Rebooting an old Spacecraft ISEE3 Reboot Achim Vollhardt, DH2VA Mario Lorenz, DL5MLO For the AMSAT-DL / Bochum Observatory Team

Transcription

1 Rebooting an old Spacecraft ISEE3 Reboot Achim Vollhardt, DH2VA Mario Lorenz, DL5MLO For the AMSAT-DL / Bochum Observatory Team 1/42

2 Outline Preliminaries Motivation: The ISEE-3 / ICE Spacecraft and it's history Talking to a Space Veteran Bochum Hardware Setup Old Protocol New Approaches & Performance Doppler Ranging 11/42

3 Disclaimer We are not members of the ISEE3-Reboot-Project Our opinions are our own and may not represent the views of ISEE3-R Though we do try to help when possible Due to lack of documents, conclusions may be wrong 12/42

4 International Sun-Earth Explorer 3 Launched August , 15:12:00 UTC Delta Launch A Halo-Orbit at L1 Study Sun/Earth Interaction: Plasmas, Waves, Fields Other in series: ISEE-1 (NASA), ISEE-2 (ESA) 13/42

5 Image Source: NASA 14/42

6 Spacecraft Firsts First S/C to achieve SEL1 Halo Orbit First Cometary Encounter (Giacobini-Zinner, 1985) First Transcontinental Antenna Arraying Image: 15/42

7 16/42

8 Further Mission of ICE 1985 Comet Flyby (tail) of Giacobini-Zinner 1986 Comet Flyby (Halley) 1991 Mission Update: Monitor Solar CME's (with Ulysses ( ) 19 Dec 1995: Modulation turned off. Carrier used for Radio Science 5 May 1997: Termination of Operations 18 Sep 2008 DSN tracks Carrier 17/42

9 Analysis of GSFC Engineering Team, Feb /42

10 Mounting Pressure to do something 19/42

11 Bochum Observatory Outside and inside 20/42

12 Getting to work (Feb 2014) Find frequencies/comms information: Celestial Location: Not on Horizons With help from GSFC and JPL and some data translations: Trajectory Data loaded into Tracking Computer by James, G3RUH USRP with SBX board in place and hooked to LHCP port No luck, but not really expected: Noise Figure ~5dB G4DDK Preamp used at EVE reinstalled (Michael, DD5ER) 21/42

13 Result: 22/42

14 About the same time: Posted Mar 3, before our announcement 23/42

15 Situation Analysis We have: Bochum Observatory Dish Downlink Carrier Xpndr B We do not have: Documentation about Telemetry Details, especially Uplink Details Confirmation of Xpndr A (RHCP) Capable Transmitter NASA contact indicated required RX level at S/C would be -120 dbm Initial estimate revised: ~10 kw Contact with NASA and had to agree: No Go. 24/42

16 More ICE/ISEE-3 Detections Mar 20: Allen Telescope Array Image: Allen Telescope Array (on 25/42

17 More ICE/ISEE-3 Detections Apr 9: Arecibo (305m) Image: NAIC (on 26/42

18 Arecibo Radio Observatory / Radar Image: NAIC 27/42

19 More ICE/ISEE-3 Detections Apr 10: Morehead State University (20m) Image: Morehead State University (on 28/42

20 Apr 23: ISEE-3 Reboot Crowdfunding Pledge for $125k within 30 days for hardware, travel expenses Turned out to be successful Build out Arecibo both for Receive and Transmit 29/42

21 May 29: Telemetry Switched On. unfortunately switching to a rate where link would not yet close in Bochum 30/42

22 Get to work Install additional hardware 2nd LNA, Second USRP for XPNDR-A 1PPS Distribution for exact time Synchronization Bandpass filters for both Receive Chains USRP N210/GPS S-Band RHCP BPF G4DDK LNA S-Band LHCP BPF G4DDK LNA Focus Room USRP N210 Z3801 Control Room 31/42

23 Focus Room 20m Dish 32/42

24 Downlink Modulation Standard Deep Space BPSK w/residual Carrier Bitrates Bits/sec, Modulation Index 45 /60 BiPhase or Sub-Carrier (coherent to bitrate) 33/42

25 Downlink Coding NASA knew back then a lesson Amateur S/C are only recently starting to learn: FEC Channel Codes improve the link significantly! Employ Convolutional Code Choosen Code is R=1/2, K=24 Non-Systematic code, G1= and G2= (oct) Massey-Costello Quick Look-In (QLI) Property: D= P1 xor P2 34/42

26 Decoding the Code Note K=24, this is an extremely long code Optimal Decoder is Viterbi-Algorithm But: Complexity grows exponentially in K Not realizable 30 yrs ago Alternative: FANO-Decoder: CPU load could be constrained, at expense of error rate 35/42

27 Decoding the Code Not having a bigger Dish: Fight for each 0.1 db Feasibility Study: Ask Phil Karn, KA9Q > We want Viterbi Experience in Viterbi Decoders (libfec defacto benchmark) Adapted K=15 Decoder (used in STEREO until TURBO took over) to K=24 Performs about 2 db better than Fano as used by NASA back then (exact comparison difficult) Apply brute force compute power: But still no 512 BPS Should be noted: Please include strong CRC Phil also volunteered to write complete Demod chain 36/42

28 Making Sense of the Telemetry ITAR Restrictions on Documents Some were found on public NASA servers Conflicting; Version Status unknown Trial & Error and Guessing Frame can be decoded Analog calibration data is ITAR? But apparently not for other contemporary S/C? 37/42

29 Old Telemetry Screen 38/42

30 39/42

31 Ranging 40/42

32 Ranging 41/42

33 Summary History of ISEE-3 Spacecraft First Detection of ISEE-3 Spacecraft since 2008 Telemetry reception setup better performance than what NASA had back then Telemetry in action Ranging Now handing over to Achim, DH2VA 42/42