vendredi 10 juin 2016



Thomas KT5TK and I are going to launch a balloon on Saturday here in Berlin. It will be a 250g-Latex Balloon which we attempt to let float.
I have no idea if it works or not. We will see...

We will attach one of our Pecan Pico 7b SSDV tracker to the balloon.

Callsign: DK0TU-11
Launch Site: Berlin
Launch Time: June 11th 2016 - 15:30 UTC (17:30 local)
Expected runtime: at least 2 days, maybe 4 days
Tracker weight: 48g (with batteries)

We will do Normal APRS every Minute but also our Special APRS/SSDV transmission. We run a special Software which picks up the packets from the APRS-IS and send them to Habhub. The APRS/SSDV packet is based on the original SSDV format, but we removed the Sync byte, CRC and FEC since we don't need it in an AX.25 frame which already contains a CRC. The packet is also base91 encoded since some characters collide with the APRS specification.

144.800 MHz Normal APRS (Cycle 1min)
144.800 MHz SSDV/APRS 1k2 (resolution QVGA, low duty cycle, ~1 picture every 30min)
144.860 MHz SSDV/APRS 9k6 (resolution VGA, packets sent twice, ~1 picture every 2min)

For 9k6 APRS/SSDV receiption there are two options of sending them to Habhub/ receiving the packets:

1. Use a ordinary 9k6 TNC and software which igates the packets to the APRS-IS. We can pick up the packets from the APRS-IS and send them to Habhub.
IMPORTANT: The image packets have a special flag (User defined, experimental) We know some programs which don't relay "User defined"-packets to the APRS-IS. Unfortunately this includes Xastir. I recommend Direwolf.

2. I've written a software for Windows which can Igate the received packets to Habhub directly without using the APRS-IS. It's based on rtl_sdr (Demodulation) and Direwolf (APRS Decoder) which can be used with an RTL SDR. I've written a short description how to use it on Github. The binaries can be downloaded here:
Please send me a mail, if there are bugs.

All pictures will be displayed on the SSDV page:

Thomas and I are not going to retrieve the balloon immediately (if it goes down) since the balloon is part of an exhibition here in Berlin (Lange Nacht der Wissenschaften, eng. Long night of science) an we probably have a lot of visitors, so we can't leave. We might do a rescue operation on Sunday. If there's someone here in Berlin who want to take place at the Launch:

Address: Strasse des 17. Juni 137 (TU-Berlin Hauptgebaeude)
Go up to 9th floor. Look for "Amateurfunk" signs.
There's an entry fee to this exhibition. If you enter the building early enough you might avoid the fee (14€, Students 9€). :P

Float Prediction:!/uuid=a811cd0274c5796f23db1c97030553e455d0e918
Burst Prediction:!/uuid=2bafdb94bfa63d98cf3a7acf696dec03dd694045

Regards Sven
Source directe :  UKHAS
From : Alan F6AGV  -  BHAF  -

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