(Feb 23 2000)
On this page you can see some images showing the signal transmitted by SM5FRH, Tobbe and received by me, SM5BSZ, Leif via reflection off the moon. The transmitted signal is a carrier of several minutes duration It was received in stereo with 20kHz bandwidth and recorded on a DAT recorder. The first figure shows the signal spectrum in several different ways side by side. The ground wave as well as the EME signal is in the order of 20dB above the noise floor. The ground wave is used to extract the momentary transmitted frequency by a digital PLL loop in the computer. The first column shows the spectrum of the ground wave with a receiver following the PLL frequency. In other words the first spectrum shows how sucessful the PLL was in following the frequency drift of the fairly unstable signal. The second spectrum is the EME signal as received with a receiver using a fixed local oscillator. The third spectrum shows the EME signal received with the same receiver local oscillator as the first spectrum, a PLL witch follows the transmitted frequency. The fourth and the fifth spectrum graphs show the EME signal received by a receiver that follows the delayed transmit signal. These figures come close to what one would obtain using frequency stable equipment. The fourth and the fifth spectra are with two orthogonal linear polarisations on the receive side.

The figure below shows the same sequence with higher resolution. Here each pixel is 0.042Hz. One can clearly see the two components of the EME signal. The specular reflection is like reflection of light on a polished steel ball. It happens on a very small area at the center of the moon and has a very narrow spectrum. The polarisation is conserved so this signal is strong in one polarisation while it goes through zero in the other as polarisation slowly twists due to farady rotation. The diffuse scattering is like light reflected from a ping-pong ball. It has a much wider spectrum because it has contributions from different parts of the moon that give rise to different doppler shifts. Polarisation is not conserved by the diffuse scattering process and it is equally strong in both polarisations. In this experiment the diffusely scattered signal is about 1Hz wide with a rectangular spectrum while the specular reflection is in the order of 0.2Hz wide. This experiment is not good enough for detailed analysis.