Fallen's experiments will be carried out February 19-22.
“This time my experiments will largely focus on artificial radio-induced airglow that potentially can be photographed from nearly anywhere in Alaska — weather permitting,” Fallen told ARRL. “I plan to start and stop each experiment block with an audio Luxembourg-style broadcast — transmitting two amplitude-modulated carrier waves at different frequencies separated by about 1 MHz, with the resulting skywave signal being a mix of both frequencies.”
Fallen said that he has prior success reproducing the “Luxembourg effect” using two DTMF tones. “But this time, I have a short simple musical composition recorded by a local musician,” he said. “It was composed specifically to take advantage of the Luxembourg effect.”
According to UAF, Fallen, an assistant research professor in space physics, will create an “artificial aurora” that can be photographed with a sensitive camera within Alaska. The phenomenon has been created in the past above HAARP during certain types of transmissions.
Just which HF frequencies Fallen will use won’t be determined until shortly before he begins his research. “The specific frequency chosen during a particular experiment depends on the experiment’s objectives, FCC regulations, and ionospheric conditions at the time,” Fallen explained. He will use ionosonde data to guide frequency selection.
In an explanatory blog, Fallen explains that HAARP scientists use the ionosonde to estimate two important parameters: (1) the amount of low-level ionosphere D-region HF radio absorption that frequently occurs due to natural, but not well understood, processes that prevent HAARP radio wave energy from reaching the higher ionosphere E and F regions; and, (2) the ionosphere vertical “critical frequency” [sometimes referred to as foF2], above which any radio transmissions pass through the ionosphere into space rather than being reflected or absorbed.”
Fallen said experiment times and frequencies for his airglow and Luxembourg experiments will be updated on his blog and on his Twitter account linked in the blog. He encourages radio amateurs and SWLs to record the events they hear and post reports to social media or e-mail him.
Built and operated by the US Air Force until August 2015, HAARP includes a 40-acre grid of antennas and a very high-power array of HF transmitters to conduct ionospheric research. Scientists later this month will use HAARP to conduct other experiments that will include a study of atmospheric effects on satellite-to-ground communications and over-the-horizon radar experiments.
About HF radio transmissions from HAARP
HAARP is essentially a large powerful radio transmitter, similar in some respects to commercial large radio stations and radar installations. Unlike a commercial radio station, where radio (electromagnetic) wave energy is usually radiated in all directions to reach the largest possible audience, most of the HAARP radio wave energy is radiated in a relatively narrow beam, steerable by approximately 30 degrees off the vertical direction. Another unique feature of HAARP is that it can be tuned to transmit at any legally allowed radio frequency between approximately 2.7 and 10 MHz, or even two frequencies simultaneously. Radio waves in this HF band can often propagate large distances, sometimes completely around the Earth, by successively reflecting off the ionosphere, the Earth surface, and the oceans. (Radio waves with higher frequencies usually do not reflect from the ionosphere and simply pass through to deep space.)
Example audio recordings of HAARP radio broadcasts
73 - Petr, OK1RP