1
$\begingroup$

The 15-Oct-2018 Planetary Society post Imaging the Earth from Lunar orbit shows an image of one of the Longjiang spacecraft (also known as DSLWP-B) where were carried with Chang'e-4 to the Moon and put into lunar orbit.

I don't understand the diagram. There are UV-antennas A and B, and a UV Transceiver. I don't believe that UV stands for ultraviolet, does it? If not, what do the "UV" antenna really look like and what band do the operate on? One of the antenna arrows ("B") points to what looks more like a camera, and the other just points to blank insulation.

enter image description here

Improve this question
$\endgroup$
3
  • 1
    $\begingroup$ I don't believe too that 'UV' stands for ultraviolet. May be it should stand for Ultra (high) Vrequency. (I know that frequency starts with a 'f', not a 'v') UHF is the frequency band 300 MHz to 3 GHZ. Something between 1 and 3 GHz seems possible. A cite from your link "Besides the scientific instruments, both Longjiang satellites carry a VHF/UHF amateur radio transmitter and receiver (a transceiver) built and operated by the Harbin Institute of Technology (in Chinese)" May be UV should stand for Uhf - Vhf, a very strange way to create new abreviations. $\endgroup$
    – Uwe
    Jan 24, 2019 at 10:29
  • $\begingroup$ @Uwe I have a hunch that you are right; UV stands for UHF/VHF. Maybe it's a strange abbreviation, maybe the antenna has more than one frequency? $\endgroup$
    – uhoh
    Jan 24, 2019 at 23:22
  • $\begingroup$ @Uwe I'm pretty sure UV is short for UHF/VHF but the arrows in the image in the question don't point to the same objects as they to in this post linked in this answer, which looks clearer and more accurate to me. I wonder if that small helical antenna can have two frequencies? Maybe one helix/tube inside of another? $\endgroup$
    – uhoh
    Feb 2, 2019 at 4:41

2 Answers 2

Reset to default
1
$\begingroup$

This post from an amateur radio guy who has received data from the satellite says:

Two transmit frequencies are used: 435.4MHz and 436.4MHz. Each transmit frequency uses a different antenna. The antenna marked below as UV Antenna A is used for 435.4MHz, while the UV Antenna B is used for 436.4MHz.

Hardly official but it's a datum.

Improve this answer
$\endgroup$
2
  • $\begingroup$ These frequencies are in the UHF range between 300 megahertz (MHz) and 3 gigahertz (GHz). But the link in the question also writes about VHF from 30 to 300 megahertz (MHz). $\endgroup$
    – Uwe
    Jan 24, 2019 at 15:31
  • $\begingroup$ What do you think, could this be the explanation? $\endgroup$
    – uhoh
    Feb 22, 2019 at 5:12
1
$\begingroup$

I'm going to forward this since nobody else has taken the plunge.

tl;dr: UV most likely stands for UHF/VHF.

From the Planetary Society's blogpost by Cees BassaTammo and Jan Dijkema Imaging the Earth from Lunar orbit which I'd originally linked to in this answer:

Besides the scientific instruments, both Longjiang satellites carry a VHF/UHF amateur radio transmitter and receiver (a transceiver) built and operated by the Harbin Institute of Technology (in Chinese). The Longjiang-2 transceiver also includes an onboard student camera, nicknamed the Inory Eye. The Harbin team built on experience gained with the Earth-orbiting LilacSat-1 and LilacSat-2 nanosatellites, which allow radio amateurs to receive satellite telemetry, relay messages and command and download images taken with an onboard camera.

This post is really interesting! @Roger linked to it in this answer, the work is cited in the Planetary Society blogpost linked above, and I think it's really quite cool!

First results of DSLWP-B Amateur VLBI (see more here):

In March this year I spoke about the Amateur VLBI with LilacSat-2 experiment. This experiment consisted of a GPS-synchronized recording of LilacSat-2 at groundstations in Harbin and Chongqing, China, which are 2500km apart. The experiment was a preparation for the Amateur VLBI project with the DSLWP lunar orbiting satellites, and I contributed with some signal processing techniques for VLBI.

As you may know, the DSLWP-B satellite is now orbiting the Moon since May 25 and the first Amateur VLBI session was performed last Sunday. The groundstations at Shahe in Beijing, China, and Dwingeloo in the Netherlands performed a GPS-synchronized recording of the 70cm signals from DSLWP-B from 04:20 to 5:40 UTC on 2018-06-10. I have adapted my VLBI correlation algorithms and processed these recordings. Here are my first results.

The baseline for these VLBI recordings (i.e., the distance between the groundstations) is roughly 7250km. The signals transmitted by DSLWP-B are 250bps GMSK using an 𝑟=1/2 turbo code. Two transmit frequencies are used: 435.4MHz and 436.4MHz. Each transmit frequency uses a different antenna. The antenna marked below as UV Antenna A is used for 435.4MHz, while the UV Antenna B is used for 436.4MHz.

enter image description here

Source DSLWP diagram

Improve this answer
$\endgroup$
3
  • $\begingroup$ But there are no frequencies in the VHF used, only in UHF range. If UV stands for VHF/UHF, there should be a used frequency below 300 MHz too. $\endgroup$
    – Uwe
    Mar 1, 2019 at 11:49
  • $\begingroup$ @Uwe Just because this communication used one frequency, it doesn't mean it is the only possible frequency. We don't yet know what frequencies the electronics is capable of. You can name something by what it is capable of doing, even if you don't use the capability. I'm still searching, this is a work in progress. Feel free to post an updated answer if you find something, or edit this one, or leave a message. $\endgroup$
    – uhoh
    Mar 1, 2019 at 11:57
  • $\begingroup$ I've accepted because I believe that this is the correct answer and it's the OP's prerogative. However if you have a different or additional please post, the accept can be quickly moved to any compelling answer. $\endgroup$
    – uhoh
    Jul 31, 2019 at 2:57

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.