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J. Mauricio Lopez R.1, Michael A. Lombardi2, N. Diaz-Muñoz1 and Eduardo de Carlos Lopez1 1Centro Nacional de Metrología (CENAM), Querétaro, Mexico
2National Institute of Standards and Technology (NIST), Boulder, Colorado, United States,
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
OUTLINE
1. Motivations
2. The SIM Time Network (SIMTN)
3. The SIM time scale (SIMT)
4. New weights algorithm
5. Conclusions and future work
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
J. Mauricio Lopez R., Michael A. Lombardi, N. Diaz-Muñoz and Eduardo de Carlos Lopez
OUTLINE
1. Motivations 2. The SIM Time Network (SIMTN)
3. The SIM time scale (SIMT)
4. New weights algorithm
5. Conclusions and future work
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
J. Mauricio Lopez R., Michael A. Lombardi, N. Diaz-Muñoz and Eduardo de Carlos Lopez
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
TIMEThe most measured physical quantity
TWO FACES OF TIME
The current SITime is the most accurate measurement
Scientific and fundamental research Technological and practical applications
OUTLINE
1. Motivations
2. The SIM Time Network (SIMTN)
3. The SIM time scale (SIMT)
4. New weights algorithm
5. Conclusions and future work
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
J. Mauricio Lopez R., Michael A. Lombardi, N. Diaz-Muñoz and Eduardo de Carlos Lopez
TIME AND FREQUENCY METROLOGY WORKING GROUPWorking to support time and frequency metrology throughout the Americas
34 NMIs
3 NMIs
7 NMIs
5 NMIs
5 NMIs
14 NMIs
TIME AND FREQUENCY METROLOGY WORKING GROUPWorking to support time and frequency metrology throughout the Americas
Current SIMTN members
18 1
TIME AND FREQUENCY METROLOGY WORKING GROUPWorking to support time and frequency metrology throughout the Americas
SIMTN Area Coverage
18 1 SIM NMIs
Clock A
Clock B
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
Clock A
Clock B
GPS satellite
Mea
surin
g sy
stem
A
Mea
surin
g sy
stem
B
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
Clock A
Clock B
GPS satellite
Mea
surin
g sy
stem
A
Mea
surin
g sy
stem
B
Time of the day
GP
S –
Clo
ck A
Time of the day
GP
S –
clo
ck B
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
Clock A
Clock B
Mea
surin
g sy
stem
A
Mea
surin
g sy
stem
B
SIMTN servers
CENAM
NIST
NRC
ONRJ
Time of the day
GP
S –
Clo
ck A
Time of the day
GP
S –
clo
ck B
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
timeClo
ck A
– C
lock
B ±
u
(Clock A – S) – (Clock B – S) = (Clock A – Clock B) + (dSA – dSB)
Time of the day
GP
S –
clo
ck B
Time of the day
GP
S –
Clo
ck A
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
21
)1(...321 N
NNNC
NC number of bilateral comparisons
N number of laboratories in the network
For
N=18
there are
NC = 153
bilateral comparisons
LNM
ICE
SIC
CENAM
NIST
NRC
ONRJ
INDP
INTNUTE
INTI
BSJ
SLBS
CENAMEP
links in the SIMTN
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
21
)1(...321 N
NNNC
NC number of bilateral comparisons
N number of laboratories in the network
For
N=18
there are
NC = 153
bilateral comparisons
LNM
ICE
SIC
CENAM
NIST
NRC
ONRJ
INDP
INTNUTE
INTI
BSJ
SLBS
CENAMEP
links in the SIMTN
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
LNM
ICE
SIC
CENAM
NIST
NRC
ONRJ
INDP
INTNUTE
INTI
BSJ
SLBS
CENAMEP
Shortest link
215.301 km baselineArgentina to Uruguay
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
links in the SIMTN
Longest link
8676.511 km baselineUSA to Argentina
http://www.tf.nist.gov/sim
CENAM Time – NIST time
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
OUTLINE
1. Motivations
2. The SIM Time Network (SIMTN)
3. The SIM time scale (SIMT)
4. New weights algorithm
5. Conclusions and future work
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
J. Mauricio Lopez R., Michael A. Lombardi, N. Diaz-Muñoz and Eduardo de Carlos Lopez
30 Cesium beam clocks
9 Active Hydrogen Masers
1 Cs fountain clock (NIST)
2 Cs fountain clocks in progress(NRC and CENAM)
4 ensemble time scales(NRC, NIST, CENAM and ONRJ)
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
SIMT(k) (clock or time scale)
SIMTN Computer
8-channel GPS Receiver
New data every 10 minutes
Time Interval Counter
FTP Server (CENAM)(processes CVGPS and
AVGPS data)
1 pps
GPS satellites
1.57542 GHz (L1 carrier)
1 pps
FTP FTP Server (NIST)(processes CVGPS and
AVGPS data)
FTP Server (NRC)(processes CVGPS and
AVGPS data)k-th member of SIMTN
(18 members)
SIMTN Web Server (NIST)(publishes comparisons every 10 minutes)
(publishes SIMT every hour)
SIMTN Web Server (CENAM)(publishes comparisons every 10 minutes)
SIMTN Web Server (NRC)(publishes comparisons every 10 minutes)
FTP
FTP
SIMT Computer (CENAM)(reads SIMTN data feeds, runs SIMT
algorithms, generates SIMT every hour)SIMTN data feeds (HTTP)
FTP
(new data every hour)
10 MHz
GPS antenna
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
2)()()( k
kkk
DtYtXtX
Prediction of the time difference between clock k and SIMT at the future time t+
Time difference between clock k and SIMT at the time t (0th order aproximation)
Correction due to sistematic frequency difference between clock k and SIMT (1st order aproximation)
Correction due to non constant (linear) frequency difference between clock k and SIMT (2th order aproximation)
Taylor series expansion on the predicted time difference of clock k respect to SIMT
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
N
jjkjjk tXtXwtX
1
)()()(
Time difference between clock k and SIMT at the current time t+
Prediction of the time difference between clock j and SIMT made at the past time t
Time difference between clock j and clock k at the time t+
Averaging
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
OUTLINE
1. Motivations
2. The SIM Time Network (SIMTN)
3. The SIM time scale (SIMT)
4. New weights algorithm
5. Conclusions and future work
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
J. Mauricio Lopez R., Michael A. Lombardi, N. Diaz-Muñoz and Eduardo de Carlos Lopez
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N
jjkjjk tXtXwtX
1
)()()(
Since February, 2012
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
55750 55800 55850 55900 55950 56000 56050 56100 56150-30
-20
-10
0
10
20
30
MJD
SIM
T - S
IMT(
NIS
T) /
ns
)(
1
ii ,
1
)(
1
fi
i
February 9, 2012
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
5561055620556305564055650556605567055680556905570055710
5561055620556305564055650556605567055680556905570055710
-30
-20
-10
0
10
20
30
40
-30
-20
-10
0
10
20
30
40
from Feb 9, 2012 to May 9, 2012
From Feb 23, 2011, to May 23, 2011
MJD
SIM
T - S
IMT(
NIS
T) /
ns
MJD
SIM
T -
SIM
T(N
IST
) /
ns
1E+03 1E+04 1E+05 1E+06 1E+071E-16
1E-14
1E-12
Feb - May 2012Feb - May 2011
Averaging time / s
AVAR
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
55960 55980 56000 56020 56040 56060 56080 56100 56120 56140-20
-15
-10
-5
0
5
10
15
20
25
SIMT - SIMT(NIST)
MJD
Tim
e di
ffere
nce
/ ns
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
55960 55980 56000 56020 56040 56060 56080 56100 56120 56140-20
-15
-10
-5
0
5
10
15
20
25
UTC - UTC(NIST)SIMT - SIMT(NIST)
MJD
Tim
e di
ffere
nce
/ ns
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
55960 55980 56000 56020 56040 56060 56080 56100 56120 56140-20
-15
-10
-5
0
5
10
15
20
25
UTC - UTC(NIST)SIMT - SIMT(NIST)UTCr - UTC(NIST)
MJD
Tim
e di
ffere
nce
/ ns
55960 55980 56000 56020 56040 56060 56080 56100 56120 56140 561600
5
10
15
20
25
UTC - UTC(NIST)
MJD
Tim
e di
ffere
nce
/ ns
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
55960 55980 56000 56020 56040 56060 560800
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
SIMT(NIST) SIMT(CNM)SIMT(NRC)SIMT(CNMP)SIMT(ONRJ)SIMT(ICE)SIMT(SIC)SIMT(INTI)
MJD
SIM
T W
eigh
ts
,1
)(
1
fi
i
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
OUTLINE
1. Motivations
2. The SIM Time Network (SIMTN)
3. The SIM time scale (SIMT)
4. New weights algorithm
5. Conclusions and future work
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
J. Mauricio Lopez R., Michael A. Lombardi, N. Diaz-Muñoz and Eduardo de Carlos Lopez
3 +1 SIMTN servers
CENAM
NIST
NRC
ONRJ
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
Computation of SIMT in 3 different locations
CENAM
NIST
NRC
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
Cs clock(s) will be included
SIMT(k) will be steered to SIMT
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
Bolivia
18 SIM NMIs
+
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
More room to improve the SIMT stability
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
Development of new SIM GPS systems with full compatibility with the BIPM algorithm to produce the UTC (in progress). More SIM NMIs contributing data to TAI.
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
J. Mauricio Lopez R.1, Michael A. Lombardi2, N. Diaz-Muñoz1 and Eduardo de Carlos Lopez1, 1Centro Nacional de Metrología (CENAM), Querétaro, Mexico
2National Institute of Standards and Technology (NIST), Boulder, Colorado, United States,
THANK YOU FOR YOUR ATTENTION!
A NEW ALGORITHM FOR CLOCK WEIGHTSFOR THE SIM TIME SCALE
J. Mauricio Lopez R., Michael A. Lombardi, N. Diaz-Muñoz and Eduardo de Carlos Lopez