Content of Presentation
Small Satellite Situation
Other Tracking & Communication Networks
Proposed Solution
Tracking by Pseudoranging
DGSN Architecture
DGSN Ground Station
DGSN Infrastructure
Direct Applications

Perspectives & Conclusions
27. Sept. 2013, IAC-13,B4,3,11,x17101


2

Small Satellite Situation

Financial and planning challenges
• Orbit
• Piggy-back launch
• Uncertainty in provided orbit
• Infrastructure
• few ground stations
• Exisiting stations sometimes „too good“ for
small satellites
• Minimum access time to satellite
• Frequency allocation
• Ham-radio operators
27. Sept. 2013, IAC-13,B4,3,11,x17101


DGSN as mandatory
secondary payload
onboard VERDE sat
(IRS, Uni Stuttgart)

3

Other Tracking & Communication Networks

• Tracking Services
• NORAD by US and RC Air Force
• DORIS by CNES
• Communication Services
• Deep Space Network
• ESTRACK
• Communication Infrastructure
• Mission specific
• GENSO

27. Sept. 2013, IAC-13,B4,3,11,x17101

Regular updates of public
two-line element set data-base
Regular updates of public
two-line element set data-bases
Own ground stations or
collaborative and time shared
stations


4

Proposed Solution

a) Time synchronization
of GS with global
GNSS time source

d) Global Data-Dump
communication
method

b) Correlation of
beacon signal with
reception time at GS. Using
correlated data for tracking.

c) Targeting of satellite
on tracked orbit using
corrected orbit
elements

27. Sept. 2013, IAC-13,B4,3,11,x17101


5

Solving „Apollonius Problem“
by Apollonius of Perga (262 BC – 190 BC)

27. Sept. 2013, IAC-13,B4,3,11,x17101

„reverse GPS“
• One beacon signal transmission
• Reception at 4 (or more) ground stations
• Correlation of the beacon signal event with
reception time at each ground station


6

Simulation Modes
0. combinatorical
1. overdetermined

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7


Pointing accuracy over ground stations

10000000
1000000

Simulation Modes
0. combinatorical
1. overdetermined

Accuracy of positioning depends on
• Number of ground stations
• Relative position of ground stations
to satellite

positioning dR [m]

100000

200 km orbit

10000

810 km orbit
1000
100
10
1

Accuracy
2m (200 km orbit, 100 x 100 km GS array)
27. Sept. 2013, IAC-13,B4,3,11,x17101

8

9

10

11

12

13

14

15

ground stations [-]
810km-mod0

810km-mod1


200km-mod0

200km-mod1

8

DGSN Architecture
DGSN
• Users serve as
„listening nodes“
• Users can be
everyone, not only
ham-operators
• Less complex
• More active users
• Real citizen science
and outreach
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9

DGSN Ground Station

16.0

GS Density
• Global coverage of
satellite in 600 km orbit
• 2.4 GHz @ 2 kbit/s

12.0

2.4GHz@0.5kbit/s
1.2GHz@0.5kbit/s

8.0

system margin [dB]

Regulations
• Amateur radio frequencies
• Reception only! (phase 1)

0.4GHz@0.5kbit/s

2.4GHz@1kbit/s
4.0

1.2GHz@1kbit/s
0.4GHz@1kbit/s
2.4GHz@2kbit/s

0.0

0

20

40

60

27. Sept. 2013, IAC-13,B4,3,11,x17101

1.2GHz@2kbit/s
0.4GHz@2kbit/s

-4.0

365 stations
worldwide

80

𝑃𝑟 = 𝑃 𝑡 𝐿 𝑑 𝐿 𝑙 𝐺 𝑡 𝐿 𝑎 𝐺 𝑟
-8.0

𝜆
4 𝜋𝑆

2

elevation angle [°]


10

DGSN Ground Station
Hardware
• Small devices
• Attachable to personal computers
• Modularity for extensions
• Open-source

27. Sept. 2013, IAC-13,B4,3,11,x17101


11

DGSN Infrastructure
Constellation
• Citizen science project since 2010
• Distributed computing (BOINC)
• Solving numerical aerospace
problems
• Virtual super-computer via the
Internet

Adding ground station devices
• Global sensor grid
• Reliable and safe system
• Sensor AND processing capabilities

Users
Constellation

Countries

TeraFlops

7848

108

3.957

(aerospaceresearch.net/constellation)
27. Sept. 2013, IAC-13,B4,3,11,x17101


12

Direct Applications
• Ground
• Fox hunt
• Air
• Quadrocopter, ADS-B
• High altitude
• Weather Balloons
• DLR/ESA REXUS/BEXUS (Team Frede)
• Space
• Small satellites (FlyingLaptop, IRS)
• Cubesats (ArduSat)

ESRANGE, Sweden
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13

Perspectives & Conclusions
Target Group
• nano and small satellites by universities
• satellite constellations and swarms
(QB50 & GENSO)

•
•
•
•
•

re-entry vessels (MIRKA 2)
high altitude experiments (REXUS/BEXUS)
balloons (weather ballons, BEXUS)
planes and drones (ADS-B, Stuttgarter Adler)
sensoring platform

Open Access
• Open for everyone
• Open tracking data-base
• Optional open payload data
• Faster, cost efficient provision of
data to small projects
• Open source

(thunder-, flash-,nuclear detonation detection)

• GNSS quality measuring (WAAS, EGNOS)
• Safety of life (avalanche)

27. Sept. 2013, IAC-13,B4,3,11,x17101


Creative ways to
extend the concept
beyond satellites!
14

Last Slide

Thank you for your attention!
Questions?
Join the Distributed Ground Station Network!
www.aerospaceresearch.net/dgsn
This work is licensed under a Creative Commons
Attribution-NonCommercial-ShareAlike 3.0 License.
27. Sept. 2013, IAC-13,B4,3,11,x17101


15

APPENDIX
Clustering: results and method

27. Sept. 2013, IAC-13,B4,3,11,x17101


16

Distributed Ground Station Network @ IAC-13

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