November 2007 - AMSAT-BB - mailman.amsat.org

A *must* read for the potential newcomer to satellites.
by John Hackett 22 Nov '07

22 Nov '07

>From OBSERVATIONS ... <http://www.observations.biz/> By LA2QAA & GM1SXX ... This observation by GM1SXX. See also ... "HOW MUCH POWER IS ENOUGH" by LA2QAA. A *must* read for potential newcomwrs to amateur satellites. .................................................................................................................................................................................................................................. “More power Egor.” - Dr Frankenstein. Here's a good question from a regular reader. > Why is it bad to use more power than absolutely necessary when >transmitting to a satellite and how does this affect the battery >capacity of the satellite? There are two answers to this one. 1) With an FM bird, power is not an issue. FM is a continuous duty mode. When a signal is present on the transponder, no matter whether you are whispering or yelling, the power consumed is, or should be, exactly the same. FM transponders operate in Class C. With Class C amplifiers, when a signal is present, the transponder consumes what would be considered a 'normal' amount of power. With no signal present, the power amplifier (PA) consumes virtually no power, and since the PA is *the* major power consumer on a satellite, this is good. Only the receiver and IF strip are active with no signal present. Power consumed from the battery therefore depends primarily on how much time the transponder is active for during each orbit. OK, I've neglected the other power consumers on the bird such as the command system etc, but these are NOT affected by the behaviour of users. 2A) With a LINEAR transponder bird, running excess power on the uplink is a VERY serious issue. On a LINEAR transponder, the transponder's bandwidth (typically 100Khz) is 'shared' between the all of the users users in the transponder's 'passband'. The transponder literally takes a chunk of spectrum, amplifies and re-transmits it's entire contents on a different frequency. The total transponder power available is therefore SHARED between the users. If one user runs excessive power, the automatic gain control (AGC) in the satellite's receiver reduces the overall passband gain to compensate. This reduces the strength of the downlink signal for EVERYONE. It's therefore easy to realise that if everyone ran the MINIMUM uplink power, the satellite AGC would never be operating and therefore the DOWNLINK signals (for everyone) would be strongest. This is an important point. If the power level of even ONE user is greater than the AGC range can cope with (all too common I'm afraid), the transponder 'limits' (bottoms out), and in extreme cases goes non-linear with the excessively strong signals 'FM modulating' it. In short, it consumes a great deal of power while NOT providing any useful communications. 2B) Now for the serious stuff. Linear transponders operate in Class AB. The power consumption of the transponder is roughly proportional to the strength of ALL the signals in the passband. If one signal dominates, it will use most of the available downlink power, If it's strong enough to trigger the AGC into action, this lowers the downlink power available for EVERYONE ... INCLUDING the offending station. So, with a linear bird, the amount of power consumed from the battery is heavily dependent of the strength of the strongest signal! You may be interested to hear that 5W is enough power (to a modest yagi) to work CW on Amsat Oscar7. It was certainly also the case for the sadly now defunct Russian radiosport satellites. Satellite receivers are generally VERY sensitive indeed. The limiting factor with Linear birds is the IQ of the most thoughtless user. Many users are sensible, but it only takes ONE user running excessive power into a linear transponder bird to ruin the party for all. Since the power consumption of a linear satellite bears an almost linear relationship to the total power in the passband, the use of excessive power will rapidly run down the battery. This compromises the expected lifespan of the satellite by degrading the battery components. Satellites in Low Earth Orbit have brutal demands made of their batteries. 14 orbits a day is typical for these birds, so the battery suffers 14 charge-discharge cycles each day. Try doing that to a set of Ni-Cd batteries and see how long they last! Because the operating regime is so harsh, the batteries need to be over-rated , in order to provide an acceptable battery life expectancy. Battery Charge Regulators (BCR's) also help greatly to provide an acceptable working life for amateur satellites. ---------------------------------------------------------------------------------------------- Put simply, here are some basic satellite facts FM satellites PRO's. Can be used with cheap FM equipment. CONS Encourages bad operating practices thanks to FM Capture Effect. Only supports one QSO. Linear satellites PRO's. Can support many concurrent users AND modes. CON's. Easily 'clobbered' by FM type operating practices. ----------------------------------------------------------------------------------------------- So the operating practices for linear and FM satellites are very different. Unfortunately some users don't realise this. LA2QAA & GM1SXX. 22-11-07.

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Re: An OSCAR day
by Robert Turlington 22 Nov '07

22 Nov '07

Hi Dave I have obtained the Special callsign GB0OO Golf Bravo Zero Oscar One,so I will be active on the 12th Dec 07 all day and untill Sunday 16th there may be some activity from GB2NSC at the national space centre in Leicester England as well.Perhaps you can spread the word round because I come in range of east coast USA and Canada on AO51 and AO7.One thing, do you have or know if there are any photo's of Oscar-1 to put on my web site etc?Regards Robert G8ATE > Date: Wed, 21 Nov 2007 20:31:03 -0800> To: rob_g8ate(a)hotmail.com> From: dguimon1(a)san.rr.com> Subject: An OSCAR day> > Hi Robert,> > I would like for you to go with this thing from G-land, if you would > be willing....> > You've probably seen my messages, and I was just throwing out ideas, > to get some of the more experienced people "out of the woodwork".> > Many of them are a little annoyed with some of the practices of > AMSAT-NA...AMSAT-NA (with their East Coast biases) tend to ignore the > rest of the world, and with my many contacts on AO 10, 13 and 40 I > want to continue that relationship, and not just the 2-meter 2 user > satellites NA seems to promote...> > I was just throwing out ideas, and what ever info I receive (not on > amsat.org). I'll just pass on to you.> > Go ahead and go with it, please...With you at the helm, worldwide > response will be much better, in my opinion...> > I'll help with whatever you decide...> > Sincerely, Dave> > > > 73, Dave wb6llo(a)amsat.org> Disagree: I learn....> > Pulling for P3E... > _________________________________________________________________ The next generation of MSN Hotmail has arrived - Windows Live Hotmail http://www.newhotmail.co.uk

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DRSI PCPAT2 packet
by renauld halbardier 22 Nov '07

22 Nov '07

Hello to the group, I am looking for the DRSI iso-card manual (pcpat2)? Can anybody send me the doc by email ? 73 Tnx Renauld on4kvi

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AMSAT's Power Developments in the news
by Tom Clark, K3IO 22 Nov '07

22 Nov '07

Many of you have heard that Lew McFadin (W5DID), working with Steve Bible (N7HPR) and Steve's colleagues (especially Keith Curtis) at Microchip (the PIC people) have been working on a next generation power conditioning system. The basic idea is to have a power charge/discharge conditioner for each cell of the spacecraft's battery pack. This will allow the use of several different battery technologies (NiCd, NiMH, LiIon, etc) and also some of the new "super capacitors". Some of you who were at Dayton may have seen the breadboard mockup of system that Steve brought and Lew was showing. Lew was also showing some ~2000 Farad(!) 3 volt capacitors (some of us dubbed them "flux gate capacitors"). The SuperCap developments have been exploding of late. One immediate service is for regenerative braking in hybrid and electric vehicles, since the capacitors seem to be able to withstand a (virtually) infinite number of charge/discharge cycles, and then can "soak up" & discharge huge currents -- must faster than any chemical batteries can do. Batteries store watt-hours of energy, while capacitors handle large numbers of watts of power. One German light-rail system employs a total of 600 2600Farad capacitors for regenerative braking. Some US electric buses have capacitor banks with 144 18Farad capacitors that deliver 400 Amps at 360 Volts. Today I received the 11.15.07 edition of Electronic Design magazine, and there is an interesting technology review paper entitled "Get the Lowdown on UltraCapacitors" starting on page 45; the article is available online at http://electronicdesign.com/Articles/ArticleID/17465/17465.html. Starting on page 50 (the 3rd page of the online version) The AMSAT/MicroChip effort is described along with schematics (figure 6, also http://electronicdesign.com/files/29/17465/Figure_06.jpg). The closing paragraph (which doesn't mention the planed use of these concepts on Suitsat2) says: > Microchip worked with AMSAT-NA, the not-for-profit private organization that develops > amateur-radio satellites. AMSAT’s next big project, the Eagle satellite, is slated for > launch in March 2009. To make Eagle function for decades, it will have a power system > based on this work that combines solar panels, lithium-ion batteries, and ultracaps > in an integrated power system that will optimize the use of each of those components. Pretty good publicity! 73, Tom

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Re: ande-tlm decode
by Henk, PA3GUO 22 Nov '07

22 Nov '07

> Can any one tell me if their is any software to decode > ande-tlm that will run on win 95. Hi Ryan, Using Hyperterminal or ASatLogger (ASatLogger is my favorite) (see http://www.billdiaz.dynip.com) you will decode strings like this: ANDE-1]BEACON,qAo,DK3WN-1:T#002,003,010,009,004,003,01000000,000 That is already a really fantastic start if you receive them ! Now if you go to Mike's website you will find a decode SW (in fact it translates these values to onboard voltages etc.) http://www.dk3wn.info/sat/afu/sat_maa.shtml Let us know if you where able to go all the way there ! Succes and see you on ANDE ! Henk, PA3GUO http://www.qsl.net/pa3guo http://www.ande-deorbit.com

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There are takers in Hungary
by Bato, Andras 22 Nov '07

22 Nov '07

Hi Bob, HA2RD is well known there in the eastern states and Canada. I myself badly need the USA and Canada for my DXCC collection. So I am on duty as many times as possible. :) Please pray for B-mode every day. Mode A cant't be used at all! gl de ah6nn Andras

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Re: ande-tlm decode
by Bob Bruninga 22 Nov '07

22 Nov '07

> Is there any software to decode ande-tlm that > ... That I can use before ande deorbits. ANDE Telemetry is just standard APRS (KPC-3+) telemetry. And you can see anyone's telemetry from any TNC, including ANDE's live and decoded on the FINDU.COM web page. Use this special URL to see FINDU's display of ANDE telemetry: http://www.ew.usna.edu/~bruninga/andeTLM1.html This link above is on the ANDE-OPS page labeled "SIDE-A Telemetry": http://www.ew.usna.edu/~bruninga/ande-ops.html Your downlink packets can go directly to this site for immediate display along with everyone else's. Just connect your receiver to your PC and run any kind of APRS or ALOGGER I-Gate software and feed packets heard into the global APRS system. As you can see, right now the data is kinda sparse because not that many people are feeding live data. But hopefully that will improve. Bob, Wb4APR

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Re: Radio Shack Rotator Voltage
by Bob Bruninga 22 Nov '07

22 Nov '07

> I just picked up a used Radio Shack 15-1254 > Rotator only..no control box or specs... > Does anyone know what the drive voltage > requirements is on these 1 I use them in my $65 tracking system. See the schematic on my web page: http://www.ew.usna.edu/~bruninga/rotator1.html Its about 24-30 VAC with a capacitor to provide phase shift to give the correct direction. Bob, WB4APR

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ande-tlm decode
by ryan woods 21 Nov '07

21 Nov '07

Hello bob wb4apr and the group Can any one tell me if their is any software to decode ande-tlm that will run on win 95. That I can use before ande deorbits. tnx and 73 Ryan kd8atf P.S. I hope every body has a happy and safe tnxgiving ____________________________________________________________________________________ Be a better sports nut! Let your teams follow you with Yahoo Mobile. Try it now. http://mobile.yahoo.com/sports;_ylt=At9_qDKvtAbMuh1G1SQtBI7ntAcJ

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Re: Right Angle BNC adapters
by John Marranca, Jr 21 Nov '07

21 Nov '07

Good Afternoon, everyone. I just wanted to pass along a whole-hearted thank you to Dave WB6LLO for sending me a much better Right Angle adapter than what I had been using. And, as many members here had noted, the differences are astounding. (My old one indeed WAS one that utilized a spring rather than any real conductor.) Happy Thanksgiving everyone. This year as I am sitting down with my family in thanks of our many blessings, I will be sure to include all of my friends here at AMSAT and in the satellite community in my prayers. John KB2HSH -- _______________________________ John Marranca, Jr PBX Technician/Shop Steward CWA Local 1122 BN Systems, Inc Orchard Park, NY (716)972-2006

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