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:mamaoli@shao.ac.cn

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!