A DISTRIBUTED COMMON GROUND SEGMENT FOR EDUCATIONAL NANOSATELLITES Quinn McGehan, Megan O’Sullivan, Michael Mozingo, Michael Trowbridge

1

Megan O’Sullivan

Theory and Background 2

Relevant Requirements

¨  DANDE science mission needs spacecraft’s position ¤ Solution: STK model and ground time of measurements ¤ Problem: spacecraft clock drift, clock resets

n Solution n  Measure time offset periodically n  Correct the measurement times on the ground (post-pass)

¨  Downlink science data from the spacecraft ¤ Problem: Data produced faster than we can downlink it

n Solution: Add more ground stations

3

The Solution

¨  Multiple Ground Stations ¤  Ithaca, NY ¤ San Juan, Puerto Rico ¤ Boulder, CO

4

Benefits

Increased Access Time Vs.

5

Impact of Access Time

Location Pass time/day (min)

Data Downlinked (Bytes)

Boulder 3.49 101,140 Cornell 14.66 424,847

Puerto Rico 11.41 330,661 Total 29.56 856,648

6

Previous work

¨  2010: HERMES S-Band Ground Station ¨  2011: DANDE AFRL demo, Verizon 3G USB dongle

7

Quinn McGehan

System Architecture 8

Component Location

InControl Client CU Boulder

InControl Server CU Boulder

Remote Gateway Remote Station

TNC Remote Station

Radio/Antenna Remote Station

General Architecture

Blue Cloud Farms

Remote Gateway

UPR (Puerto Rico)CU Boulder

Mission Operators

Remote Gateway

InControl FLITE Client workstations

TNC/Modem

RF Chain

Future satellites

TCP/IP

InControl ServerTelem

TNC

RF Chain

Modem

RF Chain

ALLSTAR

TCP/IP

TCP/IP

DANDE

Remote Gateway

9

Security Concerns

InControl Server talks to Remote Gateway over the internet

Public segment encrypted with SSH Remote Gateway

InControl Server

TCP/IP

TCP/IP

SOAP client TCP socket

ssh (AES)

ssh (AES)

socat,KISS and AX25 framing

TCP/IP

Commands, Telemetry

Commands, telemetry

Hardware Gateway

Gateway reconfiguration

To TNCRS-232

User commands, GUI

UnencryptedEncrypted SOAP Web

Service

10

Michael Trowbridge

Experiment 11

Experiment Goals

¨  Need to command DANDE during testing ¤ No internet connection at AFRL test facility

¨  If we add a mobile data link to the path, ¤ Can the remote gateway run the FLITE client? ¤ Can Boulder command the spacecraft at AFRL? ¤ Do key DANDE commands work? ¤ How does throughput affect commanding? ¤ How does latency affect commanding?

12

Network connections

Android Smartphone

`

Remote Gateway,InControl Client

3G/4G Data

WiFi tethering

CU TCP/IP

`InControl Client (MOCC)

InControl Server

CU Firewall

RS-232

DANDE

Public Internet Cell phone

tower

Radio

TNC

UHF/VHF

13

Mobile devices tested

¨  Motorola Atrix 4G ¤ OpenGarden Wi-Fi hotspot ¤ Native Android Wi-Fi hotspot

¨  Motorola Droid X ¤ Native Android Wi-Fi hotspot

¨  Pantech UML290 4G LTE USB dongle ¤  Installed in Remote Gateway computer

14

Photos: http://www.pcmag.com/article2/0,2817,2379916,00.asp http://www.pcworld.com/product/560080/motorola_droid_x.html http://www.pcmag.com/article2/0,2817,2376102,00.asp

Test Configurations

Test Device Configuration Carrier Connection 1 N/A Ethernet cable

(control) CU 100 mbps

2 Motorola Atrix 4G OpenGarden Wi-Fi tethering

T-Mobile EDGE (2G)

3 Motorola Atrix 4G Android mobile Wi-Fi hotspot

T-Mobile EDGE (2G)

4 Motorola Droid X Android mobile Wi-Fi hotspot

Verizon 3G

5 Pantech UML290 wvdial ppp client (USB)

Verizon 4G LTE

15

Procedures

1 •  Connect the remote gateway to the internet

2 •  Measure throughput to the general internet (speakeasy.net)

3 •  Determine if the VPN client is needed

4 •  Test latency & throughput to the InControl server

5 •  Attempt to launch the remote FLITE client

6 •  Test the DANDE command/telemetry link over RF

16

Telemetry and Commands

¨  Telemetry ¤ Monitor DANDE beacon frames

¨  Commanding ¤ Log in to the satellite ¤ Measure spacecraft time offset ¤ Upload a file using zmodem ¤ Download a file using zmodem

17

Michael Mozingo

Results 18

Results Overview

Test Device Configuration Carrier Connection Connected Notes 1 N/A Ethernet cable

(control) CU 100 mbps Yes

2 Motorola Atrix 4G

OpenGarden Wi-Fi tethering

T-Mobile EDGE (2G) Partial Test failure: OpenGarden blocked VPN connection

3 Motorola Atrix 4G

Android mobile Wi-Fi hotspot

T-Mobile EDGE (2G) Yes

4 Motorola Droid X

Android mobile Wi-Fi hotspot

Verizon 3G No Test failure: Unable to connect Wi-Fi

5 Pantech UML 290

wvdial ppp client (USB)

Verizon 4G LTE Partial Test failure: Unable to connect over VPN

19

Functionality

Test Ethernet Atrix Atrix Droid X USB

Initialize FLITE on remote GW Yes No No No No

Hardware gateway connects Yes No Yes No No

Dynamic DNS updates Yes Yes Yes Yes

Receive beacon frames Yes Yes

Login attempts needed 1 1

Time offset measurement works Yes No

VPN client needed No Yes Yes Yes Yes

Time to initialize jade display (sec) 4.3

Best functionality: Test 3, T-Mobile EDGE, Motorola Atrix 4G, Android Wi-Fi mobile hotspot

20

Droid X

¨  Unable to connect (Wi-Fi)

¨  NIC incompatiblity

¨  Test with a different Verizon phone

¨  Get a new NIC for the remote ground computer

¨  We were able to connect to a different computer

Issue Solution

21

Pantech 4G USB dongle

¨  Immature Ubuntu drivers ¤ vpnc unable to update

routing tables

¨  Use a 4G Wi-Fi Hotspot instead

Issue Solution

22

Throughput to internet

Downstream (kbps) Upstream (kbps) Ethernet 87601 53022 T-Mobile EDGE (test 2) 177 39 T-Mobile EDGE (test 3) 194 95 Verizon 4G LTE (test 5) 14747 3174

0 10000 20000 30000 40000 50000 60000 70000 80000 90000

100000

Thro

ughp

ut (

kbps

)

Tested using http://www.speakeasy.net/speedtest/

23

Bandwidth to InControl Server

Bandwidth (kbps) Ethernet 94100 T-Mobile EDGE (test 3) 102

0 10000 20000 30000 40000 50000 60000 70000 80000 90000

100000

Band

wid

th (

kbps

)

24

Throughput Requirements

¨  At 102 kbits/sec ¤ Commanding was successful ¤ File upload and download were successful

¨  Time Offset Measurement failed ¤ Failed pre-command check: NTP time out of sync

¨  Unable to find lowest threshold for commanding ¤ Transmit speed out of radio is 9.6 kbits/sec ¤ Could increase throughput with 3G and 4G connections

25

Latency to InControl Server

Latency (ms) Ethernet 0.228 T-Mobile EDGE (test 2) 362.525 T-Mobile EDGE (test 3) 258.619

0

50

100

150

200

250

300

350

400

Late

ncy

(ms)

26

zModem File Transfers

512 545

369

835

Upload to DANDE (bytes/sec) Download from DANDE (bytes/sec)

Ethernet T-Mobile EDGE (test 3)

27

Latency

¨  Little variation in latency (~258 ms) ¨  Too high for spacecraft time offset measurement ¨  Most commands insensitive to latency ¨  File uploading and downloading is more sensitive

¤ Uplink dropped from 512 bytes/sec to 369 bytes/sec ¤ Downlink results are misleading

28

Testing Summary

¨  Atrix connection was stable ¤ Low bandwidth and high latency

¨  4G Verizon dongle promising ¤ Support in Ubuntu is immature

¨  Best of both options: Verizon 4G Wi-Fi hotspot ¨  DNS, VPN difficult in all test setups

29

Conclusion

¨  Distributed ground network can transfer more data ¨  Lower latency in data downloaded ¨  Commanding is possible over mobile data links

¤ Functionality limited ¤ Limited equipment availability hindered our test

¨  Focus on modularity and flexibility

30

Future Work

¨  Register gateway web services with a UDDI server ¨  Automate radio, antenna actuator control ¨  Create .deb package for the remote gateway ¨  Perform experiments using 4G Wi-Fi hotspots

31

Acknowledgements

¨  L3 Communications ¤ Donation of InControl Software and licensing

¨  Mitch Seybold – thanks for all the late night and weekend assistance with our InControl gateway!

32

Questions 33

Backup Slides 34

Control - Ethernet

Bandwidth (phobos iperf) (kbps) 94100 Downstream (speakeasy) (kbps) 87601 Upstream (speakeasy) (kbps) 53022 Latency (phobos), ms 0.228 Dropped packet % (ping) 0 Can initialize FLITE on remote GW Yes Hardware gateway connects Yes Dynamic DNS updates remote GW address Yes Receive beacon frames Yes Login attempts needed 1 Time offset measurement works Yes VPN client needed No 15k zmodem download (bytes/sec) 545 15k zmodem upload (bytes/sec) 512 Time to initialize jade display (sec) 4.3 Date/time of test 4/8/2012

35

Atrix Bandwidth (phobos iperf) (kbps) 102 Downstream (speakeasy) (kbps) 194 Upstream (speakeasy) (kbps) 95.0 Latency (phobos), ms 258.619 Dropped packet % (ping) 0 Can initialize FLITE on remote GW No Hardware gateway connects Yes Dynamic DNS updates remote GW address Yes Receive beacon frames Yes Login attempts needed 1 Time offset measurement works No (NTP sync exception) VPN client needed Yes 15k zmodem download (bytes/sec) 835 15k zmodem upload (bytes/sec) 369 Time to initialize jade display (sec) N/A (test fail) Date/time of test 4/8/12 10:58 AM

36

Hermes VHF/UHF End-to-End

37

UHF/VHF Antenna

InControl Server

CU network

RF

CAT5

CAT5CAT5 Serial Audio

UHF

Audio

CORBA

ssh,TCP 12922

DB9F->DB25M AdaptorSerial

Tester A

Tester B

Kantronics KAM XL TNC

COMPUTER Port 2 (VHF)

Remote GW

/dev/ttyS0Yaesu FT-847

RadioPKT

HeadphoneJack

Yaesu VX-7R

Kantronics KPC3+ TNC

DB25FConnector

DB9F Connector

Laptop running CUBESim

COM1

Manually Configured

Hermes S-Band End-to-End

38

RadioLabs GS5000RadioLabs GS5000

Blue Cloud FarmsQwest DSL Modem/router

CAT5PoE

5.8GHz

DynDNS.org

Windows TerminalComputer

Internet

S-Band Antenna(Microhard 2420

mounted on feed)MOCC

Workstation

InControl server

CU network

S-Band~2.4GHz

CAT5

CAT5

Serial

CORBAssh,

TCP 12922

Serial

Tester A

Tester B

Microhard 2400Laptop running CUBESim

COM1

Omni hand-held antenna

Linksys Hub

CAT5PoE

CAT5

DNS updates

DNS queries