ੗൬ߺɼ଎Ғ੠ౕ

*3*69

$

Ӷ੗൬ߺɼھֱɼ๏Ғֱɼ61ർ

*350&$1 ('

ೖ࣎ɼҤౕɼܨౕɼଐౕ

᭱኱࡛ෆ㒊ࢡࣟࢵࢡࡢ࿘ᮇศ㸦㏻ᖖᩘ ns ⛬ᗘ㸧ࡢㄗᕪ

ࢆ᭷ࡋ࡚࠸ࡿ㸬ࡲࡓ㸪⾨ᫍࡢཷಙ≧ែࡀᝏ࠸ሙྜ࡟ࡣ㸪

₇⟬࡟ࡼࡿㄗᕪࡀ኱ࡁࡃ࡞ࡿࡓࡵࢱ࢖࣑ࣥࢢࡢㄗᕪࡶ

኱ࡁࡃ࡞ࡿ㸬

㸬⡆᫆ *36 ࣔࢪ࣮ࣗࣝࡢᇶᮏᛶ⬟ホ౯

GPS ࣔࢪ࣮ࣗࣝࡣ㸪ࣅࣝࡢᒇୖ➼㐽ࡿࡶࡢࡀ↓ࡃ඲

ኳࡀぢΏࡏࡿሙᡤ࡛ከࡃࡢ⾨ᫍ࠿ࡽࡢ㟁Ἴࢆ㧗࠸ရ㉁

࡛ཷಙ࡛ࡁࡿሙྜ࡟᭱㧗ࡢ⢭ᗘࢆⓎ᥹࡛ࡁࡿࡀ㸪ᐇ㝿

࡟ࡣᘓ≀➼ࡢᙳ࡟࡞ࡗ࡚ᤊ࠼ࡿࡇ࡜ࡢ࡛ࡁࡿ⾨ᫍᩘࡀ ῶᑡࡍࡿࡇ࡜࡟ࡼࡿㄗᕪࡸ㸪ᘓ≀➼࡛཯ᑕࡉࢀࡓ㟁Ἴ 㸦࣐ࣝࢳࣃࢫ㸧ࡢఏᦙ᫬㛫ᕪ࡟ࡼࡿㄗᕪࡀ⏕ࡌࡿ㸬ࡇࢀ

ࡽࡢᙳ㡪ࢆྵࡵ࡚ホ౯ࡍࡿࡓࡵ㸪 GPS ࣔࢪ࣮ࣗࣝࡣᐇ 㦂ᐊෆࡢ❆㝿㸦ᮾྥࡁ㸧࡟タ⨨ࡋࡓ㸬ࡇࡢሙྜ㸪ぢ㏻ࡋ ࡀ඲ኳࡢ༙ศ௨ୗ࡜࡞ࡿ࡜࡜ࡶ࡟㸪㏆㞄ࡢࣅࣝ࠿ࡽࡢ

཯ᑕ࡟ࡼࡿ࣐ࣝࢳࣃࢫࡶཷಙࡋࡸࡍ࠸⎔ቃ࡜࡞ࡿ㸬

ᐇ㦂⣔ࡢᵓᡂ

ᅗ 4(a) ࡟ᐇ㦂⣔ࡢᵓᡂࢆ♧ࡍ㸬 GPS ࣔࢪ࣮ࣗࣝ࠿ࡽ

ࡢ NMEA ࣇ࢛࣮࣐ࢵࢺࡢ GPS ᝟ሗࢆࢩࣜ࢔ࣝᅇ⥺ࢆ

௓ࡋ࡚ PC ࡟ྲྀࡾ㎸ࡴ࡜࡜ࡶ࡟㸪 PPS ಙྕࡢࢱ࢖࣑ࣥࢢ

ࢆ Rb Ⓨ᣺ჾࢆෆⶶࡋࡓ GPS ཷಙᶵ

࠿ࡽࡢ PPS ಙྕ

ࡢࢱ࢖࣑ࣥࢢ࡜ẚ㍑ࡋ㸪ࢱ࢖࣑ࣥࢢㄗᕪࢆ ᐃࡍࡿ㸬ࡇ ࡢ GPS ཷಙᶵࡢ࿘ἼᩘᏳᐃᗘࡣs2™10

௨ୗ࡛࠶ࡾ㸪

᫬้⢭ᗘࡣs 30ns ௨ୗ࡛࠶ࡿ㸬ࡲࡓ㸪ࢱ࢖࣑ࣥࢢㄗᕪ ࡣࣘࢽࣂ࣮ࢧࣝ࿘Ἴᩘ࢝࢘ࣥࢱ࡟ࡼࡿࢱ࢖࣒࢖ࣥࢱ࣮

ࣂࣝ ᐃ࡟ࡼࡾィ ࡍࡿ㸬ᐇ㦂࡟౑⏝ࡋࡓ GPS ࣔࢪࣗ

࣮ࣝࡢᴫせࢆ⾲ 1 ࡟♧ࡍ࡜࡜ࡶ࡟ࡑࡢእほࢆᅗ 4(b)࡟

♧ࡍ㸬 ᐃࡣྛࣔࢪ࣮ࣗࣝ࡟ࡘ࠸࡚ࡑࢀࡒࢀ 7 ᪥㛫௨

ୖ㐃⥆࡛ᐇ᪋ࡋࡓ㸬

(a)ᵓᡂ

(b)GPS ࣔࢪ࣮ࣗࣝ

ᅗ 4 㸸 ᐇ㦂⣔

⾲ 1 㸸ᐇ㦂࡟⏝࠸ࡓ GPS ࣔࢪ࣮ࣗࣝ

No. ࣋ࣥࢲ ᆺ␒ ᑐᛂࢩࢫࢸ࣒

1 ኴ㝧ㄏ㟁 GYSFDMAXB GPS

2 ኴ㝧ㄏ㟁 GYSFDMAXB

(QZSS 3 ⾨ᫍ∧)

GPS, QZSS

3 Linx RXM-GPS-RM GPS, QZSS

4 Linx RXM-GNSS-GM GPS, QZSS

GLONASS, GALILEO

ホ౯⤖ᯝ

ᅗ 5 ࡟ 7 ᪥㛫࡟ࢃࡓࡿྛࣔࢪ࣮ࣗࣝࡢ PPS ಙྕࢱ࢖

࣑ࣥࢢㄗᕪࡢ ᐃ⤖ᯝࢆ♧ࡍ㸬ࣔࢪ࣮ࣗࣝ㸯ࡢሙྜ᭱

኱ +1.5μs ⛬ᗘࡢㄗᕪࡀ⏕ࡌ࡚࠾ࡾ㸪ࡑࢀ௨እࡢࣔࢪࣗ

࣮࡛ࣝࡣ 7 ᪥㛫࡟ࢃࡓࡗ࡚s1μs ௨ୗࡢྠᮇ⢭ᗘࡀᐇ

⌧࡛ࡁ࡚࠸ࡿ㸬 GPS ࣔࢪ࣮ࣗࣝࡢ௙ᵝୖࡢྠᮇ⢭ᗘࡣ 30ns(RMS)࡛࠶ࡿࡀ㸪ࡇࢀࡣᖖ࡟༑ศ࡞ᩘࡢ⾨ᫍࢆ࣐ࣝ

ࢳࣃࢫ➼ࡢ↓࠸⎔ቃ࡛ཷಙྍ⬟࡞⌮᝿ⓗ࡞ሙྜ࡛ࡢ್

࡛࠶ࡾ㸪௒ᅇࡢሙྜ㸪඲ኳࡢ༙ศ௨ୗࡢど㔝࡛࠶ࡾ࠿ࡘ

࣐ࣝࢳࣃࢫࡢ࠶ࡿ⎔ቃ࡛࠶ࡿࡇ࡜࡟ࡼࡗ࡚௙ᵝ್ࡼࡾ

ࡶ኱ࡁ࡞ㄗᕪࡀ⏕ࡌ࡚࠸ࡿ࡜⪃࠼ࡽࢀࡿ㸬ࡲࡓ㸪ࣔࢪࣗ

࣮ࣝ 1 ࡛ㄗᕪࡀ኱ࡁ࠸⌮⏤࡜ࡋ࡚㸪ཷಙྍ⬟࡞⾨ᫍᩘ

ࡀ௚ࡢࣔࢪ࣮ࣗࣝࡼࡾᑡ࡞࠸ࡇ࡜ࡀᣲࡆࡽࢀࡿ㸬ࡇࡢ ࡓࡵ㸪ཷಙ≧ែࡢࡼࡃ࡞࠸⾨ᫍࡢᙳ㡪ࢆཷࡅࡸࡍࡃ࡞

ࡗ࡚࠸ࡿ㸬࡞࠾㸪ࣔࢪ࣮ࣗࣝ 2,4 ࡛ࡣs500ns ௨ୗࡢࡼ

ࡾ㧗࠸⢭ᗘࡀᐇ⌧ࡉࢀ࡚࠸ࡿ㸬ࡇࢀࡣ㸪࡝ࡕࡽࡢࣔࢪࣗ

࣮ࣝࡶ‽ኳ㡬⾨ᫍ(QZSS)ࡀཷಙྍ⬟࡜࡞ࡗ࡚࠾ࡾ㸪ཷ

ಙྍ⬟࠿ࡘ┤どྍ⬟࡞⾨ᫍᩘቑຍࡢຠᯝ࡟ࡼࡿࡶࡢ࡜

⪃࠼ࡽࢀࡿ㸬

▷᫬㛫࡛ࡢኚືࢆ☜ㄆࡍࡿࡓࡵ㸪ᅗ 6 ࡟ࣔࢪ࣮ࣗࣝ 4

࡛ࡢ▷᫬㛫࡛ࡢ PPS ࢱ࢖࣑ࣥࢢࡢኚືࢆ♧ࡍ㸬ᩘ⛊࿘

ᮇ࡛s 10ns ⛬ᗘࡢኚືࡀ⏕ࡌ࡚࠸ࡿ㸬ࡇࢀࡣࣔࢪ࣮ࣗ

ࣝෆⶶࡢᇶ‽ࢡࣟࢵࢡ࡜ GPS ࡢᇶ‽ࢡࣟࢵࢡࡢㄗᕪ࡟

ࡼࡾ⏕ࡌ࡚࠸ࡿࡶࡢ࡛࠶ࡿ㸬୧⪅ࡀྠᮇࡋ࡚࠸࡞࠸ࡓ

ࡵㄗᕪࡀ⣼✚ࡋ㸪ࡑࢀࡀ PPS ⏕ᡂࡢ 1 ࢡࣟࢵࢡ࿘ᮇࢆ

ୖᅇࡿ࡜ 1 ࢡࣟࢵࢡศࢫࣜࢵࣉࡍࡿࡇ࡜࡟㉳ᅉࡋ࡚࠸

ࡿ㸬ࢱ࢖࣑ࣥࢢྠᮇ⏝ࡢ GPS ࣔࢪ࣮ࣗࣝࡢሙྜ㸪఩┦

*36 Ϡζϣʖϩ

ν΢Ϟ

΢ϱνʖώϩ

଎ఈح

خ६৶ߺ

൅ਫ਼ح

5HIHUHQFH

&ORFN

⁂⁂⁅ ⁂⁂⁅

3&

⇥⇊∅∙⇖ᛚࠀ

‹⁂⁅ऴإ

≋ยˮ⅚଺Ц≌

ྠᮇ࣮ࣝࣉ࡟ࡼࡾࣔࢪ࣮ࣗࣝࡢᇶ‽ࢡࣟࢵࢡࢆ GPS ࢡ

ࣟࢵࢡ࡟ྠᮇࡉࡏࡿࡇ࡜ࡀ࡛ࡁࡿࡀ㸪ᮏ᳨ウ࡛ࡣ⡆᫆

࡞ࣔࢪ࣮ࣗࣝࢆ⏝࠸ࡓࡓࡵ㸪ㄗᕪࡀゎᾘ࡛ࡁࡎ࡟ࡇࡢ

ࡼ࠺࡞⌧㇟ࡀⓎ⏕ࡋ࡚࠸ࡿ㸬

ࡲࡓ㸪ᅗ 5 ࡟࠾࠸࡚ࡍ࡭࡚ࡢࣔࢪ࣮ࣗࣝࡢࢱ࢖࣑ࣥ

ࢢㄗᕪࡢኚື࡟࡯ࡰ 1 ᪥༢఩ࡢ࿘ᮇᛶࡀぢࡽࢀࡿ㸬ࡇ

ࢀࢆ᫂☜࡟ࡍࡿࡓࡵ㸪ࣃ࣮࣡ࢫ࣌ࢡࢺࣝࢆ⏝࠸࡚ࢱ࢖

࣑ࣥࢢㄗᕪࡢ࿘Ἴᩘ㡿ᇦ࡛ࡢゎᯒࢆ⾜ࡗࡓ㸬ࣔࢪ࣮ࣗ

ࣝ 2 ࡢ 14 ᪥ศࡢࢱ࢖࣑ࣥࢢㄗᕪࡢࣃ࣮࣡ࢫ࣌ࢡࢺࣝࢆ

ᅗ 7 ࡟♧ࡍ㸬ࡇࡇ࡛㸪ࢱ࢖࣑ࣥࢢㄗᕪኚືࡢ࿘ᮇᛶࢆ᫂

☜࡟ࡍࡿࡓࡵ㸪ᅗ࡟࠾࠸࡚㸪ᶓ㍈ࡣ࿘Ἴᩘ࡛ࡣ࡞ࡃࡑࡢ

㏫ᩘ࡛࠶ࡿྛ࿘Ἴᩘ࡟ᑐᛂࡍࡿ࿘ᮇ࡟ኚ᥮ࡋ࡚࠸ࡿ㸬

ᅗࡼࡾ㸪 1 ᪥ (86400 ⛊ ) ࿘ᮇࡢᙉ࠸ࣆ࣮ࢡ࡜ࡑࡢᩚᩘศ

ࡢ 1 ࡢ࿘ᮇࡢࣆ࣮ࢡࡀ☜ㄆ࡛ࡁࡿ㸬ࡇࢀࡣ㸪GPS ⾨ᫍ

ࡢබ㌿࿘ᮇ㸦 12 ᫬㛫㸧࡜᫨ኪ㛫ࡢ᫬㛫ᖏࡢఏᦙ≧ែࡢ

࿘ᮇ࡟㉳ᅉࡍࡿࡶࡢ࡛࠶ࡾ㸪 1 ᪥࿘ᮇ࡛࣐ࣝࢳࣃࢫࢆྵ

ࡵ࡚࡯ࡰྠࡌఏᦙ⎔ቃ࡛ ఩ࡀ⾜ࢃࢀࡿࡓࡵ㸪 ఩ㄗ ᕪ࡟୍᪥࿘ᮇࡢᙉ࠸┦㛵ࡀⓎ⏕ࡋ࡚࠸ࡿ࡜⪃࠼ࡽࢀࡿ㸬

ࡲࡓ㸪ᅗ 7 ࡟࠾࠸࡚ 1 ⛊࿘ᮇࡢᙉ࠸ࣆ࣮ࢡࡶࡳࡽࢀࡿ

ࡀ㸪ࡇࢀࡣ๓㏙ࡢࣔࢪ࣮ࣗࣝෆⶶᇶ‽ࢡࣟࢵࢡ࡜ GPS ࡢᇶ‽ࢡࣟࢵࢡࡢ㛫ࡢㄗᕪࡀཎᅉ࡛Ⓨ⏕ࡍࡿ PPS ࢱ࢖

࣑ࣥࢢࡢࢫࣜࢵࣉ࡟క࠺▷࿘ᮇࡢኚື࡛࠶ࡿ㸬

(a) ࣔࢪ࣮ࣗࣝ 1

(b) ࣔࢪ࣮ࣗࣝ 2

(c) ࣔࢪ࣮ࣗࣝ 3

(d) ࣔࢪ࣮ࣗࣝ 4

ᅗ 5 㸸 PPS ࢱ࢖࣑ࣥࢢㄗᕪ ᐃ⤖ᯝ

ᅗ 6 㸸 ▷᫬㛫࡛ࡢࢱ࢖࣑ࣥࢢㄗᕪኚື

ࢱ࢖࣑ࣥࢢㄗᕪࡢほ ᫬㛫࡟ᑐࡍࡿኚື≉ᛶࢆぢࡿ

ࡓࡵ㸪㏻ಙ⣔ࡢࢡࣟࢵࢡࡢᛶ⬟ホ౯࡛ࡼࡃ⏝࠸ࡽࢀࡿ

Maximum Time Interval Error (MTIE)

࡟ࡼࡿホ౯ࢆ⾜ࡗ

ࡓ㸬MTIE ࡣほ ᫬㛫(ȫ)ෆ࡟࠾ࡅࡿಙྕࡢࢱ࢖࣑ࣥࢢ

ㄗᕪኚືࡢ඲ ᐃᮇ㛫࡟࠾ࡅࡿ᭱኱್ (peak-to-peak) ࡛

ᐃ⩏ࡉࢀ㸪඲ ᐃ᫬㛫ࡀ ܶ ൌ ܰɒ

࡛ほ ᫬㛫ࡀ ɒ ൌ ݊ɒ

ࡢ

ሙྜ (ɒ

㸸ࢧࣥࣉࣜࣥࢢ㛫㝸 ) 㸪ḟᘧ࡛⾲ࡉࢀࡿ㸬

ܯܶܫܧሺ݊߬

ሻ ൌ ƒš

ଵஸ௞ஸேି௡

ቂ ƒš

௞ஸ௜ஸ௞ା௡

ݔሺ݅ሻ െ ‹

௞ஸ௜ஸ௞ା௡

ݔሺ݅ሻቃǡ

݊ ൌ ͳǡʹǡ ǥ ǡ ܰ െ ͳ .

ࡇࡇ࡛ x(i) ࡣྛࢧࣥࣉ್ࣝࢆ♧ࡍ㸬

ᅗ 8 ࡟ྛࣔࢪ࣮ࣗࣝࡢ MTIE ࢆ♧ࡍ㸬ࡲࡓ㸪㏻ಙ⣔

࡛ᚲせ࡜ࡉࢀࡿ MTIE ್㸦 ITU-T ࡢ࣐ࢫࢡ್㸧

ࡶేࡏ

࡚♧ࡍ㸬ᅗࡼࡾ㸪ྛࣔࢪ࣮ࣗࣝ࠿ࡽฟຊࡉࢀࡿ PPS ಙ

ྕࡢࢱ࢖࣑ࣥࢢㄗᕪࡣ࠸ࡎࢀࡶ࣐ࢫࢡ್ࢆ‶㊊ࡋ࡚࠾

ࡾ㸪㏻ಙ⣔࡛ࡢ᫬㛫ᇶ‽࡜ࡋ࡚ࡣ༑ศ౑⏝ྍ⬟࡞ࣞ࣋

࡛ࣝ࠶ࡿࡇ࡜ࡀࢃ࠿ࡿ㸬ణࡋ㸪 10 ⛊⛬ᗘࡢ▷᫬㛫࡛ぢ

ࡿ࡜㸪ࣔࢪ࣮ࣗࣝ 3 ࢆ㝖࠸࡚࣐ࢫࢡ࡟㏆࠸್࡜࡞ࡗ࡚

࠾ࡾ≉ᛶ࡜ࡋ࡚ࡣ࠶ࡲࡾࡼࡃ࡞࠸㸬㛗᫬㛫࡛ࡢᏳᐃᗘ

࡛ぢࡿ࡜㸪ᅗ 5 ࡢ⤖ᯝ࡜ྠᵝ࡟ࣔࢪ࣮ࣗࣝ 2 ࡀ᭱ࡶඃ

ࢀ࡚࠸ࡿ㸬

ᅗ 7㸸 ࢱ࢖࣑ࣥࢢㄗᕪࡢࣃ࣮࣡ࢫ࣌ࢡࢺࣝ

ᅗ 8㸸 ྛࣔࢪ࣮ࣗࣝࡢ MTIE

㸬173 ࢧ࣮ࣂ࣭ࢡࣛ࢖࢔ࣥࢺᛶ⬟ホ౯

173 ࢧ࣮ࣂ

ᅗ 9 ࡟♧ࡍࡼ࠺࡟ GPS ࣔࢪ࣮ࣗࣝ㸯ࡢฟຊࢆᑠᆺ࣐

࢖ࢥ࡛ࣥ࠶ࡿ Raspberry Pi ࡟ධຊࡋ㸪 NTP ࢧ࣮ࣂ࡜ࡋ࡚

ືసࡉࡏࡓ㸬ࡇࡇ࡛㸪࣐࢖ࢥࣥࡢ OS ࡜ࡋ࡚ࡣ Linux ࢆ

⏝࠸㸪ࡑࡢୖ࡛ NTP ࢹ࣮ࣔࣥࢆᐇ⾜ࡍࡿࡇ࡜࡟ࡼࡾ㸪 NTP ࢧ࣮ࣂࢆᐇ⌧ࡋ࡚࠸ࡿ㸬GPS ࣔࢪ࣮ࣗࣝ࠿ࡽࡢ NMEA ࣇ࢛࣮࣐ࢵࢺࡢࢹ࣮ࢱࡣ㸪ࢩࣜ࢔ࣝࢹ࣮ࢱ࡜ࡋ

࡚ GPIO ࠿ࡽධຊࡋ࡚᫬้᝟ሗ࡜ࡍࡿ㸬ࡲࡓ㸪 PPS ಙྕ

ࢆ GPIO ࠿ࡽධຊࡋ࡚ࢱ࢖࣑ࣥࢢࢆㄪᩚࡍࡿ㸬ࡇࢀࡽࡢ ಙྕ࡟ᑐᛂࡍࡿࡓࡵ㸪GPS ࡢࢯࣇࢺ࢙࢘࢔࡛࠶ࡿ gpsd

ࢆᐇ⾜ࡋ࡚࠸ࡿ㸬 NTP ࢧ࣮ࣂ⏝ࢯࣇࢺ࢙࢘࢔࡜ࡋ࡚ࡣ

Linux ୖࡢᶆ‽ⓗ࡞ NTP ࢧ࣮ࣂ

ࢆ౑⏝ࡋ㸪タᐃࣇ࢓࢖

ࣝࢆኚ᭦ࡍࡿࡇ࡜࡛ GPS ࣔࢪ࣮ࣗࣝ࠿ࡽࡢ NMEA ࣇ

࢛࣮࣐ࢵࢺ࡟ࡼࡿ᫬้ࢹ࣮ࢱ࠾ࡼࡧ PPS ಙྕࡢධຊ࡟

ᑐᛂࡉࡏ࡚࠸ࡿ㸬

ᅗ 9 㸸 ⡆᫆ NTP ࢧ࣮ࣂࡢᵓᡂ

NTP ࢧ࣮ࣂࡢྠᮇ≧ែࡢ౛ࢆᅗ 10 ࡟♧ࡍ㸬 NTP ࢧ࣮

ࣂࡀ PPS ಙྕ㸦ୖẁ㸧࡞ࡽࡧ࡟ NMEA ࣇ࢛࣮࣐ࢵࢺࡢ ࢹ࣮ࢱ㸦ୗẁ㸧࡟ྠᮇࡋ࡚ືసࡋ࡚࠸ࡿࡇ࡜ࡀࢃ࠿ࡿ㸬

᫬้ㄗᕪ(offset)ࡣ࣑ࣜ⛊༢఩࡛⾲♧ࡉࢀ࡚࠾ࡾ㸪ࡇࡢሙ

ྜ 5μs ⛬ᗘ࡜࡞ࡾ㸪 GPS ࣔࢪ࣮ࣗࣝࡢࢱ࢖࣑ࣥࢢㄗᕪ

ࡼࡾࡶ኱ࡁࡃ࡞ࡗ࡚࠸ࡿ㸬 ࡇࢀࡣ GPS ࣔࢪ࣮ࣗࣝࡢ PPS ಙྕࡢࢱ࢖࣑ࣥࢢㄗᕪ࡟ຍ࠼࡚㸪 NTP ࢧ࣮ࣂࡢฎ⌮ࡀ ࢯࣇࢺ࢙࢘࢔࡛ᐇ⿦ࡉࢀ࡚࠸ࡿࡓࡵ࡟⏕ࡌࡿㄗᕪࡀຍ

⟬ࡉࢀࡿࡓࡵ࡛࠶ࡿ㸬୍⯡࡟ㄗᕪࡢ኱ࡁࡉ࡜ࡋ࡚ࡣᚋ

⪅ࡢ᪉ࡀᨭ㓄ⓗ࡛࠶ࡿ㸬ࡲࡓ㸪 NTP ࡢ㝵ᒙ࡜ࡋ࡚ࡣ GPS

ࣔࢪ࣮ࣗࣝࡀ stratum 0 ࡜࡞ࡿࡓࡵ㸪ࡇࡢ NTP ࢧ࣮ࣂࡣ stratum 1 ࡢࢧ࣮ࣂ࡜࡞ࡿ㸬

5DVSEHUU\3L 0RGHO%

*36 0RGXOH

JSVG QWSG 1(0$ 'DWD 336

/$1

*3,2

(WKHUQHW

1736HUYHU

䢯䢷 䢲 䢷 䢳䢲

䢯䢳䢲䢲 䢲 䢳䢲䢲 䢴䢲䢲

䢲 䢴 䢶 䢸 䢺 䢳䢲 䢳䢴

䣖䣫䣯䣧䢢䢪䣪䣱䣷䣴䢫

䢯䢳䢲䢲䢲 䢲 䢳䢲䢲䢲 䢴䢲䢲䢲

NTP server

NTP Client

NTP Client (conventional)

ᅗ 10㸸 NTP ࢧ࣮ࣂࡢྠᮇ≧ែ

173 ࢡࣛ࢖࢔ࣥࢺ

NTP ࢡࣛ࢖࢔ࣥࢺࡶ Raspberry Pi ࢆ⏝࠸㸪 NTP ࢧ࣮

ࣂ࡜ྠᵝ࡟ᶆ‽ⓗ࡞ NTP ࢯࣇࢺ࢙࢘࢔ࢆ࣮࣋ࢫ࡜ࡋ࡚

ᵓᡂࡍࡿ㸬ࡇࡢሙྜ㸪 NTP ࢡࣛ࢖࢔ࣥࢺࡢࢧ࣮ࣂ࡬ࡢ ၥ࠸ྜࢃࡏ࿘ᮇࡀ᭱ᑠ࡛ 8 ⛊࡜࡞ࡗ࡚࠸ࡿࡓࡵ㸪ࡼࡾ

▷࠸࿘ᮇ (1 ⛊ ) ࡛ၥ࠸ྜࢃࡏࢆ⾜࠺ࡇ࡜࡟ࡼࡾ㧗⢭ᗘ

໬ࡀ࡛ࡁࡿࡼ࠺ᨵ㐀ࢆ⾜ࡗ࡚࠸ࡿ㸬

ホ౯⤖ᯝ

ᅗ 11 ࡟ NTP ࢧ࣮ࣂཬࡧ NTP ࢡࣛ࢖࢔ࣥࢺࡢ᫬้࢜

ࣇࢭࢵࢺࡢ 12 ᫬㛫࡛ࡢホ౯⤖ᯝࢆ♧ࡍ㸬ࡲࡓ㸪ྠᅗ࡟

࠾࠸࡚㸪ẚ㍑ࡢࡓࡵᏛෆࡢ NTP ࢧ࣮ࣂ࡟ྠᮇࡋࡓࢡࣛ

࢖࢔ࣥࢺ㸦ၥ࠸ྜࢃࡏ࿘ᮇ 64 ⛊௨ୖ㸧ࡢ᫬้࢜ࣇࢭࢵ

ࢺࡶ♧ࡋ࡚࠸ࡿ㸬 NTP ࢧ࣮ࣂ࡟ࡘ࠸࡚㸪s 10μs ௨ୗࡢ

࢜ࣇࢭࢵࢺࡀᐇ⌧࡛ࡁ࡚࠾ࡾ㸪ẚ㍑ⓗ㧗࠸᫬้⢭ᗘࡢ ࢧ࣮ࣂ࡜࠸࠼ࡿ㸬ࡲࡓ㸪 NTP ࢡࣛ࢖࢔ࣥࢺࡢ࢜ࣇࢭࢵ

ࢺࡣs200μs ௨ୗ࡛࠶ࡾ㸪ࢡࣛ࢖࢔ࣥࢺ࡟࠾࠸࡚ࡶ 1ms ௨ୗࡢ㧗࠸⢭ᗘࡀᐇ⌧࡛ࡁ࡚࠸ࡿ㸬ࡇࢀࡲ࡛ࡢᏛෆࢧ

࣮ࣂ(stratum 4)࡟ྠᮇࡉࡏࡿ᪉ἲ࡛ࡣ᭱኱ 1ms ௨ୖࡢ࢜

ࣇࢭࢵࢺࡀ⏕ࡌ࡚࠸ࡿ㸬ࡍ࡞ࢃࡕ㸪ศᩓᆺࡢ NTP ࢧ࣮

ࣂࢆ⏝࠸ࡓྠᮇࢩࢫࢸ࣒࡟ࡼࡾ㸪ࢡࣛ࢖࢔ࣥࢺ࡟࠾࠸

࡚ 1 ᱆௨ୖࡢ᫬้ྠᮇ⢭ᗘࡢྥୖࡀᐇ⌧ࡉࢀ࡚࠸ࡿ㸬

ᅗ 11 㸹 NTP ࢧ࣮ࣂ࣭ࢡࣛ࢖࢔ࣥࢺࡢ᫬้࢜ࣇࢭࢵࢺ

㸬ࡴࡍࡧ

ᮏ◊✲࡛ࡣ㸪 LAN ୖࡢศᩓᆺࡢྠᮇࢩࢫࢸ࣒ࢆ⡆᫆

࠿ࡘపࢥࢫࢺ࡛ᐇ⌧ࡍࡿࡓࡵࡢ㸪⡆᫆ GPS ࣔࢪ࣮ࣗࣝ

࡜ᑠᆺ࣐࢖ࢥࣥࢆ⏝࠸ࡓ NTP ࢧ࣮ࣂ࡜ࢡࣛ࢖࢔ࣥࢺ࡟

ࡼࡿྠᮇࢩࢫࢸ࣒࡟ࡘ࠸᳨࡚ウࢆ⾜ࡗࡓ㸬

⡆᫆ GPS ࣔࢪ࣮ࣗࣝࡢᛶ⬟࡜ࡋ࡚㸪ᒇෆタ⨨ࡢሙྜ

࡟࠾࠸࡚ࡶs1μs ௨ୗࡢ᫬้ྠᮇ⢭ᗘࢆᐇ⌧ࡋ࡚࠸ࡿ㸬

ࡲࡓ㸪ࡇࡢ GPS ࣔࢪ࣮ࣗࣝ࠿ࡽࡢ᫬้᝟ሗ࡟ᇶ࡙࠸ࡓ NTP ࢧ࣮ࣂ࡞ࡽࡧ࡟ࡑࢀ࡟ྠᮇࡍࡿ NTP ࢡࣛ࢖࢔ࣥࢺ

ࢆᵓᡂࡋ㸪 NTP ࢧ࣮ࣂࡢ᫬้⢭ᗘ࡜ࡋ࡚s 10μs ௨ୗ㸪 NTP ࢡࣛ࢖࢔ࣥࢺࡢ᫬้⢭ᗘ࡜ࡋ࡚s200μs ௨ୗࢆᐇ

⌧ࡋ࡚࠸ࡿ㸬

௒ᚋࡣ㸪GPS ࣔࢪ࣮ࣗࣝࡢ PPS ಙྕฟຊࢱ࢖࣑ࣥࢢ ࡢᖹ⁥໬࡟ࡼࡿ▷᫬㛫ኚືࡢᏳᐃ໬㸪࡞ࡽࡧ࡟ NTP ᶵ

⬟ࡢࣁ࣮ࢻ࢙࢘࢔໬࡟ࡼࡿ㧗⢭ᗘࡢ᫬้࣭࿘Ἴᩘᇶ‽

ࡢศ㓄࡟ࡘ࠸᳨࡚ウࢆ⾜࠸㸪ప㐜ᘏࢧ࣮ࣅࢫࡢ㐺⏝⠊

ᅖᣑ኱࡟ࡘ࡞ࡆࡓ࠸㸬

ㅰ ㎡

ᮏ◊✲䛷䛾᳨ウ䛻䛒䛯䜚䠈≉䛻ᐇ㦂⣔ᵓ⠏䛻䛤༠ຊ䛔 䛯䛰䛔䛯ᮡᾆ᪸ử䠈㕥ᮌ㝧ኴ䠈Ώ㑓㻌 ⋹䛾ྛẶ䛻ឤㅰ䛧䜎 䛩䠊㻌

ཧ⪃ᩥ⊩

1㸧ࢻࢥࣔ 5G ࣍࣡࢖ࢺ࣮࣌ࣃ࣮, https://www.nttdocomo.

co.jp/binary/pdf/corporate/technology/whitepaper_5g/DO COMO_5G_White_PaperJP_20141006.pdf

2 㸧 Time Sensitive Network Task Group, http://www.ieee802.

org/1/ pages/tsn.html.

3 㸧 Small cell forum, “Synchronization for LTE small cells,”

SCF075.05.01, Feb. 2014.

4 㸧⏣௦௚㸪ಙᏛ఍ㄽᩥㄅ B, Vol. J96-B, No.3, pp.321-329, Mar. 2013.

5 㸧 https://nitsuki.com/products/broadcast/3272d_gps.html 6㸧ITU-T G.8261/Y.1361, Aug. 2013.

7 㸧 http://www.ntp.org/index.html