I would assume this probably isn't publically disclosed information, but it doesn't hurt to ask. I am an amateur ham radio enthusiast and I want to listen in on the data.
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$\begingroup$ slightly related: ham.stackexchange.com/q/12375/8643 $\endgroup$– uhohJan 5, 2019 at 4:35
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$\begingroup$ possibly helpful: twitter.com/radiotelescoop and twitter.com/tammojan and twitter.com/cgbassa $\endgroup$– uhohJan 5, 2019 at 15:03
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1 Answer
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These photos and many others have been received from the Queqiao relay satellite by the 25m Dwingeloo radio telescope.
From here and Translated by Google from the original Dutch:
Recently, the webSDR has been expanded with a receiver for a Chinese moon satellite. The Dwingeloo telescope is one of the official reception ground stations for the Chinese moon satellite DSLWP-B. From Germany the uplink command signals are sent to the satellite. This satellite floats in an elliptical orbit around the moon, through which the satellite can also take pictures of the back of the moon. This is not possible from the earth. However, the nominal transmit power of this satellite is very limited and, depending on the mode used, only 1 to 2 Watt (30 - 33 dBm).
The 25m Dwingeloo telescope is used to receive the lunar photos and telemetry signals, the frequencies used in the 70cm band are 435.4 MHz and 436.4 MHz. The beautiful photos (see above) of the back of the moon and the earth can be found elsewhere on this website. Worldwide there is great interest among radio amateurs for the photos and telemetry signals of this satellite. In collaboration with Pieter Tjerk de Boer, Simon Bijlsma therefore connected a third RTL SDR dongle and connected it to the 70cm antenna of the telescope. This allows our many (international) visitors to the webSDR to follow the satellite signals in real time and decode the GMSK and FT4G signals themselves when the telescope follows the satellite.
So 70 cm band from Queqiao to Earth for some data.
Further, @Hobbes' answer says that Queqiao
...provides four 256 kBps X-band links between itself and the lander/rover and one 2 MBps S-band link towards earth.
According to a tweet quoted in this answer Chang'e-4 was transmitting to Queqiao at 8479.77 MHz. (X-band)
According to the Planetary Society post Imaging the Earth from Lunar orbit the LongJian satellites could be received from Earth at VHF/UHF as well, although I can't find a specific frequency.
This is a partial list, I'll continue to add as I find more information.
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1$\begingroup$ The grid structure of the Dwingeloo radio telescope does not look like to be used with frequencies above about 3 GHz. The small triangles are about 0.5 m high.The grid period should be small compared to the wave length. Maybe there is a fine mesh cover invisible on the images. But this telescope was designed to be used for the 21 cm hydrogen line of the neutral hydrogen in 1954. Also on various frequencies around 400, 500, 600, 800 and 1400 MHz. But I found no information about its upper frequency limit. $\endgroup$– UweJan 24, 2019 at 15:20
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1$\begingroup$ @Uwe there could be a wire mesh with much smaller holes that doesn't show up in the photo. The sky certainly looks a bit darker in the triangles than outside of the telescope i.stack.imgur.com/XcIU2.png $\endgroup$– uhohJan 24, 2019 at 23:19
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1$\begingroup$ Here is a photo of the antenna mirror covered with snow. There must be something like a wire mesh to be covered with snow. But the telescope was designed to be used with 21 cm wavelength in 1954. Was the mirror build so precisely to be used with much shorter wavelength? A 25 m mirror build more than six decades ago with a precision better than 1 cm? $\endgroup$– UweJan 25, 2019 at 14:53
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1$\begingroup$ I found data about accuracy here: " The parabolic dish, with 12 meters to the focus, is back into its original state with a 2 mm accuracy. " Very remarkable. Here some words about the mesh surface: "You don't often see the complete mesh surface closed this way... " $\endgroup$– UweJan 25, 2019 at 15:17
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1$\begingroup$ From Dwingeloo – the golden radio telescope : "In 1969 the original mesh surface, which was too coarse for short wavelengths like 6 cm, and which had moreover been affected by corrosion, was replaced by a stainless steel mesh. The new surface, with a 7.7 mm lattice, was adjusted to provide an accuracy of < 1 mm." $\endgroup$– UweJan 25, 2019 at 16:00
