MHz 10 MHz Mbps 1 C 2(a) 4 GHz MHz 56 Msps 70 MHz 70 MHz 23 MHz 14 MHz 23 MHz 2(b)

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1 ANNALS OF SHANGHAI OBSERVATORY ACADEMIA SINICA No. 32, ,2,3 1 2,3 2,3 2, ( ) V474 1 (CEI) ( VLBI ), CEI 100 nrad ( 50 km) CEI km CEI [1] NASA (DSN) CEI [2 5] km ESA [6] , ( ) (10PJ ) Shanghai Key Laboratory of Space Navigation and Position Techniques (Y ) (SFDLHZ )

2 MHz 10 MHz Mbps 1 C 2(a) 4 GHz MHz 56 Msps 70 MHz 70 MHz 23 MHz 14 MHz 23 MHz 2(b)

3 x 1 (t) x 2 (t) 1 2 X 1 (jω) = F (x 1 ) X 2 (jω) = F (x 2 ) i S i (ω) = X i 1(ω) X i 2(ω) S i (ω) = Ae jφ(t,ω) φ(t, ω) 2 2π 3.2 [7] φ(ω, t) = φ 0 (ω 0, t 0 ) + φ ω (ω ω 0) + φ t (t t 0). τ pd = φ 0 ω 0, τ gd = φ ω, τ pd = 1 φ ω 0 t 3.3.

4 [8] FFT 3(a) τ = φ 2π f f = NF F T 500f s, (1) f NF F T F F T f s n bit = τ/t sample 8 8 bits 3(b) 3(b) 3(c) 3(d) 3(c) 10 3(d) f1 f2 f3 f1 f3 f2 3 F F T (d) rad/s 1000 ns

5 ( ) ( ) F F T

6 s 1 (t) = exp(j2πft) 2 s 2 (t) = exp[j2πf(t + τ)] 1 s 1 (t) = exp[j(2π(f f LO1 )t 2πf IM1 τ inst1 )] 2 s 2 (t) = exp[j(2π(f f LO2 )t + 2πfτ 2πf IM2 τ inst2 )] 1 2 φ(t) = 2π(f LO1 f LO2 )t + 2πfτ + 2πf IM1 τ inst1 2πf IM2 τ inst2 φ(t) = 2π f LO + 2πf τ + φ IM 2 2 f LO = φ(t)/2π = /2π = Hz Hz 10 Hz 2 σ τ = f LO t int /f BW 0.02 s 10 MHz 6 ns 1 s 10 MHz 0.1 ns f LO < 1 mhz 0.1 mhz 2 2 f1 f3 f1 f2 5 f1-f3 f1-f2 5 f1 f3 2 f1 f3 5 f1-f2/f1-f3 f1 f2 f1 f (a) f f1 f3 2 f1 f3 6(b)

7 f1+f3 f2 6(c) 0.73 s 100 6(d) f1 f3 f2 7(a) f1 f2 f1 f3 7(b) 2 7(a) (b) 15 min 400 ps 7ps 7ps f2 4 f21( )

8 f22( ) f23( ) f24( ) 4 8 f2 8(a) f2 ns ns 3 f21 f22 f23 4 f24 f2 f2 f2 3 f21 f2 f1 8(b) 8(b) 7(a) 7(b)

9 RMS f22-f (a) 9 f2 (a) (b) (c) (d) (e) (f) (b) 9 4 GHz ps ps

10 VLBI mhz 1 ps 100 m CEI 100 m 10 km 1 m 10 km 10 m

11 m 1 2 m 10 m [1]., 2003, 4: 20 [2] Edwards C D. Short Baseline Phase Delay Interferometry, TDA Progress Report 42-91, 1987 [3] Edwards C D. The effect of spatial and temporal wet-troposphere fluctuations on connected element interferometry, TDA Progress Report 42-97, 1989 [4] Thurman S W. Galileo earth approach navigation using connected-element interferometer phase-delay tracking, TDA Progress Report , 1990 [5] Thurman S W, Badilla G. Using connected-element interferometer phase-delay data for Magellan navigation in Venus orbit, TDA Progress Report , 1990 [6],,., 2009, 30(3): 967 [7] Sovers, O. J., Fanselow, J. L., and Jacobs C. S. Reviews of Modern Physics, 1998, 70(4): 1393 [8] Liu Q, Kikuchi F, Goossens S et al. J Geod Soc Jpn, 2009, 55: 243 The Wide Band Signal Process and Analysis of the Collocation Geostationary Satellite in Connected-element Interferometry System CHEN Ming 1,2,3, LIU Qing-hui 1, TANG Ge-shi 2,3, CHEN Lue 2,3, LI Li 2,3, SHAO Hua 2, ZHAO Rongbin 1, DAI Zhiqiang 1 (1. Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai ; 2. Beijing aerospace control center Bejing ; 3. National Key Laboratory of Science and Technology on Aerospace Flight Dynamics, Beijing ) Abstract: The orbit resource of the geostationary satellite is becoming scarce with the increase of the human s space activity. The technology of multi-satellite sharing one orbit area is used. In the collocation satellites observation, the safety among the satellites is one of the most important problems that need to be solved. Three-way ranging measurement is always used. But it needs a long period of observation in order to get an accurate orbit. The differential phase delay can be obtained with high accuracy in connected-element interferometry. This kind of observable can give strong constraints in the plane-of-sky. One connected-element system is constructed and the data processing method is shown. The key technology of the data processing and the instrument are also described. Key words: Connected-element interferometry; collocation geostationary satellites; samebeam interferometry; differential phase delay

1 VLBI VLBI 2 32 MHz 2 Gbps X J VLBI [3] CDAS IVS [4,5] CDAS MHz, 16 MHz, 8 MHz, 4 MHz, 2 MHz [6] CDAS VLBI CDAS 2 CDAS CDAS 5 2

1 VLBI VLBI 2 32 MHz 2 Gbps X J VLBI [3] CDAS IVS [4,5] CDAS MHz, 16 MHz, 8 MHz, 4 MHz, 2 MHz [6] CDAS VLBI CDAS 2 CDAS CDAS 5 2 32 1 Vol. 32, No. 1 2014 2 PROGRESS IN ASTRONOMY Feb., 2014 doi: 10.3969/j.issn.1000-8349.2014.01.07 VLBI 1,2 1,2 (1. 200030 2. 200030) VLBI (Digital Baseband Convertor DBBC) CDAS (Chinese VLBI Data Acquisition