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The 4th of July 2022 will forever be recorded, for me, as historic: I managed to receive an emission via lunar reflection at 47GHz, with a 90cm dish!!
Manfred, DL7YC, arranged with the systems development group, EA3HMJ, EB3FRN and myself, CT1BYM, to do a late afternoon broadcast to test some components: LNA and waveguides, tracking system and antennas.
José, EA3HMJ, with a 1.2m dish, would always be better equipped to receive the transmission than me, with a 90cm kathrein.
But at these frequencies, the surface correction of the reflecting mirror is absolutely critical (see Ruze's equations on the parabolic mirror).
I took some measurements a few hours before the test. It was a hot day, 35º, 37% relative humidity, atmospheric pressure 1014 hPa.
The Moon was perfectly “visible”, with almost 1dB of noise, so it was possible to adjust the tracking manually. The rotor used in these tests is not the most suitable, so this would be the only possible solution… for now!
The adjustment was always done by monitoring SpectraVue, which, together with Rad II from LC Technologies, provided me with the data I needed to point to the Moon as best as possible. But not having an automatic aiming system meant that I wasn't focused on other areas of experience. I needed a few more arms!
Manfred, DL7YC, started broadcasting at 19:00 UTC, with 40W and a 2.4m dish. The big challenge: would it be possible to receive the transmission with such a small system? With 90cm it would be very complicated… But it had good values of Solar noise and Lunar noise! 10dB of Sun and 1dB of Moon reflected the effectiveness of the system I had set up, giving me confidence to do the test. LNA with 1.8dB NF at room temperature and all subsystems were working perfectly!
I managed to decode some cycles, good signals, despite the Spread being at levels of almost 900Hz!!!! The signals were so good that I chose to do tests with the WSJT (Ftol, QRG, etc…), to give some information to the software development team. There have been many modifications to this software with the tests currently running on the Moon at 47GHz, and every moment is precious to draw the proper conclusions.
The configuration with the callsign, when one station calls another, apparently has a lot of importance for the decoding process. Manfred called me until 19:14, then called José, EA3HMJ. The following images illustrate these moments, were acquired in real time in this test:
I had no more decodings like “CT1BYM”, so I decided to change the setting to “EA3HMJ”
And there was Manfred's report to José!! To test, because we are not issuing it yet. This is all a long process, a lot of work has already been done, there is still a lot to do!
Days later, I did a post-processing of the files saved on the day of the test.
Spread started around 860Hz, as you can see in the first image.
José, EA3HMJ, was able to decode more cycles than I did. He made an insanely good tracking system!! A luxury! And that's how the world evolves, by making good use of everyone's capabilities… Manual adjustment is not an option, it will be changed in the coming months. The antenna too… a lot of work still ahead! Iban, EB3FRN, and José, EA3HMJ, are developing an SSPA for 47GHz, the results have been very promising.
Working conditions: Kathrein offset 90cm, dual system, IC-9700 and IC-R8600, 2 computers, RFSpace SDR-14, LNA with 1.8dB NC from the Spanish mmW team (EB3FRN, EA3HMJ, EA5DOM), with a superb wirebonding of Iban and adjustments in his laboratory, waveguide system in WR19 and WR22 with adapters, feed to an f/D=0.66 (W2IMU), turned by José, transverter Kuhne, reference GPSDO HP 58503A.
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