Symmetricom SyncServer S100 User Manual page 140

Glossary Glossary
recti tions rec ons whi which ch are
ve vers rsal al Ti Time me (UTC)
The GPS The GPS na navi vigat
of of 20 2006 06 is is 14 14 se seco conds
'lo 'loca cal' l' ti time me. . New
UTC Off UTC Offset set mes
bi bits ts) ) whi whic c h, h, at at th the e cu curre
year r 2330 yea 2330. .
As oppos As opposed ed to to the
ex expre press ssed ed as as a a wee
as as a a te ten- n-bi bit t fi fiel eld d in in th the e C/A
ev every ery 1, 1,024 024 wee
19 1980 80 an and d th the e wee
21, 199 21, 1999 9 [. [... ..]. ]. To
wit with h the the app approx
To ad addre To dress ss th this is co conc ncern
on only ly re repe peat ats s ev ever ery y 8, 8,19 192 2 wee
2137." 2137."
Hardware Clock Hardware Clock
The The Hard Hardware
Gets Gets th the e ti time
n n
Appl Applie ies s th the e UTC
n n
Passe ses s th the e ti time Pas
n n
The NTP The NTP dae
be be edi edite ted d or or rem
Also see Also see TIMING TIMING - - HW
1). 1).
Leap Indicator Leap Indicator
The e Le Leap ap In Indi dica cato tor r (L (LI) I) is is a a two Th
followin following g informat
A Adv dvan ance ce warn
n n
en end d of of th the e cu curre
(BIPM) (BIP M) in in ord
Whe Wheth ther er the
n n
- Prefs - Prefs
99 997-0 7-015 1520- 20-03 03 Rev Rev. . A A ..........................................................................
are pe perio riodi dica call lly y ad added ded to to UTC.
(UTC) in in 19 1980, 80, but but has has si sinc nce e di dive verge
gatio ion n me mess ssag age e in incl clud udes es th the e di diff ffere
nds. . Rec Recei eive vers rs su subt btrac
New GPS GPS uni units ts ma may y no not t sh show
messag sage. e. The The GPS-UTC GPS-UTC off offset
rrent nt ra rate te of of ch chan ange ge of of th the e Ear
the year, year, month, month, and and day
week k num numbe ber r an and d a a da day- y-of-
C/A an and d P(Y P(Y) ) na nav v ig igat atio ion n me
weeks ks (19 (19.6 .6 ye years ars). ). GPS GPS wee
week k nu numb mber er be beca came me ze zero ro ag agai ain n fo for r th the e fi firs rst t ti time
To det determ ermin ine e th the e cu curre rrent nt Gre
roxim imat ate e da date te (to (to wit withi hin n 3, 3,58 584 4 day
ern th the e mo moder derni nize zed d GPS
weeks ks (1 (157 57 ye year ars s ), ), an and d wi will ll no not t re retu turn rn to to z z er ero o un unti til l ne near ar th the e ye year
ware Clo Clock ck ma manag nages es the the Inp
me fro from m th the e hi high ghes est t pri priori ority ty ref
UTC of offs fset et if if the the ref refere
me to to th the e NTP NTP da daem emon on. .
daemo mon n in incl clude udes s a a pre prefe ferred
remov oved ed. .
HW Clock, Clock,
NTP - Config NTP - Config
two-b -bit it bi bina nary ry nu numb
information: ion:
warnin ing g tha that t a a le leap ap se seco cond nd ad adju just stme
rrent nt day day. . Le Leap ap se seco conds
order er to to sy sync nchro hroni nize ze th the e UTC
the NTP NTP da daem emon on is is sy sync nchro
(o (on n pa page ge 33 33) ) pa page ge af affe fect ct LI LI be beha hav v io ior. r.
..........................................................................
UTC. GPS GPS ti time me was was se set t to to ma
rged. d. [. [... ..] ]
erenc nce e be betwe tween en GPS
ract t th this is of offs fset et fro from m GPS GPS ti time
ow th the e co correc rrect t UTC UTC ti time
set fie field ld can can ac accom commod
Earth th's 's ro rota tati tion on, , is is s s uf uffi fici cien ent t to to la last st un unti til l th the e
day format format of of the the Juli Julian an cale
of-week week nu numb mber. er. The The wee
mes s sa sage ges s , , an and d so so it it be beco come
week k ze zero ro st start arted ed at at 00 00:00
Grego goria rian n dat date, e, a a GPS GPS rec
days) s) to to co correc rrectl tly y tra
GPS na navi viga gati tion on me mess ssag ages es us use e a a 13 13-bi -bit t fi fiel eld, d, whi
Input ut Ref Refere erenc nces es: :
refere erenc nce e th that at is is av avai aila labl ble. e.
erenc nce e is is GPS GPS. .
rred se serv rver er as asso soci ciati ation on for for th the e Hard
(o (on n pa page ge 29 29), ), an and d
mber er in in th the e NTP NTP pa pac c ke ket t he head ader er th that at pr prov ovid ides es th the e
ment nt wil will l be be ma made de to to th the e UTC
nds are are ev even ents ts ma mand ndate ated d by by th the e worl
UTC ti time me sc scal ale e wit with h th the e ear
hroni nize zed d to to a a ti timi ming ng ref refere
Pag Page e 127
matc tch h Coo Coordi rdina nate ted d Uni
GPS ti time me an and d UTC, UTC, whi which ch as as
me to to ca calc lcul ulate ate UTC UTC and
me un unti til l af after ter rec recei eivi ving ng th the e GPS
modate ate 255 255 lea leap p se secon conds ds (eig
calendar, ndar, the the GPS GPS date date is is
week k nu numb mber er is is tra trans nsmi mitt tted ed
mes s ze zero ro ag agai ain n
:00:0 :00 0 UTC UTC [. [... ..] ] on on Ja Janua nuary ry 6, 6,
me at at 23 23:5 :59: 9:47 47 UTC UTC on on Au Augu gus s t t
recei eive ver r mu must st be be pro provi vided
trans nsla late te th the e GPS GPS da date te si signa
Hardware ware Clo Clock ck th that at ca cann nnot ot
(on (on pag
Input References Input References
UTC ti time mesc scal ale e at at th the e
world d ti time me aut autho horit rity y
earth' th's s rot rotati ation. on.
erenc nce. e. The The se sett ttin ings gs on on th the e
127
Uni- -
and
GPS- -
(eight ht
ded
gnal. l.
which ch
ar
page e
NTP NTP