2
$\begingroup$

This GBTimes article A tiny Chinese satellite is orbiting the Moon and allowing radio amateurs to download images links to this tweet which shows a high gain UHF? antenna pointed at the Moon, and that's about all I can understand.

The spacecraft is Longjiang-2 a a satellite launched together with the communications relay satellite Queqiao, (which will be the relay for the Chang'e 4 lander launching tomorrow).

The text I don't understand reads:

2018-05-08 0730-0930 UTC 32-50 degrees EL -- all 11 decodes tonight on JT4G very strong , FT991A 17db LNA, 1/4 hardline 24ft ,Gulf Alpha 8 x 11 beam H-POLE.

Question: Is it possible to translate all of that to something that someone with no VHF/UHF experience would understand?

fyi I don't know about Longjiang-2, but Queqiao is in a halo orbit behind the Moon, so it's not exactly in a lunar orbit as much as it is in orbit around the Earth, a few thousand km behind the Moon, and in 1:1 resonance with the Moon.

enter image description here

Improve this question
$\endgroup$

1 Answer 1

Reset to default
6
$\begingroup$

32-50 degrees EL -- all 11 decodes tonight on JT4G very strong , FT991A 17db LNA, 1/4 hardline 24ft ,Gulf Alpha 8 x 11 beam H-POLE.

JT4G - digital signal mode, http://physics.princeton.edu/pulsar/k1jt/JT2_JT4.TXT

FT991A - Yaesu FT991A radio

17dB LNA - low noise amplifier (with 17dB gain perhaps)

1/4 hard-line - the coax connecting the radio to the antenna

Gulf Alpha 8 x 11 beam H-POLE - the antenna being used

Improve this answer
$\endgroup$
8
  • 2
    $\begingroup$ @uhoh 1. 1/4" diameter. 2. Probably. $\endgroup$
    – Mike Waters
    Dec 7, 2018 at 2:51
  • 1
    $\begingroup$ Definitely UHF, one of the screenshots shows the frequency at 436.400MHz (in the 70cm band) $\endgroup$
    – Scott Earle ♦
    Dec 7, 2018 at 3:28
  • 1
    $\begingroup$ Based on the photo in the posted tweet, I'd guess the 8x11 beam is a cross-yagi (or similar variant) with 8 elements in one direction and 11 elements in the other. $\endgroup$
    – imabug
    Dec 7, 2018 at 10:46
  • 1
    $\begingroup$ The coax is likely LMR-240 or some variant. Antennas used for satellite comms are often dual-band - VHF/2-meter (144MHz) for uplink, and UHF/70cm (450MHz) for downlink. It's hard to tell from the perspective of the photo, but that's how it appears to me. Note to "listen" one only uses the UHF portion of the antenna. $\endgroup$
    – mike65535
    Dec 7, 2018 at 14:13
  • 2
    $\begingroup$ And it is worth noting that H-POLE refers to a horizontally polarized antenna. $\endgroup$
    – Glenn W9IQ
    Dec 7, 2018 at 16:24

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .