Delta-DOR in CE-3, MEX solar conjunction · 上海天文台 Shanghai Astronomical Observatory...
Transcript of Delta-DOR in CE-3, MEX solar conjunction · 上海天文台 Shanghai Astronomical Observatory...
上海天文台Shanghai Astronomical Observatory
Delta-DOR in CE-3,
MEX solar conjunction
Ma Maoli, Zheng Weimin, Huang Yidan, Chang Shengqi
Email:[email protected]
1
First International Workshop on VLBI observations of near-field targets
上海天文台Shanghai Astronomical Observatory
Outline
2
1. CVN in Chang’E-3 mission
2. CE-3 X-band Delta-DOR
3. MEX Interplanetary scintillation observation
上海天文台Shanghai Astronomical Observatory
1. CVN
CVN, providing VLBI
delay, delay rate, orbit,
and angle data to Beijing
Center. CE-1, CE-2, CE-3,
CE5T1.
上海天文台Shanghai Astronomical Observatory
4
CVN upgrade in CE3
1. New VLBI data center
2. Shanghai Tianma 65m radio telescope
3. New X-band receiver & digital terminal
Ur,26mBJ,50m
KM,40m
SH,65m
上海天文台Shanghai Astronomical Observatory
2. CE-3 X-band Delta-DOR
Peter Kroger: ΔDOR spacecraft tracking
Five-minute scan sequence:
Quasar-CE3-Quasar-CE3
Angular distance between CE-3 and
Quasar < 10°
Remove media & system errors
5
上海天文台Shanghai Astronomical Observatory
F1pc
F1L2 F1L1 F1R1 F1R2
F2pc
F2R2F2R1F2L2 F2L1
7.7MHz 7.7MHz
38.5MHz38.5MHz
Two series of DOR signals, F1 and F2, located at both sides of the detector.
One is coherent( ), the other is non-coherent( ).14-13- 10~10 10-9- 10~10
上海天文台Shanghai Astronomical Observatory
FX correlator in CVN
E
0,( )ES t
1d
2d
1( )T t
2 2( )T t
Et
E1V
LB
I
2VLB
I
model
model
Signal from
station A
Signal from
station B
Amp and
phase
Model for A Model for BFringe stop Fringe stop
FFT FFT
Corr of A&B
Fringe Fit
Delta - DOR
Bandwidth
synthesisQuasar
上海天文台Shanghai Astronomical Observatory
FX correlator on DOR
0 1 2-60
-40
-20
0
20
40F1R2
Ph
ase
(ra
d)
s3c09a UR-TM
-4
0
4
0 1 2-60
-40
-20
0
20
40
Frequency(MHz)
F1R1
-5
0
5
0 0.5 1 1.5 2-60
-40
-20
0
20
40 F1PC
Cro
ss s
pe
ctr
um
(dB
)
-4
0
4
0 1 2-60
-40
-20
0
20
40F1L2
-5
0
5
Samplerate 4MHz
Bandwidth 2MHz
FFT point 1024
dB181024
4000000log10
10
CNR loss due to
Spectral resolution:
上海天文台Shanghai Astronomical Observatory
Residual statistics
0.00
0.20
0.40
0.60
0.80
1.00
1.20
12/2 12/3 12/4 12/5 12/6 12/7 12/8 12/9 12/10 12/11 12/12 12/13
VLBI Delay Data Fit(unit: ns)
real-time
Trans-lunar Orbit Lunar Orbit
VLBI group delay residuals(X-band Delta-DOR):~ 1ns in trans-lunar orbit
~ 0.5ns in lunar orbit.
C
Au ( )ρ t
A B
Sc
( )tAr
E
Bu ( )ρ t
Ad ( )ρ tBd ( )ρ t
A B
Sc
( )tAr
E
Ad ( )ρ tBd ( )ρ t
coherent non-coherent
Ad 0 Au 0 'Bd 0 Bu 0DOR 0 2 2
( ) ( )( ) ( )( )
t t
c
t tt t t
c
Ad 0 'Bd 0DOR 0 1 1
( )( )( )
t
c
tt t t
c
A different correlator from FX correlator
Rogstad, Stephen P., et al.2009;Luciano Iess, Ricard AbellòPuyuelo, Alessandro
Ardito, et al. The European ΔDOR Correlator.
上海天文台Shanghai Astronomical Observatory
Correlator
Input: transmit frequency
Model: let
0fAd Sc 1 A
Au C 2 Sc 1
( ) ( ) ( )
( ) ( ) ( )
t t t
t t t
r r
r r c
ttt
)()()( AuAd
geoA
Transmit signal
Received signal
0 0( ) Re exp 2ts t a i Mf t
A A 0 geoA 0
B B 0 geoB 0
( ) Re exp 2 ( )
( ) Re exp 2 ( )
s t a i Mf t t
s t a i Mf t t
Range model
A,m 0 geoA,m 0( ) exp 2 ( )s t i Mf t t
* AA 0 geoA,m geoA 0
as (t) expi[2 M ( (t) (t)) ]
2 f
Delay, geo
)(A ts is a slow varying signal with low frequency.
上海天文台Shanghai Astronomical Observatory
Data process
CE-3, s3c07a, s3c08a,
s3c09a,
100*100km lunar orbit
Samplerate:4MHz
Bandwidth:2MHz
Quantification:2bit
0001 3C273B 2013-12-07 02:43:00 2013-12-07 03:11:00 BjKmUrTm
0002 1334-127 2013-12-07 03:13:00 2013-12-07 03:42:00 BjKmUrTm
0003 SAT-CE03 2013-12-07 03:46:00 2013-12-07 03:53:00 BjTm
0004 1741-038 2013-12-07 03:56:00 2013-12-07 04:01:00 BjKmUrTm
…….
0038 2128-123 2013-12-07 08:21:00 2013-12-07 08:26:00 BjKmUrTm
0039 SAT-CE03 2013-12-07 08:27:00 2013-12-07 08:35:00 BjKmUrTm
0040 2128-123 2013-12-07 08:36:00 2013-12-07 08:41:00 BjKmUrTm
0041 SAT-CE03 2013-12-07 08:42:00 2013-12-07 08:50:00 BjKmUrTm
0042 2128-123 2013-12-07 08:51:00 2013-12-07 08:56:00 BjKmUrTm
0043 SAT-CE03 2013-12-07 08:57:00 2013-12-07 09:05:00 BjKmUrTm
0044 2128-123 2013-12-07 09:06:00 2013-12-07 09:11:00 BjKmUrTm
0045 SAT-CE03 2013-12-07 09:12:00 2013-12-07 09:20:00 BjKmUrTm
0046 2128-123 2013-12-07 09:21:00 2013-12-07 09:26:00 BjKmUrTm
0047 SAT-CE03 2013-12-07 09:27:00 2013-12-07 09:35:00 BjKmUrTm
0048 2128-123 2013-12-07 09:36:00 2013-12-07 09:41:00 BjKmUrTm
………
0070 2128-123 2013-12-07 12:21:00 2013-12-07 12:26:00 BjKmUrTm
0071 SAT-CE03 2013-12-07 12:27:00 2013-12-07 12:35:00 BjKmUrTm
0072 2134+00 2013-12-07 12:36:00 2013-12-07 12:41:00 BjKmUrTm
0073 SAT-CE03 2013-12-07 12:42:00 2013-12-07 12:46:00 BjKmUrTm
0074 SAT-CE03 2013-12-07 12:46:00 2013-12-07 12:55:00 KmUr
0075 2134+00 2013-12-07 12:56:00 2013-12-07 13:01:00 BjKmUrTm
0076 SAT-CE03 2013-12-07 13:02:00 2013-12-07 13:12:00 KmUr
上海天文台Shanghai Astronomical Observatory
8.45 8.46 8.47 8.48 8.49 8.5
x 109
-70
-60
-50
-40
-30
-20
-10
0
10
Frequency/Hz
Po
we
r sp
ectr
um
(dB
)
s3c09a BJ
F1pc F2pcF2L2F1L2 F1R1 F1R2 F2R2F2R1
Received signal by VLBI station
CNR of s3c09a BJ(dBHz)
L2 pc R1 R2
F1, coherent 40 50 40 40
F2,non-coherent 28 40 30 25
CNR:10*log(power of signal/noise)
上海天文台Shanghai Astronomical Observatory
Coherent
In the coherent situation, the transmitted frequency from uplink
station is exactly known.0f
Judgement
F and phase from
single station
Differential phase
of two stations
Bandwidth
synthesisDelta-DOR
,D PLL
Quasar
Signal from
station A and B
Initial model
上海天文台Shanghai Astronomical Observatory
Take s3c09a as example
-8000
-6000
-4000
-2000
0
2000
Fre
qu
en
cy(m
Hz) (a)
6 8 10 12
-20000
-10000
0
Ph
ase
(ra
d)
(c)
-200
0
200 (b)
6 8 10 12
-2
0
2(d)
Time(hour)
After integral filter After PLL
BJ KM UR TM
Frequency(mHz) 8.23 52.9 9.4 11.3
Phase(rad) 0.11 0.26 0.13 0.13
上海天文台Shanghai Astronomical Observatory
-20 0 20-100
-80
-60
-40
-20
0TM main carrier 06:17:00-06:17:04
Frequency(Hz)
Po
we
r sp
ectr
um
(dB
)
0 1 2 3
-1
-0.5
0
0.5
1
Time(s)
Am
ptitu
de
TM F1pc after PLL
上海天文台Shanghai Astronomical Observatory
Phase compared with FX correlator
-100
0
100
Ph
ase
(ra
d)
s3c09a TM-UR
(a)
7 8 9 10 11 12 13
-0.5
0
0.5
1
Time(hour)
resid
ua
ls(r
ad
)
FX 0.38rad
Local 0.12rad(b)
上海天文台Shanghai Astronomical Observatory
Phase compared with FX correlator
Baseline s3c07a s3c08a s3c09a
New FX New FX New FX
BJ-KM 0.29 0.35 0.28 0.38 0.25 0.38
BJ-UR 0.13 0.35 0.20 0.35 0.11 0.37
BJ-TM 0.13 0.20 0.15 0.22 0.14 0.27
KM-UR 0.27 0.40 0.29 0.40 0.28 0.38
KM-TM 0.29 0.39 0.30 0.40 0.28 0.40
UR-TM 0.17 0.39 0.15 0.38 0.12 0.39
Phase precision from new method is better than the FX
correlator.
上海天文台Shanghai Astronomical Observatory
Non-coherent: Estimate f0 at first
7 8 9 10 11 12 13 14 15
8.4798
8.4798
8.4798
x 109
tra
nsm
it f
req
ue
ncy(H
z) s3c09a transmit frequency of F2pc
7 8 9 10 11 12 13 14 15
-20
0
20
time(hour)
difference between continuous two points
fre
qu
en
cy(H
z)
Frequency difference between adjacent points is in the range of -10~10Hz
上海天文台Shanghai Astronomical Observatory
Difference transmit frequency between two stations
6 8 10 12 14 16-0.5
0
0.5
BJ-KM
mean=-28mHz std=74mHz
6 8 10 12 14 16-0.5
0
0.5
BJ-UR
mean=-36mHz std=74mHz
6 8 10 12 14 16-0.2
0
0.2
BJ-TM
mean=-36mHz std=50mHz
6 8 10 12 14 16-0.5
0
0.5
KM-UR
mean=-7.2mHz std=93mHz
6 8 10 12 14 16-0.5
0
0.5
KM-TM
mean=-8.5mHz std=73mHz
6 8 10 12 14 16-0.5
0
0.5
s3c09a different transmit frequency between two station
mean=-0.79mHz std=84mHz
Time(hour)
Fre
qu
en
cy(H
z)
Frequency std is about 100mHz
上海天文台Shanghai Astronomical Observatory
Orbit determination results
codeDelta-DOR+range(RMS) Delta-VLBI+range(RMS) Difference with 61+62
71 51(m) 61(ns) 51(m) distance(m) velocity(mm/s)
s3c07a 0.3 2.96 0.3 1.68 26.3 20.0
s3c08a 0.4 1.28 0.3 1.65 24.6 20.3
s3c09a 0.4 0.40 0.5 0.42 8.9 9.3
Orbit determination between two correlator, F1
Orbit determination between two correlator, F2
codeDelta-DOR+range(RMS)
73 51(m)
s3c07a 0.67 4.3
s3c08a 0.67 1.27
s3c09a 0.67 0.42
Difference with 61+62
distance(m) velocity(mm/s)
29.3 22.4
15.3 13.4
7.0 7.0
上海天文台Shanghai Astronomical Observatory
Error analysis
Wu Wei-ren, Wang Guangli, et al. 2013
上海天文台Shanghai Astronomical Observatory
Conclusion
1. The delay residuals after orbit determination are 0.5ns and
0.7ns respectively. The CNR of F2 is 10dB weaker than F1.
2. The phase from the result is better than FX correlator, while
no improvement in orbit determination, system errors from
CVN should be estimated.
3. The method reported here is more suitable for weak signal
process compared with FX correlator.
上海天文台Shanghai Astronomical Observatory
3.MEX Interplanetary scintillation observation
MEX is flying around Mars. Sheshan 25m radio telescope have observed MEX
from 2014.11~2015.9. The observations are conducted by JIVE.
5.69 5.7 5.71 5.72 5.73
x 104
0
50
100
150
200
MJD
hel
ioce
ntr
ic d
ista
nce
/so
lar
rad
ius
5.7 5.71 5.72 5.73
x 104
0
20
40
60
MJD
So
lar
elo
ng
atio
n/d
egre
e (a)
Solar elongation and minimum heliocentric distance vary from 2014.11~2015.09
Orbit of MEX is got from ESA/ESOC. G. Molera Calves, et al. 2014.
上海天文台Shanghai Astronomical Observatory
Phase Frequency
11R⊙ 21.2rad 16mHz
160R⊙ 0.1rad 3mHz
0 1000 2000 3000 4000 5000
-20
0
20
40
Time(s)
Ph
ase
var
iati
on
(rad
)
上海天文台Shanghai Astronomical Observatory
Phase spectral power density at R=11R⊙ and 160 R⊙
10-3
10-2
10-1
100
101
10-10
10-5
100
105
Frequency(Hz)
Ph
ase
sp
ectr
al p
ow
er
de
nsity(r
ad
2/H
z) scintillation band noise band B>B
L
I II III
IV
fS bLaL
0 20 40 60 80 100 120 140 160 180
-3
-2.5
-2
-1.5
Scin
tillation s
lope
Slope of phase spectral power density
Close to Komlogorov index 8/3
Komlogorov Turbulence, 3mHz~0.3Hz, 1300km~130000km
上海天文台Shanghai Astronomical Observatory
Theory to explain phase scintillation
Refraction index n(x,t) , Taylor frozen-in hypothesis.
Structure function
x=0 x=L
Inhomogeneous random medium
Refraction
x
Input signal Output signal
Ra
LxcxC nn
1
20 exp)(
11
13
220
)2/(
2/)1(28033.0)(
p
pfRakcfW
p
nS
dffWf
fSS )(
2
1
2
Woo R, Yang F C. et al.1976
上海天文台Shanghai Astronomical Observatory
-150 -100 -50 0 50
-14
-13.5
-13
-12.5
-12
-11.5
-11
log
10(c
n0)
Ingress
Engress
p=3.3
model
0
d
n
Rc c
R
10107.28.3 c d = -1.98±0.27
In Woo’s paper(1976), d is
close to 2.1
refraction structure constant
上海天文台Shanghai Astronomical Observatory
Conclusions with IPS
1.We use a single VLBI station to observe MEX. Doppler is used
for IPS research. The method can be used in future Chinese Mars
solar conjunction.
2.Solar wind and IPS theory are proposed in the 80s in last
century. The research work reported here just confirmed earlier
theory. Where is the break through point in solar wind and IPS
research?
上海天文台Shanghai Astronomical Observatory
Thanks for attention!