WWCR sunrise experiment on 3210kHz
This experiment was to look for enhancements on 3.210MHz for signals arriving at right angles to the terminator from the dark portion of the earth at the local receiving station's sunrise. This is more easily seen in the model on the right.
The transmitter is the 100kW system at WWCR in Nashville Tennesse. The receiver is a Yaesu FT920 fed with an 80m loft-mounted dipole. Data gathering was via SpectrumLab using no AGC.
The data show that an enhancement can often be seen at or before sunrise, but only of the order of a few decibels. This is often shortlived or alternatively a steady growth over a period of hours.
In some cases, stronger signals were received during the nighttime period. The signals kicks in at midnight UTC when the transmitter is switched on.