2023 Solar Eclipse TDOA Event
The October 14, 2023 annular solar eclipse offers a unique opportunity to study an eclipse's effect on how long it takes radio signals to propagate via the ionosphere, as it is affected by a solar eclipse. This is known as a Time of Flight (TOF) study. The science question we hope to answer: Does the radio wave propagation time, from one location to another, change during an eclipse? We will be looking for a Time Difference of Arrival (TDOA). Numerous papers and presentations on previous TOF and TDOA studies are footnoted below.
HamSCI is actively recruiting dozens of stations capable of transmitting, receiving and recording WAV files on 40, 75 and 160 meters using SSB signals during the eclipse. If you are interested in participating, or if you have more questions, please contact (xxxxxxxx@xxxx).
Preparation - Before the Solar Eclipse
-
Pre-Register (need form and a link) as a TDOA Event participant. There is no obligation for pre-regist - we simply want to see how well stations are distributed across North America prior to the event.
-
Verify that your station can cleanly transmit and/or receive WAV files. A sound card interface (eg SignaLink, microHAM), or a radio which appears as an audio device over USB (e.g. Icom 7300, 7610, Elecraft K4 series, Kenwood TS-590SG) will work equally well.
-
For transmitting stations, visit this GitHub site, run binder and follow the instructions for generating a 'chirp file' (sample below) with your callsign and Maidenhead grid square embedded in Morse code. binder runs 'in the cloud' - the only thing you need to download is the resulting files (WAV and CSV).
-
For receiving stations, prepare a directory on your shack computer for storing the WAV files (which will ask to be manually uploaded to the HamSCI/TDOA data data repository after the eclipse).
-
Plan your solar eclipse operating around the time when the eclipse path is closest to your QTH. GreatAmericanEclipse.com provides detailed path information
-
Join the WWV-H Science HamSCI Google Group so you can receive announcements from the principal investigators of this experiment
-
Sample test signal (WAV file) consists of a callsign and Maidenhead grid locator, each sent three times in Morse code, followed by the chirps. We suggest right clicking this link, and choosing 'Open in a new browser tab (or window)': SEQP Test Signal for AF8A in EN91GN
General Methodology
- Participating stations will be asked to work in pairs or small groups.
- QSOs will established between at least two members of the group (others can simply listen, recording the chip audio, or they may choose to transmit their own chirp signals for others to receive/record, as in a 'roundtable' QSO.
- A chirp waveform will be transmitted from one station to another multiple times during the solar eclipse period. (Use enough power to consistently maintain a good signal.)
- Options: One station does the chirp transmitting (T), the other(s) the receiving/recording (R). Even better would be to alternate: Station A transmits, Station B receives. Then, Station B transmits and Station A receives
- Multiple T/R sessions are needed throughout the eclipse period. A station should be prepared to transmit a chirp signal every 6 to 10 minutes, over 2 or more hours - for at least an hour prior to maximum annularity near your QTH, and for at least an hour after.
- Save received files with callsign, date and time stamps in their names (eg W5XXX-14 Oct-1650Z.WAV)
- Help the HamSCI science team with the results analysis - we'll gladly teach you how!
Test Runs
Eclipses are infrequent events. Opportunities to study them are few and far between, so we need to be fully prepared for eclipse day. HamSCI strongly encourages all TDOA participants, especially transmitting stations, to join us in a 'dry run' approximately one month before the actual eclipse. This will give everyone a chance to check out their hardware and software, make adjustments and updates, well in advance.
Proposed Test Run: September 16, 2023, at 2000 UTC. Details have not been finalized. Participants will be notified well in advance.
Reporting Results
The research community uses various public databases to store data collected in these events. They allow for open access, and long-term (many years') storage. Once the database has been chosen and upload procedures established, they will be shared with all participants and detailed here.
Scoring and Post-Event Recognition
Unlike other the other events to be held during the Festivals of Eclipse Ionospheric Science (add link), the TDOA Event is not a competition. All participants will be acknowledged via listings on the HamSCI website. There is the possibility that one or more participating stations will receive mention in future studies, presentations and research papers. Regardless, everyone will earn the gratitude of the ionospheric science community. Only through experimentation, data gathering, rigorous analysis and sharing of results can we make progress towards understanding the physical world in which we live and operate our stations.
Background and Further Study
https://hamsci.org/publications/estimation-ionospheric-layer-height-changes-doppler-frequency-and-time-flight
