AISAT launch Apr 1

Discussion in 'Satellite and Space Communications' started by KC9SGV, Mar 31, 2019.

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  1. KE6BLR

    KE6BLR Ham Member QRZ Page

    I am reposting a note I sent to the AMSAT SIG that applies here:

    @@@

    As you know, AISAT became available recently for Satellite APRS. One of the nice things about having an APRS Digipeater mounted to the Stage 4 Rocket platform is this equipment inherits solar panels, batteries, and antennas.

    Unfortunately, the design team was given only 6 days to build and deliver the satellite. Apparently, end to end testing of the Digipeater was not possible. So, I believe they deserve a lot of slack.

    Now, there are many (4ish) quirks in the downlink.

    NOTE: the AISAT uplink appears nominal.

    To explain the downlink issue we need to examine a sample packet. For this we can thank K4KDR for transmitting the packet and KG4PID for receiving the packet. If I remember this correctly, KG4PID is running PI-TNC and APRX while K4KDR is running Direwolf and UISS. The main thing to note here is that displaying packets may require more flexible software.

    Sample packet from the APRX error log via KG4PID:

    2019-04-11 02:06:38.961 ax25_to_tnc2(KG4PID-14,len=112) rejected the message: 00 86 a2 40 40 40 40 60|96 68 96 88 a4 40 6c 82|92 a6 82 a8 54 60 40 40|40 40 40 40 61 03 f0 3a|43 51 2d 30 20 20 20 20|20 3a 3d 33 37 34 37 2e|36 36 4e 2f 30 37 37 33|36 2e 36 37 57 60 64 65|20 4b 34 4b 44 52 20 73|63 6f 74 74 32 33 31 39|32 40 67 6d 61 69 6c 2e|63 6f 6d 20 56 69 72 67|69 6e 69 61 20 20 46 4d|31 37 65 73 7b 31 39 35| = .CQ 0|K4KDR 6A|ISAT*0 | a..:|CQ-0 | :=3747.|66N/0773|6.67W`de| K4KDR s|cott2319|2@gmail.|com Virg|inia FM|17es{195|

    This same packet after byte by byte parsing with a simply Python script on my Mac laptop:

    @@@

    robertmachale@ucrwpa-2-1-10-25-34-138 ~/Documents/SCC/AISAT-EXPLAIN $ python explainAisat.py

    Space Communcator Club
    Las Flores, California 92688
    http://www.spaceCommunicator.club/igates/


    1: byteAsHex: 00, byteAsText: 0, byteAsAScii: 0, byteAsChar: , endOfDigipath: 0
    1: SSID: 0, Digipeated: 0
    2: byteAsHex: 86, byteAsText: 134, byteAsAScii: 67, byteAsChar: C, endOfDigipath: 0
    3: byteAsHex: a2, byteAsText: 162, byteAsAScii: 81, byteAsChar: Q, endOfDigipath: 0
    4: byteAsHex: 40, byteAsText: 64, byteAsAScii: 32, byteAsChar: , endOfDigipath: 0
    5: byteAsHex: 40, byteAsText: 64, byteAsAScii: 32, byteAsChar: , endOfDigipath: 0
    6: byteAsHex: 40, byteAsText: 64, byteAsAScii: 32, byteAsChar: , endOfDigipath: 0
    7: byteAsHex: 40, byteAsText: 64, byteAsAScii: 32, byteAsChar: , endOfDigipath: 0
    8: byteAsHex: 60, byteAsText: 96, byteAsAScii: 48, byteAsChar: 0, endOfDigipath: 0
    8: SSID: 0, Digipeated: 0
    9: byteAsHex: 96, byteAsText: 150, byteAsAScii: 75, byteAsChar: K, endOfDigipath: 0
    10: byteAsHex: 68, byteAsText: 104, byteAsAScii: 52, byteAsChar: 4, endOfDigipath: 0
    11: byteAsHex: 96, byteAsText: 150, byteAsAScii: 75, byteAsChar: K, endOfDigipath: 0
    12: byteAsHex: 88, byteAsText: 136, byteAsAScii: 68, byteAsChar: D, endOfDigipath: 0
    13: byteAsHex: a4, byteAsText: 164, byteAsAScii: 82, byteAsChar: R, endOfDigipath: 0
    14: byteAsHex: 40, byteAsText: 64, byteAsAScii: 32, byteAsChar: , endOfDigipath: 0
    15: byteAsHex: 6c, byteAsText: 108, byteAsAScii: 54, byteAsChar: 6, endOfDigipath: 0
    15: SSID: 12, Digipeated: 0
    16: byteAsHex: 82, byteAsText: 130, byteAsAScii: 65, byteAsChar: A, endOfDigipath: 0
    17: byteAsHex: 92, byteAsText: 146, byteAsAScii: 73, byteAsChar: I, endOfDigipath: 0
    18: byteAsHex: a6, byteAsText: 166, byteAsAScii: 83, byteAsChar: S, endOfDigipath: 0
    19: byteAsHex: 82, byteAsText: 130, byteAsAScii: 65, byteAsChar: A, endOfDigipath: 0
    20: byteAsHex: a8, byteAsText: 168, byteAsAScii: 84, byteAsChar: T, endOfDigipath: 0
    21: byteAsHex: 54, byteAsText: 84, byteAsAScii: 42, byteAsChar: *, endOfDigipath: 0
    22: byteAsHex: 60, byteAsText: 96, byteAsAScii: 48, byteAsChar: 0, endOfDigipath: 0
    22: SSID: 0, Digipeated: 0
    23: byteAsHex: 40, byteAsText: 64, byteAsAScii: 32, byteAsChar: , endOfDigipath: 0
    24: byteAsHex: 40, byteAsText: 64, byteAsAScii: 32, byteAsChar: , endOfDigipath: 0
    25: byteAsHex: 40, byteAsText: 64, byteAsAScii: 32, byteAsChar: , endOfDigipath: 0
    26: byteAsHex: 40, byteAsText: 64, byteAsAScii: 32, byteAsChar: , endOfDigipath: 0
    27: byteAsHex: 40, byteAsText: 64, byteAsAScii: 32, byteAsChar: , endOfDigipath: 0
    28: byteAsHex: 40, byteAsText: 64, byteAsAScii: 32, byteAsChar: , endOfDigipath: 0
    29: byteAsHex: 61, byteAsText: 97, byteAsAScii: 48, byteAsChar: 0, endOfDigipath: 1
    29: SSID: 0, Digipeated: 0
    robertmachale@ucrwpa-2-1-10-25-34-138 ~/Documents/SCC/AISAT-EXPLAIN $

    @@@

    Notice 3 issues with the Digipath:

    1) SSIDs arrive as ASCII rather than 4 bits in the AX.25 subfield
    2) The Digipeated flag arrives as * rather than 1 bit in the AX.25 subfield
    3) One extra (blank) callsign field exists at the end of the Digipath

    Although the Kenwood will pickup the packet we may need to tap into the TNC raw output to decipher the packet manually. I can only imagine the Kenwood display will reject the packets as malformed. So, this leaves us with APRSDroid, UISS, and custom APRS software for displaying packets received.

    Feel free to follow APRS packets from AISAT on our iGate report: http://www.spaceCommunicator.club/igates/

    Also, you will find a note on this AISAT issue including helpful screen shots here: http://www.spaceCommunicator.club

    Let me know your feedback and how I can help.

    Happy Easter + Passover + Holiday!

    73s

    Robert MacHale
    KE6BLR
    (949) 371-6319
    robert.machale@yahoo.com
     
    K3RLD, K4KDR and 9G5AR like this.
  2. KM6LYW

    KM6LYW Ham Member QRZ Page

    I heard it over CA today, however, n2yo said it was over India at the time? object name? The web provider suspended the site
    associated with this (http://www.amsatindia.org/cgi-sys/suspendedpage.cgi). edit: did anyone confirm the ARISS path on this? or any repeated packets?
    Edit Edit: I used ARISS and it looks like I made the map here: http://www1.findu.com/cgi-bin/pcsat.cgi However, I didn't show up on aprs.fi on account of the malformed packets (too short mic-e packet). It'd be nice if apris.fi could somehow accommodate the anomaly.

    [​IMG]
     
    Last edited: Apr 29, 2019
  3. W5SAT

    W5SAT Ham Member QRZ Page

    I was able to get repeated using the AISAT-1 path. I saw you on the pass earlier today.

    Yes, there is some discrepancy in the keps. Nasabare.txt seems accurate.
     
  4. KM6LYW

    KM6LYW Ham Member QRZ Page

    thanks...

    i followed up on the aprs.fi mailing list... they can't accomodate the malformed packets. I was hoping i coild use this for emergency SMS/email in the Sierra Nevada. falconsat3 might be the only choice... or Garmin InReach.
     

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