October 2006 - AMSAT-BB - mailman.amsat.org

Re: info on satellite placement
by Robert Bruninga 31 Oct '06

31 Oct '06

> Subject: RE: [amsat-bb] Re: info on satellite placement > > That is the most lucent simple explanation I could have > imagined. The missing link was the realization the rocket > headed horizontal (or a srequired for a specific orbit). > Obviously the further out, the longer it takes to do a > revolution. I imagine at some point earths gravity will not > be sufficient to hold an object of given mass in a circular orbit? Exactly, If you are at a given altitude and you are going to slow, then your satellite will "fall" towards earth.. But as it falls, it speeds up as it approaches its lowest point (on the other side) and that makes it go higher to arrive back where you are on this side... In otherwords, the circular orbit becomes an elipse with a high side and a low side. Now, If you were at a given altitude and you were going to fast for that altitude, then you would end up going higher on the other side and slower... Again an elipse.... And because it is higher and slower on the other side, it will fall back to where you were in the first place... Again, an elipse. The only problem with going too slow, or going to fast is whether the elongation of your elipse just happens to run into Earth. That makes for a bad day.. Remember, the satellite is orbiting around the CENTER of the Earth and its Gravity. The satellite has no idea how big the "earth" is... So as long as the low point of an eliptical orbit stays about 4500 miles above the center of the earth, then it wont run into earth... But if the low point gets below that, then it runs into earth or the atomsphere and dies... > Or would it have to slow down below the speed limit in weaker gravity? Whatever speed at what ever altitude will always define an eliptical orbit. The only question is, is whether the Earth gets in the way of that elipse... Neat stuff! Bob, Wb4APR > -----Original Message----- > From: amsat-bb-bounces(a)amsat.org > [mailto:[email protected]] On > Behalf Of Robert Bruninga > Sent: Tuesday, 31 October 2006 12:56 AM > To: 'Simon'; Amsat-bb(a)amsat.org > Subject: [amsat-bb] Re: info on satellite placement > > > I was wondering if any one can suggest where I might find > > information on "how a satellite" gets placed into orbit. > > I ... can only find that a rocket gets it there. > > Actually, the only thing the rocket does is get it going fast > enough. The only way to stay in orbit is to be going 17,500 MPH > You could orbit the earth at tree-top level if it were not for > air friction which would cause you to loose your speed and hence > fall to the ground. > > So the only thing the rocket does is 1) Get you going fast > enough to stay in orbit, and conicidently, get you a hundred or > so miles above tha atmosphere so you can keep that speed up long > enough to do something useful. > > Notice how the rocket almost immediately starts turning towards > the horizon after launch, because it is horizontal speed that is > what defines an orbit. It does travel upward at first to get to > less dense air friction as soon as possible, but then begins to > head horizontal until 17,500 MPH is achieved. > > > I hope to learn how and when its gets kicked off the rocket, > > and what happens after that. > > Once the rocket gets to 17,500 MPH horizontally at the altitude > you want, that is when you separate the satellite and let it > continue. Usually the rocket uses some left over fule to > slow-down and hence, fall back to earth. > > If you are not perfectly horizontal and not exactly at the right > speed, then your orbit will not be circular but will be an > elipse. AO-40 was launched into a very eliptical orbit to get > out to 40,000 km at apogee for a very large footprint. > Eliptical orbits are just fine, as long as they do not intersect > the earth or the earth's atmosphere. > > I said 17,500 MPH as a representative number. It is different > for each altitude orbit relative to the center of the earth. > Remember that a 500 mile orbit (above the Earth's surface) 1s > 4,500 miles above the center of the Earth. But a 200 mile orbit > is 4,200 miles above the center, so the speed is not that much > different. > > Hope that helps. > Bob, WB4APR > > _______________________________________________ > Sent via AMSAT-BB(a)amsat.org. Opinions expressed are those of > the author. > Not an AMSAT-NA member? Join now to support the amateur satellite > program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb > >

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AO-51 SSB/FM mode
by Alan P. Biddle 31 Oct '06

31 Oct '06

Over the past few days there are more and more people getting on. In a way, it sounds like a traditional linear transponder, with some people exactly on frequency, and most within a 100 Hz or so. It does allow people to break in more easily than the FM mode. One effect becoming more apparent is deep fading in the audio. I am wondering if this is caused by people outside the passband, but near enough to drive down the gain on the uplink? Alan WA4SCA

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OSCAR-11 Report
by Clive Wallis 31 Oct '06

31 Oct '06

OSCAR-11 REPORT 31 October 2006 OSCAR-11 is back! It was first heard by Peter ZL3TC, at 06:23 UTC on October 18. It had been silent since August 26. During the period 28 September to 30 October, the satellite was heard from 18 to 28 October. Good signals have been heard on most passes, often very strong. Further deterioration of the time/date stamp has occurred. Here is a frame of telemetry captured on 27 October at 08:43:51 UTC. UOSAT-2 060=601033448 000000010001020002030003040004050005060006070007080008090009 100001110000120003130002140005150004160007170006180009190008 20000221000322000023000124000625000726000427000528000A29000B 30000331000232000133000034000735000636000537000438000B39000A 40000441000542000643000744000045000146000247000348000C49000D 50000551000452000753000654000155000056000357000258000D59000C 60800E615FC1620105633305644402651E0C662AC467000168000E69000F The date/time stamp is the block of characters following 'UOSAT-2' having the format YYMMDDWHHMMSS (Year, month, day, day of week, hours, minutes, seconds). The month, shown as '0=' in the date stamp is now in all telemetry frames. When the satellite was heard in August the month, had stuck at 07 and the day had incremented to 60. During the ten day reception period in October, the day had correctly incremented from 51 to 60. While the satellite was silent, it appears likely that the day may have incremented to 99 and then reset to zero. It will be interesting verify this theory on future passes. During the last ten days of beacon transmission the time stamp incremented accurately, and no gain or loss was detected ( within one or two seconds). However, on one occasion, the most significant digit of the hours failed to change from zero to one, although it didn't cause a permanent error. If the satellite continues to operate normally, the beacon should switch ON around 07 November. If nothing is heard, it may be worth listening ten days later, ie. around 17 November. I am indebted Peter ZL3TC, Bob G4VRC, Paul KB5M, and Doug KA2UPW/5 for their reports and for monitoring the satellite. Peter listened for the satellite daily, often during several passes, while it was silent. Many thanks. The status of the satellite, when last heard, was that all the analogue telemetry channels, 0 to 59 are zero, ie they have failed. The status channels 60 to 67 were still working. The spacecraft computer and active attitude control system have switched OFF, ie. the satellite' attitude is controlled only by the passive gravity boom gradient, and the satellite is free to spin at any speed. When telemetry was last received it showed that one of the solar arrays had failed, and there was a large unexplained current drain on the main 14 volt bus. After 22 years in orbit the battery has undergone around 100,000 partial charge/discharge cycles, and observations suggest that it cannot power the satellite during eclipses, or sometimes during periods of poor solar attitude. The watchdog timer now operates on a 20 day cycle. The ON/OFF times have tended to be very consistent. The average of many observations show this to be 20.7 days, ie. 10.3 days ON followed by 10.4 days OFF. However, poor solar attitude may result may result in a low 14 volt line supply, which may cause the beacon to switch OFF prematurely, and reset the watchdog timer cycle. When this occurs, the beacon is OFF for 20.7 days. The Beacon frequencies are - VHF 145.826 MHz. AFSK FM ASCII Telemetry UHF 435.025 MHz. OFF S-band 2401.5 MHz. OFF Listeners to OSCAR-11 may be interested in visiting my website. If you need to know what OSCAR-11 should sound like, there is a short audio clip for you to hear. The website contains an archive of news & telemetry data. It also contains details about using a soundcard or hardware demodulators for data capture. There is software for capturing data, and decoding ASCII telemetry. The URL is www.users.zetnet.co.uk/clivew/ If you place this bulletin on a terrestrial packet network, please use the bulletin identifier $BID:U2RPT126.CWV, to prevent duplication. 73 Clive G3CWV xxxxx(a)amsat.org (please replace xxxxx by g3cwv)

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ISS status??
by Len N9IJ 31 Oct '06

31 Oct '06

Pardon my ignorance, but is ISS still not operating in digital mode? AMSAT status still shows it operational but I've not heard it in weeks. -- Len Revelle N9IJ "My career goal is to retire"

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HITSAT 0718 UTC
by Mike Rupprecht 31 Oct '06

31 Oct '06

AOS 0718 UTC Oct, 31 (JN49lr) Hit4 c1dcd1e6 Hit1 jr8yjt Hit2 a3116183222 Hit3 244c4a4b4d4c4b49 Hit4 c1dbd1e6 Hit1 jr8yjt Hit2 a311622262c Hit3 2c4c4c4a4d4c4b49 Hit4 bedbd1e6 Hit1 jr8yjt Hit2 a3116261829 73, Mike DK3WN

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PacComTiny2. Help Request
by Vincenzo Mone 31 Oct '06

31 Oct '06

Hi to the list, I have a problem with my Tiny-2 Tnc. When I switch it on I can see the Tnc initialize with All the details the I get the prompt command but Whatever I type or even I give just a carriage return, The cmd: disappear and do not get any reply from the Tnc. Anybody can tell me how to get the prompt command again? It comes out again only if I switch it off and then on again But when I do how explained above I get again the problem. Any help will be really appreciated. 73 de Enzo IK8OZV EasyLog 5 BetaTester EasyLog PDA BetaTester WinBollet BetaTester D.C.I. CheckPoint Regione Campania Skype: ik8ozv8520 *************************************** ***** GSM +39 338 9749786 ***** ***** SMS +39 338 9749786 ***** ***** FAX +39 328 7244294 ***** *** 2nd e-mail: vimone(a)tin.it *** ***************************************

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info on satellite placement
by Fred A Parker 30 Oct '06

30 Oct '06

Does anyone know the formula to tell how much energy it takes to place an object into orbit? Or a software program to calculate this? Fred

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Re: CW from an FM HT
by John W Lee 30 Oct '06

30 Oct '06

A lot of the time, you don't have to QSY much on CW, so the step isn't all that super important. Just pick a spot and give out a few CQ's. Of course you have to have some other receiver than the HT unless it receives SSB/CW. (I used to get some SSB/CW QSO's on the old birds) Call CQ on CW and get a SSB answer or vice-versa.. Of course at that time most folks could copy CW. 73 John > > I was doing some testing here at home with this. I used an IC-W32A > and IC-T7H > with a straight key plugged into the mic jack on each radio. > Nothing fancy from > the key, just an adapter to fit the 3/32" (2.5mm) jack, and I could > key the > transmitter. When I did this, listening on another radio, I could > hear only the > carrier. No audio was coming from the HTs' built-in mics. > > I might try this on FO-29 this evening, and maybe VO-52. One > additional > drawback with an HT for a CW transmitter is the fact that most HTs > (including these two I tried this morning) have 5 kHz as the > smallest tuning > step. I also have an FT-817ND, but I only have one of those > radios. > Otherwise, I would be trying all of this with a pair of FT-817s and > making > some CW and SSB contacts. > > 73! > > > Patrick WD9EWK/VA7EWK >

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LA/W5ACM on AO-51
by Andrew Glasbrenner 30 Oct '06

30 Oct '06

I worked Andy just now on AO-51 VHF SSB/ UHF FM as he is cruise ship portable in EL63. It takes dedication and skill to work this mode portable, and I'm happy to have made the QSO with him. 73, Drew KO4MA

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WTB M2 2 meter eggbeater
by Jeff Kelly 30 Oct '06

30 Oct '06

Looking for a M2 2 meter Eggbeater antenna with radials if anyone has one for sale. Jeff KT2K

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