[amsat-bb] LongJiang and Doppler correction

Wed May 30 11:56:51 UTC 2018

Hi Dimitry,

TLE are useles in lunar orbit.

You have to update the tracking file in all four decoders.

https://github.com/bg2bhc/dslwp_doc/blob/master/program_tracking_dslwp-b_201
80529.txt

(or later files)

73 Mike
DK3WN

-----Ursprüngliche Nachricht-----
Von: AMSAT-BB [mailto:amsat-bb-bounces at amsat.org] Im Auftrag von Dimitry
Borzenko
Gesendet: 30 May 2018 10:36
An: AMSAT BB
Betreff: Re: [amsat-bb] LongJiang and Doppler correction

Hello.
Have problem with running Live CD.
Have made USB bootable diskONkey , system is runs.
Mun Downlink Proxy is configured and Orbit TLE can be downloaded, but ALL
ports is NOT connected!
RTL is running and freq. calibrated.
Also while running Decoder got 4 terminals running and have some message
about "File is not find or EOF ....."

What I did wrong?

de 4z5cp.

------ Original Message ------
From: "Scott" <scott23192 at gmail.com>
To: "AMSAT BB" <amsat-bb at amsat.org>
Sent: 30.05.2018 2:30:33
Subject: Re: [amsat-bb] LongJiang and Doppler correction

>Hi Jean Marc.
>
>I have tried to follow the news of these lunar satellites.  While 
>several of the guys with DSN capability have received the S-Band 
>downlinks, I'm not aware of anyone hearing anything on 70cm past the 
>first day as the sats left Earth.
>
>In fact, even though I am listening every night for the 70cm telemetry 
>(using the team's GNU Radio flowgraphs), I have not heard any 
>confirmation that the 70cm transmitter is even on (telemetry -or- JT4).
>
>-Scott,  K4KDR
>
>
>=======================================================
>
>-----Original Message----- From: Jean Marc Momple
>Sent: Tuesday, May 29, 2018 12:37 PM
>To: AMSAT BB
>Subject: Re: [amsat-bb] LongJiang and Doppler correction
>
>Dear All,
>
>May be a stupid question for the experts, but genuine from me.
>
>Has anyone received any FT4G beacon signal from the Longiang Sats so 
>far?
>
>I have being trying to do so for the past week without success.
>
>73
>
>
>Jean Marc (3B8DU)
>
>
>
>
>>On May 26, 2018, at 8:54 PM, Nico Janssen <hamsat at xs4all.nl> wrote:
>>
>>
>>In the coming days the doppler shift on the 70 cm downlink of 
>>LongJiang 2 will vary between +2000 and -2200 Hz (for my QTH).
>>This can easily be calculated with GMAT using the script I published a 
>>couple of hours ago (see my earlier post).
>>
>>73,
>>Nico PA0DLO
>>
>>On 26-05-18 17:44, charlie at sucklingfamily.free-online.co.uk wrote:
>>>Michael
>>>
>>>I think that there are three main components to the Doppler shift for 
>>>a satellite orbiting the moon.
>>>
>>>1.  Earth rotation moving the observer toward the moon at moonrise 
>>>(+ve
>>>Doppler) and moonset (-ve).
>>>
>>>2.  Earth-moon distance variation (smaller than 1, and very slowly 
>>>changing in comparison).
>>>
>>>3.  Orbital velocity of the satellite itself.
>>>
>>>1 and 2 are easy to work out using EME software, eg WSJT-X or 
>>>Moonsked. I can't help with 3.
>>>
>>>Taking today as an example, total of 1 and 2 for the moon vary from ~
>>>+3
>>>to -4.5kHz at S-Band.
>>>
>>>With DSN satellites many of us use(d) JPL Horizons to calculate 
>>>Doppler shift for Deep Space missions.  Observing the Doppler shift 
>>>change when probes were captured by the target planet was quite 
>>>interesting (a slowly changing shift to a cyclic one).
>>>
>>>73
>>>
>>>Charlie G3WDG
>>>
>>> > I find that an interesting question. One would think that since 
>>> > the
>>>moon
>>>>orbits the earth at a much much slower rate than a satellite that 
>>>>there would be almost no Doppler correction required. If you 
>>>>compensate for the speed of the orbit around the moon that is also 
>>>>at a much lower speed than a Earth satellite would be traveling at. 
>>>>Earth satellites are in the 17,000 mph range and moon satellites are 
>>>>in the 2000 mile an hour range orbiting speed. Also the chance that 
>>>>the satellite orbiting the moon could be at such an axis where it is 
>>>>in full visibility the earth the whole time, at that point there 
>>>>would not be a Doppler correction based upon satellite velocity only 
>>>>the moon's velocity. Will be interesting to hear the experts chime 
>>>>in on this.
>>>>
>>>>Michael Vivona
>>>>Sent from my iPad
>>>>
>>>>On May 25, 2018, at 5:49 PM, Stefan Wagener <wageners at gmail.com>
>>>>wrote:
>>>>
>>>>The problem will not be the pointing (you could just point to the 
>>>>moon :-) Pending distance, speed and orbit around the moon and 
>>>>position to earth, you might have a difficult time adjusting for 
>>>>doppler. I let more knowledgable folks chip in on this one.
>>>>
>>>>Stefan, VE4NSA
>>>>
>>>>>On Fri, May 25, 2018 at 2:40 PM Jordan Trewitt 
>>>>><jmtrewitt at gmail.com>
>>>>>wrote:
>>>>>
>>>>>If it was the 70 cm downlink, you might be able to schedule 
>>>>>something with someone else's SATNOGS station (idk how that'd work 
>>>>>with getting a rotator to work though), if they have a large enough 
>>>>>yagi that is.
>>>>>-Jordan
>>>>>KF5COQ
>>>>>
>>>>>>On Fri, May 25, 2018, 12:46 PM Zach Metzinger <zmetzing at pobox.com>
>>>>>>wrote:
>>>>>>
>>>>>>>On 05/25/18 11:25, Nico Janssen wrote:
>>>>>>>
>>>>>>>It is confirmed from China that LongJiang 2 has performed a 
>>>>>>>successful braking maneuver, so that it is now in lunar orbit.
>>>>>>>No further details yet.
>>>>>>Nico,
>>>>>>
>>>>>>Do you know of any WebSDRs which are pointed and tuned to the 
>>>>>>downlink signals?
>>>>>>
>>>>>>73,
>>>>>>
>>>>>>--- Zach
>>>>>>N0ZGO
>
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_______________________________________________
Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available to all
interested persons worldwide without requiring membership. Opinions
expressed are solely those of the author, and do not reflect the official
views of AMSAT-NA.
Not an AMSAT-NA member? Join now to support the amateur satellite program!
Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb