December 2020 Eclipse Festival of Frequency Measurement

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Spanish: Español
Portuguese: Portugués

Calling all stations: Join us for
The December 2020 Eclipse Festival of Frequency Measurement

9 December 2020 0000 to 16 December 2020 2359 UTC


Changes in ionospheric electron density caused by space weather and diurnal solar changes are known to cause Doppler shifts on HF ray paths. For example, see Figure 7 in Boitman et al., 1999. HamSCI's first attempt at a measurement of these Doppler shifts was during the August 2017 total solar eclipse.  We plan a careful measurement during the 2024 eclipse. As part of the WWV centennial, 50 stations collected Doppler shift data for the original Festival of Frequency Measurement, demonstrating the value of volunteer participation in collecting this data. During the June 2020 Eclipse Festival, we enlisted participants around the globe and experimented with different data collection protocols.  This winter, we request that all amateur radio stations, shortwave listeners, and others capable of making high-quality HF frequency measurements help us collect frequency data for the December 14 total eclipse.

Contact information:

Kristina Collins:

Research Questions

  • How do the propagation paths of shortwave time standard stations vary over a calendar day?
  • What properties of the ionosphere are we able to measure by observing the variation in these HF propagation paths?
  • What effect will the eclipse have on these propagation paths?
  • How do various measurement techniques for understanding the path variation compare?
  • Is there volunteer interest in collecting data in the regions near totality for this eclipse?


  • Promote international goodwill by working with citizen scientists around the globe
  • Measure Doppler shifts caused by space weather's effects on the ionosphere.
  • Use a specified measurement protocol available to amateur radio operators and other citizen-scientists.


  • Practice Runs: 21 November 20200000 – 2359 UTC, 5 December 2020, 0000 – 2359 UTC 
  • Data recording starts: 9 December 2020, 0000 UTC
  • Data recording ends: 16 December 2020,  2359 UTC


Please begin measurements before the day's start time and end them after the finish time, if possible.

The Beacons


There are multiple time standard stations which can be heard in South America. The Brazilian station PPE (10 MHz) will be the primary beacon for this experiment. You may also pick up signals from the Venezuelan station YVTO (5 MHz), the Argentinian station LOL (10 MHz), WWV, WWVH and BPM. This experiment will use only the 10 MHz transmissions. If you can't get a good signal on 10 MHz, record another frequency and make sure the file is labeled appropriately. The recordings in this experiment are expected to show formations of the D-layer at stations' local sunrise and other daily events of the ionosphere, and the effects of the eclipse. Space weather varies day to day and some features may be prominent.  We'll see what we get!




1) Sign up on the Interest List

Fill out the survey here to sign up for the email list. You will receive occasional updates and reminders. 

2) Prepare Your Receiver

Use your most stable receiver. If you have a GPSDO or other precision frequency standard, please use it. 
To tune your radio:
  • Tune your radio (in AM mode) to the carrier signal.
  • Set your receiver's mode to USB (upper sideband). For a 10 MHz carrier, tune to 9.999 MHz (9999.000 kHz - see image) and listen for the 1000 Hz tone. This is the main thing we'll be looking for when we analyze your data. 
  • If you have an adjustable filter in your receiver, set it as close to 2.5 kHz as possible.

We will be advising most participants to use an 8kHz sampling rate in the section below. If your radio is relatively new (manufactured after the year 2000 or so) that should be just fine. If you're running an older radio, however, your filters may not have a sharp enough cutoff. (You can see this process in a video here.) To check the filter bandwidth on your receiver:

  • Tune your radio (in AM mode) to the carrier signal.
  • Set your receiver's mode to USB (upper sideband). For a 10 MHz carrier, tune to 9.999 MHz (9999.000 kHz - see image) and listen for the 1000 Hz tone. Tune down to 9.998 MHz and listen for the higher 2000 Hz tone. Finally, tune down to 9.997 MHz and see if you hear a 3000 Hz tone. If you don't hear a strong carrier signal, you're fine - stick with 8 kHz. If you do hear the tone, you may want to use a higher sampling frequency in Step 5 below. 22050 Hz is a pretty good bet. You can gauge the filesize for different settings here

3) Prepare Your Computer and Software

1) Connect your radio to your computer sound card. 
If you're controlling your radio via fldigi or flrig, you alreay know how to do this. Instructions will vary by radio. If you need a USB sound card, we recommend this one:
2) Download Audacity. 
Audacity is a well-established open-source program for audio recording. You can download it here:
If you're working in a language other than English, you can set it using Edit > Preferences > Interface Options. 
3) Set up Audacity metadata. 
Download this XML template and make a note of the directory it downloads to: EclipseTags.xml
Under Edit>Metadata, click "Load" and select the file, then edit it to fit your station.. (You can also add metadata manually using the list below.)
In Audacity, go to Edit > Metadata and fill in the following metadata fields: 
  • Under Artist Name, put your callsign. (If you are a shortwave listener and not a ham, please use your name or SWL callsign.)
  • Under Album Title, put "December 2020 Eclipse."
  • Under Year, 2020.
  • Under Genre, put your radio model. 
Add and fill in the following metadata fields. 
  • Email Address
  • Rig
  • Antenna
  • Sound Card
  • Frequency
  • AGC (on or off)
  • Latitude (please use decimals, not minutes and seconds!)
  • Longitude 
  • Elevation (m)
  • Time zone (Format example: UTC-05:00)
  • Grid Square
  • Country

IMPORTANT: If you have multiple radios collecting data simultaneously under a single callsign, add a hyphen and station number for each station wherever you would otherwise use the callsign. For example, if station W8EDU is running data collection simultaneously on a Flex radio and an Icom radio, they should label one as W8EDU-1 and the other as W8EDU-2, include a comment in the metadata for each station explaining that the operator ran multiple stations, and make sure that the metadata is correct and complete. This will make it much easier to sort through the data from the experiment during the analysis phase. 

Hit "Save" and save the XML file, then hit "Set Default." 
Check the box that says "Don't show this when exporting audio," then hit "OK." 
4) Set recording preferences.
Open the Recording tab under the Preferences menu (Edit > Preferences > Recording). Uncheck "Play other tracks while recording" and check "Record on a new track" and "Detect dropouts." 
Under "Name newly recorded tracks," type your callsign, then a single underscore, then the letter corresponding to your time zone on this list: []
For example, the station W8EDU is in Eastern Standard Time (UTC - 05:00), which corresponds to the letter R, so the correct custom track name is "W8EDU_R_". (If you're in a fractional timezone, use the letter J.) 
Make sure the boxes for "System Date" and "System Time" are also checked. When you're done, the window should look like this: 
Under "Quality," set "Default Sample Format" to 16 bits. Set "Default Sample Rate" to 8000 Hz (unless your receiver requires a higher rate, as described in Step 2 above).  
Go to "Devices" in the Preferences menu and make sure you are recording from your radio, as opposed to your computer's microphone or another source. 
When done, click OK.
5) Set recording settings and make a test recording.
Set your recording to Mono (1 channel) on the pulldown menu in the middle of the top toolbar.
Make sure your project rate is set to 8000 Hz from the pulldown menu in the bottom left corner of the screen.
Set your audio input to the sound card connected to your radio. The device names will vary. You may have to experiment to make sure the source you're recording from is the correct one.
Hit the record  button; you should see the first track start recording, with the correct track name and timestamp. If the track name is not correct, try rebooting your computer and recording again.
Hit stop ⏹️, then record  again. This time, you should see a second track appear. The name on each track will correspond to its start time.