1. Picoballoon Launch 11: The Intermittent Picoballoon

    We launched again on Monday, September 20th, 2021, from our usual spot in the Berkeley Marina. The launch party was Martin W6MRR and Robert K6RGG, and the launch time was a bit later than usual at 11:30am Pacific time (1830 UTC). The picoballoon did not wake up on launch day. After our previous halfway around the world picoballoon, we were a bit dismayed to have another failed launch.

    WSPR.rocks map overview

    But the following day it woke up! The picoballoon was meandering out in the Pacific Ocean in gridsquare CL79, somewhere between 9,900 and 11,100 meters (32.5k to 36.5k feet). While this is higher than most of our previous picoballoons, our ideal altitude is above 11,100 meters ...

    Read More →
  2. Picoballoon Launch 10: Halfway Around the World!

    At the beginning of Week 3 of Launch 10, we were getting excited that this balloon might circumnavigate the globe. The prediction made from the middle of Egypt showed strong winds would take the balloon to the West Coast within 5 days, maybe even crossing the -122 degree longitude line of our launch site before heading back out to sea.

    HYSPLIT trajectory forecast

    Flight Results

    Unfortunately, the picoballoon only survived two more days in the Middle East. In a situation eerily similar to W6MRR-17, a single packet was received from the ground in southwest Uzbekistan near the Turkmenistan border. The altitude reported was less than 900 meters (encoded in the WSPR power field as 0 dBm or 1 mW). Maybe the tracker was ...

    Read More →
  3. Picoballoon Launch 10: First Two Weeks

    After the previous three picoballoons did not turn on, we were really struggling to launch another. Was it worth it to build trackers, inflate balloons, and get up early to launch a balloon that never turned on? Luckily, we powered thru and launched another picoballoon on Saturday, Sept 4th, 2021, from our usual spot in the Berkeley Marina.

    The team met at 9am, which is a bit later than usual. It was still very cloudy, so the actual launch didn't happen until 9:50am Pacific time (1650 UTC). The launch party was Martin W6MRR, Rob NZ6J, and Robert K6RGG.

    Tracker electronics

    Tracker electronics

    The tracker was released in full sunlight without getting wet in the bay.

    Predictions

    Running HYSPLIT predictions on the morning of ...

    Read More →
  4. Receiving Monterey Bay Radiosondes

    Taking a look at SondeHub one evening in early July 2021, I noticed some radiosondes down in the Monterey Bay, about 75 miles south of San Francisco. There seemed to be one per day in the afternoon on most days. The Naval Postgraduate School launches radiosondes very infrequently for their meteorology program, but these seemed to be launched from Watsonville or Salinas, not the main NPS campus in downtown Monterey.

    Early July 2021 Monterey radiosondes

    Then, on Monday July 12th, there was a flurry of radiosondes launched. I received a total of 5 of them from my station in Los Gatos. This station does not have good coverage in the direction of Monterey, and only starts receiving radiosondes when they rise up to 5,000 ...

    Read More →
  5. Picoballoon Launch 9

    With the lessons learned from the failed previous launch, we decided to launch again the next weekend, August 28th, 2021. The launch party was Martin W6MRR, Justin, Robert K6RGG, and myself KF6ZEO. We launched again from the northwest corner of the Berkeley Marina.

    Our major lesson learned from the previous launch failure was there should be no fog or clouds at the launch site. Fog or clouds can condense on the balloon surface or tracker electronics, weighing down the picoballoon so it falls out of the sky. In addition, any winds or downdrafts associated with clouds can push the balloon into the ground.

    This morning there was no fog or clouds, but the smoke from the Caldor and Dixie fires ...

    Read More →
  6. Picoballoon Launch 7 and 8

    After a short break from the previous launch, we launched again on the morning of Saturday August 14th, 2021. The launch party was Martin W6MRR, Robert K6RGG, and myself KF6ZEO. We launched again from the northwest corner of the Berkeley Marina.

    Martin W6MRR had made some changes to the tracker PCB layout to try and mitigate GPS RFI issues, but since none of the standard layout changes made were helping at all, we decided to use an older board design that flew previously. We also decided to bring two trackers. Each tracker was identical electronics and balloon inflation, just different callsigns.

    Both trackers getting checked out before launch

    Robert K6RGG brought his drone again and took some great video of both launches.

    Launches

    After powering on and ...

    Read More →
  7. Containerized AIS Decoding with RTL-SDR Dongle

    It's been about 6 months since I started receiving AIS signals using a RTL-SDR Blog v3 dongle. My station is decoding between 35 and 70 ships at any given time, depending on time of day and how many ships there are in San Francisco Bay.

    The RTL-SDR Blog v3 dongle is a really inexpensive software-defined receiver. The "official" version costs about $25, and knockoff versions can be had for $10 or less. However, there's a reason why knockoff versions are less than half price, they use very cheap components and drift like crazy. I have many friends who bought the cheap version only to find that they just don't work, then purchased another knockoff that also didn't work. So save ...

    Read More →
  8. Kenwood TS-2000 Frequency Calibration

    I've been spending a lot of time recently listening to WSPR beacons. The recent picoballoons that I have launched all used WSPR for to transmit their location and altitude. WSPR is a great for solar-powered picoballoons because the transmit power is on the order of 10 dBm (10 milliwatts), which is extremely low.

    One night, I was just passively watching the WSPR decodes while doing other things on my shack computer. Every once in a while, I would notice a WSPR beacon that was outside of the 200 Hz WSPR band, and therefore wasn't decoded by WSJT-X. I thought this was interesting, who was transmitting out of the band? The transmissions seemed to always be on the high side.

    This ...

    Read More →
  9. Picoballoon Launch 6

    After the dissappointing results from the last balloon, we decided to respin the boards to try and fix this GPS self-interference problem. We also decided to add a low-pass filter to try and keep the WSPR transmitter harmonics out of the GPS band. The new boards did not arrive in time for the Memorial Day weekend, so we decided to launch anyways.

    After a day delay due to strong winds and high altitude clouds, we launched on the morning of Sunday May 30th 2021. The weather was beautiful. The launch party was Martin W6MRR, Robert K6RGG, and myself KF6ZEO. We launched again from the northwest corner of the Berkeley Marina.

    Bryan KF6ZEO tying the tracker to the picoballoons. Picture by K6RGG

    Martin W6MRR and Bryan KF6ZEO unspooling the 20m antenna. Picture by K6RGG

    The winds were gusting to 5 knots or so, and ...

    Read More →
  10. Two Radiosonde Recoveries in San Francisco

    The prevailing winds here in California blow from west to east, from the Pacific Ocean towards the Sierra Nevada mountains. Radiosondes launched from Oakland International Airport float in these winds, landing east of Oakland in the Central Valley, or south in the hills east of San Jose. I never recover the ones that land in the Central Valley, as driving 2 hours each direction during rush hour to recover a balloon is a bit too far for me. Only rarely do they land in populated areas in the Bay Area, and almost never on the Peninsula or in the city of San Francisco.

    This map (code below) shows the landing locations of all the radiosondes launched from Oakland since November ...

    Read More →

« Page 3 / 5 »

links