Older articles:


  1. Fairbanks Radiosonde Autolauncher

    On the last day of my recent trip to Fairbanks, Alaska, I finished up work a bit early and headed to the airport to see a radiosonde launch. Looking at satellite imagery before my trip, the launch location has a few buildings so I thought it might be a manually-launched site like Inuvik or Newfoundland.

    However, when I arrived, through the fence I saw a Vaisala AS41 autolauncher, just like my local radiosonde launch site across the bay in Oakland, California. No one to talk with this trip.

    Fairbanks Vaisala autolauncher

    I arrived just before 3pm local time (2300 UTC), and the autolauncher was beeping away, indicating that the balloon was filling with hydrogen. I set up my mobile radiosonde_auto_rx station ...

    Read More →
  2. Houston TRACER Radiosondes

    Back in October 2021, the excellent team behind Sondehub added several features to the map. They added launch site locations, grabbed from the official NOAA database. Clicking on a particular launch site allowed a user to generate a weeks worth of flight predictions based on the most recent GFS run. Cool!

    Oakland airport launch predictions

    The red lines on this prediction map of Oakland show the next 14 launches (7 days). As with any prediction of the future, the further out you go the worse the prediction.

    Reverse predictions (pdf) were also added, for predicting where a radiosonde was launched from. This feature would have been very helpful when I was trying to find the Monterey Bay launch location.

    Scrolling around the new map ...

    Read More →
  3. Inuvik Radiosonde Launch

    Now that the pandemic has tapered off a bit, I took another short trip up to Inuvik, NWT. While I was up there, I visited the Environment Canada Weather Station, and participated in a radiosonde launch.

    Dempster Highway sign

    The big news out of Inuvik during this trip was that the road from the airport to the town has been paved! The road is much smoother, and I don't need to worry about windshield cracks every time a big truck passes.

    Since my 2016 visit, the site has been upgraded with modern equipment. The old Electrolyser Corporation hydrogen generator was replaced with a Proton Hogen unit, all housed in a modern building with explosion-proof light switches, electrical outlets, etc.

    Hogen Hydrogen Generator

    I arrived just before ...

    Read More →
  4. SOTA Activation of Vollmer Peak, W6/NC-298

    The San Francisco Radio Club organized another Summits on the Air event on 23 April 2022. For this "Simul-SOTA" event, there was 11 amateur radio operators activating 9 summits around the Bay Area. Steve W1EGG made a handy map with who was activating each peak:

    Simul-SOTA activations

    I activated Vollmer Peak, which is at the southern end of Tilden Park in the hills above Berkeley. Parking at the trailhead was easy in the morning, but by the time I left parking was nonexistent.

    The hike up was short, and the views were excellent. I could clearly see Mt. Tamalpais across the bay, which was activated by Vlad K6VVP.

    Hike up Vollmer Peak

    A lot of the other peaks that were activated that morning were visible from ...

    Read More →
  5. Automated Recording of the HamSCI WWV/WWVH Science Signal for Sunrise Festival

    I'm planning on participating in the Sunrise Festival, which is a citizen science campaign run by the HamSCI group. Over the 30 April 2022 weekend, hams from all over North America are encouraged to record the WWV and WWVH Scientific Test Signal, transmitting at 8 and 48 minutes past the hour.

    I previously used my KiwiSDR to receive these signals, and luckily there is an easy API for the KiwiSDR that will allow us to save recordings from the SDR.

    kiwirecorder.py

    kiwirecorder.py, written by John Seamons ZL/KF6VO, is a simple python program that remotely connects to a KiwiSDR and saves spectrum locally. The output file can be demodulated audio (SSB or AM) like you get from a ...

    Read More →
  6. Receiving the HamSci WWV Scientific Test Signal

    I was perusing the latest edition of QST and noticed a short article on some scientific experiments that hams were doing with WWV and WWVH. I tune in to WWV occasionally to check propogation, and also for frequency calibration of my Kenwood TS-2000.

    April 2022 QST article on WWV science

    Wow, this seems cool! The HamSCI WWV webpage has a bunch of information, including a great presentation by Kristina Collins KD8OXT.

    Receiving the Signal

    I recently added a KiwiSDR at my home station, so I twisted the dial over to WWV (in software, pretty anticlimactic), and started listening. I barely heard the test signal from Hawaii because propagation that evening was very poor. There was several solar flares over the next few days, causing lots of interference ...

    Read More →
  7. Simultaneous Multi-Band WSPR Decoding with KiwiSDR and WsprDaemon

    I've been interested in receiving Weak Signal Propagation Reporting (WSPR) signals recently, for two reasons. The first is that the picoballoons that we launch use WSPR for position information. Not only do I directly receive the picoballoons after we launch them, but I also use the WSPR network to check on their location around the world. I don't have a receiver in Europe, so I rely on other amateur radio operators to receive the balloon and post its location online, and I want to give back to the network.

    The second reason is that I'm curious about how far I can receive signals with my somewhat compromised city antenna. While my fan/parallel dipole antenna will never perform as well ...

    Read More →
  8. Building a Multi-band Fan/Parallel Dipole Antenna

    Now that Solar Cycle 25 is upon us, I wanted to get active on the HF bands. My primary bands of interest are 40 and 20 meters, so I wanted to build a multi-band antenna for these frequencies. After some research, and wanting only one antenna connection for my Kenwood TS-2000 radio, I settled on a fan/parallel dipole antenna. It's very simple to build, and really hard to beat the performance of resonant dipoles.

    Choke Balun

    A balun is required when you are interfacing a BALanced device, such as a dipole antenna, to an UNbalanced device, such as a coaxial cable. Coaxial cables are unbalanced because from an RF perspective, there are actually 3 conductors in a ...

    Read More →
  9. Building a Quarter-Wave Ground Plane Antenna

    After my talk at Pacificon a few months ago, several people reached out to me about setting up a radiosonde receiving station at their house. They specifically had questions about the antenna and LNA, and after answering the same question a few times I decided to do a post about this topic.

    Building a 1/4 wave ground plane antenna is very easy to do. The overall design is simple, with a vertical element surrounded by a ground plane consisting of two or four wires bent down. Here are the dimensions for the VHF/UHF amateur radio bands (from the ARRL Handbook), but these dimensions can be scaled to any frequency.

    Quarter wave vertical antenna construction diagram

    There are many online calculators that will give you ...

    Read More →

Page 1 / 5 »

links