https://wiki.amsat-uk.org/index.php?title=Special:NewPages&feed=atom&limit=50&offset=&namespace=0&username=&tagfilter=&size-mode=max&size=0AMSAT-UK Wiki - New pages [en-gb]2024-03-29T08:36:57ZFrom AMSAT-UK WikiMediaWiki 1.35.0https://wiki.amsat-uk.org/index.php?title=Adding_new_satellite_to_GpredictAdding new satellite to Gpredict2021-12-27T17:02:39Z<p>M0nkc: </p>
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<div>Although satellite community is usually very responsive when it comes to updating satellite information, when a new satellite gets launched it may take several days before its data becomes available in popular tracking software. If you want to start using a new "bird" as soon as it gets launched, it is easy to add it manually.<br />
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For Gpredict this is a 2-step process (note the instructions pertain to Gpredict 2.3-33, your menus may be different):<br />
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=== TLE data ===<br />
Launch providers will usually provide preliminary (pre-launch) TLEs. They are just an approximation and soon after launch will start getting out of date, but will get you started at least for the first few orbits.<br />
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One point worth noting is that these [https://en.wikipedia.org/wiki/Two-line_element_set TLE]s will tend to have a dummy [https://en.wikipedia.org/wiki/Satellite_Catalog_Number Satellite Catalogue Number] because the latter is only assigned once a satellite enters its orbit. <u>Take note of the Satellite Catalogue Number used in your TLEs!</u>.<br />
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[[File:Screenshot 2022-01-12 at 15.02.32.png|Satellite Catalogue Number in TLE|alt=|center|thumb|694x694px]]<br />
Now that you've got the preliminary TLE data, save them into a file. In Gpredict select "Edit" -> "Update TLE data from local files" and select a directory you saved your file to. Note Gpredict will scan and try to import everything that looks like a file with TLE data. If you tend to have old TLEs saved in the same directory, you may prefer to create a temporary directory and save your file there.<br />
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If you get "New satellites: 1" (or, if you have previously imported this satellite, "Satellites updated: 1"), you can now track the new satellite.<br />
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=== Transponder data ===<br />
While tracking satellites is nice, where tracking software really excels is Doppler correction. In recent Gpredict versions there is an option to pull this data from the [https://db.satnogs.org/ SatNOGs database] simply by running "Edit" -> "Update transponder data". However, for new satellites this information may not have been added yet (or may not be accurate). <br />
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If in Radio Control module you select the newly added satellite and see no transponders for it, you can also add it manually. In a folder '''~/.config/Gpredict/trsp''' (on Linux/MacOS systems) create a file named after your Satellite Catalogue Number with '''.trsp''' extension, listing the satellite's transponders. <br />
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For example, for recently launched satellite XW-3, whose Satellite Catalogue Number is 50466, the file should be called 50466.trsp with the following contents (the format is pretty self-explanatory):<br />
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<pre><br />
[Mode U - Telemetry]<br />
DOWN_LOW=435575000<br />
MODE=CW<br />
BAUD=22<br />
<br />
[Mode V/U - Transponder]<br />
UP_LOW=145855000<br />
UP_HIGH=145885000<br />
DOWN_LOW=435165000<br />
DOWN_HIGH=435195000<br />
MODE=USB<br />
INVERT=true<br />
<br />
[Mode U - GMSK4k8 AX.25 Telemetry]<br />
DOWN_LOW=435725000<br />
MODE=GMSK<br />
BAUD=4800<br />
</pre><br />
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If you now select the newly added satellite in your Radio Control module, you should be able to see the transponder data.</div>M0nkchttps://wiki.amsat-uk.org/index.php?title=Satellite_News_ArchiveSatellite News Archive2021-03-20T16:34:24Z<p>2m0sql: /* ALL AMATEUR RADIO SATELLITES 1985 - 2004 */</p>
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<div><blockquote>This is historical content collated by G3CWV</blockquote>For many years, Richard G3RWL prepared monthly bulletins of Amateur Radio Satellite news. They were usually broadcast on the last Sunday of each month, in the AMSAT-UK 80 metre net. They were also distributed via packet radio and as hard copy. Many of the early bulletins were produced before the internet was available. I have now obtained a complete set of these bulletins which were broadcast from May 1985 to July 2004<br />
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This is a very detailed and useful archive, especially for research and preparation of lectures. The archive comprises 239 text files, which are zipped into four packages, for convenience. Also included are some reports of the AMSAT-UK Colloquium, and reports about individual satellites.<br />
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I have renamed the files, so that each one has a unique name, in the format YYYYMMM.TXT eg. 1996MAY.TXT. This allows all the files to be unzipped into a single directory, to permit easy searches for any text string.<br />
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Finally, I would like to congratulate Richard for a fine achievement in preparing these bulletins and to thank him for granting permission to distribute the archive.<br />
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====Archived packages====<br />
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*[https://wiki.amsat-uk.org/images/d/db/Satellite_News_1985_to_1989.zip 1985 to 1989]<br />
*[https://wiki.amsat-uk.org/images/1/1a/Satellite_News_1990_to_1994.zip 1990 to 1994]<br />
*[https://wiki.amsat-uk.org/images/7/73/Satellite_News_1995_to_1999.zip 1995 to 1999]<br />
*[https://wiki.amsat-uk.org/images/9/9b/Satellite_News_2000_to_2004.zip 2000 to 2004]</div>2m0sqlhttps://wiki.amsat-uk.org/index.php?title=DopplerDoppler2021-02-04T21:21:19Z<p>K0JM: Added content</p>
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<div>In satellite operation, being on the right frequency is complicated by a phenomenon called "'''Doppler Shift'''" or "Doppler Effect." It is named after the Austrian physicist Christian Doppler, who described the phenomenon in 1842, and is the change in frequency of a wave caused the motion of the wave source in relation to an observer. In other words, a satellite in space is moving so fast that it distorts the frequencies at which it transmits and receives. The direction and magnitude of this shift in frequencies varies depending on whether the satellite is approaching or receding, its distance from the observer, and the original frequency of the wave being distorted. Thus, the Doppler Shift will be different for every user of the satellite at any given moment.<br />
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==== FM Satellite Doppler Correction ====<br />
FM, due to its inherent characteristics, is rather forgiving about being precisely on frequency. But Doppler Shift becomes more pronounced as frequency increases. So for FM satellites, we can usually get by ignoring the Doppler Effect in the 2 meter band, but we often need to make some corrections in the 70cm band. For example, FM satellite AO-91 transmits down toward earth (the '''downlink''') on 145.960 MHz. In most instances, one may tune their receiver to that frequency and hear the satellite just fine. However, AO-91 receives signals coming up from the ground (the '''uplink''') at 435.250 MHz. A station transmitting on that frequency will probably only be successful in being heard through the satellite when it is near its closest approach to that station -- when the Doppler Shift is near minimum.<br />
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At the beginning of the satellite's pass over that station, as the satellite is approaching, the operator will have much greater success by tuning to a lower frequency -- perhaps about 435.240 MHz. Once the Doppler Effect has made its impact, that transmitted signal will appear to the satellite's receiver to be very nearly on frequency (435.250). As the satellite moves a bit closer, but is still approaching, the operator will be more successful raising the transmitted frequency a bit -- perhaps to 435.245 MHz -- because the Doppler Effect will have become somewhat less pronounced as the satellite draws closer. Similarly, as the satellite begins to recede from the station, the operator will keep tuning upward -- perhaps to 435.255. And as the satellite nears the horizon, still going away, the operator might tune up still more to 435.260 MHz.<br />
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Conversely, FM satellite SO-50 transmits its downlink at about 436.795 MHz while listening for uplink signals at 145.850 MHz. In this case, the operator may tune the transmitter to 145.850 MHz and be quite successful being heard through the satellite throughout its pass. But in order to receive SO-50 well, the operator will have to begin the pass (at '''AOS''', or Acquisition of Signal) by tuning the receiver at bit higher -- perhaps to 436.805 or so. The operator will then tune the receiver downward in frequency, passing the satellite's actual transmitted frequency of 436.795 near the Time of Closest Approach ('''TCA'''), and continuing down perhaps as low as 436.785 at Loss of Signal ('''LOS'''), when the satellite disappears below the horizon once again.<br />
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This may all seem very confusing, but it is easy to remember that one only needs to adjust the 70cm frequency -- no matter whether that happens to be the uplink or the downlink -- and to recall that ''uplinks move up, and downlinks move down''!<br />
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==== Linear Satellite Doppler Correction ====<br />
Linear satellites make use of CW and SSB modes, and these modes are less forgiving of errors in frequency. If a received SSB signal is tuned off frequency by even a few hundred Hertz, it will begin to become unintelligible. As frequencies change due to the Doppler Effect, they move by much more than this amount, particularly at UHF frequencies.<br />
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Because the Doppler shift depends on the geometrical relationship between the station location and the satellite’s path and the ground stations are in diverse locations. If each operator sets his transmitter (or receiver) at the beginning of a QSO and then doesn’t touch it, they will not stay on the same frequency. They will end up diverging because the various locations have various Doppler shift profiles.</div>K0JMhttps://wiki.amsat-uk.org/index.php?title=Frequency_bandsFrequency bands2020-12-21T13:08:29Z<p>G0TRT: </p>
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<div>Satellites are generally referred to by the bands the operate on. Those bands have alphabetical designations associated with them which makes referencing easier. The first letter is the uplink, and the second is the downlink.<br />
{| class="wikitable"<br />
|+<br />
!Freq<br />
|29 Mhz<br />
|145 MHz<br />
|435 MHz<br />
|1.2 GHz<br />
|2.4 Ghz<br />
|3.4 GHz<br />
|5 GHz<br />
|10 GHz<br />
|24 GHz<br />
|-<br />
!Band<br />
|10 m<br />
|2 m<br />
|70 cm<br />
|23 cm<br />
|13 cm<br />
|9 cm<br />
|5 cm<br />
|3 cm<br />
|1.2 cm<br />
|-<br />
!Designator<br />
|'''A'''<br />
|'''V'''<br />
|'''U'''<br />
|'''L'''<br />
|'''S'''<br />
|'''S2'''<br />
|'''C'''<br />
|'''X'''<br />
|'''K'''<br />
|}</div>G0TRT