JAMMING IMPACT ON A BITCOIN SATELLITE RECEIVER

by ANDREAS GERALD SLOVACEK B.S., University of California Davis, 2012 B.S., California State University East Bay, 2016

A thesis submitted to the Graduate Faculty of the University of Colorado Colorado Springs in partial fulfillment of the requirements for the degree of Master of Science Department of Computer Science 2020 COPYRIGHT c 2020 ANDREAS GERALD SLOVACEK ALL RIGHTS RESERVED This thesis for the Master of Science degree by Andreas Gerald Slovacek has been approved for the Department of Computer Science by

Sang-Yoon Chang, Chair C. Edward Chow Yanyan Zhuang

Date: 28 May 2020

ii Slovacek, Andreas Gerald (M.S., Computer Science) Jamming Impact on a Bitcoin Satellite Receiver Thesis directed by Assistant Professor Sang-Yoon Chang

Abstract

Satellite communication remains an important technology for networking. In 2004 over 80% of U.S. military satellite communications travelled over commercial satellites. More recently we have seen a rise in galactic enterprise new entrants, such as Blue Origin and SpaceX. These companies provide launch vehicles and are increasingly focused on high-speed data delivery from satellite constellations. This illustrates that with relatively cheap hardware and open source software a terres- trial satellite receiver can be used to participate in the Bitcoin blockchain, or be rendered useless with jamming. This work highlights how to setup a satellite receiver for Block- stream’s broadcasts, and the exact level of signal degradation an adversary can achieve depending on position relative to the receiver.

iii Dedication

To my parents and family: no matter what my goal encouraging me to pursue it with passion. Thank you for making me the person I am today through your examples of hard work, optimism, and reverence for education. I followed your advice and found what I love. It no longer feels like work.

To my wife Meghan for sharing her life and our small apartment with me and piles of coaxial cable, circuit boards, and satellite receiver equipment. Meghan you have been unwavering in your support of my pursuits, no matter how out of this world they seemed. Your support has lead me to a promising and exciting future. I appreciate everything you do for us.

iv Acknowledgements

Thank you to my advisor Dr. Sang-Yoon Chang of the College of Engineering and Applied Science at the University of Colorado Colorado Springs. He invested much time and effort coaching me on my research journey. Your methods and example led me to my next plateau in academia. Thank you.

My special thanks to Dr. Yanyan Zhuang. She gave me the opportunity to learn from her only requiring work ethic and a curious mind. Thank you so much for providing funding and guidance as I found my way at University of Colorado Colorado Springs.

Thank you to Dr. Edward Chow and the faculty at University of Colorado Colorado Springs College of Engineering and Applied Science. There are so many people who spurred my interest in radio telecommunications.

Thank you to the Networking Security Lab and Secure Software Systems group. Your feedback pushed my work beyond what I could have hoped for.

Lastly, thank you to Igor Freire at Blockstream. Your kindness in answering my questions and the quality of your responses are so appreciated.

v Contents

1 Introduction 1 1.1 SatelliteCommunication ...... 1 1.2 Blockstream...... 3 1.3 SoftwareDefinedRadio...... 6

2 Related Work 8 2.1 SatelliteCommunication ...... 8 2.2 Blockstream...... 9 2.3 SoftwareDefinedRadio...... 10

3 Methodology 11 3.1 BlockstreamSatelliteReceiver ...... 11 3.1.1 EnvironmentalConsiderations ...... 12 3.2 Jamming with Signal-to-Noise Ratio and Signal-to-Interference-Noise Ratio 12 3.2.1 EnvironmentalConsiderations ...... 14

4 Implementation 15 4.1 BlockstreamSatelliteReceiver ...... 15 4.1.1 EnvironmentalConsiderations ...... 16 4.1.2 Challenges...... 17 4.2 Jamming with Signal-to-Noise Ratio and Signal-to-Interference-Noise Ratio 18 vi 4.2.1 HardwareConfiguration ...... 18 4.2.2 EnvironmentalConsiderations ...... 19 4.2.3 Challenges...... 20 4.2.4 ExperimentSetup...... 21 4.2.5 Experiment ...... 23

5 Results 25 5.1 BlockstreamSatelliteReceiver ...... 25 5.2 BitcoinFeasibility...... 26 5.3 Jamming with Signal-to-Noise Ratio and Signal-to-Interference-Noise Ratio 28

6 Summary of Contributions 35 6.1 BlockstreamSatelliteReceiver ...... 35 6.2 Jamming with Signal-to-Noise Ratio and Signal-to-Interference-Noise Ratio 35

7 Future Work 37 7.1 BlockstreamSatelliteReceiver ...... 37 7.2 Jamming with Signal-to-Noise Ratio and Signal-to-Interference-Noise Ratio 37 7.3 Simulation of Jamming with Mobility Modeling ...... 38

8 Conclusion 40

References 41

Appendices 45

A Gnu Radio Companion Jamming Flow 46

B GnuRadioCompanionBlockstreamReceiverFlow 47

C Summary of Jamming Samples 49

vii D Signal Measures Charts 51 D.1 ReceivedSignals ...... 51 D.2 Interference ...... 54

viii List of Tables

4.1 ExampleofRecordedExperimentData ...... 23

5.1 BitcoinLedgerGrowthPriorFourMonths ...... 27

C.1 Azimuth0...... 49 C.2 Azimuth30 ...... 49 C.3 Azimuth60 ...... 49 C.4 Azimuth90 ...... 50 C.5 Azimuth180...... 50

ix List of Figures

1.1 MyBlockstreamSatelliteReceiver...... 2 1.2 ReceiverAlignment...... 3 1.3 BlockstreamSatellites ...... 3 1.4 BlockstreamSatelliteCoverage ...... 4 1.5 Satellite Communication. Graphic by United States Government Account- abilityOffice[7]...... 5 1.6 MyNooelecandRTLSDRs ...... 6

3.1 Jamming Downlink.Graphic by United States Government Accountability Office[7]...... 13

4.1 BlocksatGUIScreenshot...... 16 4.2 MixerCircuitCalculation ...... 18 4.3 MyJammerConfiguration ...... 19 4.4 AzimuthsrelativetomyBSRLNB ...... 21 4.5 AnglesrelativetomyBSRLNB...... 22 4.6 RadiiofmeasuresrelativetoBSR ...... 23

5.1 BlocksatCLIScreenshot ...... 25 5.2 blocksat-rx-guiSpectrogram ...... 26 5.3 ReceivedSignalsallAzimuths ...... 29

x 5.4 InterferenceallAzimuths...... 30 5.5 Near- and Far-Field Regions. Graphic by Goran M. Djuknic [21]. .... 31 5.6 MeasuresintheFarField-15Feet ...... 32 5.7 MeasuresintheFarField-18Feet ...... 33 5.8 JammerFacingLNB ...... 33

D.1 SNRandSINRAzimuth0 ...... 51 D.2 SNRandSINRAzimuth30 ...... 52 D.3 SNRandSINRAzimuth60 ...... 52 D.4 SNRandSINRAzimuth90 ...... 53 D.5 SNRandSINRAzimuth180...... 53 D.6 InterferenceAzimuth0 ...... 54 D.7 InterferenceAzimuth30 ...... 55 D.8 InterferenceAzimuth60 ...... 55 D.9 InterferenceAzimuth90 ...... 56 D.10InterferenceAzimuth180...... 56

xi CHAPTER 1

Introduction

1.1 Satellite Communication

Satellite communications are all around us [37]. From in-flight wifi to intercontinental packet hops, satellite communication augments the internet. Even in America, birthplace of the internet, satellites provide the only internet access to 6% of the population [38]. Blue Origin, Facebook, and SpaceX are all completing to put low earth orbit (LEO) constellations up to augment the service provided by medium earth orbit (MEO) and geosynchronous/geostationary earth orbit (GEO) satellites [24]. With GEO orbit being approximately 22,000 miles away, and LEO orbit being just 370 miles away the round trip time of a packet will be drastically decreased. From a fixed point on earth’s surface a GEO satellite never appears to move, the problem becomes drastically more difficult when trying to link to a LEO, which may be overhead for only five minutes [22].

1 Figure 1.1: My Blockstream Satellite Receiver

The satellite receiver in figure-1.1 is constructred from commercial-off-the-shelf (COTS) parts. This receiver is designed to capture a signal from GEO satellite Galaxy 18, a Space Systems Loral model 1300. In order to receive the signal you must know your latitude and longitude, to determine where Galaxy 18, or any GEO lies. An illustration of this is shown in figure-1.2. Calculate your azimuth (degrees from North) to the satellite. Then you must calculate the elevation (rise from the horizon, E in the figure) to the satellite. There are 13 SSL 1300s in orbit today, each with Space Micro transponders capable of being read by this type of receiver [4]. Receivers like the one in figure-1.1 are capable of catching almost any GEO satellite transmission. Many of them are operating on the Ku-band, 12GHz-18GHz. This band is used for broadcasting satellite service (BSS), which are signals meant to be received by the public from satellites, according to the 2 International Telecommunication Union’s Radio Regulations. The specific signal received from Galaxy 18 is 12.01692GHz, outside the range of a standard coaxial cable. Therefore the device in figure-1.1 highlighted in yellow, a low-noise block downconverter (LNB), downcoverts the incoming signal by a predetermined value. This LNB downconverts by 10.75GHz, resulting in a 1.2269GHz signal which is transmitted over the coaxial cable for processing. Figure 1.2: Receiver Alignment

1.2 Blockstream

Blockstream is a private company developing functionality beyond Bitcoin (BTC) core’s capabilities. My area of primary interest is in Blockstream Satellite- a branch of the company propagating blocks via satellite. Blockstream purchases bandwidth on five satellites [18] whose details can be found in figure-1.3.

Figure 1.3: Blockstream Satellites

BTC is a blockchain based currency whose only requirement for participation is an internet connection. Blocks store user transactions, and are propagated through the 3 network allowing all users to know the state of the ledger. BTC aims to make a currency that is decentralized and available for all. However only 59% of the world has access to the traditional internet [19], making availability for all an impossibility. Through the use of GEO satellites Blockstream makes BTC available to 99.999% of the world’s population [18]. The coverage map can be seen in figure-1.4, turquoise represents coverage. Blockstream offer an opensource channel to send remittances, and other data through Blockstream Satellite’s upload feature. Official remittances to sub-Saharan Africa in 2019 topped USD$46 billion, exceeding the amount of capital invested by foreigners, USD$32 billion [12]. The motivation for using Bitcoin in Africa is clear: no currency conversion fees, to wire transfer fees, no need for the traditional internet. This is just Africa. Blockstream covers Asia’s population centers and rural regions as well. Access to a global currency allows people in remote regions to more easily interact with the global market.

Figure 1.4: Blockstream Satellite Coverage

4 The process of distributing BTC via satellite is shown in figure-1.51. Blockstream submits the “original signal” to a ground station, to become 1 transmitted signal to Galaxy 18. 2 GEO Satellite, or Galaxy-18 in this case, then converts the frequency of the received signal, and transmits it on a designated frequency. 3 ground stations within the satellite’s coverage area can receive the signal, so long as they have followed the tuning procedure described by the satellite data provider.

Figure 1.5: Satellite Communication. Graphic by United States Government Account- ability Office [7].

1Accessed February 18, 2020

5 1.3 Software Defined Radio

In order to connect to Blockstream’s satellite broadcasts you need a Blockstream Satellite receiver (BSR) and opensource software. The output from the BSR is fed into a software-defined radio (SDR) for processing. An SDR replaces hardware functions that would be found in traditional radios, such as: filter, mixer, amplifier, oscillator, and source. But why move these functions to software? One reason is portability. With open source software like GNU Radio Companion (GRC), or Scikit-DSP-Comm, one can develop a software program that emulates those functions. In the case of Blockstream, a user needs to download GRC, and then install the gr-blocksat module from Github [28]. The gr-blocksat module synchronizes the incoming Figure 1.6: My Nooelec and RTL SDRs transmission with an expected encoding. gr-blocksat then deframes, demodulates, and decodes the signal. Due to the nature of satellite transmission the signal will be spread across a wide radio frequency (RF) spectrum to mitigate the effects of noise in transit. This process is known as frequency hopping spread spectrum (FHSS). To be more precise, FHSS spreads a transmission over many channels to avoid noise on any one channel. A $20 SDR is all that is needed to receive the satellite transmission. In figure-1.6 the RTL-SDR dongle (top) is capable of receiving transmission from 500kHz up to 1.75GHz, and the Nooelec dongle (bottom) is capable of receiving transmission from

6 25MHz up to 1.7GHz. It is important to note that 10 years ago the cheapest software defined radios on the market were produced by Ettus Research, and were approximately $5,000 for a basic receiver/transmitter. Today a basic transmitter/receiver costs $300 [9]. This has opened the field of radio research to anyone with a light background in digital communications and open source software.

7 CHAPTER 2

Related Work

Satellite data delivery is a well studied topic. Satellite communication is the reason humans put satellites in space. Replacing old, and launching new, satellites has not slowed globally, despite budget cuts to space in the US [37]. After achieving satellite communication, denying an adversary came next. These were costly exercises, but with the advent of software defined radio and miniaturization, launching satellites and researching Confidentiality, Integrity, Availability in space are available to anyone. With a budget of a few hundred dollars a receiver is an easy project, launching a LEO satellite is feasible for around USD$1M [10].

2.1 Satellite Communication

China’s increasing connectivity has inevitably them to pursue galactic ambitions [23]. Gao et al. propose a hybrid satellite constellation of GEOs and LEOs to service China’s internet needs, as well as an analysis of challenges and practicality. Some satellite communication systems, such as GPS, show resistance to noise and jamming [26]. Hu et al. showed that the C/A signal, which is broadcast by all satellites due to its legacy status [11], exhibit favorable anti-jamming properties.

8 Satellite communication relies on FHSS for to overcome noise, both intentional and unintentional. Decreased SDR costs make them a common development platform, however FHSS requires tuning techniques that stretch the capabilities of SDRs [27]. Ibrahim et al. demonstrate a novel frequency hopping algorithm to decrease tuning time and increase hops-per-second. As of 2006 the US military relied on commercial satellites for 84% of its satellite communication [35]. Though dated, it is important to keep in mind that in 2006 the US had been at war in Afghanistan and Iraq for years and had the largest defense budget in the world. This is to emphasize the necessity of satellite communications, and the difficulty of building infrastructure. Mr Rausch discusses the impacts of interference, intentional and unintentional, on US military operations.

2.2 Blockstream

Blockstream has enabled access to BTC for over 99.99% of earth’s population. Blockstream’s engineering department published an article [8] and a Github repo [28] instructing users on how to connect to their satellites transmissions. These guides are useful in tuning to any GEO satellite transmission. Blockstream continues development in an alternate blockchain [14], based on BTC, but with added functionality. Nexus Earth [17] is another blockchain enabled company aiming to send its cryptocurrency, NXS, to the stars. NXS requires mining, similar to BTC, for new coins to be found. Rewards are also given for holding NXS. NXS uses a variety of methods to ensure security post-quantum computing: FALCON for cryptographic signature and Argon2 for hashing. NXS will be distributed over the traditional internet, but also via a constellation LEO satellites [13].

9 2.3 Software Defined Radio

SDR [31] opens up satellite transceiver development with rapid prototyping, re-configurability, portability, and lower cost hardware. Maheshwarappa et al. propose an architecture using COTS hardware capable of increasing bandwidth and data rates between satellites. Using directional jamming against Ku-band receivers is feasible [25]. Hofmman and Knopp explored how a USRP and horn antenna can interfere with earth stations, due to reflection and refraction, with greater impact than previously demonstrated. With evermore personal UAVs in the skies it is imperative that a capability to stop them be developed [33]. P¨arlin et al. discuss the impacts of skies flooded with UAVs, their resistance to jamming due to FHSS, and a comparison of jamming systems implemented on SDRs to neutralize UAVs.

10 CHAPTER 3

Methodology

3.1 Blockstream Satellite Receiver

Building the BSR happened in three phases:

1. Build the physical receiver

2. Build the software receiver

3. Acquire the signal

The list of parts is purchasable for USD$150 [8]. The guide also provides instructions to users on choosing a suitable location. Modifications to the list are necessary. The suggested dish is inadequate, therefore choose a 36 inch, or greater, dish from another another provider. You will need a digital or mechanical level, and angle measurement device to determine the elevation of the dish. Lastly, a device to indicate True North will help determine your azimuth. The software receiver can be built on CentOS 7, Fedora 28, or Ubuntu 18. Being familiar with all three I started alphabetically. The copr enable command used during the binary installation on both CentOS 7 and Fedora 28 did not work. Compiling from 11 source for Centos7 and Fedora 28 failed because the gr-blocksat portion depends on a python module called protocol sink which couldn’t be found. The Ubuntu binary installation worked without issue.

3.1.1 Environmental Considerations

Setting up the BSR requires an environment with low radio frequency interference and an “open” line-of-sight to the horizon. Radio frequency interference can be caused by a number of factors [16]. Reflection off of man-made materials, such as concrete or metal, to natural materials, such as water, can alter a signal and distort results. Refraction can be caused by water vapor. Minimizing water vapor is infeasible since communication with Galaxy 18 happens over 22, 000 miles, and the receiver must be outdoors. I attempt to control man-made interference by experimenting in an area as far from buildings as possible; however the equipment requires power and thus I must be at least somewhat near a building/power outlet. Line-of-sight to the horizon should be unobstructed by trees or buildings because these could reflect, refract or diffract the signal.

3.2 Jamming with Signal-to-Noise Ratio and Signal-

to-Interference-Noise Ratio

To complete this task there are two phases: signal generation, and signal measures. Generating an interference signal will allow me to control the amount of noise experienced at the BSR/earth station figure-3.11. Measuring the signal will allow me to perform an analysis on path-loss between the jammer and BSR. Coming from a computer science background I am aware of the concept of jamming.

1Accessed February 18, 2020

12 Isn’t it just a DDoS at layer 1? Generating the appropriate signal was not straight forward. As a starting point I used techniques from my previous research: GQRX to zero in on the frequency my car key fob uses, 315.575MHz in particular with approximately a 20kHz bandwidth. Using GRC I generated a 315.575MHz with a 20kHz bandwidth and effectively jammed my keyfob. The interesting observation then was that when the interference antenna between my fob and car jammed the signal 100% of the time, whereas if the fob were between the car and my antenna I could only jam the fob sporadically.

Figure 3.1: Jamming Downlink.Graphic by United States Government Accountability Office [7].

This experience taught me to generate a signal with broad bandwidth. Generate multi-channel signal is no different, I simply widened the bandwidth, for the purpose of interfering with an FHSS signal. Additionally, when using an omnidirectional antenna for a jammer there is an angle relative to the receiver at which the jammer is most efficient. So how do we quantitatively measure the jamming signal at the receiver? Signal-to-noise ratio (SNR), equation-3.1, provides a baseline for background noise at

13 the receiver location relative to the signal power.

Signal SNR = (3.1) Noise

Signal-to-interference-noise ratio (SINR), equation-3.2, is similar to SNR, however interference, intentional or otherwise, is factored in.

Signal SINR = (3.2) Interference + Noise

Using the formulas for SNR and SINR the interference can be computed by using the initial SNR, turning on the interference source, and taking another SNR reading. Having the background noise, tune the BSR to Blockstream’s signal on Galaxy 18. Once I have Frame Timing => LOCKED and Timing Indicator: GOOD information is being received. With the noise N and an SNR value solve for S, the signal. These values will later let us derive interference I. It is worth noting that I do not control the transmitter. Intelsat owns Galaxy 18, and Blockstream leases time. Those two entities have control over the transmitted signal.

3.2.1 Environmental Considerations

The jammer is constrained by placement of the BSR due to their necessary proximity. In addition to the constraints from the BSR I consider signal leakage. Since I am transmitting a jamming signal it is necessary to ensure that no jamming signal will propagate outside of my test property. The house I tested at has a steel chain-link fence surrounding it, which acts as a reflective material and thus dampens signal leakage.

14 CHAPTER 4

Implementation

4.1 Blockstream Satellite Receiver

To assemble to physical receiver follow the instructions in [28]. This step should be straightforward. Note that connecting the “Power to SWM” to an SDR will almost certainly damage the SDR. For the SDR component of the BSR I tested a HackRF One and a Nooelec dongle. The Nooelec dongle is less cumbersome, and freed the HackRF One for jamming, so it was chosen for the SDR receiver. As previously mentioned- Ubuntu proved to be the easiest platform to run the receiver on. It was run on the 2014 Lenovo X1 Carbon mentioned in chapter-3. The blocksat-rx application is not resource intensive, so the computer did not act as a constraint.

15 Figure 4.1: Blocksat GUI Screenshot

After the physical receiver was built and tuned, and software is built, the command blocksat-rx-gui -f 1266920000 runs Blockstream’s GNU Radio Companion module tuned to Galaxy 18’s frequency. The flow in GNU Radio Companion can be found in Appendix B. Figure-4.1 shows a strong signal centered approximately −150kHz below 1.26692GHz. The waveform can be viewed in a simpler GRC extension, GQRX [20] as well. Documentation for blocksat-rx-gui indicates that the x-axis of this plot is in kilohertz, which means the signal is centered at approximately 1, 266, 770, 000Hz. blocksat-rx is the tool I used to verify that data was being received. It provides information on SNR, frame synchronization status, and data rate. This output was parsed to acquire SNR, and thus derive SINR and interference.

4.1.1 Environmental Considerations

Falcon, Colorado offers an area with a relatively low population density, 147 per square mile. Additionally, the neighborhood in which I tested has houses on, approximately, one acre plots. With a low population density, and well spaced houses I was able to

16 obtain unobstructed line-of-sight to the horizon.

4.1.2 Challenges

According to [8] and [28] building a satellite receiver targeting the Blockstream signal is almost as easy as putting eight pieces of hardware together, installing some open-source tools, and hitting Enter. After four weeks with the hardware and software no connection was established. According to Issue 32 in [28] the receiver software may not always work due to poor patching. The hardware defined in [28] is, on its own, insufficient to connect to Galaxy 18. After testing the recommended 18 inch dish a 24 inch dish was tested, it couldn’t synchronize frames, however the signal was visible on a spectrogram. I used a dish twice the recommended size, 36 inches. The increased dish size helped acquire the signal. With a 36 inch dish digital and analog satellite signal finders [3] [5] were also necessary. The analog device squeals as signal strength increases, thereby allowing manual tuning of the dish without checking a screen. The digital tuner was used to watch free-to-air (FTA) television broadcasts from Galaxy 18. Viewing the FTA broadcast indicated that I was aligned on Galaxy 18 to the point of having a decodable signal. Satellite dish mounts (tripod or otherwise) often have an elevation indicator. It is na¨ıve to assume that these will work, as I did. Additional pieces of surveyors hardware such as: plumb line and protractor, compass, and level are necessary to approximately find your GEO’s signal. Nowhere is it noted that you are searching for True North, which is different than Magnetic North [29] . In Colorado Springs True North differs from Magnetic North by about 7◦. This translates into a roughly 2, 000 mile miss when orienting from Magnetic North toward Galaxy 18 in Colorado Springs.

17 4.2 Jamming with Signal-to-Noise Ratio and Signal-

to-Interference-Noise Ratio

4.2.1 Hardware Configuration

To generate interference the HackRF One and Ettus USRP B210 were tested. The USRP B210 drivers had issues on both a 2019 MacBook Pro 15-inch running macOS Mojave v10.14.6; and 2014 Lenovo X1 Carbon with 4Gb of RAM, and a 2014 Intel i5 processor running Ubuntu 18.04. The HackRF worked as an interference signal with both laptops and was chosen as the jammer. For the antenna I chose a TSA 900 [36], which is listed as supporting frequencies ranging from 900MHz to 12GHz. This antenna was chosen because it was the only option. The risk of using this antenna is that its frequency range doesn’t reach 12.0169GHz, which is required for this experiment.

Figure 4.2: Mixer Circuit Calculation

A DS Instruments MX20000 was selected for its internal linear oscillator (LO) capable of generating a signal from 12GHz to 22GHz. Figure-4.2 shows how a mixer operates, and more importantly how to calculate the output frequency based on input frequencies. With F in1 = 12.3GHz as the LO frequency, and a lower bound on the HackRF One’s operating frequency at 1MHz, solve for F in2, shown in equations-4.1 18 and 4.2. This is hardware and design was chosen based on [34]. The implementation in GRC can be seen in Appendix A.

Fout − low = F in1 − F in2 (4.1)

∴ F in2=12.3GHz − 12.0169GHz = 283.1MHz (4.2)

Figure-4.3 shows the jammer’s physical configuration. 1 TSA 900 antenna connecting to 2 DS Instruments MX20000’s RF port. 3 HackRF One connected to 2’s IF port. 2 and 3 are connected to the 4 laptop, for power; 3 also communicates with GRC via USB.

Figure 4.3: My Jammer Configuration

4.2.2 Environmental Considerations

As mentioned in sections-3.2.1 and 4.1.1 jamming signals outside of the desired frequency, and property boundary, is undesirable and also illegal. To mitigate all signal

19 leakage I tested the range of the jammer with a 24 inch dish, and found that at the edge of the property the jamming signal was undetectable. As a further preventative measure the yard I tested in was surrounded by a steel chain-link fence, which acts as a reflective barrier, containing the signal at the property line.

4.2.3 Challenges

As previously mentioned, the BSR receives at 12.0169GHz. Therefore jamming the BSR requires generating a signal at 12.0169GHz. SDRs and signal generators capable of producing this signal are not “low cost,” the cheapest being approximately $11,000 with a six to eight week order process. The Electrical and Computer Engineering department of UCCS was contacted for software and hardware recommendations. Frequency multipliers and mixers can move a sub-6GHz signal to the 12GHz range. Due to budget constraints a Mini-circuits RMK-153+ 3x frequency multiplier was purchased for $110. It was dead-on-arrival thus the more costly hybrid mixer was required. Antennas on eBay and Amazon’s first five pages didn’t meet the specification. Search terms for antennas don’t always work because specifying “12.0169GHz antenna” is ruled out by any antenna with a bound not equal to 12.0169GHz. After UCCS closed down I continued scrolling through pages of antennas and eventually found the the TSA 900. Apparently no damage to the SDR or antenna has resulted from using an antenna rated for less power than is necessary.

20 4.2.4 Experiment Setup

Definitions

Azimuth is defined as the jamming SDR (jammer) offset from the LNB. Figure-4.4 shows that a jammer placed in front of the receiver has an azimuth of 0 radians and 0◦, whereas a jammer placed behind the receiver has an azimuth of π radians and 180◦.

Figure 4.4: Azimuths relative to my BSR LNB

Elevation: The BSR configuration depends on its latitude and longitude. Due to the static nature of the GEO satellite transmitting the signal all angles here are in reference to 0 of elevation, as measured with a plumb line and protractor. Figure-4.5 shows a signal being received from Galaxy-18. 1 Satellite Signal being received, with the receiver’s LNB arm at an elevation of 41◦ above 0◦ per the latitude 21 at my experiment locale. The angle between the jammer and LNB arm is illustrated by 2 LNB-SDR Angle. 3 SDR Elevation shows the jammer below the LNB at an apparent azimuth of 0◦.

Figure 4.5: Angles relative to my BSR LNB

22 4.2.5 Experiment

Setup

To capture the jammer-receiver configuration the azimuth, elevation and distance were all recorded before the receiver was turned on. The receiver then logged the Received Measures (SNR, Frame Sync, Timing Sync), per table-4.1, to a file. On average 83 samples were taken for each measure with jamming. Without jamming, on average, 84 samples were taken per measure.

JammerConfiguration ReceivedMeasures TxGain Azimuth Elevation Distance(feet) RxGain SNR BER Frame Sync Timing Sync π ◦ 14 2 41 9 40 1.2345 .5 Lost Lost 14 π 0 9 40 5.12346.2E − 3 Acquired Acquired

Table 4.1: Example of Recorded Experiment Data

The measures were taken from three distances: 3, 6, 9, 12, 15 and 18 feet as indicated in figure-4.6. They were taken from four azimuths: 0◦, 30◦, 60◦, 90◦, and 180◦. Elevations were 0◦ due to the constraint of getting the jammer above the LNB arm or BSR elevated. Statistical information on sampling can be seen in Appendix C.

Figure 4.6: Radii of measures relative to BSR 23 Goals for the Jamming Experiment

1. Do acute azimuths jam more effectively than obtuse?

2. Show jammer signal decreasing monotonically as the azimuth goes from 0◦ to 180◦.

3. Show the jammer signal decreasing monotonically as the distance increases.

4. Conversely, show the Galaxy 18 signal increasing monotonically as the jammer distance increases.

Challenges

Taking elevated measurements will prove challenging due to geometry. At a distance of nine feet and elevation of 41◦ means the antenna must be six feet off the ground. A location where the BSR can have six foot height in all directions was infeasible in my experiment location.

24 CHAPTER 5

Results

5.1 Blockstream Satellite Receiver

Figure-5.1 shows output captured from Blockstream’s command line tool, blocksat-rx. Figure-5.1 1 shows the SNR being captured; when the SNR is below 2dB the connection is either spotty or disconnected. Figure-5.1 2 shows the current download speed, which varies with interference. 3 shows a message indicating the connection was lost. Environmental noise in the neighborhood is around 1.5dB, the SNR of the BSR without any tuning. Figure 5.1: Blocksat CLI Screenshot Figure-5.2 is a spectrogram captured

25 from blocksat-rx-gui centered at 1.26692 GHz. The Blockstream signal is usually offset by approximately -150kHz. The spectrogram was useful in verifying that the receiver was properly tuned. If the spectrogram showed a weaker signal than this then, typically, the signal could not be decoded.

Figure 5.2: blocksat-rx-gui Spectrogram

5.2 Bitcoin Feasibility

Average block size average block size from January 2020 to April 2020 is just under 1MB [1]. Table-5.1 summarizes BTC’s ledger growth, data sourced from [2] starting in December 2019. When jamming adds 4dB of interference the download rate is slowed to 3.4Kbps. Everyday Blockstream broadcasts the ledger from the prior 24 hour period. For the month of April, and a download rate of 3.4Kbps it would take eight days to download the a single 24 hour ledger. It would take a connection speed of approximately 24.5Kbps to download a single day’s ledger, from April 2020, in just under 24 hours. I was able to achieve a maximum download rate of 13Kbps. While not astounding it was doable, but required items beyond their minimum parts list. In Colorado Springs

26 wind blew the receiver out of alignment more than once per day, foiling efforts to get a single day’s ledger. A housing, or sturdier dish mount, is necessary in order to run a BSR. A risk to those wishing to run a BSR is whether or not Blockstream will continue to provide data. In the month of April it will cost Blockstream approximately USD$1.9 million to run this service, based on a cost-per-MB found here [6] and the number of MB uplinked per day found in table-5.1 “Daily cost of upload.” Blockstream has monetized a portion of the service: you can pay to send a file via Blockstream Satellite from their website. This is potentially a useful service for customers wishing to send photos etc. , but financials of Blockstream Satellite’s feasibility are not publicly available. Anyone investing hundreds of dollars in a receiver should consider the longevity of the service they wish to connect to.

Time frame Size (MB) Growth on previous (MB) Growth month-over-month Growth (MB/day) Daily cost of upload April2020 274,025 8,561 3.2% 317.07 $63,414 March2020 265,464 4,564 1.7% 169.04 $33,808 February2020 260,900 4,648 1.8% 172.15 $34,430 January2020 256,252 4,493 1.8% 166.41 $33,282 December2019251,759 - - - -

Table 5.1: Bitcoin Ledger Growth Prior Four Months

How many blocks the receiver downloads was never discovered because synchronization was lost after several hours without ever downloading the maximum number of blocks. Because a BSR in Colorado faces wind and weather conditions that constantly interfere with the connection it would be impossible to maintain a blockstream receiver without some kind of housing.

27 5.3 Jamming with Signal-to-Noise Ratio and Signal-

to-Interference-Noise Ratio

The following tables support the number of samples taken for each SNR measurement. Knowing that the environmental noise is 1.5dB, and having a baseline SNR, I can derive I the interference by using N the noise, and S the signal. Derive S as in equation-5.1:

S S = SNR → = SNR → S =1.5 × SNR (5.1) N 1.5

An SNR measurement taken with interference present is the SINR value. Having the signal, noise, and SINR at each measurement the interference can be derived as in equation-5.2:

S S S = SINR → = I + N → I = − N (5.2) I + N SINR SINR

Figure-5.3 shows the SNR results when either Jammed dB is present, or Not Jammed dB if no jamming is present. Interference dBm was derived for each measure, and is summarized in figure-5.4. Due to the wind impacting the received signal strength I took samples without interference before jamming, represented in blue, then turned on the jammer and measured the received signal. Each bar has its 95% confidence interval. Getting the same number of samples with and without jamming is impossible due to the manual process of stopping the BSR. When the BSR starts it takes several SNR measures before synchronization with Galaxy 18 occurs. Once a connection is made the BSR runs until over thirty samples are collected.

28 Figure 5.3: Received Signals all Azimuths

Figure-5.3 summarizes the impact of the jammer on the BSR at all angles. On the x-axis 0◦, 30◦, 60◦, 90◦, and 180◦ indicate the azimuth of the jammer; and the sets 3, 6, 9, 12, 15, 18 indicate the distance between the jammer and the BSR in feet. Azimuths 60◦ and 90◦ show that at 18 feet the jamming signal is barely received, however at shorter distances the jamming signal makes Galaxy 18’s signal imperceptible. At 180◦ the jamming signal fades exponentially with distance.

29 Figure 5.4: Interference all Azimuths

As mentioned previously, I can derive the interference based on the SNR, SINR, and environmental noise. Figure-5.4 summarizes the calculated interference. On the x-axis 3, 6, 9, 12, 15, 18 indicate the distance between the jammer and the BSR in feet; and the sets 0◦, 30◦, 60◦, 90◦, and 180◦ indicate the azimuth of the jammer. This allows us to easily distinguish which angles are best for jamming. Interference gets weaker as the distance between the jammer and the BSR increases. I expected the jamming signal to monotonically decrease as distance between the BSR and jammer increased. This is perfectly illustrated with SNRs of “Jammed” and “Not Jammed” signals in Appendix D.1 at azimuth 180◦; and conversely by the interference in Appendix D.2 at azimuth 180◦. This lack of a model drove questions that required an expert on antennas and RF.

30 To discern the issue Dr. Heather Song, Dr. Rory Lewis, and Dr. Steve Lewis were consulted. They were selected for their expertise, respectively, in antenna theory, computer engineering, and satellite communications. Both Dr. Lewises noted that my testing environment had “a lot of interference factors.” Dr. Steve Lewis noted that concrete’s reflective property is so strong that it is almost always a factor in terrestrial radio systems. Dr. Steve Lewis also noted that even the yard lights, pictured in figure-1.1, will cause interference. I feel that the test environment was the best choice for my research since most people live with neighbors, and jamming a BSR will be likely be done around some structure providing power.

NEAR FIELD FAR FIELD

NON-RADIATIVE RADIATIVE (REACTIVE) (FRESNEL)

Figure 5.5: Near- and Far-Field Regions. Graphic by Goran M. Djuknic [21].

Despite a predictable path-loss pattern at azimuth 180◦, there wasn’t an evident path-loss pattern at any other azimuth. Dr. Song was able to clarify the issue. Path-loss models are only applicable in the far-field (Fraunhofer) region.A wave in the near-field region behaves less predictably than that in the far-field, hence

31 why path-loss models are inapplicable in the near-field. Figure-5.51 illustrates near and far-field regions.

2D2 The boundary of the far-field and near-field regions is determined by λ in meters. D is the largest dimension of the antenna, and λ is the signal’s the wavelength. I calculated the near- and far-field regions using the TSA 900’s length of 230mm. This means my jammer’s wavelength λ at 12.01692GHz is 2.49648 × 10−2 meters. With these parameters the far-field region is anything greater than or equal to 4.2409008 meters, or 13.91 feet. Figure-5.6 and figure-5.7 illustrate jamming efficacy in the far-field (Fraunhofer) region [16], which is discussed in detail in Chapter-8. The Fraunhofer region begins at 13.91 feet. Notice that at 15 feet jamming is effective at all azimuths except 0◦, however at 18 feet jamming is only effective at 30◦.

Figure 5.6: Measures in the Far Field - 15 Feet

1Accessed May 20, 2020

32 Figure 5.7: Measures in the Far Field - 18 Feet

Jamming from azimuths 30◦, 60◦, 90◦ and 180◦ in the near-field were all effective. I hypothesize that is because the jamming antenna has line-of-sight to the LNB’s receiving surface (at 180◦ the jammer is facing the LNB, and since no surface is 100% reflective, some of the signal penetrated the dish and hit the LNB’s receiving surface). This can be seen in figure-5.8: the antenna radiates a signal in the direction of the LNB receiver . The confidence intervals indicated in

figure-5.3 and Appendix D.1 show wider Figure 5.8: Jammer Facing LNB 33 intervals for the “Not Jammed” SNRs, which is contrary to what one would expect- that SNR fluctuates with jamming. In actuality SNRs do not fluctuate with jamming since the jamming signal is less than 20 feet from the receiver. This means the jamming signal is not subject to the environmental factors encountered by the signal from Galaxy 18 on its 22, 000 mile journey, and both signals contend with material near the BSR such as concrete and fences. A possibility for unpredictable path-loss may lie in the nature of the tools. blocksat-rx, the application provided by Blockstream to receive Galaxy 18’s transmission, which provides the SNR metric, is designed to work on a transmission travelling 22, 000 miles. Using such a tool to measure SNR at distances less than 22 feet does not seem to scale well. The results collected are sufficient to model a two-dimensional jammer-receiver configuration. Measurements with varied elevation were not delivered. A location providing numerous elevations is necessary to model a three-dimensional environment. Data illustrating the degradation of received signals can be found in Appendix D. Appendix D.1 illustrates each azimuth from figure-5.3 individually, and shows the measured SNR as distance increases. The charts in Appendix D.2 are distinguished by azimuth, and illustrate interference as distance increases, similar to figure-5.4. Re-synchronization appears to happen quickly and despite interruption. Knocking the BSR offline for several minutes doesn’t impact its ability to re-synchronize. Due to wind, the receiver never fully synced, therefore this result about re-synchronization is not conclusive.

34 CHAPTER 6

Summary of Contributions

6.1 Blockstream Satellite Receiver

Motivation: Blockstream published and maintains an in depth build guide. Following this guide should enable users to easily access the Bitcoin blockchain.

Contribution: By building a BSR I can give an accurate description of how feasible the task is for someone with moderate experience in both SDR and network hardware. Additionally, recording the steps taken should simplify development for the next Blockstream Satellite researcher.

6.2 Jamming with Signal-to-Noise Ratio and Signal-

to-Interference-Noise Ratio

Motivation: Blockstream allows access to the Bitcoin blockchain by billions of people without access to the traditional internet. Blockstream Satellite offers a functional, digital currency in areas without traditional internet or strong financial institutions.

35 Participation in Bitcoin allows people without a strong infrastructure to receive remittances, and transact in an available and accountable fiat currency. Re-synchronization must be considered because of the conditions in which a satellite receiver can operate. Disconnecting can occur due to atmospheric attenuation [30], or the receiver being pushed out of alignment due to wind or other weather. Therefore it is necessary to determine how a Blockstream receiver re-synchronizes after interruption. An adversary can intentionally jam a BSR to knock the Bitcoin node offline knowing that re-synchronization isn’t permitted. Under this scenario an attacker can could jam the BSR for X minutes, where X is the amount of time after which a BSR cannot re-synchronize. This forces the BSR to use at least X time getting re-synchronized, whereas the attacker has to use at most X time knocking the BSR offline.

Contribution: Engineering a Blockstream jammer, and taking physical measures of signal quality and attributes. Jamming the BSR locally provides insight into: Blockstream’s re-synchronization procedure, and the Ku-band signal characteristics under intentional jamming conditions. If the receiver is unable to re-synchronize after being interrupted for some minutes then an attacker has the advantage of needing moderate time to cause a large impact on the receiver. Additionally, gathering data points from a variety of attacker-receiver configurations will act as seed data for 3D simulations of innumerable attacker receiver configurations.

36 CHAPTER 7

Future Work

COVID-19 impacted the scope of experiments I could undertake. With the university closed the anechoic chamber and electrical engineering labs closed. These labs provide equipment to measure antenna properties such as gain by direction and maximum power to the antenna. Those measurements will be taken once the lab reopens.

7.1 Blockstream Satellite Receiver

Adding a mechanical tuning device to device to the BSR would enable a mobile receiver. The added cost changes the scope of the work from a “low-cost” satellite receiver implementation. This would model mobile receivers of LEO satellites.

7.2 Jamming with Signal-to-Noise Ratio and Signal-

to-Interference-Noise Ratio

By measuring the jamming antenna’s properties precise effective jamming distances will be calculable. Hofmann and Knopp [25] used an antenna ranging from $1,400 up. They were able to jam the Ku-band over 16 kilometers, 10 miles, away. A $40 antenna is 37 unlikely to achieve that distance, however its properties will give clues to achievable distances. Additional measurements are necessary to seed a robust mobility model for path-loss. UCCS’ infrastructure provides the best environment to conduct these experiments. In addition to elevation, measurements with varied transmitter gain, power and bandwidth will be collected. These will highlight critical points in the configuration. Lowering the gain could illuminate the jammer’s range relative to power. Modifying the transmitter bandwidth will define the critical point at which digital decodability is achievable. Measurements thus far enumerate the transmitter-receiver behavior in the near-field region. By collecting measurements in the far field I will have a clearer picture on what kind of path-loss models fit our data. These measures should be collected from the maximum range of the transmitter, in one foot increments, to the edge of the far-field region, approximately 14 feet.

7.3 Simulation of Jamming with Mobility Modeling

A mobility model is only as accurate as its inputs and the completeness of its development. An antenna’s properties dictate what kind of path-loss model is applicable. Due to the lab closure it was infeasible to determine the antenna properties. Without the antenna’s properties it is impossible to accurately model path-loss. Mobility models can be built to suit any scenario [15]. Temporal dependency models do a good job of describing how an attacker adjusts itself to find the optimum jamming location, however what if the receiving node can move? Mobility modeling in NS3 is limited to random way-point and temporal dependency models. As development of rapid satellite acquisition technology progresses, and becomes cheaper, the movement constraint on receiver nodes will relax. NS3 version 30.1 does not include spacial dependency models, however these are a better fit for mobile jammer-receiver 38 configurations. A suitable path-loss model is necessary to better the mobility model’s results. Rapid fading can be modeled using the Nakagami-m fast fading model [32]. This approach to path-loss accurately reflects the conditions of the experiment in that it works for ranges below 80 meters, however the model also assumes a multi-path signal. The other path-loss models I reviewed are for further distances and incorporate structures and other obstacles into signal reception.

39 CHAPTER 8

Conclusion

Building a BSR is feasible for a lay-person. One should estimate additional time and materials will be needed to offset inexperience tuning satellite receivers. Having nearly quadrupled the cost of the initial parts list the receiver could still be considered “low cost,” being under USD$1,000. After several months working with receivers I have determined that the parts list put forth by Blockstream is insufficient to receive their signal in the Colorado Springs area. In regards to path-loss: 75% of my measurements are taken in the near-field. This means that a standard path-loss model is inapplicable. Despite the lack of a path-loss model my research yields insights into the best angles for jamming a BSR in an urban environment. The results of jamming presented in Chapter-5.3 were surprising. My hypothesis was that jamming from azimuth 0◦ would be most effective, and azimuth 180◦ would be least effective. This did not appear to be the case. The most effective region to jam from is between 30◦ to 90◦. An attacker within the near-field region of a victim can successfully stop reception of Blockstream’s signal. In summary, I highlighted previously unknown complexities in building a Blockstream receiver. Having completed the receiver I investigated what path-loss of the jamming 40 signal looks like in the near-field, and discovered the region around the receiver where an attacker will be most effective. These findings build a foundation for further investigations of Ku-band signals, path-loss modeling in the near- and far-fields, and measuring how qualitative signal properties impact reception of Ku-band signals.

41 References

[1] Bitcoin average block size. https://btc.com/stats/block-size.

[2] Bitcoin blockchain size. https://www.blockchain.com/charts/blocks-size.

[3] Gt-v8 digital satellite finder on amazon. https: //www.amazon.com/GT-MEDIA-Satellite-Receiver-Adjusting/dp/B07G862F2L.

[4] µstdn-100 transponder datasheet. http://www.spacemicro.com/assets/ datasheets/rf-and-microwave/%C2%B5STDN-100_Transponder.pdf. Accessed: 2019-01-03.

[5] Skywalker analog satellite finder on amazon. https://www.amazon.com/ Skywalker-Signature-Series-Satellite-Finder/dp/B001EL68JG/.

[6] Internet vsat access via satellite: Costs. https://www.satsig.net/ivsatcos.htm, Feb 2005.

[7] wikimedia.org. Wikimedia Foundation, Oct 2011.

[8] Building your own bitcoin satellite node. https://medium.com/blockstream/ building-your-own-bitcoin-satellite-node-6061d3c93e7?source= ------3------, Nov 2019. Accessed: 2020-01-10.

[9] Hackrf one. https://greatscottgadgets.com/hackrf/one/, 2019.

[10] Schedule and pricing. https://spaceflight.com/schedule-pricing/#pricing, 2019.

[11] Codeless/semi-codeless gps access commitments. https://www.gps.gov/technical/codeless/, 2020.

[12] Covid dries up a cash cow. The Economist, page 34–34, Apr 2020.

[13] Nexus universal blockchain. https://nexus.io/, 2020.

[14] Adam Back, Matt Corallo, Luke Dashjr, Mark Friedenbach, Gregory Maxwell, Andrew Miller, Andrew Poelstra, Jorge Tim´on, and Pieter Wuille. Enabling blockchain innovations with pegged sidechains. URL: http://www. 42 opensciencereview. com/papers/123/enablingblockchain-innovations-with-pegged-sidechains, 72, 2014.

[15] Fan Bai and Ahmed Helmy. A survey of mobility models in wireless adhoc networks. 2004.

[16] Constantine A Balanis. Antenna theory: analysis and design. John wiley & sons, 2005.

[17] BitShills. Nexus - the most advanced universal blockchain. https://bitshills.com/nexus-the-most-advanced-universal-blockchain/, Feb 2020.

[18] Shaochi Cheng, Yuan Gao, Xiangyang Li, Yanchang Du, Yang Du, and Su Hu. Blockchain application in space information network security. In International Conference on Space Information Network, pages 3–9. Springer, 2018.

[19] J. Clement. Global digital population 2020. https: //www.statista.com/statistics/617136/digital-population-worldwide/, Feb 2020.

[20] Alexandru Csete. Welcome to gqrx. https://gqrx.dk/, May 2018.

[21] Goran M Djuknic. Far and Near Fields. Wikimedia Foundation, Dec 2003.

[22] Jeff Foust. Spacex’s space-internet woes: Despite technical glitches, the company plans to launch the first of nearly 12,000 satellites in 2019. IEEE Spectrum, 56(1):50–51, 2018.

[23] Yingyuan Gao, Siqian Cui, and Zhou Lu. A geo-leo hybrid architecture design of satellite internet. In 3rd International Conference on Mechatronics and Information Technology, 2018.

[24] Mark Harris. Tech giants race to build orbital internet [news]. IEEE Spectrum, 55(6):10–11, 2018.

[25] Christian A Hofmann and Andreas Knopp. Satellite downlink jamming propagation measurements at ku-band. In MILCOM 2018-2018 IEEE Military Communications Conference (MILCOM), pages 853–858. IEEE, 2018.

[26] Hui Hu and Na Wei. A study of gps jamming and anti-jamming. In 2009 2nd international conference on power electronics and intelligent transportation system (PEITS), volume 1, pages 388–391. IEEE, 2009.

[27] Mostafa Ibrahim and Islam Galal. Improved sdr frequency tuning algorithm for frequency hopping systems. ETRI Journal, 38(3):455–462, 2016.

43 [28] Blockstream Corporation Inc. Blockstream/satellite github. https://github.com/Blockstream/satellite, Jul 2019. Accessed: 2020-01-10.

[29] Alan Jones, Cameron Cook, Don, Shay, JT Allyn, Denny, Deborah Ann, Marjorie Martinez, Dennis Hungerford, Dan Cleary, and et al. Magnetic north vs geographic (true) north pole. https://gisgeography.com/magnetic-north-vs-geographic-true-pole/, Jun 2015.

[30] Roger Ludwig and Jim Taylor. Voyager telecommunications. Deep Space Communications, page 37–77, 2016.

[31] Mamatha R Maheshwarappa, Mark Bowyer, and Christopher P Bridges. Software defined radio (sdr) architecture to support multi-satellite communications. In 2015 IEEE Aerospace Conference, pages 1–10. IEEE, 2015.

[32] Minoru Nakagami. The m-distribution—a general formula of intensity distribution of rapid fading. In Statistical methods in radio wave propagation, pages 3–36. Elsevier, 1960.

[33] Karel P¨arlin, Muhammad Mahtab Alam, and Yannick Le Moullec. Jamming of uav remote control systems using software defined radio. In 2018 International Conference on Military Communications and Information Systems (ICMCIS), pages 1–6. IEEE, 2018.

[34] Ian Poole. Rf mixing- rf multiplication basics. https://www.electronics-notes. com/articles/radio/rf-mixer/rf-mixing-basics.php, Feb 2020.

[35] Hank Rausch. Jamming commercial satellite communications during wartime an empirical study. In Fourth IEEE International Workshop on Information Assurance (IWIA’06), pages 8–pp. IEEE, 2006.

[36] RFSPACE. Tsa900 ultra wide band uwb antenna. https://www.amazon.com/TSA900-Ultra-Wide-band-Antenna/dp/B01NBO8LNF, March 2020.

[37] DK Sachdev. Recent Successful Satellite Systems: Visions of the Future. American Institute of Aeronautics and Astronautics, Inc., 2017.

[38] Sascha Segan. The satellite divide: Which americans rely on satellite internet? https://www.pcmag.com/news/ the-satellite-divide-which-americans-rely-on-satellite-internet, Dec 2019.

44 Appendices

45 APPENDIX A

Gnu Radio Companion Jamming Flow

The flow used for jamming a Blockstream receiver. Available for download on Github at https://github.com/Andreas237/ThesisRadio/blob/master/flows work.

46 APPENDIX B

Gnu Radio Companion Blockstream Receiver Flow

The flow used for jamming a Blockstream receiver. Available for download on Github at https://github.com/Blockstream/satellite.

47 48 APPENDIX C

Summary of Jamming Samples

Table C.1: Azimuth 0

Distance (feet) Avg Jammed SNR (dB) Sample Count Avg Jammed SNR Avg No Jam SNR (dB) Sample Count Avg No Jam SNR Interference (dBm) 3 1.6926 43 5.4751 33 3.3522 6 4.0785 38 5.5788 31 0.5518 9 5.1423 37 5.5735 42 0.1258 12 0.9447 54 5.5718 42 7.3465 15 4.5706 66 5.521 54 0.3119 18 3.8655 109 5.542 32 0.6506

Table C.2: Azimuth 30

Distance (feet) Avg Jammed SNR (dB) Sample Count Avg Jammed SNR Avg No Jam SNR (dB) Sample Count Avg No Jam SNR Interference (dBm) 3 1.3208 68 5.8103 431 5.0986 6 1.8965 76 5.8817 85 3.1519 9 2.7879 91 5.867 40 1.6567 12 4.6912 81 5.7529 64 0.3395 15 3.1715 77 5.7733 88 1.2306 18 1.4298 41 5.7969 29 4.5813

Table C.3: Azimuth 60

Distance (feet) Avg Jammed SNR (dB) Sample Count Avg Jammed SNR Avg No Jam SNR (dB) Sample Count Avg No Jam SNR Interference (dBm) 3 1.4265 42 5.8351 73 4.6357 6 1.043 108 5.7253 57 6.734 9 2.0607 77 5.6828 104 2.6366 12 2.0135 109 5.7331 36 2.7709 15 1.624 50 5.6486 54 3.7172 18 5.3257 58 5.5708 347 0.0691

49 Table C.4: Azimuth 90

Distance (feet) Avg Jammed SNR (dB) Sample Count Avg Jammed SNR Avg No Jam SNR (dB) Sample Count Avg No Jam SNR Interference (dBm) 3 4.2089 368 5.6331 119 0.5075 6 1.6652 89 5.6877 62 3.6236 9 1.9857 100 5.6928 85 2.8004 12 1.4381 47 5.6696 90 4.4139 15 2.0413 187 5.6198 68 2.6296 18 5.1843 41 5.6121 23 0.1238

Table C.5: Azimuth 180

Distance (feet) Avg Jammed SNR (dB) Sample Count Avg Jammed SNR Avg No Jam SNR (dB) Sample Count Avg No Jam SNR Interference (dBm) 3 1.3566 36 6.6332 318 5.8346 6 1.4124 29 6.742 39 5.6602 9 1.5513 60 6.687 22 4.9657 12 1.9362 44 6.5927 27 3.6074 15 3.1618 82 6.5316 15 1.5987 18 5.4517 84 6.6353 115 0.3257

50 APPENDIX D

Signal Measures Charts

D.1 Received Signals

Figure D.1: SNR and SINR Azimuth 0

51 Figure D.2: SNR and SINR Azimuth 30

Figure D.3: SNR and SINR Azimuth 60

52 Figure D.4: SNR and SINR Azimuth 90

Figure D.5: SNR and SINR Azimuth 180

53 D.2 Interference

Figure D.6: Interference Azimuth 0

54 Figure D.7: Interference Azimuth 30

Figure D.8: Interference Azimuth 60

55 Figure D.9: Interference Azimuth 90

Figure D.10: Interference Azimuth 180

56