Falconsat?

Discussion in 'Satellite and Space Communications' started by K3RLD, Sep 22, 2017.

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  1. K3RLD

    K3RLD Ham Member QRZ Page

    What is falconsat (as listed on the Amsat status page)? I can only find reference to USAF academy projects from several years past.
     
  2. KO4MA

    KO4MA Ham Member QRZ Page

    Watch ANS this weekend.
     
    WD9EWK and K3RLD like this.
  3. K3RLD

    K3RLD Ham Member QRZ Page

    Suspense!
     
  4. K3RLD

    K3RLD Ham Member QRZ Page

    Beans have been spilled on twitter. I'll leave it at that.
     
  5. KA2CZU

    KA2CZU XML Subscriber QRZ Page

    FalconSat-3 produces over 200 new Radio Amateurs
    The US Air Force Academy satellite FalconSat-3, launched in 2007, has resulted in over 200 academy students becoming Radio Amateurs.

    FalconSat-3 carries a 145/435 MHz digital store and forward transponder supporting data rates of 9k6, 38k4, or 76k8.

    The plan is to make the satellite available for general Amateur Radio use once the primary mission had been completed.

    The Project Oscar UK website carries a news update on this satellite, read all about it at
    http://wordpress.projectoscar.co.uk/?p=720

    FalconSat-3 on IARU Satellite Coordination Pages
    http://www.amsatuk.me.uk/iaru/
    finished_detail.php?serialnum=21
     
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  6. WD9EWK

    WD9EWK Ham Member QRZ Page

  7. WD9EWK

    WD9EWK Ham Member QRZ Page

    Hi!

    If you looked at the link in my previous post, you would have seen answers to many questions about FalconSat-3, including some of what we can't do with the satellite. It's an orbiting mailbox (store-and-forward system for messages and files), as well as a digipeater. If your radio - or radios - can do packet cross-band, you can use FalconSat-3 as an APRS digipeater. The packet path is "PFS3-1", or for traditional TNCs the UNPROTO path will be something like "CQ VIA PFS3-1"..

    It appears that the full-duplex capable Kenwood APRS radios (TH-D7, TH-D72, TM-D700, TM-D710) should be able to work the digipeater without using a second radio or external computer. You will need to set the TNC to transmit from one VFO and receive from the other. To help 9600bps performance, activating the DUP function to operate full-duplex helps, since your radio will already be receiving whenever it stops transmitting. This means you'll also have to transmit and receive from certain VFOs to support full-duplex operation, just like you would for working AO-85 or SO-50 (i.e., with a TH-D72, transmit from VFO B and receive from VFO A when DUP is activated).

    Since all of these radios tune in at least 5 kHz steps, there are times during the FalconSat-3 passes where the radios won't decode 9600bps packets on the 70cm downlink. There really isn't much you can do, other than wait for the Doppler shift to move the downlink closer to the next 5 kHz step on the radio. SDR receivers and software make the concept of 5 kHz tuning steps irrelevant. More on that coming up...

    Here's a screenshot where I was decoding the RF recording I made during the FalconSat-3 pass tonight at 0218 UTC (7.18pm PDT Friday evening)...

    20170923-0222UTC-Decoding_FalconSat3.jpg

    I connected HDSDR through a virtual audio cable to UZ7HO High-Speed SoundModem to decode the 9600bps AX.25 packet. The HDSDR recording was made with an SDRplay RSP1 receiver connected to my 8-inch Windows 10 tablet running HDSDR. You may be able to see WD9EWK and KB6IGK in the Soundmodem window of the screenshot. We both were digipeated by FalconSat-3 during this pass.

    This shows two of the screens from one of my TH-D74s that received a WD9EWK packet through FalconSat-3:

    WD9EWK-D74.jpg


    For this pass, I used one Kenwood TH-D74 to transmit on 145.840 MHz, and two radios simultaneously listening on the 435.103 MHz (+/-) downlink: another TH-D74, and an SDRplay RSP1 receiver along with HDSDR running on an 8-inch Windows 10 tablet. Antenna was an Elk Antennas 2m/70cm log periodic, connected through an MFJ MFJ-916B 2m/70cm diplexer, and an ApexRadio SPL-2 splitter to have two 70cm receivers on that side of the diplexer. Eventually, I will eliminate the second TH-D74 and ApexRadio splitter, and just use the UZ7HO software along with HDSDR on the 8-inch tablet. I could possibly use just a TH-D72 connected to a tablet in KISS mode and use the 9600bps TNC in that radio, but that's another project for another time.

    Here are a couple of pictures of my setup in the yard for this pass...

    IMG_20170922_191146689.jpg


    IMG_20170922_191210608.jpg



    I had been testing FalconSat-3 along with a few other AMSAT people for a few days, so it was a really nice surprise to see another call sign coming through - and not just the PFS or PCTRL call signs from the satellite's orbiting mailbox. This satellite was not specifically designed as an APRS satellite like the digipeater on NO-84, so there won't be lots of beacons/packets from the satellite that the APRS-ready Kenwood or Yaesu radios will display on their screens - unless more stations are on and using the digipeater. Also, the downlink transmits continuously. This made it easy to track the Doppler shift on the 70cm downlink, and HDSDR's AFC function could also track the downlink.

    AMSAT has configured FalconSat-3 to transmit a message to the US Air Force. From the packet capture on the 0218 UTC pass tonight...

    Capture.JPG

    I have more files from FalconSat-3 passes I worked on my Dropbox space at http://dropbox.wd9ewk.net/ (look in folders "20170922-FalconSat3-DM43" and "20170923-FalconSat3-DM43").

    73!
     
    K6CLS, KI4LXB, KD6RF and 2 others like this.
  8. K3RLD

    K3RLD Ham Member QRZ Page

    While my D710 has instructions for operating packet in full duplex, all I can find in reference is when you are operating it in KISS mode. No matter, it has an option for Rx on "A-band" and Tx on "B-band", so I will be giving FalconSat a go later this afternoon (eastern time). Looks like the sat's orbit pretty much restricts me to passes of no higher than about 40 deg, but that should be plenty knowing how strong this sat is supposed to be.

    *I forgot to check to see if I could program a cross band memory - I'll try that out later today if I have time. Otherwise the split screen with Rx and Tx on the two "bands" should operate no worse than a single "band" cross-band memory.

    I wonder if the internal TNC is setup to operate in full duplex by default... is the satellite capable of full duplex?
     
  9. WD9EWK

    WD9EWK Ham Member QRZ Page

    Good luck with programming a single memory with RX and TX in different bands. Kenwood seems to avoid that, just like Icom, in its radios. And, as with other full-duplex operating, that sort of memory programming defeats the purpose of full-duplex operation.

    Not sure, but that could be more of a function of the radio, and the TNC will work with however you configure the radio.

    The satellite transmits a constant downlink on 70cm, and we use a 2m uplink. If I remember this stuff correctly, almost everyone using an orbiting store-and-forward system was working full-duplex, so the answer to your question above would be "yes".

    As the satellite is set up to process commands from many stations, I think you would be best served by trying to work it full-duplex - even for the digipeater - if you have the radio(s) to do that.

    73!
     
  10. K3RLD

    K3RLD Ham Member QRZ Page

    Wow! Like nothing ever before..... some observations:

    1) Packets come in fast and continuously. Most are not APRS, so my D710 just lists "??PFS3-1".
    2) The D710 TNC does NOT operate in full duplex as default. This is a big problem, because the downlink is so strong I cannot force squelch to close by turning squelch all the way up. The Tx side of the radio will NOT send a packet until both squelches are closed. I got around this by cranking the Rx VFO 2 or three positions below (or above) required to "lose" the downlink and close squelch. Then my packet would be sent. Hopefully I can figure out how to set the thing to full duplex tnc (if possible - the manual seems to suggest it is possible as Patrick noted).
    3) Absolutely "lost" a good signal between doppler changes. Too bad, not much I can do about that.

    Looks like Paul got my beacon, and I got this from him:

    20170923_152307.jpg

    [edit]
    Just checked satgate logs, no joy. But, expected. I'll let it run for the remainder of today at the nominal frequency, to see if I can get anything, and then I may try +/- 1 or 2 kHz to see if that helps (this made a big difference when I was experimenting with the UHF ISS digi, so might help here - only fundamentally limited by sat elevation I think)
     
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