U3S

Live tracking
Photos of the launch
Transmitter photos

BB01 uses callsign ZL1RS and telemetry channel 02. 

Further details, please see below!


Live tracking


Photos of the launch

Pending


Transmitter photos

A few notes from Bob ZL1RS on the BB01 flight:

The tracker transmitter uses modified QRP-Labs U3S firmware running on an ATmega328 with 20 MHz clock crystal and a 3.3V supply (so well out of spec). This is controlling a modified/cut down QRP-Labs synthesizer kit ... you may recognise it (or what is left of it!) in the picture below. As well as removing the level converters, the synth kit's 27 MHz reference xtal has been replaced with a SMD TCXO. The RF power output is just under 20mW. Four 52 x 19mm solar cells produce 2 - 2.4V in good sun and feed a 3.3V boost regulator but there is no battery, so transmissions will only occur when the sun angle is ~20 degrees and higher. The GPS is mounted upside down in 'dead bug style' where the Arduino's voltage regulator components were. The antenna is a 20m dipole made from 0.15mm copper wire. The tracker TX weighs 4.7 grams and the whole payload weighs about 9 grams. The single 'party' balloon is inflated with just enough Hydrogen to give between 3.5 and 4 grams of 'free lift'.

The transmitter is sending WSPR and JT9 on the 20m band in a 10 minute cycle starting on the 4th minute (Frame Start = 10 04):

minute 04 & 05 - standard WSPR
minute 06 & 07 - encoded WSPR transmission ('channel 0x2')
minute 08 - JT9 message #CS #M6
minute 09 - JT9 message LAT #LT
minute 10 - JT9 message LON #LN
minute 11 - JT9 message ALT #AT M
minute 12 - JT9 message TLM #A0#A3#GS
minute 13 - calibration (Cal Time = 20 30)
minute 14 - repeat

The JT9 messages for latitude and longitude need some interpretation because there is no NS/EW indication sent (but the latitude will probably always be South)
The JT9 message #A0 is the temperature A-D value and will probably be in the range 140 to 240 (approx. -5 to +25C)
The JT9 message #A3 is the solar cell A-D value and will probably be in the range 620 to 715 (approx 2.0 to 2.3V but displayed as 3.03 to 3.48V, see explanation below)
The JT9 message #GS is the ground speed value which will show as 3 characters and may include a decimal point as one of them e.g. 5.8 = 5.8 kts, 32. = 32 kts, and 127 = 127 kts.

Tracking is on Habhub at https://tracker.habhub.org/#!mt=roadmap&mz=11&qm=All&f=BB01&q=BB01 (and on APRS as ZL1RS-11) (thanks SM3ULC). The 'battery' voltage shown on Habhub is an indication of the solar array output, but needs scaling down by a factor of 1.51515 due to a 3.3V A-D reference used in my configuration instead of 5V. The 'temperature' reading seems a few degrees high for some reason. The numbers for 'GPS lock' and 'satellite' should both read 1, meaning GPS lock = OK, and the number of satellites in the fix is 8 or more. If either reading is 0 this means the GPS is 'in trouble' and the balloon's position and altitude should not be relied on. The JT9 signal can be found about 70 Hz above the 20m WSPR 'band' e.g. at 1670 Hz on the WSJT-X waterfall when the RX is tuned to the 20m band WSPR 'dial frequency' of 14.095600 MHz.

Typical decodes as seen with WSJT-X:

0334 10 -1.2 14.097171 0 ZL1RS RF64 13 74
0336 -0 -0.9 14.097171 0 0V2SST BK82 40 6978

0338 -5 -1.9 1668 @ ZL1RS RF64VS
0339 -6 -1.9 1668 @ LAT 3512.536
0340 -6 -1.9 1668 @ LON 17348.662
0341 -6 -1.9 1668 @ ALT 349.4 M
0342 -5 -1.9 1668 @ TLM 2896710.1

View the embedded image gallery online at:
http://qrp-labs.com/flights/bb01.html#sigFreeIdff7defa6d6