The Clock Mini-HOWTO

Ron Bean

rbean@execpc.com

JF Project - {

JF@linux.or.jp

v2.1, November 2000

Rs[^ɐmȎԂݒ肵āAvȂ悤ɂ@B



Table of Contents
1. ͂߂
   
    1.1. قƂ͉Ȃ񂾂H
    1.2. \tgEFA̓FȃA[JCu
    1.3. ӎ
   
2. Linux ͂ǂ̂悤ɎԂvĂ̂
   
    2.1. {IȎdg
    2.2. RtNg̉\
    2.3. RTC ɂ̓[J^C UTC ̂ǂgׂH DST ĉ
        H
    2.4. ^C][̐ݒɂ
    2.5. ǂ̒x̐xKv
   
3. \tgEFA
   
    3.1. clock(8)  hwclock(8)
    3.2. Adjtimex(8)
    3.3. xntpd  ntpd - lbg[N^CvgR
    3.4. chrony vO
    3.5. clockspeed vO
   
4. dgv
   
    4.1. CHU ƁuGadget Boxv
    4.2. WWV ƁuMost Accurate Clockv
    4.3. GPS ƁuTotally Accurate Clockv
    4.4. g^CVOiF DCF77, MSF(Rugby), WWVB
   
5. {ɂ

1. ͂߂

1.1. قƂ͉Ȃ񂾂H

PC }U[{[h̃A^CNbN (Real-Time-Clock, RTC) `bv
sm͗LłBĂx肷̂ŁA
vĂ܂ [1]BALinux ɂ̓\tgEFAłC
ȒPȕ@܂B̕@g΁AO̎\[Xɗ炸
vɐmɕۂƂł܂BA̐ݒ@ml
܂肢Ȃ̂́A(炭) ȉ̂悤ȗR邩炾Ǝv܂B

 

 E Linux ̐ݒSʂł͂قƂǂɐGĂ炸A
    (O̎\[X𗘗pꍇȊO) Iɐݒ肳邱ƂȂ
    ̂ŁAftHgł͗pȂƁB
   
 E man clock ƃR}hł clock (3) \܂Aɂ͑S
    Rʂ̎LڂĂ邱ƁBman 8 clock  man 8 hwclock
    Ă (ZNVw肹 man page ꍇA
    ʂ̃fBXgr[Vł̓ZNV̎Ⴂɕ\
    悤ɂȂĂ܂B/etc/man.config Ŏw肵ɌfBXg
    r[V܂)B
   
 E Ԏ̂CɂĂȂl炵ƁB
   
 E v̎ԂCɂЂƂ́Albg[N^CT[o (netwok time
    server) dgv (radio clock) ƂO̎\[XɃVXe
    NbN𓯊 (sync) Ăl唼ł邱ƁB̏ꍇARTC
    mǂ(قƂ) ֌WȂȂ܂B
   
 

 mini-HOWTO ł́A[eNȕAv[`܂ (ꂾŁA
v͔ɐmɂȂ܂)B܂AƐꂽ@ŎԒ
l̂߂ɁAȅ񌹂ЉĂ܂B҂̏ꍇA̎̉̕
͂ނ˂肵Ă̂ŁA{ł͏ډ܂B

{̑Oo[Wł́AÂVXe܂gĂl̂߂ɋ 
clock (8) vOɂďڂĂ܂A͂̃ZNV
ȗ܂Bݑ̃fBXgr[V clock (8) ɂ
 hwclock (8) ̗pĂAhwclock (8) vOɊւ镶̕
ƗDĂ邩łBclock (8) ̉Kvȏꍇ́A҂Ƀ[
Œm点ĂBȀꍇ́A悸 hwclock (8) ɂĂ̏͂
ǂłɂĂB

    : RTC VXeNbNCvOsɂ
    "root" ŃOCȂ΂Ȃ܂B̕ŏqׂvO
    唼́Aroot KvłBiOtBJC^[tFCX
    gĂȂꍇ́A{I UNIX ̃VFR}hw
    Kv邩܂B
   
    : }Vŕ OS gĂꍇ́ÂЂƂ
    RTC ̐ݒsA OS Ƃ̊ԂŎԂHႤƂȂ悤ɂ
    Kv܂BAN 2 x̉ĎԂ̒ɂĂ͕ʂł (
    ́A DST ̃ZNV)B
   
fAu[gVXeŎ Windows gĂȂALinux łł͂Ȃ
AWindows ł̃NbN\tgEFAɂĒׂƎv܂
B̏ꍇ́A NTP EFuTCg̐Bhttp://
www.eecis.udel.edu/~ntp/software.htmlB{ł̓dgv̐̑́A
Windows p\tgEFAɊւ̂܂܂Ă܂B



1.2. \tgEFA̓FȃA[JCu

{ł̓\tgEFA_E[hłꏊƂĂ̃TCg
܂ACD-ROM łɓȂꍇ Linux VXeŜ
_E[h邱Ƃł܂B̂́Â悤ȃTCg
sunsite.unc.edu  ftp A[JCuƊễ~[TCgłƑꂪ
܂Ă܂A sunsite  http://metalab.unc.edu/linux/ Ɖ
Ă܂ (󒍁F 2001N10݂ł ibiblio http://
www.ibiblio.org/pub/linux/ Ƃ̂ɕύXĂ܂)BfBXgr
[V̒ɂ͓Ǝ̃EFuTCgĂ̂ÂȂ
͂̕ň\tgEFA܂܂Ăꍇ܂B

ŋ߂ł Linux  CD œ肷lقƂǂłA CD ɂ̓ft
HgŃCXg[Ȃ悤Ȋe\tgEFAĂ܂܂Ă
̂ŁAł͈ӎĂȂƂ{ŏqׂvOɎ茳ɂ
ꍇƎv܂B

 mini-HOWTO ̍ŐVo[ẂALinux Documentation Project ̃z[
y[Wɂ܂BLDP ̃z[y[ẂA http://www.linuxdoc.org/
ł (q metalab TCg肪\ł)BÂNw肵
ꍇłK݂̃TCg forward 悤ɂȂĂƎv܂B

ׂĂ HOWTO  SGML ŋLqĂAKiɊÂϊvO
gĊetH[}bgɕϊĂ܂BĂ̐l HTML `
œǂނƎv܂BHTML ł́A http://www.linuxdoc.org/HOWTO/mini/
Clock.html łB SGML \[XɃRgƂċLڂĂ܂B
啔̃fBXgr[Vł́AS HOWTO  /usr/doc/HOWTO/ 
/usr/doc/HOWTO/mini/ ɃCXg[Ă܂B



1.3. ӎ

 mini-HOWTO ́A1996N̏ňȗA҂Ƀ[𑗂Ăꂽ
X̂ő啝ɉPĂ܂Bɂ́A󂯎͂
̂ɁAǂ炪낢ƋĂƂx܂Bc
OȂA҂͂܂̎̃̕Xg쐬Ă܂ (
ł͑LڂłƎv܂)BŜ́ÂƂ
ɂȂƎv܂ :)



2. Linux ͂ǂ̂悤ɎԂvĂ̂

2.1. {IȎdg

Linux VXeɂ 2 ނ̎v܂BЂƂ́Aobe[쓮̃
A^CNbN(RTC  CMOS NbN̓n[hEFANbNƂ
Ă΂Ă܂)łA̓VXe̓dIt̎ɂĂ܂
AVXẻғ͎g܂BЂƂ́AVXeNbN
(System Clock, J[lNbN̓\tgEFANbNƂĂ΂
) łA̓^C}荞݂ɊÂ\tgEFAEJE^(software
counter)łBVXeNbN̓VXẻғȊOɂ݂͑Ȃ̂
AN RTC (͂ȊO̊Ov) ɂďKv
܂Bntpd ̕tŁuNbNvQƂƂꍇARTC ł͂
VXeNbN̎QƂӖĂ܂B

 2 ނ̎ṽY͈قȂĂ̂ŁA҂͏XɐH
AoƂ񂾂Ǝۂ̐mȎԂ痣Ă܂B
mɕۂōłȒPȕ@́AԂY銄vZă\tgEFA
łC邱ƂłBRTC ̓VXẻғĂȂgp
̂Ȃ̂ŁARTC ̏ĆANɎǂݍލۂ clock(8)  
hwclock(8) gčs܂BVXeNbN̏ĆA^C}荞݂
VXeԂiލۂ adjtimex(8) găYC邱Ƃɂ
{܂B

adjtimex(8) ̑ cron g clock(8)  hwclock(8) I
sAVXeNbN(mɒ)RTC ɓƂ@
Ȃ킯ł͂܂B clock(8) ̃}jAy[WŐ
܂Axpɂɓ邱Ƃŗ҂̎Ԃ̃YăV
XeNbN̎啝ɁuWvv邱ƂȂΖȂ@\
܂Aadjtimex(8) gĒGKgłBAvP[V
̂Ȃɂ́AԒŎvk点ꍇɂ̓G[ɂȂ̂
܂B

Ԓ̕@ƂẮAɂ ntpd ƂvOgălbg[
N^CT[odgvIɎԂǂݍŌpIɃVXeN
bŇ덷𒲐邱ƂŁAVXeNbN̎̑啝ȁuWv
v@܂BNɕKlbg[NRlNV
邱ƂoȂARTC SɖAntpdate ( ntpd pbP[W
ɕtĂ܂) g LAN ̃[J}VC^[lbg̃
[g}Vɂ^CT[oɂVXeNbN邱Ƃ
ł܂BAKlbg[NRlNV𒣂ȂƂ
ꍇANɐmȎԂ擾Ƀlbg[NɌqȂ
ȂȂꍇ́A RTC ̎ԂĂKv܂B



2.2. RtNg̉\

ntpd ̂悤ȃvOgĂȂARTC  (ς݂)VXeN
bNɓ悤Ǝv܂BA̓VXe
ȏɓnĎՒf\ꍇɂ͗\zʂɏ肭͂܂
BN RTC 𒲐vOƊĂ܂łB

VXeyȂ 24 ԉғAdՒfꂽꍇłɍċN
悤ɂȂĂȂAVXeNbNԂɊÂčċNO
RTC ݒ肷邱Ƃ͉\łB̍ۂ RTC ɂ̓u[ǧoߎԂ̔
͓ł덷Ȃ̂ŁARTC ̃YmKvȂȂ܂B

VXeɂ͗\zȌQt̂łBŁAVXeNb
N炩̃vOɂĐmɒĂꍇAJ[l̃o[
WɂĂ RTC  11 ƂɃVXeNbNɓ̂
܂Bʏ 11 Ԃ̂ RTC VXeNbNƑ傫HႤ
͂܂񂪁AVXeԃ_E RTC Ԃ傫Yꍇ
肪܂BȂȂ RTC ̌덷𒲐vÓA RTC
ŌɃZbg𐳊mɋLĂKv̂łAJ[l
ɂ͂̂悤ȏ͋L^ĂȂłB

UNIX ̓`d񂶂l̒ɂ́ALinux VXe͂Ƃ 24 ԘA
̂Ȃ̂ƎvĂ邱Ƃł傤BAfAu
[gŎX͕ʂ OS sĂ郆[U܂Abvgbv
Linux gĂ郆[U͓d𗎂ƂƂŎgpȊO̎Ԃł̃obe
[̏ՂhĂ܂BȊOɂAPɎgĂȂ}V
𒷎Ԏsɂ̂D܂Ȃl܂ (ނAd
܂܂ɂǂƂc_͏[m͂Ă܂)B̂悤ȏꍇ
A 11 Ƃɓs@\͔ɕssȋ@\ƂƂɂȂ܂B

(ꍇɂĂ͕ss)@\́AJ[l̃o[WقȂƐU
قȂ悤ł (炭 xntpd  ntpd ̃o[WقȂꍇ
AU镑ς悤ł)B䂦A ntpd  hwclock ̗
sĂȂA\߃eXgsāA̋@\ۂɂǂU镑
̂mFKvł傤BJ[l RTC Zbg
~߂邱ƂłȂꍇ́ARTC ɑ΂鎞Ԓ؍sȂ
ɂKvł傤B

Ƃ𐧌䂵Ă̂́AJ[l /usr/src/linux-2.0.34/arch
/i386/kernel/time.c ł (pX̃o[Wԍ́A莝̃J[l
̃o[WԍɒuĂ)Bϐ time_status  TIME_OK ɐ
肳ƁAJ[l̓VXeԂ 11 Ƃ RTC ɏƂA
ȊO̒l RTC ɂ͊܂B(Ⴆ΁Antpd  timed g)
adjtimex(2) ĂяoƂŁAIɂ邱Ƃł܂B
settimeofday (2) Ăׂ΁Atime_status  TIME_UNSYNC ɐݒ肷邱Ƃ
ł܂B́AJ[l RTC ̒Ȃ悤ŵłB
̕ӂ̂Ƃڂ𒘎҂͒m܂B

J[l̃o[WɂẮACPU ւ̓dՒfăobe[
 sleep @\ɖ肪̂Ƃ񍐂󂯂Ă܂B
ŗǂ̉́AJ[lɍŐV̏ԂɍXVĂ䂭ƂłAJ[
l̊Ǘ҂ɖ񍐂悤ɂ邱ƂłB

RTC ̋ȏꍇ́An[hEFA̖肩܂BRTC `b
vɂ̓`EdrĂ܂A̓dr؂ꂽ̂܂
B܂A}U[{[hɂĂ͊Oobe[g悤ɐ݌vꂽ
̂܂(Wp̐ݒmFĂ)B CMOS RAM  RTC Ɠ
drœĂ̂łAv̕d͂̏̂łĂ
ɓȂȂ܂BVXeNbN̕\ꍇ́A荞݂
肪邩܂B



2.3. RTC ɂ̓[J^C UTC ̂ǂgׂH DST ĉH

Linux ̃VXeNbNۂɃJEgĂ̂́A1970N11
̌oߕbłA͕K萢E (UTC, Coodinated Universal Time)
g܂ (UTC  GMT (Greenwich Mean Time) Ƃقړ`łB҂͋Zp
Iɂ͕ʕłɎʂĂ̂ŁAʂ̃[U͓ӖŎg
Ƃ悤ł)BUTC ́AĎ (DST, Daylight Saving Time) Kv
ꍇłύX邱Ƃ͂܂Bς̂́AUTC ƃ[J^C
̊Ԃł̕ϊ@łB[J^Cւ̕ΐAAvP[Vv
OɃNꂽCu֐ɂĎs܂B (󒍁FDST
(T}[^C)ɂẮA܂̂Ƃ{ł͊֌W܂B)

́AʓIɓ̈Ӗ܂B܂ɁAAvP[V
[J^CmKvꍇ́ADST Lł邩ۂɊւ炸A
Ƀ[Ũ^C][mKvƂƂł (^C][
ẮA͂QlɂĂ)BɁADST ɂȂꍇłA
UTC ̂ɕύX͂Ȃ̂ŁAJ[l̓VXeNbN RTC ύXK
vȂƂƂłB䂦 Linux 点Ȃ}V̏ꍇA RTC
̓[J^Cł͂Ȃ UTC ɐݒ肷ׂłB

ȂARTC [J^C\Ă邱ƂOɂ OS 
āAfAu[gVXeɂĂl͑Ǝv܂B̏
A hwclock  RTC [J^C UTC ł邩mKvA
ɂ̎ 1970N11 (UTC) ̌oߕbւƕϊKv
܂BA RTC ɑ΂ĎԒ܂ł͍sȂƂAĎ
ւ̕ύX Linux ȊO OS ŎsKv܂ ( RTC ̎
ԂύXۂ͒PvOgAdύXsȂƂ[
̗Oɓ܂)B

cOȂARTC  CMOS RAM ɂ̓[J^C̕\ɊւĕWԂ
DST Ȃ̂ʂ邽߂̃tOȂ̂ŁAOS ́Â̑ OS 
͕Ȃꏊɂ̏ۑĂ܂B܂AĎԂ̎nI
̑O Linux ȊO OS NĎԒĂȂꍇłĂA 
hwclock ́ARTC [J^C\ĂƉ肵Ȃ
΂ȂȂ킯łB

ĎԒ̎nȊO Linux ĂꍇAVXeNbN
͉̂e󂯂Ȃ킯łAAvP[Vϊ
ł傤BA炩̗R Linux ċNȂ΂ȂꍇA
VXeNbN RTC Ԃɍ킹Đݒ肳܂B̏ꍇAVXeN
bN͑ OS (ʏ Windows) s܂Ŏ 1 ԋĂ
܂܂B

ɑΏ@͂Ȃ̂łALinux ͂߂ȂƂł̓NbV
Ȃ̂ŁAfAu[gVXeŃu[ĝ͂Ă Linux 
瑼 OS ɐ؂ւ邽߂łBAԃRs[^g
Ƃɓd؂^Cv̐lȂA܂ĎԒ̕ύXĂ
OS g@ȂȂA OS 𑖂点܂ RTC ͈ꎞԋ
ƂɂȂ̂YȂłB

̂Ȃɂ́ARTC  UTC ɐݒ肷邱Ƃ Linux  DST 肭
悤ɂȂƐĂ̂܂B͑S̊ԈႢł͂Ȃ
AsmłBu[gȂA(RTC ̃obe[؂Ă
łA) RTC ǂ̎Ԃ\Ă邩͖ɂȂ܂BLinux
́Au[g܂ł͂ꂩ̕@ŐԂ\Ă킯
łB_Iɂ́ANɈ񂵂u[gȂȂ(́ALinux 
ꍇAɒƂł͂܂)ADST ɂȂꍇłVXeN
bN͂ƐmȎԂ`Ă̂ŁARTC ƂĂ
CtȂł傤BAu[g邩ƂƂ͗\ߗ\
tȂ̂ŁA[J^CKvƂ OS gĂȂꍇ́A RTC
 UTC ɐݒ肵ł傤B

Dallas Semiconductor  RTC `bv (́AMotorola `bv̑
IBM AT @₻̌݊@ɓڂ悤ɂȂ`bvł) ́AۂɃ`b
v̂ UTC  DST ɕϊ\͂Ă܂AύXׂt
炩߃n[hIɌŒ肳ĂĂ\tgIɕς邱ƂłȂ
̂ŁA̋@\͎gĂ܂BŐṼo[WXV 2000N4̑
j 10̍ŏIjɎ{܂AȑÕo[W̃`
bvł́AꂼقȂgĂ܂B (܂A(O
)ႤtgĂ鍑ł́A炩ɋ@\܂B) ɁARTC 
(P̂̃`bvł͂Ȃ) }U[{[h̃`bvZbg̒ɑgݍ܂Ă
ꍇȂĂ̂ŁA炷ׂĂ̔\͂Ă邩ǂ
҂ɂ͕܂B



2.4. ^C][̐ݒɂ

炭 Linux CXg[̍ۂɁAǎ҂̓^C][𐳂ݒ肵Ă
Ǝv܂BA炩̗RłύXȂ΂ȂȂ
A DST Ɋւ鎩̖@ύXꂽꍇ(@ύX
pɂɋN鍑܂)A^C][ύX@mKv
ł傤BVXeԂ萔ԂĂ悤ȂƂ́A^C]
[ (́ADST) ̐ݒɖ肪܂B

^C][ DST ̏́A/usr/share/zoneinfo ( /usr/lib/
zoneinfo) ɕۑĂ܂B[Jȃ^C][́A/etc/localtime
L̃t@CQ̂ЂƂɃV{bNN𒣂邱ƂŌ肳
܂B^C][ύXɂ́ÃN𒣂ւ܂傤B
DST ̓tςȂꍇ́Ãt@CҏWKv܂B

܂Aϐ TZ gČ݂̃^C][ύX邱Ƃł܂B
͈قȂ^C][ɂ鉓u}VɃOCĂꍇɂ́A
ȕ@łBڂ́Atzset  tzfile ̃}jAy[W
B

ɂẮÃTCgŕՂĂ܂B http://
www.linuxsa.org.au/tips/time.html



2.5. ǂ̒x̐xKv

~bPʂł̐msvȂAhwclock(8)  adjtimex(8) ł
[łB^CT[odgvɖɂȂƂĂ͂
񂪁A҂͌Â clock(8) vOłN΂炵ʂ
Ă܂BALAN ɕ̃}Vꍇ́A݂ɎvI
邱ƂłΕ֗ł(邢́Aꂪsȏꍇ
)BȊOɂAɕKvȂĂgĂ݂Ėʔc[ނ܂
B

Linux 点Ȃ}VȂ΁ARTC  UTC ( GMT) ɐݒ
܂傤BRTC [J^Cɐݒ肷Kv̂fAu[gVX
ȅꍇ́Aӂׂ_܂BĎԂ̕ύXO Linux 
u[gȂ΂ȂȂƂ́AvbIɈꎞԂĂ܂Ƃ
ƂƂłB̏Ԃ́A OS N܂őƂ
Ȃ܂B3 ȏ OS ڂĂꍇ́ÂЂƂ OS 
DST 𒲐悤CtĂB



3. \tgEFA

3.1. clock(8)  hwclock(8)

ǂ̂悤ȃfBXgr[VłÂ clock(8) V hwclock(8)
̂ǂ炩̓CXg[܂ ( Ԃ͎̒łKv
)Badjtimex(8) CXg[邩AIvVƂ CD ɓ
Ăł傤 (adjtimex ͒ʏ Linux A[JCuTCg_E[
h邱Ƃł܂)BfBXgr[VɂĂ X Window ŃO
tBJɃNbNݒ肷vO܂ł肵܂A
͂܂ŃC^NeBuȎg悤ɂȂĂ̂ (ݒ
łȂ̂)Aclock(8)  hwclock(8) CXg[ꏉXN
vgŎݒ肪o悤ɂȂĂ܂B

clock ̏ꍇAԒ̂߂̐l͎蓮ŌvZȂ΂Ȃ܂B
 hwclock ̏ꍇÃR}hg RTC Zbg邽тƂɒ
ŌvZĂ܂ (݂Ɏg RTC ݒ肷ƎԒ
Ă܂̂ŁA̍ۂ͕Kǂ炩g悤ɂĂ
)B clock ĂȂÂVXegĂăAbvO[h
ꍇ́A hwclock  util-linux pbP[W̃o[W 2.7 ȍ~
܂܂Ă܂Bڂ̓}jAy[WB

    Note: hwclock(8) ̃}jAy[ẂAʌ݊ۂ߂ clock
    ̃R}hŌĂяoݒɂȂĂ邱Ƃ̂ŁÃR}
    hĂBhwclock  clock p̃R}hɂ͂܂
    Ȁꍇʂ clock ̎Ƃ͈قȂ邩܂B 
    hwclock -a ́Aclock -a Ƃ͂ȂقȂĂ܂B hwclock ɃA
    bvO[hĂȂAXNvg clock pR}hg
    Ă镔ׂ͂ hwclock ̃lCeBuR}hɍւ邱Ƃ
    ߂܂B
   
XNvg̓fBXgr[VƂɈقȂ̂ŁAׂȂ
ƃNbNݒ肵ĂꏊȂ܂BT^Iȏꏊ
 /etc/rc.local  /etc/rc.d/rc.sysinitA/etc/rc.d/boot ȂǂłB

RTC ̎Ԓp̐ĺA/etc/adjtime ɕۑĂ܂BRed Hat ̏
 etc/sysconfig/clock ɃXNvgÃXNvg hwclock 
IvV𐧌䂵Ă܂B

NbN̐ݒŎv̋KIȃY𒲐ꍇ́Adbł̎񂪐m
ł͂Ȃꍇ蓾邱ƂOɒuĂ (󒍁F܂AAJ
ł̘bƎv܂)BZgWI GPS V[oĂȂƂ́A
(303)499-7111 ɓdbāA WWV 玞𕷂Ƃł܂(́A
Rh̃{_[ւ̒dbɂȂ܂)B3 ŎIɐ؂܂A
NbN̐ݒɂ͏[łBUSNO Ji_ CHU T[rXĂ
܂A҂ WWV ̂قƎv܂BԂ̃AiEXƎ񉹂̊
ułBɂ ntpd t ntpdate gălbg[N^C
T[o玞𓾂邱Ƃł܂A www.time.gov <http://
www.time.gov/> ɂ javaclock ܂B

ǂgꍇłݒ肷̂̓VXeNbNłARTC ł͂
(date R}h̃}jAy[WāAǂtH[}bgg
̂mFĂ)BāA hwclock gp RTC ݒ肵AKI
ȃY̊vZ܂B蓮łꍇA1 b 2 bȓ̌덷ɐݒ肵
āATԌɂ悻̃Y̗mF悤ɂĂB 
adjtimex sAVXeNbN𒲐ĂB



3.2. Adjtimex(8)

adjtimex R}h́AJ[l̎ԕϐ̒ł̂ŁAɂ
VXeNbÑXs[hύX悤ɂȂĂ܂(s̍ۂɂ
root ŃOCKv܂)Bhwclock ͐݌vGłAVXe
NbN RTC ̎rۂ /etc/adjtime ɕۑꂽAclock
ł hwclock łg铯̒lg悤ɂȂĂ܂B䂦
RTC ̋KIY𒼂Ă܂΁AVXeNbN𒲐̂
ȒPłBUNbNXs[hœ悤ɏoȂAX
NvgɐݒsǉċNɃJ[lϐK؂ɐݒ肷邱Ƃ
܂Badjtimex  clock ł hwclock łg悤ɐ݌vĂ
ŁAOqu11 ƁṽoOł悤ɂȂĂ܂B

adjtimex ̃CXg[ς񂾂AݒɊւڂ𓾂ɂ man
8 adjtimex ƃ^Cv邩 (ݒȊȌɊւ adjtimex ̃}jA
y[W܂)A/usr/doc/adjtimex-1.3/README  README t@C
ނĂ (fBNgpX̃o[Wԍ́Aadjtimex ̍ŐV
o[W̔ԍƂȂ܂)B



3.3. xntpd  ntpd - lbg[N^CvgR

xntpd (NTPv3) ́Antpd (NTPv4) ɒu܂BÂo[W͌
eiX̑ΏۊOƂȂĂ܂B

ntpd ́Albg[NzɎv𓯊WIȃvOłAv
Oɂ͐ڑ\ȃpubN^CT[õXgtĂ܂B
ݒɂĂ͖{ŏqׂĂ悤ȃvO╡G
񂪁A̎̎ɋȂ܂ƒ߂Ă݂邱Ƃ
܂B

ntpd Ɋւ NTP ̃EFuTCgł http://www.eecis.udel.edu/
~ntp/ ɏW񂳂Ă܂B܂ɂ́AԂɊ֘AlXȎ (
OS p̃\tgEFA܂) ւ̃NfڂĂ܂BfBXgr
[VɂĂ ntpd  CD Ɏ߂Ăꍇ܂Bpub
N^CT[õXǵA http://www.eecis.udel.edu/~mills/ntp/
clock2.html B

ntpd ̔rIV@\ɁAuo[Xg[h(burst mode)v܂B
̓_CAAbvŎXC^[lbgɐڑȂ}Vpɐ݌v
ꂽ@\łB

ntpd ɂ́AdgvphCo܂܂Ă܂ (AȂɂ͂
萫\̗ǂȂ̂܂)Bdgv̑啔͏pƂč쐬
āAh̒lit肵܂AɂȎi݂
܂ (ɂĂ͌قǉ܂)BȑO͂قƂǂ WWV  WWVB 
V[ołA݂ł͑啔 GPS V[oƂȂĂ܂BNIST ̃E
FuTCgɂ PDF t@C`ł̓dgv̐ꗗ\܂B 
http://www.boulder.nist.gov/timefreq/links.htm (y[W̖ł)B܂
NTP EFuTCgɂdgv̐Ђւ̃NfڂĂ܂
B http://www.eecis.udel.edu/~ntp/hardware.htm  http://
www.eecis.udel.edu/~mills/ntp/refclock.htmBǂ̃XgAXV
ꂽ肳Ȃ̂悤ł :-)@ ntpd ̃hCóA http://
www.eecis.udel.edu/~ntp/ntp_spool/html/refclock.htm ɂ܂B

ntpd ɂ́A_CAAbvp̃^CT[rXɂẴhCo܂܂
܂Bׂ͂ĒdbĝŁAvOgOɓdb
ǂꂭ炢ɂȂ邩vẐYȂłB



3.4. chrony vO

xntpd ͂Ƃƃlbg[N^CT[odgvɏ펞ڑł}V
pɍĂ܂B_Iɂ͎XڑȂ}Vłg
łARichard Curnow ͎vʂ̕@ xntpd 𓮂ƂłȂ
߁Achrony ƂvO쐬AISP Ƀ_CAAbvŐڑ
Ƃlbg[NɃANZXȂ[Uɕʂ̎i񋟂Ă
܂ ( ntpd V@\ł burst mode ŉ悤Ƃ̂
ł)Bchrony ݂̌̃o[Wɂ́AԓdItɂ}
Vp RTC ̋KIY@\܂܂Ă܂B 

ڂ Richard Curnow ̃EFuTCg http://
www.rrbcurnow.freeuk.com/chrony  http://go.to/chrony B
chrony ɂ͓̃[OXgAЂƂ̓AiEXpAЂ
̓[Uɂc_̏ƂȂĂ܂Bڂ
<hrony-users-subscribe@egroups.com> 
<chrony-announce-subscribe@egroups.com> Ƀ[𑗐MĂB

chrony ͒ʏ\[XR[ĥ݂̔zzƂȂĂ܂A Debian ł́A
unstable ̂ȂɃoCił܂܂Ă܂B\[Xt@CɂĂA
 Linux A[JCuTCgœł܂B



3.5. clockspeed vO

ȊȎIƂāADJ Bernstein ɂ clockspeed ƂvO
܂B̓lbg[N^CT[o玞Ԃ擾āA3 b
ɃVXeNbNĐݒ肷ƂPȕ@ĝłB܂ LAN
ɂ邢̃}V𓯊邽߂ɎgƂł܂B

ނ̃EFuTCg http://Cr.yp.to/clockspeed.html ͂Ƃǂgu
悤łB DNS G[o悤ȂAēxɃANZXĂ݂Ă
B̕ɂĂ͏ڂ񂪓莟AXV܂B



4. dgv

4.1. CHU ƁuGadget Boxv

CHU Ƃ́AI^ߍxɂJi_Zg (Canadian shortwave time
station) ̂ƂłAO WWV ɗގgDłA҂ɂ͂Ђ
dvȈႢ܂BCHU ͉pƃtXŎ񋟂邾
łȂAÂ "Bell 103" (300 baud) fg[gĈꕪԊuŎ
ĂƂ_łB̃g[̓fR[hɗeՂł邽߁A
Bill Rossi ̓f(fR[_)g܂łȂAZgWIƃTEhJ[
hŉ͂ł邱Ƃ𔭌܂BCHU ̐MMłȂA
͍łオȓdgvƂĎg܂BZg̎M󋵂͈̂ɉ
xω܂ABill ɂƁAɓ (Ɨ[) gς΂
 24 ԎMł邻łBCHU ̕ 3.33, 7.335,  14.670
MHz łB

ڍׂ Bill Rossi ̃EFuTCg http://www.rossi.com/chu/ 
B\[Xt@C͒ȃA[JCuTCgł܂B CHU ̎
T[rXɂẮA http://www.nrc.ca/inms/time/ctse.html ĉ
B

uGadget BoxvƂv NTP EFuTCgɂ܂B͈
300 baud ̃fƓKȒZgWIg CHU ̎fR[h
̂ł http://www.eecis.udel.edu/~ntp/ntp_spool/html/gadget.htmB
̃vł͐p̗ʃvgՂɊւ PostScript }fڂĂ
܂AՎ͎̂ōȂ΂Ȃ܂ (́AĂ
lTKv܂)B

ntpd ɂ CHU V[op̃hCo (type 7) ܂܂Ă܂B́u
Gadget Boxv̂悤ȃfgA Sun SPARCstation (邢
̌݊I[fBIhCo}V) ̃}CN͂ɒډ
邱Ƃœ悤ɂȂĂ܂B



4.2. WWV ƁuMost Accurate Clockv

Heathkit Ђ́uMost Accurate ClockvƂ̂𕷂Ƃ
ł傤B WWV ̎MăfR[hAIvṼVA|
[ggăRs[^ɐڑƂ̂łBHeathkit ͐܂
̃Lbg̔̔~߂Ă܂܂A1995N܂ł͂̎v̊i
̔̔𑱂Ă܂ (݂͔̔Ă܂)B(vȊO̐i܂
) Heathkit Ђւ̃mX^WAy[W http://
www.heathkit-museum.com ɂ܂BHeathkit Ў͍݂̂łAw
Kp̋ނ̔Ă܂Bڂ http://www.heathkit.com 
B

Dave Mills ɂƁAHeathkit Ђ́uMost Accurate ClockvɊւ
؂ɂȂ̂ŁAƂ̃N[VO`bv IC
ƂĔoЂoĂ邩ȂłB

NTP EFuTCgɂ DSP vO (т PDF t@C)
܂ http://www.eecis.udel.edu/~mills/resource.htmB͒Zg
WI TAPR/AMSAT DSP-93 Ƃ (݂ł͔̔ĂȂ) DSP Lbgg
 WWV fR[ĥłB̃Lbg Texas Instruments 
TMS320C25 DSP `bvx[Xɂ̂łBTAPR ̃EFuTCg http://
www.tapr.org ɂ͎ЊJ DSP vOɊւ񂪖Lxɂ܂
B

ntpd pbP[Wɂ IRIG-B  IRIG-E ^CR[h̃hCo (type 6) 
܂܂Ă܂B Sun SPARCstation  /dev/audio 𗘗p̂
AȊÕVXeɂڐA\łB WWV ł IRIG-H ^C
R[hgĂ܂B

WWV  NIST ɂ^cĂAEFuTCg http://
www.boulder.nist.gov/timefreq/index.html łB̃TCgɂ "Special
Publication 432" ƂAɂ͎ԂƎgɂĂ̋Lq
܂B http://www.boulder.nist.gov/timefreq/pubs/sp432/sp432.htm.
WWV  2.5, 5, 10, 15, 20 MHz ŕĂ܂B



4.3. GPS ƁuTotally Accurate Clockv

GPS Mɂ͐mȎԂ܂܂ĂāAGPS V[ôȂɂ̓VA|
[ĝ܂Bntpd ɂ͊e GPS V[op̃hCo
Ă܂B1PPS @\ ("One Pulse Per Second", ͂Ȃ荂x
vꍇɎĝł) ́AʏʂȃC^[tFCXgăR
s[^ɌqKv܂B

TAPR (Tuscon Amateur Packet Radio) ɂ TAC-2 ("Totally Accurate Clock"
̗) ƂC^[tFCXp̃Lbg܂B̓VA|[g
ɍ GPS V[oƌq߂̃C^[tFCXłA1PPS ̏o
͂ GPS V[oȂǂȂ̂łg܂B܂ɂ͉HՂ
ڍڂ邱ƂłxA{[hf (bare board model) ܂B
ڂ http://www.tapr.org/ ̃EFuTCgB(1999N6
_ł) líAGPS V[o 140 hOłB̃Lbgɂ
̂HՎtp̕i͊܂܂Ă܂B

(ʂ̏͂ŏqׂ) CHU uGadget Boxv 1PPS M̃C^[tFCXƂ
gƂł܂BNTP EFuTCgɂ͂ɊւLڂĂ
܂ http://www.eecis.udel.edu/~ntp/ntp_spool/html/pps.htmB



4.4. g^CVOiF DCF77, MSF(Rugby), WWVB

gǂł́ALÃIEIt؂ւɂă^CVOi
Ă܂BǂƂɓƎ̃R[hgĂÅTv NTP
EFuTCgɌfڂĂ܂Bhttp://www.eecis.udel.edu/~mills/ntp/
index.htm (̃y[W̍Ō̂قł)BhCc DCF77 ł 77.5kHzAC
MX MSF (͏ݒnɂȂ "Rugby" ƂĂ΂Ă܂) ƃR
h WWVB ͂ǂ 60 kHz ŕĂ܂B

WWVB ̎Mx͈肵Ă܂񂪁Ao͂iKIɏグ悤Ƃv
悪܂B̐i󋵂ɂĂ NIST ̃EFuTCg 
http://www.boulder.nist.gov/timefreq/wwvstatus.html B

VA|[gɐڑłȃV[o[bpœ\
B ntpd ɂ͂ MSF V[op̃hCo܂܂Ă܂B

Ȏ̉Ђ WWVB V[ogݍ񂾔rIȎv̔
Ă܂ (ɂ͕Ǌ|p̎v܂܂Ă܂)BA
̒mARs[^ɐڑł̂ 2 @킵܂B

Ultralink Model 320 Ƃv (1999N6_) 120 hxłA
̓VAC^[tFCX ASCII ɂR}hZbgg
悤ɂȂĂ܂B䂦AvÔ͂قǓȂ
łB̓VA|[g 1 mA ̓d܂BAei̓R
s[^ 100 tB[g܂ŗƂłAVOiȂꍇ
đgݍ݂̓NbNŎԂ𑪒肵邱Ƃł܂B
Ultralink ł̓xA{[ł 80 hxŔ̔Ă܂B "BASIC
Stamp" V[Ỹ}CNRg[œ悤ɐ݌vĂ܂Bڂ
͎̃EFuy[WB http://www.ulio.com/timepr.html.

Arcron Technology ́AVA|[gIvV㎞v 80
hŔ̔Ă܂Bɂ Windows p̃\tgEFA܂܂Ă܂
Bڂ͎̃EFuy[WB http://www.arctime.com.



5. {ɂ

E뎚EEɂẮA<JF@linux.or.jp> ܂ł肢܂B

|                                (1997
 gp                       /01) 
F                                     
X                                (2001
V UTi                       /10/ 
F                                06)  
Z                                     
 鐳                            
F                                     
   щT                            

Notes

[1] 󒍁FRs[^̃NbNǂ̒xmĂAʐM 
    񌤋̃y[W http://www2.crl.go.jp/pub/jst/index-J.html
    B                                                               

