Naval Research Laboratory 22 June 1960

SIGINT: The Mission CubeSats are Made For A Small Country’s Perspective

32nd Annual AIAA/USU Conference on Small Satellites 1 ISIS - Innovative Solutions In Space Vertically Integrated Company

SATELLITE CUBESAT LAUNCH SERVICES R&D SERVICES SOLUTIONS PRODUCTS

2 SIGINT – ELINT – Spectrum Monitoring

SIGINT

SpectrumCOMINT Monitoring ELINT

FISINT/TELINT TECHNICAL OPERATIONAL • Discover new systems • Location • Details about emissions • Schedule • Performance estimation • Movement • ECM development • Warning

3 Spectrum Monitoring Causes of Interference

Source: Eutelsat briefing to the ITU (2013)

4 Miniturization

5 ELINT: Single-Satellite Solution Lotos-S/Pion-NKS

8 - 12 m

Images courtesy of RussianSpaceWeb

6 ELINT: Direction Finding Direction of Arrival/Angle of Arrival

7 Fundamental Limits Why the Shrink-Ray Won’t Work Size has effect on direction finding accuracy because of: • Antenna gain (i.e. SNR) • Number of array elements that can be placed • Array element spacing

A 6U-face of CubeSat offers very limited real estate

Images courtesy of NASA

8 BRIK-II Royal Netherlannds Air Force

9 ELINT: Multi-Satellite Solution Naval Ocean Surveillance System

Picture by John C. Murphy

10 Capacité de Renseignement Electromagnétique Spatiale (CERES)

781 M€

Essaim 216 M€ 2004 Elisa 115 M€ 2007 2009 2011 CERES 450 M€ 2013 2015 2020

Images courtesy of CNES

11 Miniturization through Distribution Opening Up The Trade Space

Number of satellites in orbit

Image courtesy of the Science and Technology Policy Institute

12 Radio Astronomy An Intransparent Affair

13 Orbiting Low Frequency Antennas for Radio Astronomy

< 100 km

> 50 satellites

= 0.006° (30 MHz)

𝑑𝑑𝜃𝜃 14 Maturing CubeSats for ELINT/Spectrum Monitoring & Astronomy Development Areas

Station-Keeping ISL & Synchronization

2-100 Satellites

Relative Position Knowledge From A. Budianu et al. (2011) Reliability

15 In Progress…

16 Summary

• Fundamental limits to miniturization of single satellite ELINT solutions can be overcome by distributed architectures

• Fundamental limits to ground-based radio astronomy due to frequencies of interest can also be overcome by distributed space-based architectures

• Similiarity in mission characteristics of ELINT, Spectrum Monitoring and Radio Astronomy points towards alignment of CubeSat development efforts

• Development in the fields of CubeSat reliability, station-keeping, ISL & synchronization and none-GNSS based position determination still required [email protected] www.isispace.nl | www.isilaunch.com | www.cubesatshop.com

17 A Familiar Trade

Source: Electronic Warfare and Radar Systems Engineering Handbook Naval Air Warfare Center Weapons Division

18 19 TDOA Geometry versus Accuracy

20 Direction Finding (DOA)

Angular Error Angular Error

DOA-vector DOA-vector

nadir nadir Geolocation: Geolocation Given known position Error Geolocation intersection between Error DOA-vector and Earth surface:

Hence for the same Same Angular Error angular accuracy the geolocation error grows Larger Geolocation Error with distance from receiver

21 Tselina-D

Image: Ralf Vandebergh

22 Direction Finding (DOA)

Angular Error

DOA-vector EORSAT (RU) Elevation (ε) Tselnia (RU) Accuracy: 2 km nadir Altitude: 410 km Altitude: 650 km Geolocation ε = 90° Accuracy: ε = 5° ε = 30° Error (nadir) • 9 km – 46 km Angular 0.027° 0.076° 0.279° 8 – 230 km Geolocation: Error • Given known position intersection • 10 km between DOA-vector and Earth ε = 90° ε = 5° ε = 30° surface: (nadir) Angular Error (8 km) 0.196° 0.705° Hence for the same angular Angular Error (220 km) 0.330° accuracy the geolocation error Angular Error (10 km) 0.020° 0.247° 0.881° grows with distance from receiver If 0.705° at nadir is accurate, this would give an εmin of 9° for 220 km

23 Result

Angular Error Smallest Mode Largest Angular Error 0.03° 0.1° - 0.3° 0.881° DOA-vector Elevation (ε) Typical direction finding accuracy nadir (DOA) from literature Geolocation (research funded by USAF, USN, DOD): Error 1° - 0.1°

24 DOA versus SNR

𝐴𝐴 𝐺𝐺 ≅ 4𝜋𝜋 2 𝜂𝜂 = 𝜆𝜆 𝑃𝑃𝑡𝑡𝐺𝐺𝑡𝑡 𝑟𝑟 =𝑟𝑟 2 𝑃𝑃𝑡𝑡𝐺𝐺𝑡𝑡 𝑃𝑃 𝐴𝐴 𝜂𝜂 4𝜋𝜋𝑅𝑅 2 𝑃𝑃𝑟𝑟 � ⇒ 𝑆𝑆𝑆𝑆𝑆𝑆 ∝ 𝐴𝐴𝑟𝑟𝜂𝜂 4𝜋𝜋𝑅𝑅 𝑆𝑆𝑆𝑆𝑆𝑆 �𝑃𝑃𝑛𝑛𝑛𝑛𝑛𝑛𝑛𝑛𝑛𝑛

Higher SNR: + • beam width of DOA + estimation spectrum � 𝑆𝑆𝑆𝑆𝑆𝑆 becomes narrow • of the signal becomes clearer • accuracy of MUSIC algorithm is increased

25 DOA versus Number of Array Elements

Increasing the number of + array elements: + • beam width of DOA � 𝑁𝑁𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒 estimation spectrum becomes narrow • directivity of the array improves

26 DOA versus Array Element Spacing

Increasing array element spacing : • beam width of DOA estimation spectrum −⁄− 𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆 becomes narrow • resolution of MUSIC algorithm improves Provided the spacing < half the wavelength

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